1.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
2
3******************
4Variables Glossary
5******************
6
7This chapter lists common variables used in the OpenEmbedded build
8system and gives an overview of their function and contents.
9
10:term:`A <ABIEXTENSION>` :term:`B` :term:`C <CACHE>`
11:term:`D` :term:`E <EFI_PROVIDER>` :term:`F <FEATURE_PACKAGES>`
12:term:`G <GCCPIE>` :term:`H <HOMEPAGE>` :term:`I <ICECC_DISABLED>`
13:term:`K <KARCH>` :term:`L <LABELS>` :term:`M <MACHINE>`
14:term:`N <NATIVELSBSTRING>` :term:`O <OBJCOPY>` :term:`P`
15:term:`R <RANLIB>` :term:`S` :term:`T`
16:term:`U <UBOOT_CONFIG>` :term:`V <VOLATILE_LOG_DIR>`
17:term:`W <WARN_QA>` :term:`X <XSERVER>`
18
19.. glossary::
20   :sorted:
21
22   :term:`ABIEXTENSION`
23      Extension to the Application Binary Interface (ABI) field of the GNU
24      canonical architecture name (e.g. "eabi").
25
26      ABI extensions are set in the machine include files. For example, the
27      ``meta/conf/machine/include/arm/arch-arm.inc`` file sets the
28      following extension::
29
30         ABIEXTENSION = "eabi"
31
32   :term:`ALLOW_EMPTY`
33      Specifies whether to produce an output package even if it is empty.
34      By default, BitBake does not produce empty packages. This default
35      behavior can cause issues when there is an
36      :term:`RDEPENDS` or some other hard runtime
37      requirement on the existence of the package.
38
39      Like all package-controlling variables, you must always use them in
40      conjunction with a package name override, as in::
41
42         ALLOW_EMPTY:${PN} = "1"
43         ALLOW_EMPTY:${PN}-dev = "1"
44         ALLOW_EMPTY:${PN}-staticdev = "1"
45
46   :term:`ALTERNATIVE`
47      Lists commands in a package that need an alternative binary naming
48      scheme. Sometimes the same command is provided in multiple packages.
49      When this occurs, the OpenEmbedded build system needs to use the
50      alternatives system to create a different binary naming scheme so the
51      commands can co-exist.
52
53      To use the variable, list out the package's commands that are also
54      provided by another package. For example, if the ``busybox`` package
55      has four such commands, you identify them as follows::
56
57         ALTERNATIVE:busybox = "sh sed test bracket"
58
59      For more information on the alternatives system, see the
60      ":ref:`ref-classes-update-alternatives`"
61      section.
62
63   :term:`ALTERNATIVE_LINK_NAME`
64      Used by the alternatives system to map duplicated commands to actual
65      locations. For example, if the ``bracket`` command provided by the
66      ``busybox`` package is duplicated through another package, you must
67      use the :term:`ALTERNATIVE_LINK_NAME` variable to specify the actual
68      location::
69
70         ALTERNATIVE_LINK_NAME[bracket] = "/usr/bin/["
71
72      In this example, the binary for the ``bracket`` command (i.e. ``[``)
73      from the ``busybox`` package resides in ``/usr/bin/``.
74
75      .. note::
76
77         If :term:`ALTERNATIVE_LINK_NAME` is not defined, it defaults to ``${bindir}/name``.
78
79      For more information on the alternatives system, see the
80      ":ref:`ref-classes-update-alternatives`"
81      section.
82
83   :term:`ALTERNATIVE_PRIORITY`
84      Used by the alternatives system to create default priorities for
85      duplicated commands. You can use the variable to create a single
86      default regardless of the command name or package, a default for
87      specific duplicated commands regardless of the package, or a default
88      for specific commands tied to particular packages. Here are the
89      available syntax forms::
90
91         ALTERNATIVE_PRIORITY = "priority"
92         ALTERNATIVE_PRIORITY[name] = "priority"
93         ALTERNATIVE_PRIORITY_pkg[name] = "priority"
94
95      For more information on the alternatives system, see the
96      ":ref:`ref-classes-update-alternatives`"
97      section.
98
99   :term:`ALTERNATIVE_TARGET`
100      Used by the alternatives system to create default link locations for
101      duplicated commands. You can use the variable to create a single
102      default location for all duplicated commands regardless of the
103      command name or package, a default for specific duplicated commands
104      regardless of the package, or a default for specific commands tied to
105      particular packages. Here are the available syntax forms::
106
107         ALTERNATIVE_TARGET = "target"
108         ALTERNATIVE_TARGET[name] = "target"
109         ALTERNATIVE_TARGET_pkg[name] = "target"
110
111      .. note::
112
113         If :term:`ALTERNATIVE_TARGET` is not defined, it inherits the value
114         from the :term:`ALTERNATIVE_LINK_NAME` variable.
115
116         If :term:`ALTERNATIVE_LINK_NAME` and :term:`ALTERNATIVE_TARGET` are the
117         same, the target for :term:`ALTERNATIVE_TARGET` has "``.{BPN}``"
118         appended to it.
119
120         Finally, if the file referenced has not been renamed, the
121         alternatives system will rename it to avoid the need to rename
122         alternative files in the :ref:`ref-tasks-install`
123         task while retaining support for the command if necessary.
124
125      For more information on the alternatives system, see the
126      ":ref:`ref-classes-update-alternatives`" section.
127
128   :term:`ANY_OF_DISTRO_FEATURES`
129      When inheriting the :ref:`ref-classes-features_check`
130      class, this variable identifies a list of distribution features where
131      at least one must be enabled in the current configuration in order
132      for the OpenEmbedded build system to build the recipe. In other words,
133      if none of the features listed in :term:`ANY_OF_DISTRO_FEATURES`
134      appear in :term:`DISTRO_FEATURES` within the current configuration, then
135      the recipe will be skipped, and if the build system attempts to build
136      the recipe then an error will be triggered.
137
138   :term:`APPEND`
139      An override list of append strings for each target specified with
140      :term:`LABELS`.
141
142      See the :ref:`ref-classes-grub-efi` class for more
143      information on how this variable is used.
144
145   :term:`AR`
146      The minimal command and arguments used to run ``ar``.
147
148   :term:`ARCHIVER_MODE`
149      When used with the :ref:`ref-classes-archiver` class,
150      determines the type of information used to create a released archive.
151      You can use this variable to create archives of patched source,
152      original source, configured source, and so forth by employing the
153      following variable flags (varflags)::
154
155         ARCHIVER_MODE[src] = "original"                   # Uses original (unpacked) source files.
156         ARCHIVER_MODE[src] = "patched"                    # Uses patched source files. This is the default.
157         ARCHIVER_MODE[src] = "configured"                 # Uses configured source files.
158         ARCHIVER_MODE[diff] = "1"                         # Uses patches between do_unpack and do_patch.
159         ARCHIVER_MODE[diff-exclude] ?= "file file ..."    # Lists files and directories to exclude from diff.
160         ARCHIVER_MODE[dumpdata] = "1"                     # Uses environment data.
161         ARCHIVER_MODE[recipe] = "1"                       # Uses recipe and include files.
162         ARCHIVER_MODE[srpm] = "1"                         # Uses RPM package files.
163
164      For information on how the variable works, see the
165      ``meta/classes/archiver.bbclass`` file in the :term:`Source Directory`.
166
167   :term:`AS`
168      Minimal command and arguments needed to run the assembler.
169
170   :term:`ASSUME_PROVIDED`
171      Lists recipe names (:term:`PN` values) BitBake does not
172      attempt to build. Instead, BitBake assumes these recipes have already
173      been built.
174
175      In OpenEmbedded-Core, :term:`ASSUME_PROVIDED` mostly specifies native
176      tools that should not be built. An example is ``git-native``, which
177      when specified, allows for the Git binary from the host to be used
178      rather than building ``git-native``.
179
180   :term:`ASSUME_SHLIBS`
181      Provides additional ``shlibs`` provider mapping information, which
182      adds to or overwrites the information provided automatically by the
183      system. Separate multiple entries using spaces.
184
185      As an example, use the following form to add an ``shlib`` provider of
186      shlibname in packagename with the optional version::
187
188         shlibname:packagename[_version]
189
190      Here is an example that adds a shared library named ``libEGL.so.1``
191      as being provided by the ``libegl-implementation`` package::
192
193         ASSUME_SHLIBS = "libEGL.so.1:libegl-implementation"
194
195   :term:`AUTO_LIBNAME_PKGS`
196      When the :ref:`ref-classes-debian` class is inherited,
197      which is the default behavior, :term:`AUTO_LIBNAME_PKGS` specifies which
198      packages should be checked for libraries and renamed according to
199      Debian library package naming.
200
201      The default value is "${PACKAGES}", which causes the
202      :ref:`ref-classes-debian` class to act on all packages that are
203      explicitly generated by the recipe.
204
205   :term:`AUTOREV`
206      When :term:`SRCREV` is set to the value of this variable, it specifies to
207      use the latest source revision in the repository. Here is an example::
208
209         SRCREV = "${AUTOREV}"
210
211      If you use the previous statement to retrieve the latest version of
212      software, you need to be sure :term:`PV` contains
213      ``${``\ :term:`SRCPV`\ ``}``. For example, suppose you have a kernel
214      recipe that inherits the :ref:`ref-classes-kernel` class and you
215      use the previous statement. In this example, ``${SRCPV}`` does not
216      automatically get into :term:`PV`. Consequently, you need to change
217      :term:`PV` in your recipe so that it does contain ``${SRCPV}``.
218
219      For more information see the
220      ":ref:`dev-manual/packages:automatically incrementing a package version number`"
221      section in the Yocto Project Development Tasks Manual.
222
223   :term:`AUTO_SYSLINUXMENU`
224      Enables creating an automatic menu for the syslinux bootloader. You
225      must set this variable in your recipe. The
226      :ref:`ref-classes-syslinux` class checks this variable.
227
228   :term:`AVAILTUNES`
229      The list of defined CPU and Application Binary Interface (ABI)
230      tunings (i.e. "tunes") available for use by the OpenEmbedded build
231      system.
232
233      The list simply presents the tunes that are available. Not all tunes
234      may be compatible with a particular machine configuration, or with
235      each other in a
236      :ref:`Multilib <dev-manual/libraries:combining multiple versions of library files into one image>`
237      configuration.
238
239      To add a tune to the list, be sure to append it with spaces using the
240      "+=" BitBake operator. Do not simply replace the list by using the
241      "=" operator. See the
242      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:basic syntax`" section in the BitBake
243      User Manual for more information.
244
245   :term:`AZ_SAS`
246      Azure Storage Shared Access Signature, when using the
247      :ref:`Azure Storage fetcher (az://) <bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
248      This variable can be defined to be used by the fetcher to authenticate
249      and gain access to non-public artifacts::
250
251         AZ_SAS = ""se=2021-01-01&sp=r&sv=2018-11-09&sr=c&skoid=<skoid>&sig=<signature>""
252
253      For more information see Microsoft's Azure Storage documentation at
254      https://docs.microsoft.com/en-us/azure/storage/common/storage-sas-overview
255
256   :term:`B`
257      The directory within the :term:`Build Directory` in which the
258      OpenEmbedded build system places generated objects during a recipe's
259      build process. By default, this directory is the same as the
260      :term:`S` directory, which is defined as::
261
262         S = "${WORKDIR}/${BP}"
263
264      You can separate the (:term:`S`) directory and the directory pointed to
265      by the :term:`B` variable. Most Autotools-based recipes support
266      separating these directories. The build system defaults to using
267      separate directories for ``gcc`` and some kernel recipes.
268
269   :term:`BAD_RECOMMENDATIONS`
270      Lists "recommended-only" packages to not install. Recommended-only
271      packages are packages installed only through the
272      :term:`RRECOMMENDS` variable. You can prevent any
273      of these "recommended" packages from being installed by listing them
274      with the :term:`BAD_RECOMMENDATIONS` variable::
275
276         BAD_RECOMMENDATIONS = "package_name package_name package_name ..."
277
278      You can set this variable globally in your ``local.conf`` file or you
279      can attach it to a specific image recipe by using the recipe name
280      override::
281
282         BAD_RECOMMENDATIONS:pn-target_image = "package_name"
283
284      It is important to realize that if you choose to not install packages
285      using this variable and some other packages are dependent on them
286      (i.e. listed in a recipe's :term:`RDEPENDS`
287      variable), the OpenEmbedded build system ignores your request and
288      will install the packages to avoid dependency errors.
289
290      This variable is supported only when using the IPK and RPM
291      packaging backends. DEB is not supported.
292
293      See the :term:`NO_RECOMMENDATIONS` and the
294      :term:`PACKAGE_EXCLUDE` variables for related
295      information.
296
297   :term:`BASE_LIB`
298      The library directory name for the CPU or Application Binary
299      Interface (ABI) tune. The :term:`BASE_LIB` applies only in the Multilib
300      context. See the ":ref:`dev-manual/libraries:combining multiple versions of library files into one image`"
301      section in the Yocto Project Development Tasks Manual for information
302      on Multilib.
303
304      The :term:`BASE_LIB` variable is defined in the machine include files in
305      the :term:`Source Directory`. If Multilib is not
306      being used, the value defaults to "lib".
307
308   :term:`BASE_WORKDIR`
309      Points to the base of the work directory for all recipes. The default
310      value is "${TMPDIR}/work".
311
312   :term:`BB_ALLOWED_NETWORKS`
313      Specifies a space-delimited list of hosts that the fetcher is allowed
314      to use to obtain the required source code. Here are
315      considerations surrounding this variable:
316
317      -  This host list is only used if :term:`BB_NO_NETWORK` is either not set
318         or set to "0".
319
320      -  There is limited support for wildcard matching against the beginning of
321         host names. For example, the following setting matches
322         ``git.gnu.org``, ``ftp.gnu.org``, and ``foo.git.gnu.org``::
323
324            BB_ALLOWED_NETWORKS = "*.gnu.org"
325
326         .. note::
327
328            The use of the "``*``" character only works at the beginning of
329            a host name and it must be isolated from the remainder of the
330            host name. You cannot use the wildcard character in any other
331            location of the name or combined with the front part of the
332            name.
333
334            For example, ``*.foo.bar`` is supported, while ``*aa.foo.bar``
335            is not.
336
337      -  Mirrors not in the host list are skipped and logged in debug.
338
339      -  Attempts to access networks not in the host list cause a failure.
340
341      Using :term:`BB_ALLOWED_NETWORKS` in conjunction with
342      :term:`PREMIRRORS` is very useful. Adding the host
343      you want to use to :term:`PREMIRRORS` results in the source code being
344      fetched from an allowed location and avoids raising an error when a
345      host that is not allowed is in a :term:`SRC_URI`
346      statement. This is because the fetcher does not attempt to use the
347      host listed in :term:`SRC_URI` after a successful fetch from the
348      :term:`PREMIRRORS` occurs.
349
350   :term:`BB_BASEHASH_IGNORE_VARS`
351      See :term:`bitbake:BB_BASEHASH_IGNORE_VARS` in the BitBake manual.
352
353   :term:`BB_CACHEDIR`
354      See :term:`bitbake:BB_CACHEDIR` in the BitBake manual.
355
356   :term:`BB_CHECK_SSL_CERTS`
357      See :term:`bitbake:BB_CHECK_SSL_CERTS` in the BitBake manual.
358
359   :term:`BB_CONSOLELOG`
360      See :term:`bitbake:BB_CONSOLELOG` in the BitBake manual.
361
362   :term:`BB_CURRENTTASK`
363      See :term:`bitbake:BB_CURRENTTASK` in the BitBake manual.
364
365   :term:`BB_DANGLINGAPPENDS_WARNONLY`
366      Defines how BitBake handles situations where an append file
367      (``.bbappend``) has no corresponding recipe file (``.bb``). This
368      condition often occurs when layers get out of sync (e.g. ``oe-core``
369      bumps a recipe version and the old recipe no longer exists and the
370      other layer has not been updated to the new version of the recipe
371      yet).
372
373      The default fatal behavior is safest because it is the sane reaction
374      given something is out of sync. It is important to realize when your
375      changes are no longer being applied.
376
377      You can change the default behavior by setting this variable to "1",
378      "yes", or "true" in your ``local.conf`` file, which is located in the
379      :term:`Build Directory`: Here is an example::
380
381         BB_DANGLINGAPPENDS_WARNONLY = "1"
382
383   :term:`BB_DEFAULT_TASK`
384      See :term:`bitbake:BB_DEFAULT_TASK` in the BitBake manual.
385
386   :term:`BB_DEFAULT_UMASK`
387      See :term:`bitbake:BB_DEFAULT_UMASK` in the BitBake manual.
388
389   :term:`BB_DISKMON_DIRS`
390      Monitors disk space and available inodes during the build and allows
391      you to control the build based on these parameters.
392
393      Disk space monitoring is disabled by default. To enable monitoring,
394      add the :term:`BB_DISKMON_DIRS` variable to your ``conf/local.conf`` file
395      found in the :term:`Build Directory`. Use the
396      following form:
397
398      .. code-block:: none
399
400         BB_DISKMON_DIRS = "action,dir,threshold [...]"
401
402         where:
403
404            action is:
405               ABORT:     Immediately stop the build when
406                          a threshold is broken.
407               STOPTASKS: Stop the build after the currently
408                          executing tasks have finished when
409                          a threshold is broken.
410               WARN:      Issue a warning but continue the
411                          build when a threshold is broken.
412                          Subsequent warnings are issued as
413                          defined by the BB_DISKMON_WARNINTERVAL
414                          variable, which must be defined in
415                          the conf/local.conf file.
416
417            dir is:
418               Any directory you choose. You can specify one or
419               more directories to monitor by separating the
420               groupings with a space.  If two directories are
421               on the same device, only the first directory
422               is monitored.
423
424            threshold is:
425               Either the minimum available disk space,
426               the minimum number of free inodes, or
427               both.  You must specify at least one.  To
428               omit one or the other, simply omit the value.
429               Specify the threshold using G, M, K for Gbytes,
430               Mbytes, and Kbytes, respectively. If you do
431               not specify G, M, or K, Kbytes is assumed by
432               default.  Do not use GB, MB, or KB.
433
434      Here are some examples::
435
436         BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K"
437         BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G"
438         BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
439
440      The first example works only if you also provide the
441      :term:`BB_DISKMON_WARNINTERVAL`
442      variable in the ``conf/local.conf``. This example causes the build
443      system to immediately stop when either the disk space in
444      ``${TMPDIR}`` drops below 1 Gbyte or the available free inodes drops
445      below 100 Kbytes. Because two directories are provided with the
446      variable, the build system also issue a warning when the disk space
447      in the ``${SSTATE_DIR}`` directory drops below 1 Gbyte or the number
448      of free inodes drops below 100 Kbytes. Subsequent warnings are issued
449      during intervals as defined by the :term:`BB_DISKMON_WARNINTERVAL`
450      variable.
451
452      The second example stops the build after all currently executing
453      tasks complete when the minimum disk space in the ``${TMPDIR}``
454      directory drops below 1 Gbyte. No disk monitoring occurs for the free
455      inodes in this case.
456
457      The final example immediately stops the build when the number of
458      free inodes in the ``${TMPDIR}`` directory drops below 100 Kbytes. No
459      disk space monitoring for the directory itself occurs in this case.
460
461   :term:`BB_DISKMON_WARNINTERVAL`
462      Defines the disk space and free inode warning intervals. To set these
463      intervals, define the variable in your ``conf/local.conf`` file in
464      the :term:`Build Directory`.
465
466      If you are going to use the :term:`BB_DISKMON_WARNINTERVAL` variable, you
467      must also use the :term:`BB_DISKMON_DIRS`
468      variable and define its action as "WARN". During the build,
469      subsequent warnings are issued each time disk space or number of free
470      inodes further reduces by the respective interval.
471
472      If you do not provide a :term:`BB_DISKMON_WARNINTERVAL` variable and you
473      do use :term:`BB_DISKMON_DIRS` with the "WARN" action, the disk
474      monitoring interval defaults to the following::
475
476         BB_DISKMON_WARNINTERVAL = "50M,5K"
477
478      When specifying the variable in your configuration file, use the
479      following form:
480
481      .. code-block:: none
482
483         BB_DISKMON_WARNINTERVAL = "disk_space_interval,disk_inode_interval"
484
485         where:
486
487            disk_space_interval is:
488               An interval of memory expressed in either
489               G, M, or K for Gbytes, Mbytes, or Kbytes,
490               respectively. You cannot use GB, MB, or KB.
491
492            disk_inode_interval is:
493               An interval of free inodes expressed in either
494               G, M, or K for Gbytes, Mbytes, or Kbytes,
495               respectively. You cannot use GB, MB, or KB.
496
497      Here is an example::
498
499         BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K"
500         BB_DISKMON_WARNINTERVAL = "50M,5K"
501
502      These variables cause the
503      OpenEmbedded build system to issue subsequent warnings each time the
504      available disk space further reduces by 50 Mbytes or the number of
505      free inodes further reduces by 5 Kbytes in the ``${SSTATE_DIR}``
506      directory. Subsequent warnings based on the interval occur each time
507      a respective interval is reached beyond the initial warning (i.e. 1
508      Gbytes and 100 Kbytes).
509
510   :term:`BB_ENV_PASSTHROUGH`
511      See :term:`bitbake:BB_ENV_PASSTHROUGH` in the BitBake manual.
512
513   :term:`BB_ENV_PASSTHROUGH_ADDITIONS`
514      See :term:`bitbake:BB_ENV_PASSTHROUGH_ADDITIONS` in the BitBake manual.
515
516   :term:`BB_FETCH_PREMIRRORONLY`
517      See :term:`bitbake:BB_FETCH_PREMIRRORONLY` in the BitBake manual.
518
519   :term:`BB_FILENAME`
520      See :term:`bitbake:BB_FILENAME` in the BitBake manual.
521
522   :term:`BB_GENERATE_MIRROR_TARBALLS`
523      Causes tarballs of the source control repositories (e.g. Git
524      repositories), including metadata, to be placed in the
525      :term:`DL_DIR` directory.
526
527      For performance reasons, creating and placing tarballs of these
528      repositories is not the default action by the OpenEmbedded build
529      system::
530
531         BB_GENERATE_MIRROR_TARBALLS = "1"
532
533      Set this variable in your
534      ``local.conf`` file in the :term:`Build Directory`.
535
536      Once you have the tarballs containing your source files, you can
537      clean up your :term:`DL_DIR` directory by deleting any Git or other
538      source control work directories.
539
540   :term:`BB_GENERATE_SHALLOW_TARBALLS`
541      See :term:`bitbake:BB_GENERATE_SHALLOW_TARBALLS` in the BitBake manual.
542
543   :term:`BB_GIT_SHALLOW`
544      See :term:`bitbake:BB_GIT_SHALLOW` in the BitBake manual.
545
546   :term:`BB_GIT_SHALLOW_DEPTH`
547      See :term:`bitbake:BB_GIT_SHALLOW_DEPTH` in the BitBake manual.
548
549   :term:`BB_HASHCHECK_FUNCTION`
550      See :term:`bitbake:BB_HASHCHECK_FUNCTION` in the BitBake manual.
551
552   :term:`BB_HASHCONFIG_IGNORE_VARS`
553      See :term:`bitbake:BB_HASHCONFIG_IGNORE_VARS` in the BitBake manual.
554
555   :term:`BB_HASHSERVE`
556      See :term:`bitbake:BB_HASHSERVE` in the BitBake manual.
557
558   :term:`BB_HASHSERVE_UPSTREAM`
559      See :term:`bitbake:BB_HASHSERVE_UPSTREAM` in the BitBake manual.
560
561   :term:`BB_INVALIDCONF`
562      See :term:`bitbake:BB_INVALIDCONF` in the BitBake manual.
563
564   :term:`BB_LOGCONFIG`
565      See :term:`bitbake:BB_LOGCONFIG` in the BitBake manual.
566
567   :term:`BB_LOGFMT`
568      See :term:`bitbake:BB_LOGFMT` in the BitBake manual.
569
570   :term:`BB_MULTI_PROVIDER_ALLOWED`
571      See :term:`bitbake:BB_MULTI_PROVIDER_ALLOWED` in the BitBake manual.
572
573   :term:`BB_NICE_LEVEL`
574      See :term:`bitbake:BB_NICE_LEVEL` in the BitBake manual.
575
576   :term:`BB_NO_NETWORK`
577      See :term:`bitbake:BB_NO_NETWORK` in the BitBake manual.
578
579   :term:`BB_NUMBER_PARSE_THREADS`
580      See :term:`bitbake:BB_NUMBER_PARSE_THREADS` in the BitBake manual.
581
582   :term:`BB_NUMBER_THREADS`
583      The maximum number of tasks BitBake should run in parallel at any one
584      time. The OpenEmbedded build system automatically configures this
585      variable to be equal to the number of cores on the build system. For
586      example, a system with a dual core processor that also uses
587      hyper-threading causes the :term:`BB_NUMBER_THREADS` variable to default
588      to "4".
589
590      For single socket systems (i.e. one CPU), you should not have to
591      override this variable to gain optimal parallelism during builds.
592      However, if you have very large systems that employ multiple physical
593      CPUs, you might want to make sure the :term:`BB_NUMBER_THREADS` variable
594      is not set higher than "20".
595
596      For more information on speeding up builds, see the
597      ":ref:`dev-manual/speeding-up-build:speeding up a build`"
598      section in the Yocto Project Development Tasks Manual.
599
600      On the other hand, if your goal is to limit the amount of system
601      resources consumed by BitBake tasks, setting :term:`BB_NUMBER_THREADS`
602      to a number lower than the number of CPU threads in your machine
603      won't be sufficient. That's because each package will still be built
604      and installed through a number of parallel jobs specified by the
605      :term:`PARALLEL_MAKE` variable, which is by default the number of CPU
606      threads in your system, and is not impacted by the
607      :term:`BB_NUMBER_THREADS` value.
608
609      So, if you set :term:`BB_NUMBER_THREADS` to "1" but don't set
610      :term:`PARALLEL_MAKE`, most of your system resources will be consumed
611      anyway.
612
613      Therefore, if you intend to reduce the load of your build system by
614      setting :term:`BB_NUMBER_THREADS` to a relatively low value compared
615      to the number of CPU threads on your system, you should also set
616      :term:`PARALLEL_MAKE` to a similarly low value.
617
618      An alternative to using :term:`BB_NUMBER_THREADS` to keep the usage
619      of build system resources under control is to use the smarter
620      :term:`BB_PRESSURE_MAX_CPU`, :term:`BB_PRESSURE_MAX_IO` or
621      :term:`BB_PRESSURE_MAX_MEMORY` controls. They will prevent BitBake
622      from starting new tasks as long as thresholds are exceeded. Anyway,
623      as with :term:`BB_NUMBER_THREADS`, such controls won't prevent the
624      tasks already being run from using all CPU threads on the system
625      if :term:`PARALLEL_MAKE` is not set to a low value.
626
627   :term:`BB_ORIGENV`
628      See :term:`bitbake:BB_ORIGENV` in the BitBake manual.
629
630   :term:`BB_PRESERVE_ENV`
631      See :term:`bitbake:BB_PRESERVE_ENV` in the BitBake manual.
632
633   :term:`BB_PRESSURE_MAX_CPU`
634      See :term:`bitbake:BB_PRESSURE_MAX_CPU` in the BitBake manual.
635
636   :term:`BB_PRESSURE_MAX_IO`
637      See :term:`bitbake:BB_PRESSURE_MAX_IO` in the BitBake manual.
638
639   :term:`BB_PRESSURE_MAX_MEMORY`
640      See :term:`bitbake:BB_PRESSURE_MAX_MEMORY` in the BitBake manual.
641
642   :term:`BB_RUNFMT`
643      See :term:`bitbake:BB_RUNFMT` in the BitBake manual.
644
645   :term:`BB_RUNTASK`
646      See :term:`bitbake:BB_RUNTASK` in the BitBake manual.
647
648   :term:`BB_SCHEDULER`
649      See :term:`bitbake:BB_SCHEDULER` in the BitBake manual.
650
651   :term:`BB_SCHEDULERS`
652      See :term:`bitbake:BB_SCHEDULERS` in the BitBake manual.
653
654   :term:`BB_SERVER_TIMEOUT`
655      Specifies the time (in seconds) after which to unload the BitBake
656      server due to inactivity. Set :term:`BB_SERVER_TIMEOUT` to determine how
657      long the BitBake server stays resident between invocations.
658
659      For example, the following statement in your ``local.conf`` file
660      instructs the server to be unloaded after 20 seconds of inactivity::
661
662         BB_SERVER_TIMEOUT = "20"
663
664      If you want the server to never be unloaded,
665      set :term:`BB_SERVER_TIMEOUT` to "-1".
666
667   :term:`BB_SETSCENE_DEPVALID`
668      See :term:`bitbake:BB_SETSCENE_DEPVALID` in the BitBake manual.
669
670   :term:`BB_SIGNATURE_EXCLUDE_FLAGS`
671      See :term:`bitbake:BB_SIGNATURE_EXCLUDE_FLAGS` in the BitBake manual.
672
673   :term:`BB_SIGNATURE_HANDLER`
674      See :term:`bitbake:BB_SIGNATURE_HANDLER` in the BitBake manual.
675
676   :term:`BB_SRCREV_POLICY`
677      See :term:`bitbake:BB_SRCREV_POLICY` in the BitBake manual.
678
679   :term:`BB_STRICT_CHECKSUM`
680      See :term:`bitbake:BB_STRICT_CHECKSUM` in the BitBake manual.
681
682   :term:`BB_TASK_IONICE_LEVEL`
683      See :term:`bitbake:BB_TASK_IONICE_LEVEL` in the BitBake manual.
684
685   :term:`BB_TASK_NICE_LEVEL`
686      See :term:`bitbake:BB_TASK_NICE_LEVEL` in the BitBake manual.
687
688   :term:`BB_TASKHASH`
689      See :term:`bitbake:BB_TASKHASH` in the BitBake manual.
690
691   :term:`BB_VERBOSE_LOGS`
692      See :term:`bitbake:BB_VERBOSE_LOGS` in the BitBake manual.
693
694   :term:`BB_WORKERCONTEXT`
695      See :term:`bitbake:BB_WORKERCONTEXT` in the BitBake manual.
696
697   :term:`BBCLASSEXTEND`
698      Allows you to extend a recipe so that it builds variants of the
699      software. There are common variants for recipes as "natives" like
700      ``quilt-native``, which is a copy of Quilt built to run on the build
701      system; "crosses" such as ``gcc-cross``, which is a compiler built to
702      run on the build machine but produces binaries that run on the target
703      :term:`MACHINE`; ":ref:`ref-classes-nativesdk`", which
704      targets the SDK machine instead of :term:`MACHINE`; and "mulitlibs" in
705      the form "``multilib:``\ multilib_name".
706
707      To build a different variant of the recipe with a minimal amount of
708      code, it usually is as simple as adding the following to your recipe::
709
710         BBCLASSEXTEND =+ "native nativesdk"
711         BBCLASSEXTEND =+ "multilib:multilib_name"
712
713      .. note::
714
715         Internally, the :term:`BBCLASSEXTEND` mechanism generates recipe
716         variants by rewriting variable values and applying overrides such
717         as ``:class-native``. For example, to generate a native version of
718         a recipe, a :term:`DEPENDS` on "foo" is rewritten
719         to a :term:`DEPENDS` on "foo-native".
720
721         Even when using :term:`BBCLASSEXTEND`, the recipe is only parsed once.
722         Parsing once adds some limitations. For example, it is not
723         possible to include a different file depending on the variant,
724         since ``include`` statements are processed when the recipe is
725         parsed.
726
727   :term:`BBDEBUG`
728      See :term:`bitbake:BBDEBUG` in the BitBake manual.
729
730   :term:`BBFILE_COLLECTIONS`
731      Lists the names of configured layers. These names are used to find
732      the other ``BBFILE_*`` variables. Typically, each layer will append
733      its name to this variable in its ``conf/layer.conf`` file.
734
735   :term:`BBFILE_PATTERN`
736      Variable that expands to match files from
737      :term:`BBFILES` in a particular layer. This variable
738      is used in the ``conf/layer.conf`` file and must be suffixed with the
739      name of the specific layer (e.g. ``BBFILE_PATTERN_emenlow``).
740
741   :term:`BBFILE_PRIORITY`
742      Assigns the priority for recipe files in each layer.
743
744      This variable is useful in situations where the same recipe appears
745      in more than one layer. Setting this variable allows you to
746      prioritize a layer against other layers that contain the same recipe
747      --- effectively letting you control the precedence for the multiple
748      layers. The precedence established through this variable stands
749      regardless of a recipe's version (:term:`PV` variable). For
750      example, a layer that has a recipe with a higher :term:`PV` value but for
751      which the :term:`BBFILE_PRIORITY` is set to have a lower precedence still
752      has a lower precedence.
753
754      A larger value for the :term:`BBFILE_PRIORITY` variable results in a
755      higher precedence. For example, the value 6 has a higher precedence
756      than the value 5. If not specified, the :term:`BBFILE_PRIORITY` variable
757      is set based on layer dependencies (see the :term:`LAYERDEPENDS` variable
758      for more information. The default priority, if unspecified for a
759      layer with no dependencies, is the lowest defined priority + 1 (or 1
760      if no priorities are defined).
761
762      .. tip::
763
764         You can use the command ``bitbake-layers show-layers``
765         to list all configured layers along with their priorities.
766
767   :term:`BBFILES`
768      A space-separated list of recipe files BitBake uses to build
769      software.
770
771      When specifying recipe files, you can pattern match using Python's
772      `glob <https://docs.python.org/3/library/glob.html>`__ syntax.
773      For details on the syntax, see the documentation by following the
774      previous link.
775
776   :term:`BBFILES_DYNAMIC`
777      Activates content when identified layers are present. You identify
778      the layers by the collections that the layers define.
779
780      Use the :term:`BBFILES_DYNAMIC` variable to avoid ``.bbappend`` files
781      whose corresponding ``.bb`` file is in a layer that attempts to
782      modify other layers through ``.bbappend`` but does not want to
783      introduce a hard dependency on those other layers.
784
785      Use the following form for :term:`BBFILES_DYNAMIC`:
786      ``collection_name:filename_pattern``.
787
788      The following example identifies two collection names and two
789      filename patterns::
790
791         BBFILES_DYNAMIC += " \
792            clang-layer:${LAYERDIR}/bbappends/meta-clang/*/*/*.bbappend \
793            core:${LAYERDIR}/bbappends/openembedded-core/meta/*/*/*.bbappend \
794            "
795
796      This next example shows an error message that occurs because invalid
797      entries are found, which cause parsing to fail:
798
799      .. code-block:: none
800
801         ERROR: BBFILES_DYNAMIC entries must be of the form <collection name>:<filename pattern>, not:
802             /work/my-layer/bbappends/meta-security-isafw/*/*/*.bbappend
803             /work/my-layer/bbappends/openembedded-core/meta/*/*/*.bbappend
804
805   :term:`BBINCLUDED`
806      See :term:`bitbake:BBINCLUDED` in the BitBake manual.
807
808   :term:`BBINCLUDELOGS`
809      Variable that controls how BitBake displays logs on build failure.
810
811   :term:`BBINCLUDELOGS_LINES`
812      If :term:`BBINCLUDELOGS` is set, specifies the
813      maximum number of lines from the task log file to print when
814      reporting a failed task. If you do not set :term:`BBINCLUDELOGS_LINES`,
815      the entire log is printed.
816
817   :term:`BBLAYERS`
818      Lists the layers to enable during the build. This variable is defined
819      in the ``bblayers.conf`` configuration file in the :term:`Build Directory`.
820      Here is an example::
821
822         BBLAYERS = " \
823             /home/scottrif/poky/meta \
824             /home/scottrif/poky/meta-poky \
825             /home/scottrif/poky/meta-yocto-bsp \
826             /home/scottrif/poky/meta-mykernel \
827             "
828
829      This example enables four layers, one of which is a custom,
830      user-defined layer named ``meta-mykernel``.
831
832   :term:`BBLAYERS_FETCH_DIR`
833      See :term:`bitbake:BBLAYERS_FETCH_DIR` in the BitBake manual.
834
835   :term:`BBMASK`
836      Prevents BitBake from processing recipes and recipe append files.
837
838      You can use the :term:`BBMASK` variable to "hide" these ``.bb`` and
839      ``.bbappend`` files. BitBake ignores any recipe or recipe append
840      files that match any of the expressions. It is as if BitBake does not
841      see them at all. Consequently, matching files are not parsed or
842      otherwise used by BitBake.
843
844      The values you provide are passed to Python's regular expression
845      compiler. Consequently, the syntax follows Python's Regular
846      Expression (re) syntax. The expressions are compared against the full
847      paths to the files. For complete syntax information, see Python's
848      documentation at https://docs.python.org/3/library/re.html#regular-expression-syntax.
849
850      The following example uses a complete regular expression to tell
851      BitBake to ignore all recipe and recipe append files in the
852      ``meta-ti/recipes-misc/`` directory::
853
854         BBMASK = "meta-ti/recipes-misc/"
855
856      If you want to mask out multiple directories or recipes, you can
857      specify multiple regular expression fragments. This next example
858      masks out multiple directories and individual recipes::
859
860         BBMASK += "/meta-ti/recipes-misc/ meta-ti/recipes-ti/packagegroup/"
861         BBMASK += "/meta-oe/recipes-support/"
862         BBMASK += "/meta-foo/.*/openldap"
863         BBMASK += "opencv.*\.bbappend"
864         BBMASK += "lzma"
865
866      .. note::
867
868         When specifying a directory name, use the trailing slash character
869         to ensure you match just that directory name.
870
871   :term:`BBMULTICONFIG`
872      Specifies each additional separate configuration when you are
873      building targets with multiple configurations. Use this variable in
874      your ``conf/local.conf`` configuration file. Specify a
875      multiconfigname for each configuration file you are using. For
876      example, the following line specifies three configuration files::
877
878         BBMULTICONFIG = "configA configB configC"
879
880      Each configuration file you use must reside in a ``multiconfig``
881      subdirectory of a configuration directory within a layer, or
882      within the :term:`Build Directory` (e.g.
883      ``build_directory/conf/multiconfig/configA.conf`` or
884      ``mylayer/conf/multiconfig/configB.conf``).
885
886      For information on how to use :term:`BBMULTICONFIG` in an environment
887      that supports building targets with multiple configurations, see the
888      ":ref:`dev-manual/building:building images for multiple targets using multiple configurations`"
889      section in the Yocto Project Development Tasks Manual.
890
891   :term:`BBPATH`
892      See :term:`bitbake:BBPATH` in the BitBake manual.
893
894   :term:`BBSERVER`
895      If defined in the BitBake environment, :term:`BBSERVER` points to the
896      BitBake remote server.
897
898      Use the following format to export the variable to the BitBake
899      environment::
900
901         export BBSERVER=localhost:$port
902
903      By default, :term:`BBSERVER` also appears in :term:`BB_BASEHASH_IGNORE_VARS`.
904      Consequently, :term:`BBSERVER` is excluded from checksum and dependency
905      data.
906
907   :term:`BBTARGETS`
908      See :term:`bitbake:BBTARGETS` in the BitBake manual.
909
910   :term:`BINCONFIG`
911      When inheriting the :ref:`ref-classes-binconfig-disabled` class, this
912      variable specifies binary configuration scripts to disable in favor of
913      using ``pkg-config`` to query the information. The
914      :ref:`ref-classes-binconfig-disabled` class will modify the specified
915      scripts to return an error so that calls to them can be easily found
916      and replaced.
917
918      To add multiple scripts, separate them by spaces. Here is an example
919      from the ``libpng`` recipe::
920
921         BINCONFIG = "${bindir}/libpng-config ${bindir}/libpng16-config"
922
923   :term:`BINCONFIG_GLOB`
924      When inheriting the :ref:`ref-classes-binconfig` class,
925      this variable specifies a wildcard for configuration scripts that
926      need editing. The scripts are edited to correct any paths that have
927      been set up during compilation so that they are correct for use when
928      installed into the sysroot and called by the build processes of other
929      recipes.
930
931      .. note::
932
933         The :term:`BINCONFIG_GLOB` variable uses
934         `shell globbing <https://tldp.org/LDP/abs/html/globbingref.html>`__,
935         which is recognition and expansion of wildcards during pattern
936         matching. Shell globbing is very similar to
937         `fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__
938         and `glob <https://docs.python.org/3/library/glob.html>`__.
939
940      For more information on how this variable works, see
941      ``meta/classes-recipe/binconfig.bbclass`` in the :term:`Source Directory`.
942      You can also find general
943      information on the class in the
944      ":ref:`ref-classes-binconfig`" section.
945
946   :term:`BITBAKE_UI`
947      See :term:`bitbake:BITBAKE_UI` in the BitBake manual.
948
949   :term:`BP`
950      The base recipe name and version but without any special recipe name
951      suffix (i.e. ``-native``, ``lib64-``, and so forth). :term:`BP` is
952      comprised of the following::
953
954         ${BPN}-${PV}
955
956   :term:`BPN`
957      This variable is a version of the :term:`PN` variable with
958      common prefixes and suffixes removed, such as ``nativesdk-``,
959      ``-cross``, ``-native``, and multilib's ``lib64-`` and ``lib32-``.
960      The exact lists of prefixes and suffixes removed are specified by the
961      :term:`MLPREFIX` and
962      :term:`SPECIAL_PKGSUFFIX` variables,
963      respectively.
964
965   :term:`BUGTRACKER`
966      Specifies a URL for an upstream bug tracking website for a recipe.
967      The OpenEmbedded build system does not use this variable. Rather, the
968      variable is a useful pointer in case a bug in the software being
969      built needs to be manually reported.
970
971   :term:`BUILD_ARCH`
972      Specifies the architecture of the build host (e.g. ``i686``). The
973      OpenEmbedded build system sets the value of :term:`BUILD_ARCH` from the
974      machine name reported by the ``uname`` command.
975
976   :term:`BUILD_AS_ARCH`
977      Specifies the architecture-specific assembler flags for the build
978      host. By default, the value of :term:`BUILD_AS_ARCH` is empty.
979
980   :term:`BUILD_CC_ARCH`
981      Specifies the architecture-specific C compiler flags for the build
982      host. By default, the value of :term:`BUILD_CC_ARCH` is empty.
983
984   :term:`BUILD_CCLD`
985      Specifies the linker command to be used for the build host when the C
986      compiler is being used as the linker. By default, :term:`BUILD_CCLD`
987      points to GCC and passes as arguments the value of
988      :term:`BUILD_CC_ARCH`, assuming
989      :term:`BUILD_CC_ARCH` is set.
990
991   :term:`BUILD_CFLAGS`
992      Specifies the flags to pass to the C compiler when building for the
993      build host. When building in the ``-native`` context,
994      :term:`CFLAGS` is set to the value of this variable by
995      default.
996
997   :term:`BUILD_CPPFLAGS`
998      Specifies the flags to pass to the C preprocessor (i.e. to both the C
999      and the C++ compilers) when building for the build host. When
1000      building in the ``-native`` context, :term:`CPPFLAGS`
1001      is set to the value of this variable by default.
1002
1003   :term:`BUILD_CXXFLAGS`
1004      Specifies the flags to pass to the C++ compiler when building for the
1005      build host. When building in the ``-native`` context,
1006      :term:`CXXFLAGS` is set to the value of this variable
1007      by default.
1008
1009   :term:`BUILD_FC`
1010      Specifies the Fortran compiler command for the build host. By
1011      default, :term:`BUILD_FC` points to Gfortran and passes as arguments the
1012      value of :term:`BUILD_CC_ARCH`, assuming
1013      :term:`BUILD_CC_ARCH` is set.
1014
1015   :term:`BUILD_LD`
1016      Specifies the linker command for the build host. By default,
1017      :term:`BUILD_LD` points to the GNU linker (ld) and passes as arguments
1018      the value of :term:`BUILD_LD_ARCH`, assuming
1019      :term:`BUILD_LD_ARCH` is set.
1020
1021   :term:`BUILD_LD_ARCH`
1022      Specifies architecture-specific linker flags for the build host. By
1023      default, the value of :term:`BUILD_LD_ARCH` is empty.
1024
1025   :term:`BUILD_LDFLAGS`
1026      Specifies the flags to pass to the linker when building for the build
1027      host. When building in the ``-native`` context,
1028      :term:`LDFLAGS` is set to the value of this variable
1029      by default.
1030
1031   :term:`BUILD_OPTIMIZATION`
1032      Specifies the optimization flags passed to the C compiler when
1033      building for the build host or the SDK. The flags are passed through
1034      the :term:`BUILD_CFLAGS` and
1035      :term:`BUILDSDK_CFLAGS` default values.
1036
1037      The default value of the :term:`BUILD_OPTIMIZATION` variable is "-O2
1038      -pipe".
1039
1040   :term:`BUILD_OS`
1041      Specifies the operating system in use on the build host (e.g.
1042      "linux"). The OpenEmbedded build system sets the value of
1043      :term:`BUILD_OS` from the OS reported by the ``uname`` command --- the
1044      first word, converted to lower-case characters.
1045
1046   :term:`BUILD_PREFIX`
1047      The toolchain binary prefix used for native recipes. The OpenEmbedded
1048      build system uses the :term:`BUILD_PREFIX` value to set the
1049      :term:`TARGET_PREFIX` when building for :ref:`ref-classes-native` recipes.
1050
1051   :term:`BUILD_STRIP`
1052      Specifies the command to be used to strip debugging symbols from
1053      binaries produced for the build host. By default, :term:`BUILD_STRIP`
1054      points to
1055      ``${``\ :term:`BUILD_PREFIX`\ ``}strip``.
1056
1057   :term:`BUILD_SYS`
1058      Specifies the system, including the architecture and the operating
1059      system, to use when building for the build host (i.e. when building
1060      :ref:`ref-classes-native` recipes).
1061
1062      The OpenEmbedded build system automatically sets this variable based
1063      on :term:`BUILD_ARCH`,
1064      :term:`BUILD_VENDOR`, and
1065      :term:`BUILD_OS`. You do not need to set the
1066      :term:`BUILD_SYS` variable yourself.
1067
1068   :term:`BUILD_VENDOR`
1069      Specifies the vendor name to use when building for the build host.
1070      The default value is an empty string ("").
1071
1072   :term:`BUILDDIR`
1073      Points to the location of the :term:`Build Directory`. You can define
1074      this directory indirectly through the :ref:`structure-core-script` script
1075      by passing in a :term:`Build Directory` path when you run the script. If
1076      you run the script and do not provide a :term:`Build Directory` path, the
1077      :term:`BUILDDIR` defaults to ``build`` in the current directory.
1078
1079   :term:`BUILDHISTORY_COMMIT`
1080      When inheriting the :ref:`ref-classes-buildhistory` class, this variable
1081      specifies whether or not to commit the build history output in a local
1082      Git repository. If set to "1", this local repository will be maintained
1083      automatically by the :ref:`ref-classes-buildhistory` class and a commit
1084      will be created on every build for changes to each top-level subdirectory
1085      of the build history output (images, packages, and sdk). If you want to
1086      track changes to build history over time, you should set this value to
1087      "1".
1088
1089      By default, the :ref:`ref-classes-buildhistory` class
1090      enables committing the buildhistory output in a local Git repository::
1091
1092         BUILDHISTORY_COMMIT ?= "1"
1093
1094   :term:`BUILDHISTORY_COMMIT_AUTHOR`
1095      When inheriting the :ref:`ref-classes-buildhistory`
1096      class, this variable specifies the author to use for each Git commit.
1097      In order for the :term:`BUILDHISTORY_COMMIT_AUTHOR` variable to work, the
1098      :term:`BUILDHISTORY_COMMIT` variable must
1099      be set to "1".
1100
1101      Git requires that the value you provide for the
1102      :term:`BUILDHISTORY_COMMIT_AUTHOR` variable takes the form of "name
1103      email@host". Providing an email address or host that is not valid
1104      does not produce an error.
1105
1106      By default, the :ref:`ref-classes-buildhistory` class sets the variable
1107      as follows::
1108
1109         BUILDHISTORY_COMMIT_AUTHOR ?= "buildhistory <buildhistory@${DISTRO}>"
1110
1111   :term:`BUILDHISTORY_DIR`
1112      When inheriting the :ref:`ref-classes-buildhistory`
1113      class, this variable specifies the directory in which build history
1114      information is kept. For more information on how the variable works,
1115      see the :ref:`ref-classes-buildhistory` class.
1116
1117      By default, the :ref:`ref-classes-buildhistory` class sets the directory
1118      as follows::
1119
1120         BUILDHISTORY_DIR ?= "${TOPDIR}/buildhistory"
1121
1122   :term:`BUILDHISTORY_FEATURES`
1123      When inheriting the :ref:`ref-classes-buildhistory`
1124      class, this variable specifies the build history features to be
1125      enabled. For more information on how build history works, see the
1126      ":ref:`dev-manual/build-quality:maintaining build output quality`"
1127      section in the Yocto Project Development Tasks Manual.
1128
1129      You can specify these features in the form of a space-separated list:
1130
1131      -  *image:* Analysis of the contents of images, which includes the
1132         list of installed packages among other things.
1133
1134      -  *package:* Analysis of the contents of individual packages.
1135
1136      -  *sdk:* Analysis of the contents of the software development kit
1137         (SDK).
1138
1139      -  *task:* Save output file signatures for
1140         :ref:`shared state <overview-manual/concepts:shared state cache>`
1141         (sstate) tasks.
1142         This saves one file per task and lists the SHA-256 checksums for
1143         each file staged (i.e. the output of the task).
1144
1145      By default, the :ref:`ref-classes-buildhistory` class enables the
1146      following features::
1147
1148         BUILDHISTORY_FEATURES ?= "image package sdk"
1149
1150   :term:`BUILDHISTORY_IMAGE_FILES`
1151      When inheriting the :ref:`ref-classes-buildhistory`
1152      class, this variable specifies a list of paths to files copied from
1153      the image contents into the build history directory under an
1154      "image-files" directory in the directory for the image, so that you
1155      can track the contents of each file. The default is to copy
1156      ``/etc/passwd`` and ``/etc/group``, which allows you to monitor for
1157      changes in user and group entries. You can modify the list to include
1158      any file. Specifying an invalid path does not produce an error.
1159      Consequently, you can include files that might not always be present.
1160
1161      By default, the :ref:`ref-classes-buildhistory` class provides paths to
1162      the following files::
1163
1164         BUILDHISTORY_IMAGE_FILES ?= "/etc/passwd /etc/group"
1165
1166   :term:`BUILDHISTORY_PATH_PREFIX_STRIP`
1167      When inheriting the :ref:`ref-classes-buildhistory`
1168      class, this variable specifies a common path prefix that should be
1169      stripped off the beginning of paths in the task signature list when the
1170      ``task`` feature is active in :term:`BUILDHISTORY_FEATURES`. This can be
1171      useful when build history is populated from multiple sources that may not
1172      all use the same top level directory.
1173
1174      By default, the :ref:`ref-classes-buildhistory` class sets the variable
1175      as follows::
1176
1177         BUILDHISTORY_PATH_PREFIX_STRIP ?= ""
1178
1179      In this case, no prefixes will be stripped.
1180
1181   :term:`BUILDHISTORY_PUSH_REPO`
1182      When inheriting the :ref:`ref-classes-buildhistory` class, this variable
1183      optionally specifies a remote repository to which build history pushes
1184      Git changes. In order for :term:`BUILDHISTORY_PUSH_REPO` to work,
1185      :term:`BUILDHISTORY_COMMIT` must be set to "1".
1186
1187      The repository should correspond to a remote address that specifies a
1188      repository as understood by Git, or alternatively to a remote name
1189      that you have set up manually using ``git remote`` within the local
1190      repository.
1191
1192      By default, the :ref:`ref-classes-buildhistory` class sets the variable
1193      as follows::
1194
1195         BUILDHISTORY_PUSH_REPO ?= ""
1196
1197   :term:`BUILDNAME`
1198      See :term:`bitbake:BUILDNAME` in the BitBake manual.
1199
1200   :term:`BUILDSDK_CFLAGS`
1201      Specifies the flags to pass to the C compiler when building for the
1202      SDK. When building in the ``nativesdk-`` context,
1203      :term:`CFLAGS` is set to the value of this variable by
1204      default.
1205
1206   :term:`BUILDSDK_CPPFLAGS`
1207      Specifies the flags to pass to the C pre-processor (i.e. to both the
1208      C and the C++ compilers) when building for the SDK. When building in
1209      the ``nativesdk-`` context, :term:`CPPFLAGS` is set
1210      to the value of this variable by default.
1211
1212   :term:`BUILDSDK_CXXFLAGS`
1213      Specifies the flags to pass to the C++ compiler when building for the
1214      SDK. When building in the ``nativesdk-`` context,
1215      :term:`CXXFLAGS` is set to the value of this variable
1216      by default.
1217
1218   :term:`BUILDSDK_LDFLAGS`
1219      Specifies the flags to pass to the linker when building for the SDK.
1220      When building in the ``nativesdk-`` context,
1221      :term:`LDFLAGS` is set to the value of this variable
1222      by default.
1223
1224   :term:`BUILDSTATS_BASE`
1225      Points to the location of the directory that holds build statistics
1226      when you use and enable the :ref:`ref-classes-buildstats` class. The
1227      :term:`BUILDSTATS_BASE` directory defaults to
1228      ``${``\ :term:`TMPDIR`\ ``}/buildstats/``.
1229
1230   :term:`BUSYBOX_SPLIT_SUID`
1231      For the BusyBox recipe, specifies whether to split the output
1232      executable file into two parts: one for features that require
1233      ``setuid root``, and one for the remaining features (i.e. those that
1234      do not require ``setuid root``).
1235
1236      The :term:`BUSYBOX_SPLIT_SUID` variable defaults to "1", which results in
1237      splitting the output executable file. Set the variable to "0" to get
1238      a single output executable file.
1239
1240   :term:`BZRDIR`
1241      See :term:`bitbake:BZRDIR` in the BitBake manual.
1242
1243   :term:`CACHE`
1244      Specifies the directory BitBake uses to store a cache of the
1245      :term:`Metadata` so it does not need to be parsed every time
1246      BitBake is started.
1247
1248   :term:`CC`
1249      The minimal command and arguments used to run the C compiler.
1250
1251   :term:`CFLAGS`
1252      Specifies the flags to pass to the C compiler. This variable is
1253      exported to an environment variable and thus made visible to the
1254      software being built during the compilation step.
1255
1256      Default initialization for :term:`CFLAGS` varies depending on what is
1257      being built:
1258
1259      -  :term:`TARGET_CFLAGS` when building for the
1260         target
1261
1262      -  :term:`BUILD_CFLAGS` when building for the
1263         build host (i.e. ``-native``)
1264
1265      -  :term:`BUILDSDK_CFLAGS` when building for
1266         an SDK (i.e. ``nativesdk-``)
1267
1268   :term:`CLASSOVERRIDE`
1269      An internal variable specifying the special class override that
1270      should currently apply (e.g. "class-target", "class-native", and so
1271      forth). The classes that use this variable (e.g.
1272      :ref:`ref-classes-native`, :ref:`ref-classes-nativesdk`, and so forth)
1273      set the variable to appropriate values.
1274
1275      .. note::
1276
1277         :term:`CLASSOVERRIDE` gets its default "class-target" value from the
1278         ``bitbake.conf`` file.
1279
1280      As an example, the following override allows you to install extra
1281      files, but only when building for the target::
1282
1283         do_install:append:class-target() {
1284             install my-extra-file ${D}${sysconfdir}
1285         }
1286
1287      Here is an example where ``FOO`` is set to
1288      "native" when building for the build host, and to "other" when not
1289      building for the build host::
1290
1291         FOO:class-native = "native"
1292         FOO = "other"
1293
1294      The underlying mechanism behind :term:`CLASSOVERRIDE` is simply
1295      that it is included in the default value of
1296      :term:`OVERRIDES`.
1297
1298   :term:`CLEANBROKEN`
1299      If set to "1" within a recipe, :term:`CLEANBROKEN` specifies that the
1300      ``make clean`` command does not work for the software being built.
1301      Consequently, the OpenEmbedded build system will not try to run
1302      ``make clean`` during the :ref:`ref-tasks-configure`
1303      task, which is the default behavior.
1304
1305   :term:`COMBINED_FEATURES`
1306      Provides a list of hardware features that are enabled in both
1307      :term:`MACHINE_FEATURES` and
1308      :term:`DISTRO_FEATURES`. This select list of
1309      features contains features that make sense to be controlled both at
1310      the machine and distribution configuration level. For example, the
1311      "bluetooth" feature requires hardware support but should also be
1312      optional at the distribution level, in case the hardware supports
1313      Bluetooth but you do not ever intend to use it.
1314
1315   :term:`COMMERCIAL_AUDIO_PLUGINS`
1316      This variable is specific to the :yocto_git:`GStreamer recipes
1317      </poky/tree/meta/recipes-multimedia/gstreamer/gstreamer1.0-meta-base.bb>`.
1318      It allows to build the GStreamer `"ugly"
1319      <https://github.com/GStreamer/gst-plugins-ugly>`__ and
1320      `"bad" <https://github.com/GStreamer/gst-plugins-bad>`__ audio plugins.
1321
1322      See the :ref:`dev-manual/licenses:other variables related to commercial licenses`
1323      section for usage details.
1324
1325   :term:`COMMERCIAL_VIDEO_PLUGINS`
1326      This variable is specific to the :yocto_git:`GStreamer recipes
1327      </poky/tree/meta/recipes-multimedia/gstreamer/gstreamer1.0-meta-base.bb>`.
1328      It allows to build the GStreamer `"ugly"
1329      <https://github.com/GStreamer/gst-plugins-ugly>`__ and
1330      `"bad" <https://github.com/GStreamer/gst-plugins-bad>`__ video plugins.
1331
1332      See the :ref:`dev-manual/licenses:other variables related to commercial licenses`
1333      section for usage details.
1334
1335   :term:`COMMON_LICENSE_DIR`
1336      Points to ``meta/files/common-licenses`` in the
1337      :term:`Source Directory`, which is where generic license
1338      files reside.
1339
1340   :term:`COMPATIBLE_HOST`
1341      A regular expression that resolves to one or more hosts (when the
1342      recipe is native) or one or more targets (when the recipe is
1343      non-native) with which a recipe is compatible. The regular expression
1344      is matched against :term:`HOST_SYS`. You can use the
1345      variable to stop recipes from being built for classes of systems with
1346      which the recipes are not compatible. Stopping these builds is
1347      particularly useful with kernels. The variable also helps to increase
1348      parsing speed since the build system skips parsing recipes not
1349      compatible with the current system.
1350
1351   :term:`COMPATIBLE_MACHINE`
1352      A regular expression that resolves to one or more target machines
1353      with which a recipe is compatible. The regular expression is matched
1354      against :term:`MACHINEOVERRIDES`. You can use
1355      the variable to stop recipes from being built for machines with which
1356      the recipes are not compatible. Stopping these builds is particularly
1357      useful with kernels. The variable also helps to increase parsing
1358      speed since the build system skips parsing recipes not compatible
1359      with the current machine.
1360
1361      If one wants to have a recipe only available for some architectures
1362      (here ``aarch64`` and ``mips64``), the following can be used::
1363
1364         COMPATIBLE_MACHINE = "^$"
1365         COMPATIBLE_MACHINE:arch64 = "^(aarch64)$"
1366         COMPATIBLE_MACHINE:mips64 = "^(mips64)$"
1367
1368      The first line means "match all machines whose :term:`MACHINEOVERRIDES`
1369      contains the empty string", which will always be none.
1370
1371      The second is for matching all machines whose :term:`MACHINEOVERRIDES`
1372      contains one override which is exactly ``aarch64``.
1373
1374      The third is for matching all machines whose :term:`MACHINEOVERRIDES`
1375      contains one override which is exactly ``mips64``.
1376
1377      The same could be achieved with::
1378
1379         COMPATIBLE_MACHINE = "^(aarch64|mips64)$"
1380
1381      .. note::
1382
1383         When :term:`COMPATIBLE_MACHINE` is set in a recipe inherits from
1384         native, the recipe is always skipped. All native recipes must be
1385         entirely target independent and should not rely on :term:`MACHINE`.
1386
1387   :term:`COMPLEMENTARY_GLOB`
1388      Defines wildcards to match when installing a list of complementary
1389      packages for all the packages explicitly (or implicitly) installed in
1390      an image.
1391
1392      The :term:`COMPLEMENTARY_GLOB` variable uses Unix filename pattern matching
1393      (`fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__),
1394      which is similar to the Unix style pathname pattern expansion
1395      (`glob <https://docs.python.org/3/library/glob.html>`__).
1396
1397      The resulting list of complementary packages is associated with an
1398      item that can be added to
1399      :term:`IMAGE_FEATURES`. An example usage of
1400      this is the "dev-pkgs" item that when added to :term:`IMAGE_FEATURES`
1401      will install -dev packages (containing headers and other development
1402      files) for every package in the image.
1403
1404      To add a new feature item pointing to a wildcard, use a variable flag
1405      to specify the feature item name and use the value to specify the
1406      wildcard. Here is an example::
1407
1408         COMPLEMENTARY_GLOB[dev-pkgs] = '*-dev'
1409
1410      .. note::
1411
1412         When installing complementary packages, recommends relationships
1413         (set via :term:`RRECOMMENDS`) are always ignored.
1414
1415   :term:`COMPONENTS_DIR`
1416      Stores sysroot components for each recipe. The OpenEmbedded build
1417      system uses :term:`COMPONENTS_DIR` when constructing recipe-specific
1418      sysroots for other recipes.
1419
1420      The default is
1421      "``${``\ :term:`STAGING_DIR`\ ``}-components``."
1422      (i.e.
1423      "``${``\ :term:`TMPDIR`\ ``}/sysroots-components``").
1424
1425   :term:`CONF_VERSION`
1426      Tracks the version of the local configuration file (i.e.
1427      ``local.conf``). The value for :term:`CONF_VERSION` increments each time
1428      ``build/conf/`` compatibility changes.
1429
1430   :term:`CONFFILES`
1431      Identifies editable or configurable files that are part of a package.
1432      If the Package Management System (PMS) is being used to update
1433      packages on the target system, it is possible that configuration
1434      files you have changed after the original installation and that you
1435      now want to remain unchanged are overwritten. In other words,
1436      editable files might exist in the package that you do not want reset
1437      as part of the package update process. You can use the :term:`CONFFILES`
1438      variable to list the files in the package that you wish to prevent
1439      the PMS from overwriting during this update process.
1440
1441      To use the :term:`CONFFILES` variable, provide a package name override
1442      that identifies the resulting package. Then, provide a
1443      space-separated list of files. Here is an example::
1444
1445         CONFFILES:${PN} += "${sysconfdir}/file1 \
1446             ${sysconfdir}/file2 ${sysconfdir}/file3"
1447
1448      There is a relationship between the :term:`CONFFILES` and :term:`FILES`
1449      variables. The files listed within :term:`CONFFILES` must be a subset of
1450      the files listed within :term:`FILES`. Because the configuration files
1451      you provide with :term:`CONFFILES` are simply being identified so that
1452      the PMS will not overwrite them, it makes sense that the files must
1453      already be included as part of the package through the :term:`FILES`
1454      variable.
1455
1456      .. note::
1457
1458         When specifying paths as part of the :term:`CONFFILES` variable, it is
1459         good practice to use appropriate path variables.
1460         For example, ``${sysconfdir}`` rather than ``/etc`` or ``${bindir}``
1461         rather than ``/usr/bin``. You can find a list of these variables at
1462         the top of the ``meta/conf/bitbake.conf`` file in the
1463         :term:`Source Directory`.
1464
1465   :term:`CONFIG_INITRAMFS_SOURCE`
1466      Identifies the initial RAM filesystem (:term:`Initramfs`) source files. The
1467      OpenEmbedded build system receives and uses this kernel Kconfig
1468      variable as an environment variable. By default, the variable is set
1469      to null ("").
1470
1471      The :term:`CONFIG_INITRAMFS_SOURCE` can be either a single cpio archive
1472      with a ``.cpio`` suffix or a space-separated list of directories and
1473      files for building the :term:`Initramfs` image. A cpio archive should contain
1474      a filesystem archive to be used as an :term:`Initramfs` image. Directories
1475      should contain a filesystem layout to be included in the :term:`Initramfs`
1476      image. Files should contain entries according to the format described
1477      by the ``usr/gen_init_cpio`` program in the kernel tree.
1478
1479      If you specify multiple directories and files, the :term:`Initramfs` image
1480      will be the aggregate of all of them.
1481
1482      For information on creating an :term:`Initramfs`, see the
1483      ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
1484      in the Yocto Project Development Tasks Manual.
1485
1486   :term:`CONFIG_SITE`
1487      A list of files that contains ``autoconf`` test results relevant to
1488      the current build. This variable is used by the Autotools utilities
1489      when running ``configure``.
1490
1491   :term:`CONFIGURE_FLAGS`
1492      The minimal arguments for GNU configure.
1493
1494   :term:`CONFLICT_DISTRO_FEATURES`
1495      When inheriting the :ref:`ref-classes-features_check`
1496      class, this variable identifies distribution features that would be
1497      in conflict should the recipe be built. In other words, if the
1498      :term:`CONFLICT_DISTRO_FEATURES` variable lists a feature that also
1499      appears in :term:`DISTRO_FEATURES` within the current configuration, then
1500      the recipe will be skipped, and if the build system attempts to build
1501      the recipe then an error will be triggered.
1502
1503   :term:`CONVERSION_CMD`
1504      This variable is used for storing image conversion commands.
1505      Image conversion can convert an image into different objects like:
1506
1507      -   Compressed version of the image
1508
1509      -   Checksums for the image
1510
1511      An example of :term:`CONVERSION_CMD` from :ref:`ref-classes-image_types`
1512      class is::
1513
1514         CONVERSION_CMD:lzo = "lzop -9 ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}"
1515
1516   :term:`COPY_LIC_DIRS`
1517      If set to "1" along with the
1518      :term:`COPY_LIC_MANIFEST` variable, the
1519      OpenEmbedded build system copies into the image the license files,
1520      which are located in ``/usr/share/common-licenses``, for each
1521      package. The license files are placed in directories within the image
1522      itself during build time.
1523
1524      .. note::
1525
1526         The :term:`COPY_LIC_DIRS` does not offer a path for adding licenses for
1527         newly installed packages to an image, which might be most suitable for
1528         read-only filesystems that cannot be upgraded. See the
1529         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1530         You can also reference the ":ref:`dev-manual/licenses:providing license text`"
1531         section in the Yocto Project Development Tasks Manual for
1532         information on providing license text.
1533
1534   :term:`COPY_LIC_MANIFEST`
1535      If set to "1", the OpenEmbedded build system copies the license
1536      manifest for the image to
1537      ``/usr/share/common-licenses/license.manifest`` within the image
1538      itself during build time.
1539
1540      .. note::
1541
1542         The :term:`COPY_LIC_MANIFEST` does not offer a path for adding licenses for
1543         newly installed packages to an image, which might be most suitable for
1544         read-only filesystems that cannot be upgraded. See the
1545         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1546         You can also reference the ":ref:`dev-manual/licenses:providing license text`"
1547         section in the Yocto Project Development Tasks Manual for
1548         information on providing license text.
1549
1550   :term:`COPYLEFT_LICENSE_EXCLUDE`
1551      A space-separated list of licenses to exclude from the source archived by
1552      the :ref:`ref-classes-archiver` class. In other words, if a license in a
1553      recipe's :term:`LICENSE` value is in the value of
1554      :term:`COPYLEFT_LICENSE_EXCLUDE`, then its source is not archived by the
1555      class.
1556
1557      .. note::
1558
1559         The :term:`COPYLEFT_LICENSE_EXCLUDE` variable takes precedence over the
1560         :term:`COPYLEFT_LICENSE_INCLUDE` variable.
1561
1562      The default value, which is "CLOSED Proprietary", for
1563      :term:`COPYLEFT_LICENSE_EXCLUDE` is set by the
1564      :ref:`ref-classes-copyleft_filter` class, which
1565      is inherited by the :ref:`ref-classes-archiver` class.
1566
1567   :term:`COPYLEFT_LICENSE_INCLUDE`
1568      A space-separated list of licenses to include in the source archived
1569      by the :ref:`ref-classes-archiver` class. In other
1570      words, if a license in a recipe's :term:`LICENSE`
1571      value is in the value of :term:`COPYLEFT_LICENSE_INCLUDE`, then its
1572      source is archived by the class.
1573
1574      The default value is set by the :ref:`ref-classes-copyleft_filter` class,
1575      which is inherited by the :ref:`ref-classes-archiver` class. The default
1576      value includes "GPL*", "LGPL*", and "AGPL*".
1577
1578   :term:`COPYLEFT_PN_EXCLUDE`
1579      A list of recipes to exclude in the source archived by the
1580      :ref:`ref-classes-archiver` class. The :term:`COPYLEFT_PN_EXCLUDE`
1581      variable overrides the license inclusion and exclusion caused through the
1582      :term:`COPYLEFT_LICENSE_INCLUDE` and :term:`COPYLEFT_LICENSE_EXCLUDE`
1583      variables, respectively.
1584
1585      The default value, which is "" indicating to not explicitly exclude
1586      any recipes by name, for :term:`COPYLEFT_PN_EXCLUDE` is set by the
1587      :ref:`ref-classes-copyleft_filter` class, which is inherited by the
1588      :ref:`ref-classes-archiver` class.
1589
1590   :term:`COPYLEFT_PN_INCLUDE`
1591      A list of recipes to include in the source archived by the
1592      :ref:`ref-classes-archiver` class. The :term:`COPYLEFT_PN_INCLUDE`
1593      variable overrides the license inclusion and exclusion caused through the
1594      :term:`COPYLEFT_LICENSE_INCLUDE` and :term:`COPYLEFT_LICENSE_EXCLUDE`
1595      variables, respectively.
1596
1597      The default value, which is "" indicating to not explicitly include
1598      any recipes by name, for :term:`COPYLEFT_PN_INCLUDE` is set by the
1599      :ref:`ref-classes-copyleft_filter` class, which is inherited by the
1600      :ref:`ref-classes-archiver` class.
1601
1602   :term:`COPYLEFT_RECIPE_TYPES`
1603      A space-separated list of recipe types to include in the source
1604      archived by the :ref:`archiver <ref-classes-archiver>` class.
1605      Recipe types are ``target``, :ref:`ref-classes-native`,
1606      :ref:`ref-classes-nativesdk`, :ref:`ref-classes-cross`,
1607      :ref:`ref-classes-crosssdk`, and :ref:`ref-classes-cross-canadian`.
1608
1609      The default value, which is "target*", for :term:`COPYLEFT_RECIPE_TYPES`
1610      is set by the :ref:`ref-classes-copyleft_filter` class, which is
1611      inherited by the :ref:`ref-classes-archiver` class.
1612
1613   :term:`CORE_IMAGE_EXTRA_INSTALL`
1614      Specifies the list of packages to be added to the image. You should
1615      only set this variable in the ``local.conf`` configuration file found
1616      in the :term:`Build Directory`.
1617
1618      This variable replaces ``POKY_EXTRA_INSTALL``, which is no longer
1619      supported.
1620
1621   :term:`COREBASE`
1622      Specifies the parent directory of the OpenEmbedded-Core Metadata
1623      layer (i.e. ``meta``).
1624
1625      It is an important distinction that :term:`COREBASE` points to the parent
1626      of this layer and not the layer itself. Consider an example where you
1627      have cloned the Poky Git repository and retained the ``poky`` name
1628      for your local copy of the repository. In this case, :term:`COREBASE`
1629      points to the ``poky`` folder because it is the parent directory of
1630      the ``poky/meta`` layer.
1631
1632   :term:`COREBASE_FILES`
1633      Lists files from the :term:`COREBASE` directory that
1634      should be copied other than the layers listed in the
1635      ``bblayers.conf`` file. The :term:`COREBASE_FILES` variable allows
1636      to copy metadata from the OpenEmbedded build system
1637      into the extensible SDK.
1638
1639      Explicitly listing files in :term:`COREBASE` is needed because it
1640      typically contains build directories and other files that should not
1641      normally be copied into the extensible SDK. Consequently, the value
1642      of :term:`COREBASE_FILES` is used in order to only copy the files that
1643      are actually needed.
1644
1645   :term:`CPP`
1646      The minimal command and arguments used to run the C preprocessor.
1647
1648   :term:`CPPFLAGS`
1649      Specifies the flags to pass to the C pre-processor (i.e. to both the
1650      C and the C++ compilers). This variable is exported to an environment
1651      variable and thus made visible to the software being built during the
1652      compilation step.
1653
1654      Default initialization for :term:`CPPFLAGS` varies depending on what is
1655      being built:
1656
1657      -  :term:`TARGET_CPPFLAGS` when building for
1658         the target
1659
1660      -  :term:`BUILD_CPPFLAGS` when building for the
1661         build host (i.e. ``-native``)
1662
1663      -  :term:`BUILDSDK_CPPFLAGS` when building
1664         for an SDK (i.e. ``nativesdk-``)
1665
1666   :term:`CROSS_COMPILE`
1667      The toolchain binary prefix for the target tools. The
1668      :term:`CROSS_COMPILE` variable is the same as the
1669      :term:`TARGET_PREFIX` variable.
1670
1671      .. note::
1672
1673         The OpenEmbedded build system sets the :term:`CROSS_COMPILE`
1674         variable only in certain contexts (e.g. when building for kernel
1675         and kernel module recipes).
1676
1677   :term:`CVE_CHECK_IGNORE`
1678      This variable is deprecated and should be replaced by :term:`CVE_STATUS`.
1679
1680   :term:`CVE_CHECK_SHOW_WARNINGS`
1681      Specifies whether or not the :ref:`ref-classes-cve-check`
1682      class should generate warning messages on the console when unpatched
1683      CVEs are found. The default is "1", but you may wish to set it to "0" if
1684      you are already examining/processing the logs after the build has
1685      completed and thus do not need the warning messages.
1686
1687   :term:`CVE_CHECK_SKIP_RECIPE`
1688      The list of package names (:term:`PN`) for which
1689      CVEs (Common Vulnerabilities and Exposures) are ignored.
1690
1691   :term:`CVE_DB_UPDATE_INTERVAL`
1692      Specifies the CVE database update interval in seconds, as used by
1693      ``cve-update-db-native``. The default value is "86400" i.e. once a day
1694      (24*60*60). If the value is set to "0" then the update will be forced
1695      every time. Alternatively, a negative value e.g. "-1" will disable
1696      updates entirely.
1697
1698   :term:`CVE_PRODUCT`
1699      In a recipe, defines the name used to match the recipe name
1700      against the name in the upstream `NIST CVE database <https://nvd.nist.gov/>`__.
1701
1702      The default is ${:term:`BPN`} (except for recipes that inherit the
1703      :ref:`ref-classes-pypi` class where it is set based upon
1704      :term:`PYPI_PACKAGE`). If it does not match the name in the NIST CVE
1705      database or matches with multiple entries in the database, the default
1706      value needs to be changed.
1707
1708      Here is an example from the :oe_layerindex:`Berkeley DB recipe </layerindex/recipe/544>`::
1709
1710         CVE_PRODUCT = "oracle_berkeley_db berkeley_db"
1711
1712      Sometimes the product name is not specific enough, for example
1713      "tar" has been matching CVEs for the GNU ``tar`` package and also
1714      the ``node-tar`` node.js extension. To avoid this problem, use the
1715      vendor name as a prefix. The syntax for this is::
1716
1717         CVE_PRODUCT = "vendor:package"
1718
1719   :term:`CVE_STATUS`
1720      The CVE ID which is patched or should be ignored. Here is
1721      an example from the :oe_layerindex:`Python3 recipe</layerindex/recipe/23823>`::
1722
1723         CVE_STATUS[CVE-2020-15523] = "not-applicable-platform: Issue only applies on Windows"
1724
1725      It has the format "reason: description" and the description is optional.
1726      The Reason is mapped to the final CVE state by mapping via
1727      :term:`CVE_CHECK_STATUSMAP`. See :ref:`dev-manual/vulnerabilities:fixing vulnerabilities in recipes`
1728      for details.
1729
1730   :term:`CVE_STATUS_GROUPS`
1731      If there are many CVEs with the same status and reason, they can by simplified by using this
1732      variable instead of many similar lines with :term:`CVE_STATUS`::
1733
1734         CVE_STATUS_GROUPS = "CVE_STATUS_WIN CVE_STATUS_PATCHED"
1735
1736         CVE_STATUS_WIN = "CVE-1234-0001 CVE-1234-0002"
1737         CVE_STATUS_WIN[status] = "not-applicable-platform: Issue only applies on Windows"
1738         CVE_STATUS_PATCHED = "CVE-1234-0003 CVE-1234-0004"
1739         CVE_STATUS_PATCHED[status] = "fixed-version: Fixed externally"
1740
1741   :term:`CVE_CHECK_STATUSMAP`
1742      Mapping variable for all possible reasons of :term:`CVE_STATUS`:
1743      ``Patched``, ``Unpatched`` and ``Ignored``.
1744      See :ref:`ref-classes-cve-check` or ``meta/conf/cve-check-map.conf`` for more details::
1745
1746         CVE_CHECK_STATUSMAP[cpe-incorrect] = "Ignored"
1747
1748   :term:`CVE_VERSION`
1749      In a recipe, defines the version used to match the recipe version
1750      against the version in the `NIST CVE database <https://nvd.nist.gov/>`__
1751      when usign :ref:`ref-classes-cve-check`.
1752
1753      The default is ${:term:`PV`} but if recipes use custom version numbers
1754      which do not map to upstream software component release versions and the versions
1755      used in the CVE database, then this variable can be used to set the
1756      version number for :ref:`ref-classes-cve-check`. Example::
1757
1758          CVE_VERSION = "2.39"
1759
1760   :term:`CVSDIR`
1761      The directory in which files checked out under the CVS system are
1762      stored.
1763
1764   :term:`CXX`
1765      The minimal command and arguments used to run the C++ compiler.
1766
1767   :term:`CXXFLAGS`
1768      Specifies the flags to pass to the C++ compiler. This variable is
1769      exported to an environment variable and thus made visible to the
1770      software being built during the compilation step.
1771
1772      Default initialization for :term:`CXXFLAGS` varies depending on what is
1773      being built:
1774
1775      -  :term:`TARGET_CXXFLAGS` when building for
1776         the target
1777
1778      -  :term:`BUILD_CXXFLAGS` when building for the
1779         build host (i.e. ``-native``)
1780
1781      -  :term:`BUILDSDK_CXXFLAGS` when building
1782         for an SDK (i.e. ``nativesdk-``)
1783
1784   :term:`D`
1785      The destination directory. The location in the :term:`Build Directory`
1786      where components are installed by the
1787      :ref:`ref-tasks-install` task. This location defaults
1788      to::
1789
1790         ${WORKDIR}/image
1791
1792      .. note::
1793
1794         Tasks that read from or write to this directory should run under
1795         :ref:`fakeroot <overview-manual/concepts:fakeroot and pseudo>`.
1796
1797   :term:`DATE`
1798      The date the build was started. Dates appear using the year, month,
1799      and day (YMD) format (e.g. "20150209" for February 9th, 2015).
1800
1801   :term:`DATETIME`
1802      The date and time on which the current build started. The format is
1803      suitable for timestamps.
1804
1805   :term:`DEBIAN_NOAUTONAME`
1806      When the :ref:`ref-classes-debian` class is inherited,
1807      which is the default behavior, :term:`DEBIAN_NOAUTONAME` specifies a
1808      particular package should not be renamed according to Debian library
1809      package naming. You must use the package name as an override when you
1810      set this variable. Here is an example from the ``fontconfig`` recipe::
1811
1812         DEBIAN_NOAUTONAME:fontconfig-utils = "1"
1813
1814   :term:`DEBIANNAME`
1815      When the :ref:`ref-classes-debian` class is inherited,
1816      which is the default behavior, :term:`DEBIANNAME` allows you to override
1817      the library name for an individual package. Overriding the library
1818      name in these cases is rare. You must use the package name as an
1819      override when you set this variable. Here is an example from the
1820      ``dbus`` recipe::
1821
1822         DEBIANNAME:${PN} = "dbus-1"
1823
1824   :term:`DEBUG_BUILD`
1825      Specifies to build packages with debugging information. This
1826      influences the value of the :term:`SELECTED_OPTIMIZATION` variable.
1827
1828   :term:`DEBUG_OPTIMIZATION`
1829      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
1830      compiling a system for debugging. This variable defaults to "-O
1831      -fno-omit-frame-pointer ${DEBUG_FLAGS} -pipe".
1832
1833   :term:`DEBUG_PREFIX_MAP`
1834      Allows to set C compiler options, such as ``-fdebug-prefix-map``,
1835      ``-fmacro-prefix-map``, and ``-ffile-prefix-map``, which allow to
1836      replace build-time paths by install-time ones in the debugging sections
1837      of binaries.  This makes compiler output files location independent,
1838      at the cost of having to pass an extra command to tell the debugger
1839      where source files are.
1840
1841      This is used by the Yocto Project to guarantee
1842      :doc:`/test-manual/reproducible-builds` even when the source code of
1843      a package uses the ``__FILE__`` or ``assert()`` macros. See the
1844      `reproducible-builds.org <https://reproducible-builds.org/docs/build-path/>`__
1845      website for details.
1846
1847      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1848      not intended to be user-configurable.
1849
1850   :term:`DEFAULT_PREFERENCE`
1851      Specifies a weak bias for recipe selection priority.
1852
1853      The most common usage of this is variable is to set it to "-1" within
1854      a recipe for a development version of a piece of software. Using the
1855      variable in this way causes the stable version of the recipe to build
1856      by default in the absence of :term:`PREFERRED_VERSION` being used to
1857      build the development version.
1858
1859      .. note::
1860
1861         The bias provided by :term:`DEFAULT_PREFERENCE` is weak and is overridden
1862         by :term:`BBFILE_PRIORITY` if that variable is different between two
1863         layers that contain different versions of the same recipe.
1864
1865   :term:`DEFAULTTUNE`
1866      The default CPU and Application Binary Interface (ABI) tunings (i.e.
1867      the "tune") used by the OpenEmbedded build system. The
1868      :term:`DEFAULTTUNE` helps define
1869      :term:`TUNE_FEATURES`.
1870
1871      The default tune is either implicitly or explicitly set by the
1872      machine (:term:`MACHINE`). However, you can override
1873      the setting using available tunes as defined with
1874      :term:`AVAILTUNES`.
1875
1876   :term:`DEPENDS`
1877      Lists a recipe's build-time dependencies. These are dependencies on
1878      other recipes whose contents (e.g. headers and shared libraries) are
1879      needed by the recipe at build time.
1880
1881      As an example, consider a recipe ``foo`` that contains the following
1882      assignment::
1883
1884          DEPENDS = "bar"
1885
1886      The practical effect of the previous assignment is that all files
1887      installed by bar will be available in the appropriate staging sysroot,
1888      given by the :term:`STAGING_DIR* <STAGING_DIR>` variables, by the time
1889      the :ref:`ref-tasks-configure` task for ``foo`` runs. This mechanism is
1890      implemented by having :ref:`ref-tasks-configure` depend on the
1891      :ref:`ref-tasks-populate_sysroot` task of each recipe listed in
1892      :term:`DEPENDS`, through a
1893      ``[``\ :ref:`deptask <bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]``
1894      declaration in the :ref:`ref-classes-base` class.
1895
1896      .. note::
1897
1898         It seldom is necessary to reference, for example, :term:`STAGING_DIR_HOST`
1899         explicitly. The standard classes and build-related variables are
1900         configured to automatically use the appropriate staging sysroots.
1901
1902      As another example, :term:`DEPENDS` can also be used to add utilities
1903      that run on the build machine during the build. For example, a recipe
1904      that makes use of a code generator built by the recipe ``codegen``
1905      might have the following::
1906
1907         DEPENDS = "codegen-native"
1908
1909      For more
1910      information, see the :ref:`ref-classes-native` class and
1911      the :term:`EXTRANATIVEPATH` variable.
1912
1913      .. note::
1914
1915         -  :term:`DEPENDS` is a list of recipe names. Or, to be more precise,
1916            it is a list of :term:`PROVIDES` names, which
1917            usually match recipe names. Putting a package name such as
1918            "foo-dev" in :term:`DEPENDS` does not make sense. Use "foo"
1919            instead, as this will put files from all the packages that make
1920            up ``foo``, which includes those from ``foo-dev``, into the
1921            sysroot.
1922
1923         -  One recipe having another recipe in :term:`DEPENDS` does not by
1924            itself add any runtime dependencies between the packages
1925            produced by the two recipes. However, as explained in the
1926            ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
1927            section in the Yocto Project Overview and Concepts Manual,
1928            runtime dependencies will often be added automatically, meaning
1929            :term:`DEPENDS` alone is sufficient for most recipes.
1930
1931         -  Counterintuitively, :term:`DEPENDS` is often necessary even for
1932            recipes that install precompiled components. For example, if
1933            ``libfoo`` is a precompiled library that links against
1934            ``libbar``, then linking against ``libfoo`` requires both
1935            ``libfoo`` and ``libbar`` to be available in the sysroot.
1936            Without a :term:`DEPENDS` from the recipe that installs ``libfoo``
1937            to the recipe that installs ``libbar``, other recipes might
1938            fail to link against ``libfoo``.
1939
1940      For information on runtime dependencies, see the :term:`RDEPENDS`
1941      variable. You can also see the
1942      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
1943      ":ref:`bitbake-user-manual/bitbake-user-manual-execution:dependencies`"
1944      sections in the BitBake User Manual for additional information on tasks
1945      and dependencies.
1946
1947   :term:`DEPLOY_DIR`
1948      Points to the general area that the OpenEmbedded build system uses to
1949      place images, packages, SDKs, and other output files that are ready
1950      to be used outside of the build system. By default, this directory
1951      resides within the :term:`Build Directory` as ``${TMPDIR}/deploy``.
1952
1953      For more information on the structure of the Build Directory, see
1954      ":ref:`ref-manual/structure:the build directory --- \`\`build/\`\``" section.
1955      For more detail on the contents of the ``deploy`` directory, see the
1956      ":ref:`overview-manual/concepts:images`",
1957      ":ref:`overview-manual/concepts:package feeds`", and
1958      ":ref:`overview-manual/concepts:application development sdk`" sections all in the
1959      Yocto Project Overview and Concepts Manual.
1960
1961   :term:`DEPLOY_DIR_DEB`
1962      Points to the area that the OpenEmbedded build system uses to place
1963      Debian packages that are ready to be used outside of the build
1964      system. This variable applies only when :term:`PACKAGE_CLASSES` contains
1965      ":ref:`ref-classes-package_deb`".
1966
1967      The BitBake configuration file initially defines the
1968      :term:`DEPLOY_DIR_DEB` variable as a sub-folder of
1969      :term:`DEPLOY_DIR`::
1970
1971         DEPLOY_DIR_DEB = "${DEPLOY_DIR}/deb"
1972
1973      The :ref:`ref-classes-package_deb` class uses the
1974      :term:`DEPLOY_DIR_DEB` variable to make sure the
1975      :ref:`ref-tasks-package_write_deb` task
1976      writes Debian packages into the appropriate folder. For more
1977      information on how packaging works, see the
1978      ":ref:`overview-manual/concepts:package feeds`" section
1979      in the Yocto Project Overview and Concepts Manual.
1980
1981   :term:`DEPLOY_DIR_IMAGE`
1982      Points to the area that the OpenEmbedded build system uses to place
1983      images and other associated output files that are ready to be
1984      deployed onto the target machine. The directory is machine-specific
1985      as it contains the ``${MACHINE}`` name. By default, this directory
1986      resides within the :term:`Build Directory` as
1987      ``${DEPLOY_DIR}/images/${MACHINE}/``.
1988
1989      It must not be used directly in recipes when deploying files. Instead,
1990      it's only useful when a recipe needs to "read" a file already deployed
1991      by a dependency. So, it should be filled with the contents of
1992      :term:`DEPLOYDIR` by the :ref:`ref-classes-deploy` class or with the
1993      contents of :term:`IMGDEPLOYDIR` by the :ref:`ref-classes-image` class.
1994
1995      For more information on the structure of the :term:`Build Directory`, see
1996      ":ref:`ref-manual/structure:the build directory --- \`\`build/\`\``" section.
1997      For more detail on the contents of the ``deploy`` directory, see the
1998      ":ref:`overview-manual/concepts:images`" and
1999      ":ref:`overview-manual/concepts:application development sdk`" sections both in
2000      the Yocto Project Overview and Concepts Manual.
2001
2002   :term:`DEPLOY_DIR_IPK`
2003      Points to the area that the OpenEmbedded build system uses to place
2004      IPK packages that are ready to be used outside of the build system.
2005      This variable applies only when :term:`PACKAGE_CLASSES` contains
2006      ":ref:`ref-classes-package_ipk`".
2007
2008      The BitBake configuration file initially defines this variable as a
2009      sub-folder of :term:`DEPLOY_DIR`::
2010
2011         DEPLOY_DIR_IPK = "${DEPLOY_DIR}/ipk"
2012
2013      The :ref:`ref-classes-package_ipk` class uses the :term:`DEPLOY_DIR_IPK`
2014      variable to make sure the :ref:`ref-tasks-package_write_ipk` task
2015      writes IPK packages into the appropriate folder. For more information
2016      on how packaging works, see the
2017      ":ref:`overview-manual/concepts:package feeds`" section
2018      in the Yocto Project Overview and Concepts Manual.
2019
2020   :term:`DEPLOY_DIR_RPM`
2021      Points to the area that the OpenEmbedded build system uses to place
2022      RPM packages that are ready to be used outside of the build system.
2023      This variable applies only when :term:`PACKAGE_CLASSES` contains
2024      ":ref:`ref-classes-package_rpm`".
2025
2026      The BitBake configuration file initially defines this variable as a
2027      sub-folder of :term:`DEPLOY_DIR`::
2028
2029         DEPLOY_DIR_RPM = "${DEPLOY_DIR}/rpm"
2030
2031      The :ref:`ref-classes-package_rpm` class uses the
2032      :term:`DEPLOY_DIR_RPM` variable to make sure the
2033      :ref:`ref-tasks-package_write_rpm` task
2034      writes RPM packages into the appropriate folder. For more information
2035      on how packaging works, see the
2036      ":ref:`overview-manual/concepts:package feeds`" section
2037      in the Yocto Project Overview and Concepts Manual.
2038
2039   :term:`DEPLOYDIR`
2040      When inheriting the :ref:`ref-classes-deploy` class, the
2041      :term:`DEPLOYDIR` points to a temporary work area for deployed files that
2042      is set in the :ref:`ref-classes-deploy` class as follows::
2043
2044         DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
2045
2046      Recipes inheriting the :ref:`ref-classes-deploy` class should copy files to be
2047      deployed into :term:`DEPLOYDIR`, and the class will take care of copying
2048      them into :term:`DEPLOY_DIR_IMAGE`
2049      afterwards.
2050
2051   :term:`DESCRIPTION`
2052      The package description used by package managers. If not set,
2053      :term:`DESCRIPTION` takes the value of the :term:`SUMMARY`
2054      variable.
2055
2056   :term:`DEV_PKG_DEPENDENCY`
2057      Provides an easy way for recipes to disable or adjust the runtime recommendation
2058      (:term:`RRECOMMENDS`) of the ``${PN}-dev`` package on the main
2059      (``${PN}``) package.
2060
2061   :term:`DISABLE_STATIC`
2062      Used in order to disable static linking by default (in order to save
2063      space, since static libraries are often unused in embedded systems.)
2064      The default value is " --disable-static", however it can be set to ""
2065      in order to enable static linking if desired. Certain recipes do this
2066      individually, and also there is a
2067      ``meta/conf/distro/include/no-static-libs.inc`` include file that
2068      disables static linking for a number of recipes. Some software
2069      packages or build tools (such as CMake) have explicit support for
2070      enabling / disabling static linking, and in those cases
2071      :term:`DISABLE_STATIC` is not used.
2072
2073   :term:`DISTRO`
2074      The short name of the distribution. For information on the long name
2075      of the distribution, see the :term:`DISTRO_NAME`
2076      variable.
2077
2078      The :term:`DISTRO` variable corresponds to a distribution configuration
2079      file whose root name is the same as the variable's argument and whose
2080      filename extension is ``.conf``. For example, the distribution
2081      configuration file for the Poky distribution is named ``poky.conf``
2082      and resides in the ``meta-poky/conf/distro`` directory of the
2083      :term:`Source Directory`.
2084
2085      Within that ``poky.conf`` file, the :term:`DISTRO` variable is set as
2086      follows::
2087
2088         DISTRO = "poky"
2089
2090      Distribution configuration files are located in a ``conf/distro``
2091      directory within the :term:`Metadata` that contains the
2092      distribution configuration. The value for :term:`DISTRO` must not contain
2093      spaces, and is typically all lower-case.
2094
2095      .. note::
2096
2097         If the :term:`DISTRO` variable is blank, a set of default configurations
2098         are used, which are specified within
2099         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
2100
2101   :term:`DISTRO_CODENAME`
2102      Specifies a codename for the distribution being built.
2103
2104   :term:`DISTRO_EXTRA_RDEPENDS`
2105      Specifies a list of distro-specific packages to add to all images.
2106      This variable takes effect through ``packagegroup-base`` so the
2107      variable only really applies to the more full-featured images that
2108      include ``packagegroup-base``. You can use this variable to keep
2109      distro policy out of generic images. As with all other distro
2110      variables, you set this variable in the distro ``.conf`` file.
2111
2112   :term:`DISTRO_EXTRA_RRECOMMENDS`
2113      Specifies a list of distro-specific packages to add to all images if
2114      the packages exist. The packages might not exist or be empty (e.g.
2115      kernel modules). The list of packages are automatically installed but
2116      you can remove them.
2117
2118   :term:`DISTRO_FEATURES`
2119      The software support you want in your distribution for various
2120      features. You define your distribution features in the distribution
2121      configuration file.
2122
2123      In most cases, the presence or absence of a feature in
2124      :term:`DISTRO_FEATURES` is translated to the appropriate option supplied
2125      to the configure script during the
2126      :ref:`ref-tasks-configure` task for recipes that
2127      optionally support the feature. For example, specifying "x11" in
2128      :term:`DISTRO_FEATURES`, causes every piece of software built for the
2129      target that can optionally support X11 to have its X11 support
2130      enabled.
2131
2132      .. note::
2133
2134         Just enabling :term:`DISTRO_FEATURES` alone doesn't
2135         enable feature support for packages. Mechanisms such as making
2136         :term:`PACKAGECONFIG` track :term:`DISTRO_FEATURES` are used
2137         to enable/disable package features.
2138
2139      Two more examples are Bluetooth and NFS support. For a more complete
2140      list of features that ships with the Yocto Project and that you can
2141      provide with this variable, see the ":ref:`ref-features-distro`" section.
2142
2143   :term:`DISTRO_FEATURES_BACKFILL`
2144      A space-separated list of features to be added to :term:`DISTRO_FEATURES`
2145      if not also present in :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`.
2146
2147      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
2148      not intended to be user-configurable. It is best to just reference
2149      the variable to see which distro features are being
2150      :ref:`backfilled <ref-features-backfill>` for all distro configurations.
2151
2152   :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`
2153      A space-separated list of features from :term:`DISTRO_FEATURES_BACKFILL`
2154      that should not be :ref:`backfilled <ref-features-backfill>` (i.e. added
2155      to :term:`DISTRO_FEATURES`) during the build.
2156
2157      This corresponds to an opt-out mechanism. When new default distro
2158      features are introduced, distribution maintainers can review (`consider`)
2159      them and decide to exclude them from the
2160      :ref:`backfilled <ref-features-backfill>` features. Therefore, the
2161      combination of :term:`DISTRO_FEATURES_BACKFILL` and
2162      :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED` makes it possible to
2163      add new default features without breaking existing distributions.
2164
2165
2166   :term:`DISTRO_FEATURES_DEFAULT`
2167      A convenience variable that gives you the default list of distro
2168      features with the exception of any features specific to the C library
2169      (``libc``).
2170
2171      When creating a custom distribution, you might find it useful to be
2172      able to reuse the default
2173      :term:`DISTRO_FEATURES` options without the
2174      need to write out the full set. Here is an example that uses
2175      :term:`DISTRO_FEATURES_DEFAULT` from a custom distro configuration file::
2176
2177         DISTRO_FEATURES ?= "${DISTRO_FEATURES_DEFAULT} myfeature"
2178
2179   :term:`DISTRO_FEATURES_FILTER_NATIVE`
2180      Specifies a list of features that if present in the target
2181      :term:`DISTRO_FEATURES` value should be
2182      included in :term:`DISTRO_FEATURES` when building native recipes. This
2183      variable is used in addition to the features filtered using the
2184      :term:`DISTRO_FEATURES_NATIVE`
2185      variable.
2186
2187   :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
2188      Specifies a list of features that if present in the target
2189      :term:`DISTRO_FEATURES` value should be included in
2190      :term:`DISTRO_FEATURES` when building :ref:`ref-classes-nativesdk`
2191      recipes. This variable is used in addition to the features filtered using
2192      the :term:`DISTRO_FEATURES_NATIVESDK` variable.
2193
2194   :term:`DISTRO_FEATURES_NATIVE`
2195      Specifies a list of features that should be included in
2196      :term:`DISTRO_FEATURES` when building native
2197      recipes. This variable is used in addition to the features filtered
2198      using the
2199      :term:`DISTRO_FEATURES_FILTER_NATIVE`
2200      variable.
2201
2202   :term:`DISTRO_FEATURES_NATIVESDK`
2203      Specifies a list of features that should be included in
2204      :term:`DISTRO_FEATURES` when building
2205      :ref:`ref-classes-nativesdk` recipes. This variable is used
2206      in addition to the features filtered using the
2207      :term:`DISTRO_FEATURES_FILTER_NATIVESDK` variable.
2208
2209   :term:`DISTRO_NAME`
2210      The long name of the distribution. For information on the short name
2211      of the distribution, see the :term:`DISTRO` variable.
2212
2213      The :term:`DISTRO_NAME` variable corresponds to a distribution
2214      configuration file whose root name is the same as the variable's
2215      argument and whose filename extension is ``.conf``. For example, the
2216      distribution configuration file for the Poky distribution is named
2217      ``poky.conf`` and resides in the ``meta-poky/conf/distro`` directory
2218      of the :term:`Source Directory`.
2219
2220      Within that ``poky.conf`` file, the :term:`DISTRO_NAME` variable is set
2221      as follows::
2222
2223         DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
2224
2225      Distribution configuration files are located in a ``conf/distro``
2226      directory within the :term:`Metadata` that contains the
2227      distribution configuration.
2228
2229      .. note::
2230
2231         If the :term:`DISTRO_NAME` variable is blank, a set of default
2232         configurations are used, which are specified within
2233         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
2234
2235   :term:`DISTRO_VERSION`
2236      The version of the distribution.
2237
2238   :term:`DISTROOVERRIDES`
2239      A colon-separated list of overrides specific to the current
2240      distribution. By default, this list includes the value of
2241      :term:`DISTRO`.
2242
2243      You can extend :term:`DISTROOVERRIDES` to add extra overrides that should
2244      apply to the distribution.
2245
2246      The underlying mechanism behind :term:`DISTROOVERRIDES` is simply that it
2247      is included in the default value of
2248      :term:`OVERRIDES`.
2249
2250      Here is an example from :yocto_git:`meta-poky/conf/distro/poky-tiny.conf
2251      </poky/tree/meta-poky/conf/distro/poky-tiny.conf>`::
2252
2253         DISTROOVERRIDES = "poky:poky-tiny"
2254
2255   :term:`DL_DIR`
2256      The central download directory used by the build process to store
2257      downloads. By default, :term:`DL_DIR` gets files suitable for mirroring
2258      for everything except Git repositories. If you want tarballs of Git
2259      repositories, use the
2260      :term:`BB_GENERATE_MIRROR_TARBALLS`
2261      variable.
2262
2263      You can set this directory by defining the :term:`DL_DIR` variable in the
2264      ``conf/local.conf`` file. This directory is self-maintaining and you
2265      should not have to touch it. By default, the directory is
2266      ``downloads`` in the :term:`Build Directory`::
2267
2268         #DL_DIR ?= "${TOPDIR}/downloads"
2269
2270      To specify a different download directory,
2271      simply remove the comment from the line and provide your directory.
2272
2273      During a first build, the system downloads many different source code
2274      tarballs from various upstream projects. Downloading can take a
2275      while, particularly if your network connection is slow. Tarballs are
2276      all stored in the directory defined by :term:`DL_DIR` and the build
2277      system looks there first to find source tarballs.
2278
2279      .. note::
2280
2281         When wiping and rebuilding, you can preserve this directory to
2282         speed up this part of subsequent builds.
2283
2284      You can safely share this directory between multiple builds on the
2285      same development machine. For additional information on how the build
2286      process gets source files when working behind a firewall or proxy
2287      server, see this specific question in the ":doc:`faq`"
2288      chapter. You can also refer to the
2289      ":yocto_wiki:`Working Behind a Network Proxy </Working_Behind_a_Network_Proxy>`"
2290      Wiki page.
2291
2292   :term:`DOC_COMPRESS`
2293      When inheriting the :ref:`ref-classes-compress_doc`
2294      class, this variable sets the compression policy used when the
2295      OpenEmbedded build system compresses man pages and info pages. By
2296      default, the compression method used is gz (gzip). Other policies
2297      available are xz and bz2.
2298
2299      For information on policies and on how to use this variable, see the
2300      comments in the ``meta/classes-recipe/compress_doc.bbclass`` file.
2301
2302   :term:`DT_FILES`
2303      Space-separated list of device tree source files to compile using
2304      a recipe that inherits the :ref:`ref-classes-devicetree` class. These
2305      are relative to the :term:`DT_FILES_PATH`.
2306
2307      For convenience, both ``.dts`` and ``.dtb`` extensions can be used.
2308
2309      Use an empty string (default) to build all device tree sources within
2310      the :term:`DT_FILES_PATH` directory.
2311
2312   :term:`DT_FILES_PATH`
2313      When compiling out-of-tree device tree sources using a recipe that
2314      inherits the :ref:`ref-classes-devicetree` class, this variable specifies
2315      the path to the directory containing dts files to build.
2316
2317      Defaults to the :term:`S` directory.
2318
2319   :term:`DT_PADDING_SIZE`
2320      When inheriting the :ref:`ref-classes-devicetree` class, this variable
2321      specifies the size of padding appended to the device tree blob, used as
2322      extra space typically for additional properties during boot.
2323
2324   :term:`EFI_PROVIDER`
2325      When building bootable images (i.e. where ``hddimg``, ``iso``, or
2326      ``wic.vmdk`` is in :term:`IMAGE_FSTYPES`), the
2327      :term:`EFI_PROVIDER` variable specifies the EFI bootloader to use. The
2328      default is "grub-efi", but "systemd-boot" can be used instead.
2329
2330      See the :ref:`ref-classes-systemd-boot` and :ref:`ref-classes-image-live`
2331      classes for more information.
2332
2333   :term:`ENABLE_BINARY_LOCALE_GENERATION`
2334      Variable that controls which locales for ``glibc`` are generated
2335      during the build (useful if the target device has 64Mbytes of RAM or
2336      less).
2337
2338   :term:`ERR_REPORT_DIR`
2339      When used with the :ref:`ref-classes-report-error` class, specifies the
2340      path used for storing the debug files created by the :ref:`error reporting
2341      tool <dev-manual/error-reporting-tool:using the error reporting tool>`,
2342      which allows you to submit build errors you encounter to a central
2343      database. By default, the value of this variable is
2344      ``${``\ :term:`LOG_DIR`\ ``}/error-report``.
2345
2346      You can set :term:`ERR_REPORT_DIR` to the path you want the error
2347      reporting tool to store the debug files as follows in your
2348      ``local.conf`` file::
2349
2350         ERR_REPORT_DIR = "path"
2351
2352   :term:`ERROR_QA`
2353      Specifies the quality assurance checks whose failures are reported as
2354      errors by the OpenEmbedded build system. You set this variable in
2355      your distribution configuration file. For a list of the checks you
2356      can control with this variable, see the
2357      ":ref:`ref-classes-insane`" section.
2358
2359   :term:`ESDK_CLASS_INHERIT_DISABLE`
2360      A list of classes to remove from the :term:`INHERIT`
2361      value globally within the extensible SDK configuration. The
2362      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class sets the
2363      default value::
2364
2365         ESDK_CLASS_INHERIT_DISABLE ?= "buildhistory icecc"
2366
2367      Some classes are not generally applicable within the extensible SDK
2368      context. You can use this variable to disable those classes.
2369
2370      For additional information on how to customize the extensible SDK's
2371      configuration, see the
2372      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2373      section in the Yocto Project Application Development and the
2374      Extensible Software Development Kit (eSDK) manual.
2375
2376   :term:`ESDK_LOCALCONF_ALLOW`
2377      A list of variables allowed through from the OpenEmbedded build
2378      system configuration into the extensible SDK configuration. By
2379      default, the list of variables is empty and is set in the
2380      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class.
2381
2382      This list overrides the variables specified using the
2383      :term:`ESDK_LOCALCONF_REMOVE` variable as well as
2384      other variables automatically added due to the "/" character
2385      being found at the start of the
2386      value, which is usually indicative of being a path and thus might not
2387      be valid on the system where the SDK is installed.
2388
2389      For additional information on how to customize the extensible SDK's
2390      configuration, see the
2391      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2392      section in the Yocto Project Application Development and the
2393      Extensible Software Development Kit (eSDK) manual.
2394
2395   :term:`ESDK_LOCALCONF_REMOVE`
2396      A list of variables not allowed through from the OpenEmbedded build
2397      system configuration into the extensible SDK configuration. Usually,
2398      these are variables that are specific to the machine on which the
2399      build system is running and thus would be potentially problematic
2400      within the extensible SDK.
2401
2402      By default, :term:`ESDK_LOCALCONF_REMOVE` is set in the
2403      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class and
2404      excludes the following variables:
2405
2406      - :term:`CONF_VERSION`
2407      - :term:`BB_NUMBER_THREADS`
2408      - :term:`BB_NUMBER_PARSE_THREADS`
2409      - :term:`PARALLEL_MAKE`
2410      - :term:`PRSERV_HOST`
2411      - :term:`SSTATE_MIRRORS` :term:`DL_DIR`
2412      - :term:`SSTATE_DIR` :term:`TMPDIR`
2413      - :term:`BB_SERVER_TIMEOUT`
2414
2415      For additional information on how to customize the extensible SDK's
2416      configuration, see the
2417      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2418      section in the Yocto Project Application Development and the
2419      Extensible Software Development Kit (eSDK) manual.
2420
2421   :term:`EXCLUDE_FROM_SHLIBS`
2422      Triggers the OpenEmbedded build system's shared libraries resolver to
2423      exclude an entire package when scanning for shared libraries.
2424
2425      .. note::
2426
2427         The shared libraries resolver's functionality results in part from
2428         the internal function ``package_do_shlibs``, which is part of the
2429         :ref:`ref-tasks-package` task. You should be aware that the shared
2430         libraries resolver might implicitly define some dependencies between
2431         packages.
2432
2433      The :term:`EXCLUDE_FROM_SHLIBS` variable is similar to the
2434      :term:`PRIVATE_LIBS` variable, which excludes a
2435      package's particular libraries only and not the whole package.
2436
2437      Use the :term:`EXCLUDE_FROM_SHLIBS` variable by setting it to "1" for a
2438      particular package::
2439
2440         EXCLUDE_FROM_SHLIBS = "1"
2441
2442   :term:`EXCLUDE_FROM_WORLD`
2443      Directs BitBake to exclude a recipe from world builds (i.e.
2444      ``bitbake world``). During world builds, BitBake locates, parses and
2445      builds all recipes found in every layer exposed in the
2446      ``bblayers.conf`` configuration file.
2447
2448      To exclude a recipe from a world build using this variable, set the
2449      variable to "1" in the recipe.
2450
2451      .. note::
2452
2453         Recipes added to :term:`EXCLUDE_FROM_WORLD` may still be built during a
2454         world build in order to satisfy dependencies of other recipes. Adding
2455         a recipe to :term:`EXCLUDE_FROM_WORLD` only ensures that the recipe is not
2456         explicitly added to the list of build targets in a world build.
2457
2458   :term:`EXTENDPE`
2459      Used with file and pathnames to create a prefix for a recipe's
2460      version based on the recipe's :term:`PE` value. If :term:`PE`
2461      is set and greater than zero for a recipe, :term:`EXTENDPE` becomes that
2462      value (e.g if :term:`PE` is equal to "1" then :term:`EXTENDPE` becomes "1").
2463      If a recipe's :term:`PE` is not set (the default) or is equal to zero,
2464      :term:`EXTENDPE` becomes "".
2465
2466      See the :term:`STAMP` variable for an example.
2467
2468   :term:`EXTENDPKGV`
2469      The full package version specification as it appears on the final
2470      packages produced by a recipe. The variable's value is normally used
2471      to fix a runtime dependency to the exact same version of another
2472      package in the same recipe::
2473
2474         RDEPENDS:${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
2475
2476      The dependency relationships are intended to force the package
2477      manager to upgrade these types of packages in lock-step.
2478
2479   :term:`EXTERNAL_KERNEL_TOOLS`
2480      When set, the :term:`EXTERNAL_KERNEL_TOOLS` variable indicates that these
2481      tools are not in the source tree.
2482
2483      When kernel tools are available in the tree, they are preferred over
2484      any externally installed tools. Setting the :term:`EXTERNAL_KERNEL_TOOLS`
2485      variable tells the OpenEmbedded build system to prefer the installed
2486      external tools. See the :ref:`ref-classes-kernel-yocto` class in
2487      ``meta/classes-recipe`` to see how the variable is used.
2488
2489   :term:`KERNEL_LOCALVERSION`
2490      This variable allows to append a string to the version
2491      of the kernel image. This corresponds to the ``CONFIG_LOCALVERSION``
2492      kernel configuration parameter.
2493
2494      Using this variable is only useful when you are using a kernel recipe
2495      inheriting the :ref:`ref-classes-kernel` class, and which doesn't
2496      already set a local version. Therefore, setting this variable has no
2497      impact on ``linux-yocto`` kernels.
2498
2499   :term:`EXTERNAL_TOOLCHAIN`
2500      When you intend to use an
2501      :ref:`external toolchain <dev-manual/external-toolchain:optionally using an external toolchain>`,
2502      this variable allows to specify the directory where this toolchain was
2503      installed.
2504
2505   :term:`EXTERNALSRC`
2506      When inheriting the :ref:`ref-classes-externalsrc`
2507      class, this variable points to the source tree, which is outside of
2508      the OpenEmbedded build system. When set, this variable sets the
2509      :term:`S` variable, which is what the OpenEmbedded build
2510      system uses to locate unpacked recipe source code.
2511
2512      See the ":ref:`ref-classes-externalsrc`" section for details. You
2513      can also find information on how to use this variable in the
2514      ":ref:`dev-manual/building:building software from an external source`"
2515      section in the Yocto Project Development Tasks Manual.
2516
2517   :term:`EXTERNALSRC_BUILD`
2518      When inheriting the :ref:`ref-classes-externalsrc`
2519      class, this variable points to the directory in which the recipe's
2520      source code is built, which is outside of the OpenEmbedded build
2521      system. When set, this variable sets the :term:`B` variable,
2522      which is what the OpenEmbedded build system uses to locate the
2523      :term:`Build Directory`.
2524
2525      See the ":ref:`ref-classes-externalsrc`" section for details. You
2526      can also find information on how to use this variable in the
2527      ":ref:`dev-manual/building:building software from an external source`"
2528      section in the Yocto Project Development Tasks Manual.
2529
2530   :term:`EXTRA_AUTORECONF`
2531      For recipes inheriting the :ref:`ref-classes-autotools`
2532      class, you can use :term:`EXTRA_AUTORECONF` to specify extra options to
2533      pass to the ``autoreconf`` command that is executed during the
2534      :ref:`ref-tasks-configure` task.
2535
2536      The default value is "--exclude=autopoint".
2537
2538   :term:`EXTRA_IMAGE_FEATURES`
2539      A list of additional features to include in an image. When listing
2540      more than one feature, separate them with a space.
2541
2542      Typically, you configure this variable in your ``local.conf`` file,
2543      which is found in the :term:`Build Directory`. Although you can use this
2544      variable from within a recipe, best practices dictate that you do not.
2545
2546      .. note::
2547
2548         To enable primary features from within the image recipe, use the
2549         :term:`IMAGE_FEATURES` variable.
2550
2551      Here are some examples of features you can add:
2552
2553        - "dbg-pkgs" --- adds -dbg packages for all installed packages including
2554          symbol information for debugging and profiling.
2555
2556        - "debug-tweaks" --- makes an image suitable for debugging. For example, allows root logins without passwords and
2557          enables post-installation logging. See the 'allow-empty-password' and
2558          'post-install-logging' features in the ":ref:`ref-features-image`"
2559          section for more information.
2560        - "dev-pkgs" --- adds -dev packages for all installed packages. This is
2561          useful if you want to develop against the libraries in the image.
2562        - "read-only-rootfs" --- creates an image whose root filesystem is
2563          read-only. See the
2564          ":ref:`dev-manual/read-only-rootfs:creating a read-only root filesystem`"
2565          section in the Yocto Project Development Tasks Manual for more
2566          information
2567        - "tools-debug" --- adds debugging tools such as gdb and strace.
2568        - "tools-sdk" --- adds development tools such as gcc, make,
2569          pkgconfig and so forth.
2570        - "tools-testapps" --- adds useful testing tools
2571          such as ts_print, aplay, arecord and so forth.
2572
2573      For a complete list of image features that ships with the Yocto
2574      Project, see the ":ref:`ref-features-image`" section.
2575
2576      For an example that shows how to customize your image by using this
2577      variable, see the ":ref:`dev-manual/customizing-images:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
2578      section in the Yocto Project Development Tasks Manual.
2579
2580   :term:`EXTRA_IMAGECMD`
2581      Specifies additional options for the image creation command that has
2582      been specified in :term:`IMAGE_CMD`. When setting
2583      this variable, use an override for the associated image type. Here is
2584      an example::
2585
2586         EXTRA_IMAGECMD:ext3 ?= "-i 4096"
2587
2588   :term:`EXTRA_IMAGEDEPENDS`
2589      A list of recipes to build that do not provide packages for
2590      installing into the root filesystem.
2591
2592      Sometimes a recipe is required to build the final image but is not
2593      needed in the root filesystem. You can use the :term:`EXTRA_IMAGEDEPENDS`
2594      variable to list these recipes and thus specify the dependencies. A
2595      typical example is a required bootloader in a machine configuration.
2596
2597      .. note::
2598
2599         To add packages to the root filesystem, see the various
2600         :term:`RDEPENDS` and :term:`RRECOMMENDS` variables.
2601
2602   :term:`EXTRA_OECMAKE`
2603      Additional `CMake <https://cmake.org/overview/>`__ options. See the
2604      :ref:`ref-classes-cmake` class for additional information.
2605
2606   :term:`EXTRA_OECONF`
2607      Additional ``configure`` script options. See
2608      :term:`PACKAGECONFIG_CONFARGS` for
2609      additional information on passing configure script options.
2610
2611   :term:`EXTRA_OEMAKE`
2612      Additional GNU ``make`` options.
2613
2614      Because the :term:`EXTRA_OEMAKE` defaults to "", you need to set the
2615      variable to specify any required GNU options.
2616
2617      :term:`PARALLEL_MAKE` and
2618      :term:`PARALLEL_MAKEINST` also make use of
2619      :term:`EXTRA_OEMAKE` to pass the required flags.
2620
2621   :term:`EXTRA_OESCONS`
2622      When inheriting the :ref:`ref-classes-scons` class, this
2623      variable specifies additional configuration options you want to pass
2624      to the ``scons`` command line.
2625
2626   :term:`EXTRA_OEMESON`
2627      Additional `Meson <https://mesonbuild.com/>`__ options. See the
2628      :ref:`ref-classes-meson` class for additional information.
2629
2630      In addition to standard Meson options, such options correspond to
2631      `Meson build options <https://mesonbuild.com/Build-options.html>`__
2632      defined in the ``meson_options.txt`` file in the sources to build.
2633      Here is an example::
2634
2635         EXTRA_OEMESON = "-Dpython=disabled -Dvalgrind=disabled"
2636
2637      Note that any custom value for the Meson ``--buildtype`` option
2638      should be set through the :term:`MESON_BUILDTYPE` variable.
2639
2640   :term:`EXTRA_USERS_PARAMS`
2641      When inheriting the :ref:`ref-classes-extrausers`
2642      class, this variable provides image level user and group operations.
2643      This is a more global method of providing user and group
2644      configuration as compared to using the
2645      :ref:`ref-classes-useradd` class, which ties user and
2646      group configurations to a specific recipe.
2647
2648      The set list of commands you can configure using the
2649      :term:`EXTRA_USERS_PARAMS` is shown in the
2650      :ref:`ref-classes-extrausers` class. These commands map to the normal
2651      Unix commands of the same names::
2652
2653         # EXTRA_USERS_PARAMS = "\
2654         # useradd -p '' tester; \
2655         # groupadd developers; \
2656         # userdel nobody; \
2657         # groupdel -g video; \
2658         # groupmod -g 1020 developers; \
2659         # usermod -s /bin/sh tester; \
2660         # "
2661
2662      Hardcoded passwords are supported via the ``-p`` parameters for
2663      ``useradd`` or ``usermod``, but only hashed.
2664
2665      Here is an example that adds two users named "tester-jim" and "tester-sue" and assigns
2666      passwords. First on host, create the (escaped) password hash::
2667
2668         printf "%q" $(mkpasswd -m sha256crypt tester01)
2669
2670      The resulting hash is set to a variable and used in ``useradd`` command parameters::
2671
2672         inherit extrausers
2673         PASSWD = "\$X\$ABC123\$A-Long-Hash"
2674         EXTRA_USERS_PARAMS = "\
2675             useradd -p '${PASSWD}' tester-jim; \
2676             useradd -p '${PASSWD}' tester-sue; \
2677             "
2678
2679      Finally, here is an example that sets the root password::
2680
2681         inherit extrausers
2682         EXTRA_USERS_PARAMS = "\
2683             usermod -p '${PASSWD}' root; \
2684             "
2685
2686      .. note::
2687
2688         From a security perspective, hardcoding a default password is not
2689         generally a good idea or even legal in some jurisdictions. It is
2690         recommended that you do not do this if you are building a production
2691         image.
2692
2693      Additionally there is a special ``passwd-expire`` command that will
2694      cause the password for a user to be expired and thus force changing it
2695      on first login, for example::
2696
2697         EXTRA_USERS_PARAMS += " useradd myuser; passwd-expire myuser;"
2698
2699      .. note::
2700
2701         At present, ``passwd-expire`` may only work for remote logins when
2702         using OpenSSH and not dropbear as an SSH server.
2703
2704   :term:`EXTRANATIVEPATH`
2705      A list of subdirectories of
2706      ``${``\ :term:`STAGING_BINDIR_NATIVE`\ ``}``
2707      added to the beginning of the environment variable ``PATH``. As an
2708      example, the following prepends
2709      "${STAGING_BINDIR_NATIVE}/foo:${STAGING_BINDIR_NATIVE}/bar:" to
2710      ``PATH``::
2711
2712         EXTRANATIVEPATH = "foo bar"
2713
2714   :term:`FAKEROOT`
2715      See :term:`bitbake:FAKEROOT` in the BitBake manual.
2716
2717   :term:`FAKEROOTBASEENV`
2718      See :term:`bitbake:FAKEROOTBASEENV` in the BitBake manual.
2719
2720   :term:`FAKEROOTCMD`
2721      See :term:`bitbake:FAKEROOTCMD` in the BitBake manual.
2722
2723   :term:`FAKEROOTDIRS`
2724      See :term:`bitbake:FAKEROOTDIRS` in the BitBake manual.
2725
2726   :term:`FAKEROOTENV`
2727      See :term:`bitbake:FAKEROOTENV` in the BitBake manual.
2728
2729   :term:`FAKEROOTNOENV`
2730      See :term:`bitbake:FAKEROOTNOENV` in the BitBake manual.
2731
2732   :term:`FEATURE_PACKAGES`
2733      Defines one or more packages to include in an image when a specific
2734      item is included in :term:`IMAGE_FEATURES`.
2735      When setting the value, :term:`FEATURE_PACKAGES` should have the name of
2736      the feature item as an override. Here is an example::
2737
2738         FEATURE_PACKAGES_widget = "package1 package2"
2739
2740      In this example, if "widget" were added to :term:`IMAGE_FEATURES`,
2741      package1 and package2 would be included in the image.
2742
2743      .. note::
2744
2745         Packages installed by features defined through :term:`FEATURE_PACKAGES`
2746         are often package groups. While similarly named, you should not
2747         confuse the :term:`FEATURE_PACKAGES` variable with package groups, which
2748         are discussed elsewhere in the documentation.
2749
2750   :term:`FEED_DEPLOYDIR_BASE_URI`
2751      Points to the base URL of the server and location within the
2752      document-root that provides the metadata and packages required by
2753      OPKG to support runtime package management of IPK packages. You set
2754      this variable in your ``local.conf`` file.
2755
2756      Consider the following example::
2757
2758         FEED_DEPLOYDIR_BASE_URI = "http://192.168.7.1/BOARD-dir"
2759
2760      This example assumes you are serving
2761      your packages over HTTP and your databases are located in a directory
2762      named ``BOARD-dir``, which is underneath your HTTP server's
2763      document-root. In this case, the OpenEmbedded build system generates
2764      a set of configuration files for you in your target that work with
2765      the feed.
2766
2767   :term:`FETCHCMD`
2768      See :term:`bitbake:FETCHCMD` in the BitBake manual.
2769
2770   :term:`FILE`
2771      See :term:`bitbake:FILE` in the BitBake manual.
2772
2773   :term:`FILES`
2774      The list of files and directories that are placed in a package. The
2775      :term:`PACKAGES` variable lists the packages
2776      generated by a recipe.
2777
2778      To use the :term:`FILES` variable, provide a package name override that
2779      identifies the resulting package. Then, provide a space-separated
2780      list of files or paths that identify the files you want included as
2781      part of the resulting package. Here is an example::
2782
2783         FILES:${PN} += "${bindir}/mydir1 ${bindir}/mydir2/myfile"
2784
2785      .. note::
2786
2787         -  When specifying files or paths, you can pattern match using
2788            Python's
2789            `glob <https://docs.python.org/3/library/glob.html>`__
2790            syntax. For details on the syntax, see the documentation by
2791            following the previous link.
2792
2793         -  When specifying paths as part of the :term:`FILES` variable, it is
2794            good practice to use appropriate path variables. For example,
2795            use ``${sysconfdir}`` rather than ``/etc``, or ``${bindir}``
2796            rather than ``/usr/bin``. You can find a list of these
2797            variables at the top of the ``meta/conf/bitbake.conf`` file in
2798            the :term:`Source Directory`. You will also
2799            find the default values of the various ``FILES:*`` variables in
2800            this file.
2801
2802      If some of the files you provide with the :term:`FILES` variable are
2803      editable and you know they should not be overwritten during the
2804      package update process by the Package Management System (PMS), you
2805      can identify these files so that the PMS will not overwrite them. See
2806      the :term:`CONFFILES` variable for information on
2807      how to identify these files to the PMS.
2808
2809   :term:`FILES_SOLIBSDEV`
2810      Defines the file specification to match
2811      :term:`SOLIBSDEV`. In other words,
2812      :term:`FILES_SOLIBSDEV` defines the full path name of the development
2813      symbolic link (symlink) for shared libraries on the target platform.
2814
2815      The following statement from the ``bitbake.conf`` shows how it is
2816      set::
2817
2818         FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}"
2819
2820   :term:`FILESEXTRAPATHS`
2821      A colon-separated list to extend the search path the OpenEmbedded build
2822      system uses when looking for files and patches as it processes recipes
2823      and append files. The default directories BitBake uses when it processes
2824      recipes are initially defined by the :term:`FILESPATH` variable. You can
2825      extend :term:`FILESPATH` variable by using :term:`FILESEXTRAPATHS`.
2826
2827      Best practices dictate that you accomplish this by using
2828      :term:`FILESEXTRAPATHS` from within a ``.bbappend`` file and that you
2829      prepend paths as follows::
2830
2831         FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
2832
2833      In the above example, the build system first
2834      looks for files in a directory that has the same name as the
2835      corresponding append file.
2836
2837      .. note::
2838
2839         When extending :term:`FILESEXTRAPATHS`, be sure to use the immediate
2840         expansion (``:=``) operator. Immediate expansion makes sure that
2841         BitBake evaluates :term:`THISDIR` at the time the
2842         directive is encountered rather than at some later time when
2843         expansion might result in a directory that does not contain the
2844         files you need.
2845
2846         Also, include the trailing separating colon character if you are
2847         prepending. The trailing colon character is necessary because you
2848         are directing BitBake to extend the path by prepending directories
2849         to the search path.
2850
2851      Here is another common use::
2852
2853         FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
2854
2855      In this example, the build system extends the
2856      :term:`FILESPATH` variable to include a directory named ``files`` that is
2857      in the same directory as the corresponding append file.
2858
2859      This next example specifically adds three paths::
2860
2861         FILESEXTRAPATHS:prepend := "path_1:path_2:path_3:"
2862
2863      A final example shows how you can extend the search path and include
2864      a :term:`MACHINE`-specific override, which is useful
2865      in a BSP layer::
2866
2867          FILESEXTRAPATHS:prepend:intel-x86-common := "${THISDIR}/${PN}:"
2868
2869      The previous statement appears in the
2870      ``linux-yocto-dev.bbappend`` file, which is found in the
2871      :ref:`overview-manual/development-environment:yocto project source repositories` in
2872      ``meta-intel/common/recipes-kernel/linux``. Here, the machine
2873      override is a special :term:`PACKAGE_ARCH`
2874      definition for multiple ``meta-intel`` machines.
2875
2876      .. note::
2877
2878         For a layer that supports a single BSP, the override could just be
2879         the value of :term:`MACHINE`.
2880
2881      By prepending paths in ``.bbappend`` files, you allow multiple append
2882      files that reside in different layers but are used for the same
2883      recipe to correctly extend the path.
2884
2885   :term:`FILESOVERRIDES`
2886      A colon-separated list to specify a subset of :term:`OVERRIDES` used by
2887      the OpenEmbedded build system for creating :term:`FILESPATH`. The
2888      :term:`FILESOVERRIDES` variable uses overrides to automatically extend
2889      the :term:`FILESPATH` variable. For an example of how that works, see the
2890      :term:`FILESPATH` variable description. Additionally, you find more
2891      information on how overrides are handled in the
2892      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
2893      section of the BitBake User Manual.
2894
2895      By default, the :term:`FILESOVERRIDES` variable is defined as::
2896
2897         FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
2898
2899      .. note::
2900
2901         Do not hand-edit the :term:`FILESOVERRIDES` variable. The values match up
2902         with expected overrides and are used in an expected manner by the
2903         build system.
2904
2905   :term:`FILESPATH`
2906      A colon-separated list specifying the default set of directories the
2907      OpenEmbedded build system uses when searching for patches and files.
2908
2909      During the build process, BitBake searches each directory in
2910      :term:`FILESPATH` in the specified order when looking for files and
2911      patches specified by each ``file://`` URI in a recipe's
2912      :term:`SRC_URI` statements.
2913
2914      The default value for the :term:`FILESPATH` variable is defined in the
2915      :ref:`ref-classes-base` class found in ``meta/classes-global`` in the
2916      :term:`Source Directory`::
2917
2918         FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
2919             "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
2920
2921      The
2922      :term:`FILESPATH` variable is automatically extended using the overrides
2923      from the :term:`FILESOVERRIDES` variable.
2924
2925      .. note::
2926
2927         -  Do not hand-edit the :term:`FILESPATH` variable. If you want the
2928            build system to look in directories other than the defaults,
2929            extend the :term:`FILESPATH` variable by using the
2930            :term:`FILESEXTRAPATHS` variable.
2931
2932         -  Be aware that the default :term:`FILESPATH` directories do not map
2933            to directories in custom layers where append files
2934            (``.bbappend``) are used. If you want the build system to find
2935            patches or files that reside with your append files, you need
2936            to extend the :term:`FILESPATH` variable by using the
2937            :term:`FILESEXTRAPATHS` variable.
2938
2939      You can take advantage of this searching behavior in useful ways. For
2940      example, consider a case where there is the following directory structure
2941      for general and machine-specific configurations::
2942
2943         files/defconfig
2944         files/MACHINEA/defconfig
2945         files/MACHINEB/defconfig
2946
2947      Also in the example, the :term:`SRC_URI` statement contains
2948      "file://defconfig". Given this scenario, you can set
2949      :term:`MACHINE` to "MACHINEA" and cause the build
2950      system to use files from ``files/MACHINEA``. Set :term:`MACHINE` to
2951      "MACHINEB" and the build system uses files from ``files/MACHINEB``.
2952      Finally, for any machine other than "MACHINEA" and "MACHINEB", the
2953      build system uses files from ``files/defconfig``.
2954
2955      You can find out more about the patching process in the
2956      ":ref:`overview-manual/concepts:patching`" section
2957      in the Yocto Project Overview and Concepts Manual and the
2958      ":ref:`dev-manual/new-recipe:patching code`" section in
2959      the Yocto Project Development Tasks Manual. See the
2960      :ref:`ref-tasks-patch` task as well.
2961
2962   :term:`FILESYSTEM_PERMS_TABLES`
2963      Allows you to define your own file permissions settings table as part
2964      of your configuration for the packaging process. For example, suppose
2965      you need a consistent set of custom permissions for a set of groups
2966      and users across an entire work project. It is best to do this in the
2967      packages themselves but this is not always possible.
2968
2969      By default, the OpenEmbedded build system uses the ``fs-perms.txt``,
2970      which is located in the ``meta/files`` folder in the :term:`Source Directory`.
2971      If you create your own file
2972      permissions setting table, you should place it in your layer or the
2973      distro's layer.
2974
2975      You define the :term:`FILESYSTEM_PERMS_TABLES` variable in the
2976      ``conf/local.conf`` file, which is found in the :term:`Build Directory`,
2977      to point to your custom ``fs-perms.txt``. You can specify more than a
2978      single file permissions setting table. The paths you specify to these
2979      files must be defined within the :term:`BBPATH` variable.
2980
2981      For guidance on how to create your own file permissions settings
2982      table file, examine the existing ``fs-perms.txt``.
2983
2984   :term:`FIT_ADDRESS_CELLS`
2985      Specifies the value of the ``#address-cells`` value for the
2986      description of the FIT image.
2987
2988      The default value is set to "1" by the :ref:`ref-classes-kernel-fitimage`
2989      class, which corresponds to 32 bit addresses.
2990
2991      For platforms that need to set 64 bit addresses, for example in
2992      :term:`UBOOT_LOADADDRESS` and :term:`UBOOT_ENTRYPOINT`, you need to
2993      set this value to "2", as two 32 bit values (cells) will be needed
2994      to represent such addresses.
2995
2996      Here is an example setting "0x400000000" as a load address::
2997
2998         FIT_ADDRESS_CELLS = "2"
2999         UBOOT_LOADADDRESS= "0x04 0x00000000"
3000
3001      See `more details about #address-cells <https://elinux.org/Device_Tree_Usage#How_Addressing_Works>`__.
3002
3003   :term:`FIT_CONF_DEFAULT_DTB`
3004      Specifies the default device tree binary (dtb) file for a FIT image
3005      when multiple ones are provided.
3006
3007      This variable is used in the :ref:`ref-classes-kernel-fitimage` class.
3008
3009   :term:`FIT_DESC`
3010      Specifies the description string encoded into a FIT image. The
3011      default value is set by the :ref:`ref-classes-kernel-fitimage` class as
3012      follows::
3013
3014         FIT_DESC ?= "U-Boot fitImage for ${DISTRO_NAME}/${PV}/${MACHINE}"
3015
3016   :term:`FIT_GENERATE_KEYS`
3017      Decides whether to generate the keys for signing the FIT image if
3018      they don't already exist. The keys are created in
3019      :term:`UBOOT_SIGN_KEYDIR`. The default value is set to "0"
3020      by the :ref:`ref-classes-kernel-fitimage` class.
3021
3022   :term:`FIT_HASH_ALG`
3023      Specifies the hash algorithm used in creating the FIT Image.
3024      This variable is set by default to "sha256" by the
3025      :ref:`ref-classes-kernel-fitimage` class.
3026
3027   :term:`FIT_KERNEL_COMP_ALG`
3028      The compression algorithm to use for the kernel image inside the FIT Image.
3029      At present, the only supported values are "gzip" (default), "lzo" or "none".
3030      If you set this variable to anything other than "none" you may also need
3031      to set :term:`FIT_KERNEL_COMP_ALG_EXTENSION`.
3032
3033      This variable is used in the :ref:`ref-classes-kernel-uboot` class.
3034
3035   :term:`FIT_KERNEL_COMP_ALG_EXTENSION`
3036      File extension corresponding to :term:`FIT_KERNEL_COMP_ALG`. The default
3037      value is set ".gz" by the :ref:`ref-classes-kernel-uboot` class. If you
3038      set :term:`FIT_KERNEL_COMP_ALG` to "lzo", you may want to set this
3039      variable to ".lzo".
3040
3041   :term:`FIT_KEY_GENRSA_ARGS`
3042      Arguments to ``openssl genrsa`` for generating a RSA private key for
3043      signing the FIT image. The default value is set to "-F4" by the
3044      :ref:`ref-classes-kernel-fitimage` class.
3045
3046   :term:`FIT_KEY_REQ_ARGS`
3047      Arguments to ``openssl req`` for generating a certificate for signing
3048      the FIT image. The default value is "-batch -new" by the
3049      :ref:`ref-classes-kernel-fitimage` class, "batch" for
3050      non interactive mode and "new" for generating new keys.
3051
3052   :term:`FIT_KEY_SIGN_PKCS`
3053      Format for the public key certificate used for signing the FIT image.
3054      The default value is set to "x509" by the
3055      :ref:`ref-classes-kernel-fitimage` class.
3056
3057   :term:`FIT_SIGN_ALG`
3058      Specifies the signature algorithm used in creating the FIT Image.
3059      This variable is set by default to "rsa2048" by the
3060      :ref:`ref-classes-kernel-fitimage` class.
3061
3062   :term:`FIT_PAD_ALG`
3063      Specifies the padding algorithm used in creating the FIT Image.
3064      The default value is set to "pkcs-1.5" by the
3065      :ref:`ref-classes-kernel-fitimage` class.
3066
3067   :term:`FIT_SIGN_INDIVIDUAL`
3068      If set to "1", then the :ref:`ref-classes-kernel-fitimage`
3069      class will sign the kernel, dtb and ramdisk images individually in addition
3070      to signing the FIT image itself. This could be useful if you are
3071      intending to verify signatures in another context than booting via
3072      U-Boot.
3073
3074      This variable is set to "0" by default.
3075
3076   :term:`FIT_SIGN_NUMBITS`
3077      Size of the private key used in the FIT image, in number of bits.
3078      The default value for this variable is set to "2048"
3079      by the :ref:`ref-classes-kernel-fitimage` class.
3080
3081   :term:`FONT_EXTRA_RDEPENDS`
3082      When inheriting the :ref:`ref-classes-fontcache` class,
3083      this variable specifies the runtime dependencies for font packages.
3084      By default, the :term:`FONT_EXTRA_RDEPENDS` is set to "fontconfig-utils".
3085
3086   :term:`FONT_PACKAGES`
3087      When inheriting the :ref:`ref-classes-fontcache` class, this variable
3088      identifies packages containing font files that need to be cached by
3089      Fontconfig. By default, the :ref:`ref-classes-fontcache` class assumes
3090      that fonts are in the recipe's main package (i.e.
3091      ``${``\ :term:`PN`\ ``}``). Use this variable if fonts you
3092      need are in a package other than that main package.
3093
3094   :term:`FORCE_RO_REMOVE`
3095      Forces the removal of the packages listed in ``ROOTFS_RO_UNNEEDED``
3096      during the generation of the root filesystem.
3097
3098      Set the variable to "1" to force the removal of these packages.
3099
3100   :term:`FULL_OPTIMIZATION`
3101      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
3102      compiling an optimized system. This variable defaults to "-O2 -pipe
3103      ${DEBUG_FLAGS}".
3104
3105   :term:`GCCPIE`
3106      Enables Position Independent Executables (PIE) within the GNU C
3107      Compiler (GCC). Enabling PIE in the GCC makes Return Oriented
3108      Programming (ROP) attacks much more difficult to execute.
3109
3110      By default the ``security_flags.inc`` file enables PIE by setting the
3111      variable as follows::
3112
3113         GCCPIE ?= "--enable-default-pie"
3114
3115   :term:`GCCVERSION`
3116      Specifies the default version of the GNU C Compiler (GCC) used for
3117      compilation. By default, :term:`GCCVERSION` is set to "8.x" in the
3118      ``meta/conf/distro/include/tcmode-default.inc`` include file::
3119
3120         GCCVERSION ?= "8.%"
3121
3122      You can override this value by setting it in a
3123      configuration file such as the ``local.conf``.
3124
3125   :term:`GDB`
3126      The minimal command and arguments to run the GNU Debugger.
3127
3128   :term:`GIR_EXTRA_LIBS_PATH`
3129      Allows to specify an extra search path for ``.so`` files
3130      in GLib related recipes using GObject introspection,
3131      and which do not compile without this setting.
3132      See the ":ref:`dev-manual/gobject-introspection:enabling gobject introspection support`"
3133      section for details.
3134
3135   :term:`GITDIR`
3136      The directory in which a local copy of a Git repository is stored
3137      when it is cloned.
3138
3139   :term:`GITHUB_BASE_URI`
3140      When inheriting the :ref:`ref-classes-github-releases`
3141      class, specifies the base URL for fetching releases for the github
3142      project you wish to fetch sources from. The default value is as follows::
3143
3144         GITHUB_BASE_URI ?= "https://github.com/${BPN}/${BPN}/releases/"
3145
3146   :term:`GLIBC_GENERATE_LOCALES`
3147      Specifies the list of GLIBC locales to generate should you not wish
3148      to generate all LIBC locals, which can be time consuming.
3149
3150      .. note::
3151
3152         If you specifically remove the locale ``en_US.UTF-8``, you must set
3153         :term:`IMAGE_LINGUAS` appropriately.
3154
3155      You can set :term:`GLIBC_GENERATE_LOCALES` in your ``local.conf`` file.
3156      By default, all locales are generated::
3157
3158         GLIBC_GENERATE_LOCALES = "en_GB.UTF-8 en_US.UTF-8"
3159
3160   :term:`GO_IMPORT`
3161      When inheriting the :ref:`ref-classes-go` class, this mandatory variable
3162      sets the import path for the Go package that will be created for the code
3163      to build. If you have a ``go.mod`` file in the source directory, this
3164      typically matches the path in the ``module`` line in this file.
3165
3166      Other Go programs importing this package will use this path.
3167
3168      Here is an example setting from the
3169      :yocto_git:`go-helloworld_0.1.bb </poky/tree/meta/recipes-extended/go-examples/go-helloworld_0.1.bb>`
3170      recipe::
3171
3172          GO_IMPORT = "golang.org/x/example"
3173
3174   :term:`GO_INSTALL`
3175      When inheriting the :ref:`ref-classes-go` class, this optional variable
3176      specifies which packages in the sources should be compiled and
3177      installed in the Go build space by the
3178      `go install <https://go.dev/ref/mod#go-install>`__ command.
3179
3180      Here is an example setting from the
3181      :oe_git:`crucible </meta-openembedded/tree/meta-oe/recipes-support/crucible/>`
3182      recipe::
3183
3184         GO_INSTALL = "\
3185             ${GO_IMPORT}/cmd/crucible \
3186             ${GO_IMPORT}/cmd/habtool \
3187         "
3188
3189      By default, :term:`GO_INSTALL` is defined as::
3190
3191         GO_INSTALL ?= "${GO_IMPORT}/..."
3192
3193      The ``...`` wildcard means that it will catch all
3194      packages found in the sources.
3195
3196      See the :term:`GO_INSTALL_FILTEROUT` variable for
3197      filtering out unwanted packages from the ones
3198      found from the :term:`GO_INSTALL` value.
3199
3200   :term:`GO_INSTALL_FILTEROUT`
3201      When using the Go "vendor" mechanism to bring in dependencies for a Go
3202      package, the default :term:`GO_INSTALL` setting, which uses the ``...``
3203      wildcard, will include the vendored packages in the build, which produces
3204      incorrect results.
3205
3206      There are also some Go packages that are structured poorly, so that the
3207      ``...`` wildcard results in building example or test code that should not
3208      be included in the build, or could fail to build.
3209
3210      This optional variable allows for filtering out a subset of the sources.
3211      It defaults to excluding everything under the ``vendor`` subdirectory
3212      under package's main directory. This is the normal location for vendored
3213      packages, but it can be overridden by a recipe to filter out other
3214      subdirectories if needed.
3215
3216   :term:`GO_WORKDIR`
3217      When using Go Modules, the current working directory must be the directory
3218      containing the ``go.mod`` file, or one of its subdirectories. When the
3219      ``go`` tool is used, it will automatically look for the ``go.mod`` file
3220      in the Go working directory or in any parent directory, but not in
3221      subdirectories.
3222
3223      When using the :ref:`ref-classes-go-mod` class to use Go modules,
3224      the optional :term:`GO_WORKDIR` variable, defaulting to the value
3225      of :term:`GO_IMPORT`, allows to specify a different Go working directory.
3226
3227   :term:`GROUPADD_PARAM`
3228      When inheriting the :ref:`ref-classes-useradd` class,
3229      this variable specifies for a package what parameters should be
3230      passed to the ``groupadd`` command if you wish to add a group to the
3231      system when the package is installed.
3232
3233      Here is an example from the ``dbus`` recipe::
3234
3235         GROUPADD_PARAM:${PN} = "-r netdev"
3236
3237      For information on the standard Linux shell command
3238      ``groupadd``, see https://linux.die.net/man/8/groupadd.
3239
3240   :term:`GROUPMEMS_PARAM`
3241      When inheriting the :ref:`ref-classes-useradd` class,
3242      this variable specifies for a package what parameters should be
3243      passed to the ``groupmems`` command if you wish to modify the members
3244      of a group when the package is installed.
3245
3246      For information on the standard Linux shell command ``groupmems``,
3247      see https://linux.die.net/man/8/groupmems.
3248
3249   :term:`GRUB_GFXSERIAL`
3250      Configures the GNU GRand Unified Bootloader (GRUB) to have graphics
3251      and serial in the boot menu. Set this variable to "1" in your
3252      ``local.conf`` or distribution configuration file to enable graphics
3253      and serial in the menu.
3254
3255      See the :ref:`ref-classes-grub-efi` class for more
3256      information on how this variable is used.
3257
3258   :term:`GRUB_OPTS`
3259      Additional options to add to the GNU GRand Unified Bootloader (GRUB)
3260      configuration. Use a semi-colon character (``;``) to separate
3261      multiple options.
3262
3263      The :term:`GRUB_OPTS` variable is optional. See the
3264      :ref:`ref-classes-grub-efi` class for more information
3265      on how this variable is used.
3266
3267   :term:`GRUB_TIMEOUT`
3268      Specifies the timeout before executing the default ``LABEL`` in the
3269      GNU GRand Unified Bootloader (GRUB).
3270
3271      The :term:`GRUB_TIMEOUT` variable is optional. See the
3272      :ref:`ref-classes-grub-efi` class for more information
3273      on how this variable is used.
3274
3275   :term:`GTKIMMODULES_PACKAGES`
3276      When inheriting the :ref:`ref-classes-gtk-immodules-cache` class,
3277      this variable specifies the packages that contain the GTK+ input
3278      method modules being installed when the modules are in packages other
3279      than the main package.
3280
3281   :term:`HGDIR`
3282      See :term:`bitbake:HGDIR` in the BitBake manual.
3283
3284   :term:`HOMEPAGE`
3285      Website where more information about the software the recipe is
3286      building can be found.
3287
3288   :term:`HOST_ARCH`
3289      The name of the target architecture, which is normally the same as
3290      :term:`TARGET_ARCH`. The OpenEmbedded build system
3291      supports many architectures. Here is an example list of architectures
3292      supported. This list is by no means complete as the architecture is
3293      configurable:
3294
3295      - arm
3296      - i586
3297      - x86_64
3298      - powerpc
3299      - powerpc64
3300      - mips
3301      - mipsel
3302
3303   :term:`HOST_CC_ARCH`
3304      Specifies architecture-specific compiler flags that are passed to the
3305      C compiler.
3306
3307      Default initialization for :term:`HOST_CC_ARCH` varies depending on what
3308      is being built:
3309
3310      -  :term:`TARGET_CC_ARCH` when building for the
3311         target
3312
3313      -  :term:`BUILD_CC_ARCH` when building for the build host (i.e.
3314         ``-native``)
3315
3316      -  ``BUILDSDK_CC_ARCH`` when building for an SDK (i.e.
3317         ``nativesdk-``)
3318
3319   :term:`HOST_OS`
3320      Specifies the name of the target operating system, which is normally
3321      the same as the :term:`TARGET_OS`. The variable can
3322      be set to "linux" for ``glibc``-based systems and to "linux-musl" for
3323      ``musl``. For ARM/EABI targets, there are also "linux-gnueabi" and
3324      "linux-musleabi" values possible.
3325
3326   :term:`HOST_PREFIX`
3327      Specifies the prefix for the cross-compile toolchain. :term:`HOST_PREFIX`
3328      is normally the same as :term:`TARGET_PREFIX`.
3329
3330   :term:`HOST_SYS`
3331      Specifies the system, including the architecture and the operating
3332      system, for which the build is occurring in the context of the
3333      current recipe.
3334
3335      The OpenEmbedded build system automatically sets this variable based
3336      on :term:`HOST_ARCH`,
3337      :term:`HOST_VENDOR`, and
3338      :term:`HOST_OS` variables.
3339
3340      .. note::
3341
3342         You do not need to set the variable yourself.
3343
3344      Consider these two examples:
3345
3346      -  Given a native recipe on a 32-bit x86 machine running Linux, the
3347         value is "i686-linux".
3348
3349      -  Given a recipe being built for a little-endian MIPS target running
3350         Linux, the value might be "mipsel-linux".
3351
3352   :term:`HOST_VENDOR`
3353      Specifies the name of the vendor. :term:`HOST_VENDOR` is normally the
3354      same as :term:`TARGET_VENDOR`.
3355
3356   :term:`HOSTTOOLS`
3357      A space-separated list (filter) of tools on the build host that
3358      should be allowed to be called from within build tasks. Using this
3359      filter helps reduce the possibility of host contamination. If a tool
3360      specified in the value of :term:`HOSTTOOLS` is not found on the build
3361      host, the OpenEmbedded build system produces an error and the build
3362      is not started.
3363
3364      For additional information, see
3365      :term:`HOSTTOOLS_NONFATAL`.
3366
3367   :term:`HOSTTOOLS_NONFATAL`
3368      A space-separated list (filter) of tools on the build host that
3369      should be allowed to be called from within build tasks. Using this
3370      filter helps reduce the possibility of host contamination. Unlike
3371      :term:`HOSTTOOLS`, the OpenEmbedded build system
3372      does not produce an error if a tool specified in the value of
3373      :term:`HOSTTOOLS_NONFATAL` is not found on the build host. Thus, you can
3374      use :term:`HOSTTOOLS_NONFATAL` to filter optional host tools.
3375
3376   :term:`ICECC_CLASS_DISABLE`
3377      Identifies user classes that you do not want the Icecream distributed
3378      compile support to consider. This variable is used by the
3379      :ref:`ref-classes-icecc` class. You set this variable in
3380      your ``local.conf`` file.
3381
3382      When you list classes using this variable, the recipes inheriting
3383      those classes will not benefit from distributed compilation across
3384      remote hosts. Instead they will be built locally.
3385
3386   :term:`ICECC_DISABLED`
3387      Disables or enables the ``icecc`` (Icecream) function. For more
3388      information on this function and best practices for using this
3389      variable, see the ":ref:`ref-classes-icecc`"
3390      section.
3391
3392      Setting this variable to "1" in your ``local.conf`` disables the
3393      function::
3394
3395         ICECC_DISABLED ??= "1"
3396
3397      To enable the function, set the variable as follows::
3398
3399         ICECC_DISABLED = ""
3400
3401   :term:`ICECC_ENV_EXEC`
3402      Points to the ``icecc-create-env`` script that you provide. This
3403      variable is used by the :ref:`ref-classes-icecc` class. You
3404      set this variable in your ``local.conf`` file.
3405
3406      If you do not point to a script that you provide, the OpenEmbedded
3407      build system uses the default script provided by the
3408      :oe_git:`icecc-create-env_0.1.bb
3409      </openembedded-core/tree/meta/recipes-devtools/icecc-create-env/icecc-create-env_0.1.bb>`
3410      recipe, which is a modified version and not the one that comes with
3411      ``icecream``.
3412
3413   :term:`ICECC_PARALLEL_MAKE`
3414      Extra options passed to the ``make`` command during the
3415      :ref:`ref-tasks-compile` task that specify parallel
3416      compilation. This variable usually takes the form of "-j x", where x
3417      represents the maximum number of parallel threads ``make`` can run.
3418
3419      .. note::
3420
3421         The options passed affect builds on all enabled machines on the
3422         network, which are machines running the ``iceccd`` daemon.
3423
3424      If your enabled machines support multiple cores, coming up with the
3425      maximum number of parallel threads that gives you the best
3426      performance could take some experimentation since machine speed,
3427      network lag, available memory, and existing machine loads can all
3428      affect build time. Consequently, unlike the
3429      :term:`PARALLEL_MAKE` variable, there is no
3430      rule-of-thumb for setting :term:`ICECC_PARALLEL_MAKE` to achieve optimal
3431      performance.
3432
3433      If you do not set :term:`ICECC_PARALLEL_MAKE`, the build system does not
3434      use it (i.e. the system does not detect and assign the number of
3435      cores as is done with :term:`PARALLEL_MAKE`).
3436
3437   :term:`ICECC_PATH`
3438      The location of the ``icecc`` binary. You can set this variable in
3439      your ``local.conf`` file. If your ``local.conf`` file does not define
3440      this variable, the :ref:`ref-classes-icecc` class attempts
3441      to define it by locating ``icecc`` using ``which``.
3442
3443   :term:`ICECC_RECIPE_DISABLE`
3444      Identifies user recipes that you do not want the Icecream distributed
3445      compile support to consider. This variable is used by the
3446      :ref:`ref-classes-icecc` class. You set this variable in
3447      your ``local.conf`` file.
3448
3449      When you list recipes using this variable, you are excluding them
3450      from distributed compilation across remote hosts. Instead they will
3451      be built locally.
3452
3453   :term:`ICECC_RECIPE_ENABLE`
3454      Identifies user recipes that use an empty
3455      :term:`PARALLEL_MAKE` variable that you want to
3456      force remote distributed compilation on using the Icecream
3457      distributed compile support. This variable is used by the
3458      :ref:`ref-classes-icecc` class. You set this variable in
3459      your ``local.conf`` file.
3460
3461   :term:`IMAGE_BASENAME`
3462      The base name of image output files. This variable defaults to the
3463      recipe name (``${``\ :term:`PN`\ ``}``).
3464
3465   :term:`IMAGE_BOOT_FILES`
3466      A space-separated list of files installed into the boot partition
3467      when preparing an image using the Wic tool with the
3468      ``bootimg-partition`` source plugin. By default,
3469      the files are
3470      installed under the same name as the source files. To change the
3471      installed name, separate it from the original name with a semi-colon
3472      (;). Source files need to be located in
3473      :term:`DEPLOY_DIR_IMAGE`. Here are two
3474      examples::
3475
3476         IMAGE_BOOT_FILES = "u-boot.img uImage;kernel"
3477         IMAGE_BOOT_FILES = "u-boot.${UBOOT_SUFFIX} ${KERNEL_IMAGETYPE}"
3478
3479      Alternatively, source files can be picked up using a glob pattern. In
3480      this case, the destination file must have the same name as the base
3481      name of the source file path. To install files into a directory
3482      within the target location, pass its name after a semi-colon (;).
3483      Here are two examples::
3484
3485         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*"
3486         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*;boot/"
3487
3488      The first example
3489      installs all files from ``${DEPLOY_DIR_IMAGE}/bcm2835-bootfiles``
3490      into the root of the target partition. The second example installs
3491      the same files into a ``boot`` directory within the target partition.
3492
3493      You can find information on how to use the Wic tool in the
3494      ":ref:`dev-manual/wic:creating partitioned images using wic`"
3495      section of the Yocto Project Development Tasks Manual. Reference
3496      material for Wic is located in the
3497      ":doc:`/ref-manual/kickstart`" chapter.
3498
3499   :term:`IMAGE_BUILDINFO_FILE`
3500      When using the :ref:`ref-classes-image-buildinfo` class,
3501      specifies the file in the image to write the build information into. The
3502      default value is "``${sysconfdir}/buildinfo``".
3503
3504   :term:`IMAGE_BUILDINFO_VARS`
3505      When using the :ref:`ref-classes-image-buildinfo` class,
3506      specifies the list of variables to include in the `Build Configuration`
3507      section of the output file (as a space-separated list). Defaults to
3508      ":term:`DISTRO` :term:`DISTRO_VERSION`".
3509
3510   :term:`IMAGE_CLASSES`
3511      A list of classes that all images should inherit. This is typically used
3512      to enable functionality across all image recipes.
3513
3514      Classes specified in :term:`IMAGE_CLASSES` must be located in the
3515      ``classes-recipe/`` or ``classes/`` subdirectories.
3516
3517   :term:`IMAGE_CMD`
3518      Specifies the command to create the image file for a specific image
3519      type, which corresponds to the value set in
3520      :term:`IMAGE_FSTYPES`, (e.g. ``ext3``,
3521      ``btrfs``, and so forth). When setting this variable, you should use
3522      an override for the associated type. Here is an example::
3523
3524         IMAGE_CMD:jffs2 = "mkfs.jffs2 --root=${IMAGE_ROOTFS} --faketime \
3525             --output=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.jffs2 \
3526             ${EXTRA_IMAGECMD}"
3527
3528      You typically do not need to set this variable unless you are adding
3529      support for a new image type. For more examples on how to set this
3530      variable, see the :ref:`ref-classes-image_types`
3531      class file, which is ``meta/classes-recipe/image_types.bbclass``.
3532
3533   :term:`IMAGE_DEVICE_TABLES`
3534      Specifies one or more files that contain custom device tables that
3535      are passed to the ``makedevs`` command as part of creating an image.
3536      These files list basic device nodes that should be created under
3537      ``/dev`` within the image. If :term:`IMAGE_DEVICE_TABLES` is not set,
3538      ``files/device_table-minimal.txt`` is used, which is located by
3539      :term:`BBPATH`. For details on how you should write
3540      device table files, see ``meta/files/device_table-minimal.txt`` as an
3541      example.
3542
3543   :term:`IMAGE_EFI_BOOT_FILES`
3544      A space-separated list of files installed into the boot partition
3545      when preparing an image using the Wic tool with the
3546      ``bootimg-efi`` source plugin. By default,
3547      the files are
3548      installed under the same name as the source files. To change the
3549      installed name, separate it from the original name with a semi-colon
3550      (;). Source files need to be located in
3551      :term:`DEPLOY_DIR_IMAGE`. Here are two
3552      examples::
3553
3554         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE};bz2"
3555         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE} microcode.cpio"
3556
3557      Alternatively, source files can be picked up using a glob pattern. In
3558      this case, the destination file must have the same name as the base
3559      name of the source file path. To install files into a directory
3560      within the target location, pass its name after a semi-colon (;).
3561      Here are two examples::
3562
3563         IMAGE_EFI_BOOT_FILES = "boot/loader/*"
3564         IMAGE_EFI_BOOT_FILES = "boot/loader/*;boot/"
3565
3566      The first example
3567      installs all files from ``${DEPLOY_DIR_IMAGE}/boot/loader/``
3568      into the root of the target partition. The second example installs
3569      the same files into a ``boot`` directory within the target partition.
3570
3571      You can find information on how to use the Wic tool in the
3572      ":ref:`dev-manual/wic:creating partitioned images using wic`"
3573      section of the Yocto Project Development Tasks Manual. Reference
3574      material for Wic is located in the
3575      ":doc:`/ref-manual/kickstart`" chapter.
3576
3577   :term:`IMAGE_FEATURES`
3578      The primary list of features to include in an image. Typically, you
3579      configure this variable in an image recipe. Although you can use this
3580      variable from your ``local.conf`` file, which is found in the
3581      :term:`Build Directory`, best practices dictate that you do
3582      not.
3583
3584      .. note::
3585
3586         To enable extra features from outside the image recipe, use the
3587         :term:`EXTRA_IMAGE_FEATURES` variable.
3588
3589      For a list of image features that ships with the Yocto Project, see
3590      the ":ref:`ref-features-image`" section.
3591
3592      For an example that shows how to customize your image by using this
3593      variable, see the ":ref:`dev-manual/customizing-images:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
3594      section in the Yocto Project Development Tasks Manual.
3595
3596   :term:`IMAGE_FSTYPES`
3597      Specifies the formats the OpenEmbedded build system uses during the
3598      build when creating the root filesystem. For example, setting
3599      :term:`IMAGE_FSTYPES` as follows causes the build system to create root
3600      filesystems using two formats: ``.ext3`` and ``.tar.bz2``::
3601
3602         IMAGE_FSTYPES = "ext3 tar.bz2"
3603
3604      For the complete list of supported image formats from which you can
3605      choose, see :term:`IMAGE_TYPES`.
3606
3607      .. note::
3608
3609         -  If an image recipe uses the "inherit image" line and you are
3610            setting :term:`IMAGE_FSTYPES` inside the recipe, you must set
3611            :term:`IMAGE_FSTYPES` prior to using the "inherit image" line.
3612
3613         -  Due to the way the OpenEmbedded build system processes this
3614            variable, you cannot update its contents by using ``:append``
3615            or ``:prepend``. You must use the ``+=`` operator to add one or
3616            more options to the :term:`IMAGE_FSTYPES` variable.
3617
3618   :term:`IMAGE_INSTALL`
3619      Used by recipes to specify the packages to install into an image
3620      through the :ref:`ref-classes-image` class. Use the
3621      :term:`IMAGE_INSTALL` variable with care to avoid ordering issues.
3622
3623      Image recipes set :term:`IMAGE_INSTALL` to specify the packages to
3624      install into an image through :ref:`ref-classes-image`. Additionally,
3625      there are "helper" classes such as the :ref:`ref-classes-core-image`
3626      class which can take lists used with :term:`IMAGE_FEATURES` and turn
3627      them into auto-generated entries in :term:`IMAGE_INSTALL` in addition
3628      to its default contents.
3629
3630      When you use this variable, it is best to use it as follows::
3631
3632         IMAGE_INSTALL:append = " package-name"
3633
3634      Be sure to include the space
3635      between the quotation character and the start of the package name or
3636      names.
3637
3638      .. note::
3639
3640         -  When working with a
3641            :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
3642            image, do not use the :term:`IMAGE_INSTALL` variable to specify
3643            packages for installation. Instead, use the
3644            :term:`PACKAGE_INSTALL` variable, which
3645            allows the initial RAM filesystem (:term:`Initramfs`) recipe to use a
3646            fixed set of packages and not be affected by :term:`IMAGE_INSTALL`.
3647            For information on creating an :term:`Initramfs`, see the
3648            ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`"
3649            section in the Yocto Project Development Tasks Manual.
3650
3651         -  Using :term:`IMAGE_INSTALL` with the
3652            :ref:`+= <bitbake-user-manual/bitbake-user-manual-metadata:appending (+=) and prepending (=+) with spaces>`
3653            BitBake operator within the ``/conf/local.conf`` file or from
3654            within an image recipe is not recommended. Use of this operator in
3655            these ways can cause ordering issues. Since
3656            :ref:`ref-classes-core-image` sets :term:`IMAGE_INSTALL` to a
3657            default value using the
3658            :ref:`?= <bitbake-user-manual/bitbake-user-manual-metadata:setting a default value (?=)>`
3659            operator, using a ``+=`` operation against :term:`IMAGE_INSTALL`
3660            results in unexpected behavior when used within
3661            ``conf/local.conf``. Furthermore, the same operation from within an
3662            image recipe may or may not succeed depending on the specific
3663            situation. In both these cases, the behavior is contrary to how
3664            most users expect the ``+=`` operator to work.
3665
3666   :term:`IMAGE_LINGUAS`
3667      Specifies the list of locales to install into the image during the
3668      root filesystem construction process. The OpenEmbedded build system
3669      automatically splits locale files, which are used for localization,
3670      into separate packages. Setting the :term:`IMAGE_LINGUAS` variable
3671      ensures that any locale packages that correspond to packages already
3672      selected for installation into the image are also installed. Here is
3673      an example::
3674
3675         IMAGE_LINGUAS = "pt-br de-de"
3676
3677      In this example, the build system ensures any Brazilian Portuguese
3678      and German locale files that correspond to packages in the image are
3679      installed (i.e. ``*-locale-pt-br`` and ``*-locale-de-de`` as well as
3680      ``*-locale-pt`` and ``*-locale-de``, since some software packages
3681      only provide locale files by language and not by country-specific
3682      language).
3683
3684      See the :term:`GLIBC_GENERATE_LOCALES`
3685      variable for information on generating GLIBC locales.
3686
3687
3688   :term:`IMAGE_LINK_NAME`
3689      The name of the output image symlink (which does not include
3690      the version part as :term:`IMAGE_NAME` does). The default value
3691      is derived using the :term:`IMAGE_BASENAME` and
3692      :term:`IMAGE_MACHINE_SUFFIX` variables::
3693
3694         IMAGE_LINK_NAME ?= "${IMAGE_BASENAME}${IMAGE_MACHINE_SUFFIX}"
3695
3696      .. note::
3697
3698         It is possible to set this to "" to disable symlink creation,
3699         however, you also need to set :term:`IMAGE_NAME` to still have
3700         a reasonable value e.g.::
3701
3702            IMAGE_LINK_NAME = ""
3703            IMAGE_NAME = "${IMAGE_BASENAME}${IMAGE_MACHINE_SUFFIX}${IMAGE_VERSION_SUFFIX}"
3704
3705   :term:`IMAGE_MACHINE_SUFFIX`
3706      Specifies the by default machine-specific suffix for image file names
3707      (before the extension). The default value is set as follows::
3708
3709         IMAGE_MACHINE_SUFFIX ??= "-${MACHINE}"
3710
3711      The default :term:`DEPLOY_DIR_IMAGE` already has a :term:`MACHINE`
3712      subdirectory, so you may find it unnecessary to also include this suffix
3713      in the name of every image file. If you prefer to remove the suffix you
3714      can set this variable to an empty string::
3715
3716         IMAGE_MACHINE_SUFFIX = ""
3717
3718      (Not to be confused with :term:`IMAGE_NAME_SUFFIX`.)
3719
3720   :term:`IMAGE_MANIFEST`
3721      The manifest file for the image. This file lists all the installed
3722      packages that make up the image. The file contains package
3723      information on a line-per-package basis as follows::
3724
3725          packagename packagearch version
3726
3727      The :ref:`rootfs-postcommands <ref-classes-rootfs*>` class defines the manifest
3728      file as follows::
3729
3730         IMAGE_MANIFEST ="${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.manifest"
3731
3732      The location is
3733      derived using the :term:`IMGDEPLOYDIR`
3734      and :term:`IMAGE_NAME` variables. You can find
3735      information on how the image is created in the ":ref:`overview-manual/concepts:image generation`"
3736      section in the Yocto Project Overview and Concepts Manual.
3737
3738   :term:`IMAGE_NAME`
3739      The name of the output image files minus the extension. By default
3740      this variable is set using the :term:`IMAGE_LINK_NAME`, and
3741      :term:`IMAGE_VERSION_SUFFIX` variables::
3742
3743         IMAGE_NAME ?= "${IMAGE_LINK_NAME}${IMAGE_VERSION_SUFFIX}"
3744
3745   :term:`IMAGE_NAME_SUFFIX`
3746      Suffix used for the image output filename --- defaults to ``".rootfs"``
3747      to distinguish the image file from other files created during image
3748      building; however if this suffix is redundant or not desired you can
3749      clear the value of this variable (set the value to ""). For example,
3750      this is typically cleared in :term:`Initramfs` image recipes.
3751
3752   :term:`IMAGE_OVERHEAD_FACTOR`
3753      Defines a multiplier that the build system applies to the initial
3754      image size for cases when the multiplier times the returned disk
3755      usage value for the image is greater than the sum of
3756      :term:`IMAGE_ROOTFS_SIZE` and :term:`IMAGE_ROOTFS_EXTRA_SPACE`. The result of
3757      the multiplier applied to the initial image size creates free disk
3758      space in the image as overhead. By default, the build process uses a
3759      multiplier of 1.3 for this variable. This default value results in
3760      30% free disk space added to the image when this method is used to
3761      determine the final generated image size. You should be aware that
3762      post install scripts and the package management system uses disk
3763      space inside this overhead area. Consequently, the multiplier does
3764      not produce an image with all the theoretical free disk space. See
3765      :term:`IMAGE_ROOTFS_SIZE` for information on how the build system
3766      determines the overall image size.
3767
3768      The default 30% free disk space typically gives the image enough room
3769      to boot and allows for basic post installs while still leaving a
3770      small amount of free disk space. If 30% free space is inadequate, you
3771      can increase the default value. For example, the following setting
3772      gives you 50% free space added to the image::
3773
3774         IMAGE_OVERHEAD_FACTOR = "1.5"
3775
3776      Alternatively, you can ensure a specific amount of free disk space is
3777      added to the image by using the :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3778      variable.
3779
3780   :term:`IMAGE_PKGTYPE`
3781      Defines the package type (i.e. DEB, RPM, IPK, or TAR) used by the
3782      OpenEmbedded build system. The variable is defined appropriately by
3783      the :ref:`ref-classes-package_deb`, :ref:`ref-classes-package_rpm`,
3784      or :ref:`ref-classes-package_ipk` class.
3785
3786      The :ref:`ref-classes-populate-sdk-*` and :ref:`ref-classes-image`
3787      classes use the :term:`IMAGE_PKGTYPE` for packaging up images and SDKs.
3788
3789      You should not set the :term:`IMAGE_PKGTYPE` manually. Rather, the
3790      variable is set indirectly through the appropriate
3791      :ref:`package_* <ref-classes-package>` class using the
3792      :term:`PACKAGE_CLASSES` variable. The
3793      OpenEmbedded build system uses the first package type (e.g. DEB, RPM,
3794      or IPK) that appears with the variable
3795
3796      .. note::
3797
3798         Files using the ``.tar`` format are never used as a substitute
3799         packaging format for DEB, RPM, and IPK formatted files for your image
3800         or SDK.
3801
3802   :term:`IMAGE_POSTPROCESS_COMMAND`
3803      Specifies a list of functions to call once the OpenEmbedded build
3804      system creates the final image output files. You can specify
3805      functions separated by spaces::
3806
3807         IMAGE_POSTPROCESS_COMMAND += "function"
3808
3809      If you need to pass the root filesystem path to a command within the
3810      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3811      directory that becomes the root filesystem image. See the
3812      :term:`IMAGE_ROOTFS` variable for more
3813      information.
3814
3815   :term:`IMAGE_PREPROCESS_COMMAND`
3816      Specifies a list of functions to call before the OpenEmbedded build
3817      system creates the final image output files. You can specify
3818      functions separated by spaces::
3819
3820         IMAGE_PREPROCESS_COMMAND += "function"
3821
3822      If you need to pass the root filesystem path to a command within the
3823      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3824      directory that becomes the root filesystem image. See the
3825      :term:`IMAGE_ROOTFS` variable for more
3826      information.
3827
3828   :term:`IMAGE_ROOTFS`
3829      The location of the root filesystem while it is under construction
3830      (i.e. during the :ref:`ref-tasks-rootfs` task). This
3831      variable is not configurable. Do not change it.
3832
3833   :term:`IMAGE_ROOTFS_ALIGNMENT`
3834      Specifies the alignment for the output image file in Kbytes. If the
3835      size of the image is not a multiple of this value, then the size is
3836      rounded up to the nearest multiple of the value. The default value is
3837      "1". See :term:`IMAGE_ROOTFS_SIZE` for
3838      additional information.
3839
3840   :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3841      Defines additional free disk space created in the image in Kbytes. By
3842      default, this variable is set to "0". This free disk space is added
3843      to the image after the build system determines the image size as
3844      described in :term:`IMAGE_ROOTFS_SIZE`.
3845
3846      This variable is particularly useful when you want to ensure that a
3847      specific amount of free disk space is available on a device after an
3848      image is installed and running. For example, to be sure 5 Gbytes of
3849      free disk space is available, set the variable as follows::
3850
3851         IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
3852
3853      For example, the Yocto Project Build Appliance specifically requests
3854      40 Gbytes of extra space with the line::
3855
3856         IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
3857
3858   :term:`IMAGE_ROOTFS_SIZE`
3859      Defines the size in Kbytes for the generated image. The OpenEmbedded
3860      build system determines the final size for the generated image using
3861      an algorithm that takes into account the initial disk space used for
3862      the generated image, a requested size for the image, and requested
3863      additional free disk space to be added to the image. Programatically,
3864      the build system determines the final size of the generated image as
3865      follows::
3866
3867         if (image-du * overhead) < rootfs-size:
3868             internal-rootfs-size = rootfs-size + xspace
3869         else:
3870             internal-rootfs-size = (image-du * overhead) + xspace
3871         where:
3872             image-du = Returned value of the du command on the image.
3873             overhead = IMAGE_OVERHEAD_FACTOR
3874             rootfs-size = IMAGE_ROOTFS_SIZE
3875             internal-rootfs-size = Initial root filesystem size before any modifications.
3876             xspace = IMAGE_ROOTFS_EXTRA_SPACE
3877
3878      See the :term:`IMAGE_OVERHEAD_FACTOR`
3879      and :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3880      variables for related information.
3881
3882   :term:`IMAGE_TYPEDEP`
3883      Specifies a dependency from one image type on another. Here is an
3884      example from the :ref:`ref-classes-image-live` class::
3885
3886         IMAGE_TYPEDEP:live = "ext3"
3887
3888      In the previous example, the variable ensures that when "live" is
3889      listed with the :term:`IMAGE_FSTYPES` variable,
3890      the OpenEmbedded build system produces an ``ext3`` image first since
3891      one of the components of the live image is an ``ext3`` formatted
3892      partition containing the root filesystem.
3893
3894   :term:`IMAGE_TYPES`
3895      Specifies the complete list of supported image types by default:
3896
3897      - btrfs
3898      - container
3899      - cpio
3900      - cpio.gz
3901      - cpio.lz4
3902      - cpio.lzma
3903      - cpio.xz
3904      - cramfs
3905      - erofs
3906      - erofs-lz4
3907      - erofs-lz4hc
3908      - ext2
3909      - ext2.bz2
3910      - ext2.gz
3911      - ext2.lzma
3912      - ext3
3913      - ext3.gz
3914      - ext4
3915      - ext4.gz
3916      - f2fs
3917      - hddimg
3918      - iso
3919      - jffs2
3920      - jffs2.sum
3921      - multiubi
3922      - squashfs
3923      - squashfs-lz4
3924      - squashfs-lzo
3925      - squashfs-xz
3926      - tar
3927      - tar.bz2
3928      - tar.gz
3929      - tar.lz4
3930      - tar.xz
3931      - tar.zst
3932      - ubi
3933      - ubifs
3934      - wic
3935      - wic.bz2
3936      - wic.gz
3937      - wic.lzma
3938
3939      For more information about these types of images, see
3940      ``meta/classes-recipe/image_types*.bbclass`` in the :term:`Source Directory`.
3941
3942   :term:`IMAGE_VERSION_SUFFIX`
3943      Version suffix that is part of the default :term:`IMAGE_NAME` and
3944      :term:`KERNEL_ARTIFACT_NAME` values.
3945      Defaults to ``"-${DATETIME}"``, however you could set this to a
3946      version string that comes from your external build environment if
3947      desired, and this suffix would then be used consistently across
3948      the build artifacts.
3949
3950   :term:`IMGDEPLOYDIR`
3951      When inheriting the :ref:`ref-classes-image` class directly or
3952      through the :ref:`ref-classes-core-image` class, the
3953      :term:`IMGDEPLOYDIR` points to a temporary work area for deployed files
3954      that is set in the ``image`` class as follows::
3955
3956         IMGDEPLOYDIR = "${WORKDIR}/deploy-${PN}-image-complete"
3957
3958      Recipes inheriting the :ref:`ref-classes-image` class should copy
3959      files to be deployed into :term:`IMGDEPLOYDIR`, and the class will take
3960      care of copying them into :term:`DEPLOY_DIR_IMAGE` afterwards.
3961
3962   :term:`INCOMPATIBLE_LICENSE`
3963      Specifies a space-separated list of license names (as they would
3964      appear in :term:`LICENSE`) that should be excluded
3965      from the build (if set globally), or from an image (if set locally
3966      in an image recipe).
3967
3968      When the variable is set globally, recipes that provide no alternatives to listed
3969      incompatible licenses are not built. Packages that are individually
3970      licensed with the specified incompatible licenses will be deleted.
3971      Most of the time this does not allow a feasible build (because it becomes impossible
3972      to satisfy build time dependencies), so the recommended way to
3973      implement license restrictions is to set the variable in specific
3974      image recipes where the restrictions must apply. That way there
3975      are no build time restrictions, but the license check is still
3976      performed when the image's filesystem is assembled from packages.
3977
3978      There is some support for wildcards in this variable's value,
3979      however it is restricted to specific licenses. Currently only
3980      these wildcards are allowed and expand as follows:
3981
3982      - ``AGPL-3.0*"``: ``AGPL-3.0-only``, ``AGPL-3.0-or-later``
3983      - ``GPL-3.0*``: ``GPL-3.0-only``, ``GPL-3.0-or-later``
3984      - ``LGPL-3.0*``: ``LGPL-3.0-only``, ``LGPL-3.0-or-later``
3985
3986      .. note::
3987
3988         This functionality is only regularly tested using the following
3989         setting::
3990
3991                 INCOMPATIBLE_LICENSE = "GPL-3.0* LGPL-3.0* AGPL-3.0*"
3992
3993
3994         Although you can use other settings, you might be required to
3995         remove dependencies on (or provide alternatives to) components that
3996         are required to produce a functional system image.
3997
3998   :term:`INCOMPATIBLE_LICENSE_EXCEPTIONS`
3999      Specifies a space-separated list of package and license pairs that
4000      are allowed to be used even if the license is specified in
4001      :term:`INCOMPATIBLE_LICENSE`. The package and license pairs are
4002      separated using a colon. Example::
4003
4004         INCOMPATIBLE_LICENSE_EXCEPTIONS = "gdbserver:GPL-3.0-only gdbserver:LGPL-3.0-only"
4005
4006   :term:`INHERIT`
4007      Causes the named class or classes to be inherited globally. Anonymous
4008      functions in the class or classes are not executed for the base
4009      configuration and in each individual recipe. The OpenEmbedded build
4010      system ignores changes to :term:`INHERIT` in individual recipes.
4011      Classes inherited using :term:`INHERIT` must be located in the
4012      ``classes-global/`` or ``classes/`` subdirectories.
4013
4014      For more information on :term:`INHERIT`, see the
4015      :ref:`bitbake-user-manual/bitbake-user-manual-metadata:\`\`inherit\`\` configuration directive`"
4016      section in the BitBake User Manual.
4017
4018   :term:`INHERIT_DISTRO`
4019      Lists classes that will be inherited at the distribution level. It is
4020      unlikely that you want to edit this variable.
4021
4022      Classes specified in :term:`INHERIT_DISTRO` must be located in the
4023      ``classes-global/`` or ``classes/`` subdirectories.
4024
4025      The default value of the variable is set as follows in the
4026      ``meta/conf/distro/defaultsetup.conf`` file::
4027
4028         INHERIT_DISTRO ?= "debian devshell sstate license"
4029
4030   :term:`INHIBIT_DEFAULT_DEPS`
4031      Prevents the default dependencies, namely the C compiler and standard
4032      C library (libc), from being added to :term:`DEPENDS`.
4033      This variable is usually used within recipes that do not require any
4034      compilation using the C compiler.
4035
4036      Set the variable to "1" to prevent the default dependencies from
4037      being added.
4038
4039   :term:`INHIBIT_PACKAGE_DEBUG_SPLIT`
4040      Prevents the OpenEmbedded build system from splitting out debug
4041      information during packaging. By default, the build system splits out
4042      debugging information during the
4043      :ref:`ref-tasks-package` task. For more information on
4044      how debug information is split out, see the
4045      :term:`PACKAGE_DEBUG_SPLIT_STYLE`
4046      variable.
4047
4048      To prevent the build system from splitting out debug information
4049      during packaging, set the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable as
4050      follows::
4051
4052         INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
4053
4054   :term:`INHIBIT_PACKAGE_STRIP`
4055      If set to "1", causes the build to not strip binaries in resulting
4056      packages and prevents the ``-dbg`` package from containing the source
4057      files.
4058
4059      By default, the OpenEmbedded build system strips binaries and puts
4060      the debugging symbols into ``${``\ :term:`PN`\ ``}-dbg``.
4061      Consequently, you should not set :term:`INHIBIT_PACKAGE_STRIP` when you
4062      plan to debug in general.
4063
4064   :term:`INHIBIT_SYSROOT_STRIP`
4065      If set to "1", causes the build to not strip binaries in the
4066      resulting sysroot.
4067
4068      By default, the OpenEmbedded build system strips binaries in the
4069      resulting sysroot. When you specifically set the
4070      :term:`INHIBIT_SYSROOT_STRIP` variable to "1" in your recipe, you inhibit
4071      this stripping.
4072
4073      If you want to use this variable, include the :ref:`ref-classes-staging`
4074      class. This class uses a ``sys_strip()`` function to test for the variable
4075      and acts accordingly.
4076
4077      .. note::
4078
4079         Use of the :term:`INHIBIT_SYSROOT_STRIP` variable occurs in rare and
4080         special circumstances. For example, suppose you are building
4081         bare-metal firmware by using an external GCC toolchain. Furthermore,
4082         even if the toolchain's binaries are strippable, there are other files
4083         needed for the build that are not strippable.
4084
4085   :term:`INIT_MANAGER`
4086      Specifies the system init manager to use. Available options are:
4087
4088      -  ``sysvinit``
4089      -  ``systemd``
4090      -  ``mdev-busybox``
4091
4092      With ``sysvinit``, the init manager is set to
4093      :wikipedia:`SysVinit <Init#SysV-style>`, the traditional UNIX init
4094      system. This is the default choice in the Poky distribution, together with
4095      the Udev device manager (see the ":ref:`device-manager`" section).
4096
4097      With ``systemd``, the init manager becomes :wikipedia:`systemd <Systemd>`,
4098      which comes with the :wikipedia:`udev <Udev>` device manager.
4099
4100      With ``mdev-busybox``, the init manager becomes the much simpler BusyBox
4101      init, together with the BusyBox mdev device manager. This is the simplest
4102      and lightest solution, and probably the best choice for low-end systems
4103      with a rather slow CPU and a limited amount of RAM.
4104
4105      More concretely, this is used to include
4106      ``conf/distro/include/init-manager-${INIT_MANAGER}.inc`` into the global
4107      configuration. You can have a look at the
4108      :yocto_git:`meta/conf/distro/include/init-manager-*.inc </poky/tree/meta/conf/distro/include>`
4109      files for more information, and also the ":ref:`init-manager`"
4110      section in the Yocto Project Development Tasks Manual.
4111
4112   :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
4113      Indicates the deploy directory used by :ref:`ref-tasks-bundle_initramfs`
4114      where the :term:`INITRAMFS_IMAGE` will be fetched from. This variable is
4115      set by default to ``${DEPLOY_DIR_IMAGE}`` in the
4116      :ref:`ref-classes-kernel` class and it's only meant to be changed when
4117      building an :term:`Initramfs` image from a separate multiconfig via
4118      :term:`INITRAMFS_MULTICONFIG`.
4119
4120   :term:`INITRAMFS_FSTYPES`
4121      Defines the format for the output image of an initial RAM filesystem
4122      (:term:`Initramfs`), which is used during boot. Supported formats are the
4123      same as those supported by the
4124      :term:`IMAGE_FSTYPES` variable.
4125
4126      The default value of this variable, which is set in the
4127      ``meta/conf/bitbake.conf`` configuration file in the
4128      :term:`Source Directory`, is "cpio.gz". The Linux kernel's
4129      :term:`Initramfs` mechanism, as opposed to the initial RAM filesystem
4130      :wikipedia:`initrd <Initrd>` mechanism, expects
4131      an optionally compressed cpio archive.
4132
4133   :term:`INITRAMFS_IMAGE`
4134      Specifies the :term:`PROVIDES` name of an image
4135      recipe that is used to build an initial RAM filesystem (:term:`Initramfs`)
4136      image. In other words, the :term:`INITRAMFS_IMAGE` variable causes an
4137      additional recipe to be built as a dependency to whatever root
4138      filesystem recipe you might be using (e.g. ``core-image-sato``). The
4139      :term:`Initramfs` image recipe you provide should set
4140      :term:`IMAGE_FSTYPES` to
4141      :term:`INITRAMFS_FSTYPES`.
4142
4143      An :term:`Initramfs` image provides a temporary root filesystem used for
4144      early system initialization (e.g. loading of modules needed to locate
4145      and mount the "real" root filesystem).
4146
4147      .. note::
4148
4149         See the ``meta/recipes-core/images/core-image-minimal-initramfs.bb``
4150         recipe in the :term:`Source Directory`
4151         for an example :term:`Initramfs` recipe. To select this sample recipe as
4152         the one built to provide the :term:`Initramfs` image, set :term:`INITRAMFS_IMAGE`
4153         to "core-image-minimal-initramfs".
4154
4155      You can also find more information by referencing the
4156      ``meta-poky/conf/templates/default/local.conf.sample.extended``
4157      configuration file in the Source Directory, the :ref:`ref-classes-image`
4158      class, and the :ref:`ref-classes-kernel` class to see how to use the
4159      :term:`INITRAMFS_IMAGE` variable.
4160
4161      If :term:`INITRAMFS_IMAGE` is empty, which is the default, then no
4162      :term:`Initramfs` image is built.
4163
4164      For more information, you can also see the
4165      :term:`INITRAMFS_IMAGE_BUNDLE`
4166      variable, which allows the generated image to be bundled inside the
4167      kernel image. Additionally, for information on creating an :term:`Initramfs`
4168      image, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
4169      in the Yocto Project Development Tasks Manual.
4170
4171   :term:`INITRAMFS_IMAGE_BUNDLE`
4172      Controls whether or not the image recipe specified by
4173      :term:`INITRAMFS_IMAGE` is run through an
4174      extra pass
4175      (:ref:`ref-tasks-bundle_initramfs`) during
4176      kernel compilation in order to build a single binary that contains
4177      both the kernel image and the initial RAM filesystem (:term:`Initramfs`)
4178      image. This makes use of the
4179      :term:`CONFIG_INITRAMFS_SOURCE` kernel
4180      feature.
4181
4182      .. note::
4183
4184         Bundling the :term:`Initramfs` with the kernel conflates the code in the
4185         :term:`Initramfs` with the GPLv2 licensed Linux kernel binary. Thus only GPLv2
4186         compatible software may be part of a bundled :term:`Initramfs`.
4187
4188      .. note::
4189
4190         Using an extra compilation pass to bundle the :term:`Initramfs` avoids a
4191         circular dependency between the kernel recipe and the :term:`Initramfs`
4192         recipe should the :term:`Initramfs` include kernel modules. Should that be
4193         the case, the :term:`Initramfs` recipe depends on the kernel for the
4194         kernel modules, and the kernel depends on the :term:`Initramfs` recipe
4195         since the :term:`Initramfs` is bundled inside the kernel image.
4196
4197      The combined binary is deposited into the ``tmp/deploy`` directory,
4198      which is part of the :term:`Build Directory`.
4199
4200      Setting the variable to "1" in a configuration file causes the
4201      OpenEmbedded build system to generate a kernel image with the
4202      :term:`Initramfs` specified in :term:`INITRAMFS_IMAGE` bundled within::
4203
4204         INITRAMFS_IMAGE_BUNDLE = "1"
4205
4206      By default, the :ref:`ref-classes-kernel` class sets this variable to a
4207      null string as follows::
4208
4209         INITRAMFS_IMAGE_BUNDLE ?= ""
4210
4211      .. note::
4212
4213         You must set the :term:`INITRAMFS_IMAGE_BUNDLE` variable in a
4214         configuration file. You cannot set the variable in a recipe file.
4215
4216      See the
4217      :yocto_git:`local.conf.sample.extended </poky/tree/meta-poky/conf/templates/default/local.conf.sample.extended>`
4218      file for additional information. Also, for information on creating an
4219      :term:`Initramfs`, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
4220      in the Yocto Project Development Tasks Manual.
4221
4222   :term:`INITRAMFS_IMAGE_NAME`
4223
4224      This value needs to stay in sync with :term:`IMAGE_LINK_NAME`, but with
4225      :term:`INITRAMFS_IMAGE` instead of :term:`IMAGE_BASENAME`. The default value
4226      is set as follows:
4227
4228         INITRAMFS_IMAGE_NAME ?= "${@['${INITRAMFS_IMAGE}${IMAGE_MACHINE_SUFFIX}', ''][d.getVar('INITRAMFS_IMAGE') == '']}"
4229
4230      That is, if :term:`INITRAMFS_IMAGE` is set, the value of
4231      :term:`INITRAMFS_IMAGE_NAME` will be set based upon
4232      :term:`INITRAMFS_IMAGE` and :term:`IMAGE_MACHINE_SUFFIX`.
4233
4234
4235   :term:`INITRAMFS_LINK_NAME`
4236      The link name of the initial RAM filesystem image. This variable is
4237      set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4238      follows::
4239
4240         INITRAMFS_LINK_NAME ?= "initramfs-${KERNEL_ARTIFACT_LINK_NAME}"
4241
4242      The value of the
4243      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4244      file, has the following value::
4245
4246         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4247
4248      See the :term:`MACHINE` variable for additional
4249      information.
4250
4251   :term:`INITRAMFS_MULTICONFIG`
4252      Defines the multiconfig to create a multiconfig dependency to be used by
4253      the :ref:`ref-classes-kernel` class.
4254
4255      This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
4256      a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
4257
4258      For more information on how to bundle an :term:`Initramfs` image from a separate
4259      multiconfig see the ":ref:`dev-manual/building:Bundling an Initramfs Image From a Separate Multiconfig`"
4260      section in the Yocto Project Development Tasks Manual.
4261
4262   :term:`INITRAMFS_NAME`
4263      The base name of the initial RAM filesystem image. This variable is
4264      set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4265      follows::
4266
4267         INITRAMFS_NAME ?= "initramfs-${KERNEL_ARTIFACT_NAME}"
4268
4269      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4270
4271   :term:`INITRD`
4272      Indicates list of filesystem images to concatenate and use as an
4273      initial RAM disk (``initrd``).
4274
4275      The :term:`INITRD` variable is an optional variable used with the
4276      :ref:`ref-classes-image-live` class.
4277
4278   :term:`INITRD_IMAGE`
4279      When building a "live" bootable image (i.e. when
4280      :term:`IMAGE_FSTYPES` contains "live"),
4281      :term:`INITRD_IMAGE` specifies the image recipe that should be built to
4282      provide the initial RAM disk image. The default value is
4283      "core-image-minimal-initramfs".
4284
4285      See the :ref:`ref-classes-image-live` class for more information.
4286
4287   :term:`INITSCRIPT_NAME`
4288      The filename of the initialization script as installed to
4289      ``${sysconfdir}/init.d``.
4290
4291      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
4292      The variable is mandatory.
4293
4294   :term:`INITSCRIPT_PACKAGES`
4295      A list of the packages that contain initscripts. If multiple packages
4296      are specified, you need to append the package name to the other
4297      ``INITSCRIPT_*`` as an override.
4298
4299      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
4300      The variable is optional and defaults to the :term:`PN`
4301      variable.
4302
4303   :term:`INITSCRIPT_PARAMS`
4304      Specifies the options to pass to ``update-rc.d``. Here is an example::
4305
4306         INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
4307
4308      In this example, the script has a runlevel of 99, starts the script
4309      in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
4310
4311      The variable's default value is "defaults", which is set in the
4312      :ref:`ref-classes-update-rc.d` class.
4313
4314      The value in :term:`INITSCRIPT_PARAMS` is passed through to the
4315      ``update-rc.d`` command. For more information on valid parameters,
4316      please see the ``update-rc.d`` manual page at
4317      https://manpages.debian.org/buster/init-system-helpers/update-rc.d.8.en.html
4318
4319   :term:`INSANE_SKIP`
4320      Specifies the QA checks to skip for a specific package within a
4321      recipe. For example, to skip the check for symbolic link ``.so``
4322      files in the main package of a recipe, add the following to the
4323      recipe. The package name override must be used, which in this example
4324      is ``${PN}``::
4325
4326         INSANE_SKIP:${PN} += "dev-so"
4327
4328      See the ":ref:`ref-classes-insane`" section for a
4329      list of the valid QA checks you can specify using this variable.
4330
4331   :term:`INSTALL_TIMEZONE_FILE`
4332      By default, the ``tzdata`` recipe packages an ``/etc/timezone`` file.
4333      Set the :term:`INSTALL_TIMEZONE_FILE` variable to "0" at the
4334      configuration level to disable this behavior.
4335
4336   :term:`IPK_FEED_URIS`
4337      When the IPK backend is in use and package management is enabled on
4338      the target, you can use this variable to set up ``opkg`` in the
4339      target image to point to package feeds on a nominated server. Once
4340      the feed is established, you can perform installations or upgrades
4341      using the package manager at runtime.
4342
4343   :term:`KARCH`
4344      Defines the kernel architecture used when assembling the
4345      configuration. Architectures supported for this release are:
4346
4347      - powerpc
4348      - i386
4349      - x86_64
4350      - arm
4351      - qemu
4352      - mips
4353
4354      You define the :term:`KARCH` variable in the :ref:`kernel-dev/advanced:bsp descriptions`.
4355
4356   :term:`KBRANCH`
4357      A regular expression used by the build process to explicitly identify
4358      the kernel branch that is validated, patched, and configured during a
4359      build. You must set this variable to ensure the exact kernel branch
4360      you want is being used by the build process.
4361
4362      Values for this variable are set in the kernel's recipe file and the
4363      kernel's append file. For example, if you are using the
4364      ``linux-yocto_4.12`` kernel, the kernel recipe file is the
4365      ``meta/recipes-kernel/linux/linux-yocto_4.12.bb`` file. :term:`KBRANCH`
4366      is set as follows in that kernel recipe file::
4367
4368         KBRANCH ?= "standard/base"
4369
4370      This variable is also used from the kernel's append file to identify
4371      the kernel branch specific to a particular machine or target
4372      hardware. Continuing with the previous kernel example, the kernel's
4373      append file is located in the
4374      BSP layer for a given machine. For example, the append file for the
4375      Beaglebone and generic versions of both 32 and 64-bit IA
4376      machines (``meta-yocto-bsp``) is named
4377      ``meta-yocto-bsp/recipes-kernel/linux/linux-yocto_6.1.bbappend``.
4378      Here are the related statements from that append file::
4379
4380         KBRANCH:genericx86  = "v6.1/standard/base"
4381         KBRANCH:genericx86-64  = "v6.1/standard/base"
4382         KBRANCH:beaglebone-yocto = "v6.1/standard/beaglebone"
4383
4384      The :term:`KBRANCH` statements
4385      identify the kernel branch to use when building for each supported
4386      BSP.
4387
4388   :term:`KBUILD_DEFCONFIG`
4389      When used with the :ref:`ref-classes-kernel-yocto`
4390      class, specifies an "in-tree" kernel configuration file for use
4391      during a kernel build.
4392
4393      Typically, when using a ``defconfig`` to configure a kernel during a
4394      build, you place the file in your layer in the same manner as you
4395      would place patch files and configuration fragment files (i.e.
4396      "out-of-tree"). However, if you want to use a ``defconfig`` file that
4397      is part of the kernel tree (i.e. "in-tree"), you can use the
4398      :term:`KBUILD_DEFCONFIG` variable and append the
4399      :term:`KMACHINE` variable to point to the
4400      ``defconfig`` file.
4401
4402      To use the variable, set it in the append file for your kernel recipe
4403      using the following form::
4404
4405         KBUILD_DEFCONFIG:<machine> ?= "defconfig_file"
4406
4407      Here is an example from a "raspberrypi2" :term:`MACHINE` build that uses
4408      a ``defconfig`` file named "bcm2709_defconfig"::
4409
4410         KBUILD_DEFCONFIG:raspberrypi2 = "bcm2709_defconfig"
4411
4412      As an alternative, you can use the following within your append file::
4413
4414         KBUILD_DEFCONFIG:pn-linux-yocto ?= "defconfig_file"
4415
4416      For more
4417      information on how to use the :term:`KBUILD_DEFCONFIG` variable, see the
4418      ":ref:`kernel-dev/common:using an "in-tree" \`\`defconfig\`\` file`"
4419      section in the Yocto Project Linux Kernel Development Manual.
4420
4421   :term:`KCONFIG_MODE`
4422      When used with the :ref:`ref-classes-kernel-yocto`
4423      class, specifies the kernel configuration values to use for options
4424      not specified in the provided ``defconfig`` file. Valid options are::
4425
4426         KCONFIG_MODE = "alldefconfig"
4427         KCONFIG_MODE = "allnoconfig"
4428
4429      In ``alldefconfig`` mode the options not explicitly specified will be
4430      assigned their Kconfig default value. In ``allnoconfig`` mode the
4431      options not explicitly specified will be disabled in the kernel
4432      config.
4433
4434      In case :term:`KCONFIG_MODE` is not set the behaviour will depend on where
4435      the ``defconfig`` file is coming from. An "in-tree" ``defconfig`` file
4436      will be handled in ``alldefconfig`` mode, a ``defconfig`` file placed
4437      in ``${WORKDIR}`` through a meta-layer will be handled in
4438      ``allnoconfig`` mode.
4439
4440      An "in-tree" ``defconfig`` file can be selected via the
4441      :term:`KBUILD_DEFCONFIG` variable. :term:`KCONFIG_MODE` does not need to
4442      be explicitly set.
4443
4444      A ``defconfig`` file compatible with ``allnoconfig`` mode can be
4445      generated by copying the ``.config`` file from a working Linux kernel
4446      build, renaming it to ``defconfig`` and placing it into the Linux
4447      kernel ``${WORKDIR}`` through your meta-layer. :term:`KCONFIG_MODE` does
4448      not need to be explicitly set.
4449
4450      A ``defconfig`` file compatible with ``alldefconfig`` mode can be
4451      generated using the
4452      :ref:`ref-tasks-savedefconfig`
4453      task and placed into the Linux kernel ``${WORKDIR}`` through your
4454      meta-layer. Explicitely set :term:`KCONFIG_MODE`::
4455
4456         KCONFIG_MODE = "alldefconfig"
4457
4458   :term:`KERNEL_ALT_IMAGETYPE`
4459      Specifies an alternate kernel image type for creation in addition to
4460      the kernel image type specified using the :term:`KERNEL_IMAGETYPE` and
4461      :term:`KERNEL_IMAGETYPES` variables.
4462
4463   :term:`KERNEL_ARTIFACT_NAME`
4464      Specifies the name of all of the build artifacts. You can change the
4465      name of the artifacts by changing the :term:`KERNEL_ARTIFACT_NAME`
4466      variable.
4467
4468      The value of :term:`KERNEL_ARTIFACT_NAME`, which is set in the
4469      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file, has the
4470      following default value::
4471
4472         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}${IMAGE_MACHINE_SUFFIX}${IMAGE_VERSION_SUFFIX}"
4473
4474      See the :term:`PKGE`, :term:`PKGV`, :term:`PKGR`, :term:`IMAGE_MACHINE_SUFFIX`
4475      and :term:`IMAGE_VERSION_SUFFIX` variables for additional information.
4476
4477   :term:`KERNEL_CLASSES`
4478      A list of classes defining kernel image types that the
4479      :ref:`ref-classes-kernel` class should inherit. You typically
4480      append this variable to enable extended image types. An example is
4481      ":ref:`ref-classes-kernel-fitimage`", which enables
4482      FIT image support and resides in ``meta/classes-recipe/kernel-fitimage.bbclass``.
4483      You can register custom kernel image types with the
4484      :ref:`ref-classes-kernel` class using this variable.
4485
4486   :term:`KERNEL_DANGLING_FEATURES_WARN_ONLY`
4487      When kernel configuration fragments are missing for some
4488      :term:`KERNEL_FEATURES` specified by layers or BSPs,
4489      building and configuring the kernel stops with an error.
4490
4491      You can turn these errors into warnings by setting the
4492      following in ``conf/local.conf``::
4493
4494         KERNEL_DANGLING_FEATURES_WARN_ONLY = "1"
4495
4496      You will still be warned that runtime issues may occur,
4497      but at least the kernel configuration and build process will
4498      be allowed to continue.
4499
4500   :term:`KERNEL_DEBUG_TIMESTAMPS`
4501      If set to "1", enables timestamping functionality during building
4502      the kernel. The default is "0" to disable this for reproducibility
4503      reasons.
4504
4505   :term:`KERNEL_DEPLOY_DEPEND`
4506      Provides a means of controlling the dependency of an image recipe
4507      on the kernel. The default value is "virtual/kernel:do_deploy",
4508      however for a small initramfs image or other images that do not
4509      need the kernel, this can be set to "" in the image recipe.
4510
4511   :term:`KERNEL_DEVICETREE`
4512      Specifies the name of the generated Linux kernel device tree (i.e.
4513      the ``.dtb``) file.
4514
4515      .. note::
4516
4517         There is legacy support for specifying the full path to the device
4518         tree. However, providing just the ``.dtb`` file is preferred.
4519
4520      In order to use this variable, the :ref:`ref-classes-kernel-devicetree`
4521      class must be inherited.
4522
4523   :term:`KERNEL_DEVICETREE_BUNDLE`
4524      When set to "1", this variable allows to bundle the Linux kernel
4525      and the Device Tree Binary together in a single file.
4526
4527      This feature is currently only supported on the "arm" (32 bit)
4528      architecture.
4529
4530      This variable is set to "0" by default by the
4531      :ref:`ref-classes-kernel-devicetree` class.
4532
4533   :term:`KERNEL_DTB_LINK_NAME`
4534      The link name of the kernel device tree binary (DTB). This variable
4535      is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4536      follows::
4537
4538         KERNEL_DTB_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4539
4540      The
4541      value of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in
4542      the same file, has the following value::
4543
4544         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4545
4546      See the :term:`MACHINE` variable for additional
4547      information.
4548
4549   :term:`KERNEL_DTB_NAME`
4550      The base name of the kernel device tree binary (DTB). This variable
4551      is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4552      follows::
4553
4554         KERNEL_DTB_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4555
4556      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4557
4558   :term:`KERNEL_DTBDEST`
4559      This variable, used by the :ref:`ref-classes-kernel-devicetree`
4560      class, allows to change the installation directory of the DTB
4561      (Device Tree Binary) files.
4562
4563      It is set by default to "${KERNEL_IMAGEDEST}" by the
4564      :ref:`ref-classes-kernel` class.
4565
4566   :term:`KERNEL_DTBVENDORED`
4567      This variable, used by the :ref:`ref-classes-kernel-devicetree`,
4568      allows to ignore vendor subdirectories when installing DTB
4569      (Device Tree Binary) files, when it is set to "false".
4570
4571      To keep vendor subdirectories, set this variable to "true".
4572
4573      It is set by default to "false" by the :ref:`ref-classes-kernel` class.
4574
4575   :term:`KERNEL_DTC_FLAGS`
4576      Specifies the ``dtc`` flags that are passed to the Linux kernel build
4577      system when generating the device trees (via ``DTC_FLAGS`` environment
4578      variable).
4579
4580      In order to use this variable, the :ref:`ref-classes-kernel-devicetree`
4581      class must be inherited.
4582
4583   :term:`KERNEL_EXTRA_ARGS`
4584      Specifies additional ``make`` command-line arguments the OpenEmbedded
4585      build system passes on when compiling the kernel.
4586
4587   :term:`KERNEL_FEATURES`
4588      Includes additional kernel metadata. In the OpenEmbedded build
4589      system, the default Board Support Packages (BSPs)
4590      :term:`Metadata` is provided through the
4591      :term:`KMACHINE` and :term:`KBRANCH`
4592      variables. You can use the :term:`KERNEL_FEATURES` variable from within
4593      the kernel recipe or kernel append file to further add metadata for
4594      all BSPs or specific BSPs.
4595
4596      The metadata you add through this variable includes config fragments
4597      and features descriptions, which usually includes patches as well as
4598      config fragments. You typically override the :term:`KERNEL_FEATURES`
4599      variable for a specific machine. In this way, you can provide
4600      validated, but optional, sets of kernel configurations and features.
4601
4602      For example, the following example from the ``linux-yocto-rt_4.12``
4603      kernel recipe adds "netfilter" and "taskstats" features to all BSPs
4604      as well as "virtio" configurations to all QEMU machines. The last two
4605      statements add specific configurations to targeted machine types::
4606
4607         KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc features/taskstats/taskstats.scc"
4608         KERNEL_FEATURES:append = " ${KERNEL_EXTRA_FEATURES}"
4609         KERNEL_FEATURES:append:qemuall = " cfg/virtio.scc"
4610         KERNEL_FEATURES:append:qemux86 = "  cfg/sound.scc cfg/paravirt_kvm.scc"
4611         KERNEL_FEATURES:append:qemux86-64 = " cfg/sound.scc"
4612
4613   :term:`KERNEL_FIT_LINK_NAME`
4614      The link name of the kernel flattened image tree (FIT) image. This
4615      variable is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass``
4616      file as follows::
4617
4618         KERNEL_FIT_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4619
4620      The value of the
4621      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4622      file, has the following value::
4623
4624         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4625
4626      See the :term:`MACHINE` variable for additional
4627      information.
4628
4629   :term:`KERNEL_FIT_NAME`
4630      The base name of the kernel flattened image tree (FIT) image. This
4631      variable is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass``
4632      file as follows::
4633
4634         KERNEL_FIT_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4635
4636      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4637
4638   :term:`KERNEL_IMAGE_LINK_NAME`
4639      The link name for the kernel image. This variable is set in the
4640      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
4641
4642         KERNEL_IMAGE_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4643
4644      The value of
4645      the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4646      file, has the following value::
4647
4648         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4649
4650      See the :term:`MACHINE` variable for additional
4651      information.
4652
4653   :term:`KERNEL_IMAGE_MAXSIZE`
4654      Specifies the maximum size of the kernel image file in kilobytes. If
4655      :term:`KERNEL_IMAGE_MAXSIZE` is set, the size of the kernel image file is
4656      checked against the set value during the
4657      :ref:`ref-tasks-sizecheck` task. The task fails if
4658      the kernel image file is larger than the setting.
4659
4660      :term:`KERNEL_IMAGE_MAXSIZE` is useful for target devices that have a
4661      limited amount of space in which the kernel image must be stored.
4662
4663      By default, this variable is not set, which means the size of the
4664      kernel image is not checked.
4665
4666   :term:`KERNEL_IMAGE_NAME`
4667      The base name of the kernel image. This variable is set in the
4668      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
4669
4670         KERNEL_IMAGE_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4671
4672      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4673
4674   :term:`KERNEL_IMAGETYPE`
4675      The type of kernel to build for a device, usually set by the machine
4676      configuration files and defaults to "zImage". This variable is used
4677      when building the kernel and is passed to ``make`` as the target to
4678      build.
4679
4680      To build additional kernel image types, use :term:`KERNEL_IMAGETYPES`.
4681
4682   :term:`KERNEL_IMAGETYPES`
4683      Lists additional types of kernel images to build for a device in addition
4684      to image type specified in :term:`KERNEL_IMAGETYPE`. Usually set by the
4685      machine configuration files.
4686
4687   :term:`KERNEL_MODULE_AUTOLOAD`
4688      Lists kernel modules that need to be auto-loaded during boot.
4689
4690      .. note::
4691
4692         This variable replaces the deprecated :term:`module_autoload`
4693         variable.
4694
4695      You can use the :term:`KERNEL_MODULE_AUTOLOAD` variable anywhere that it
4696      can be recognized by the kernel recipe or by an out-of-tree kernel
4697      module recipe (e.g. a machine configuration file, a distribution
4698      configuration file, an append file for the recipe, or the recipe
4699      itself).
4700
4701      Specify it as follows::
4702
4703         KERNEL_MODULE_AUTOLOAD += "module_name1 module_name2 module_name3"
4704
4705      Including :term:`KERNEL_MODULE_AUTOLOAD` causes the OpenEmbedded build
4706      system to populate the ``/etc/modules-load.d/modname.conf`` file with
4707      the list of modules to be auto-loaded on boot. The modules appear
4708      one-per-line in the file. Here is an example of the most common use
4709      case::
4710
4711         KERNEL_MODULE_AUTOLOAD += "module_name"
4712
4713      For information on how to populate the ``modname.conf`` file with
4714      ``modprobe.d`` syntax lines, see the :term:`KERNEL_MODULE_PROBECONF` variable.
4715
4716   :term:`KERNEL_MODULE_PROBECONF`
4717      Provides a list of modules for which the OpenEmbedded build system
4718      expects to find ``module_conf_``\ modname values that specify
4719      configuration for each of the modules. For information on how to
4720      provide those module configurations, see the
4721      :term:`module_conf_* <module_conf>` variable.
4722
4723   :term:`KERNEL_PACKAGE_NAME`
4724      Specifies the base name of the kernel packages, such as "kernel"
4725      in the kernel packages such as "kernel-modules", "kernel-image" and
4726      "kernel-dbg".
4727
4728      The default value for this variable is set to "kernel" by the
4729      :ref:`ref-classes-kernel` class.
4730
4731   :term:`KERNEL_PATH`
4732      The location of the kernel sources. This variable is set to the value
4733      of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`
4734      class. For information on how this variable is used, see the
4735      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4736      section in the Yocto Project Linux Kernel Development Manual.
4737
4738      To help maximize compatibility with out-of-tree drivers used to build
4739      modules, the OpenEmbedded build system also recognizes and uses the
4740      :term:`KERNEL_SRC` variable, which is identical to
4741      the :term:`KERNEL_PATH` variable. Both variables are common variables
4742      used by external Makefiles to point to the kernel source directory.
4743
4744   :term:`KERNEL_SRC`
4745      The location of the kernel sources. This variable is set to the value
4746      of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`
4747      class. For information on how this variable is used, see the
4748      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4749      section in the Yocto Project Linux Kernel Development Manual.
4750
4751      To help maximize compatibility with out-of-tree drivers used to build
4752      modules, the OpenEmbedded build system also recognizes and uses the
4753      :term:`KERNEL_PATH` variable, which is identical
4754      to the :term:`KERNEL_SRC` variable. Both variables are common variables
4755      used by external Makefiles to point to the kernel source directory.
4756
4757   :term:`KERNEL_STRIP`
4758      Allows to specific which ``strip`` command to use to strip the kernel
4759      binary, typically either GNU binutils ``strip`` or ``llvm-strip``.
4760
4761   :term:`KERNEL_VERSION`
4762      Specifies the version of the kernel as extracted from ``version.h``
4763      or ``utsrelease.h`` within the kernel sources. Effects of setting
4764      this variable do not take effect until the kernel has been
4765      configured. Consequently, attempting to refer to this variable in
4766      contexts prior to configuration will not work.
4767
4768   :term:`KERNELDEPMODDEPEND`
4769      Specifies whether the data referenced through
4770      :term:`PKGDATA_DIR` is needed or not.
4771      :term:`KERNELDEPMODDEPEND` does not control whether or not that data
4772      exists, but simply whether or not it is used. If you do not need to
4773      use the data, set the :term:`KERNELDEPMODDEPEND` variable in your
4774      :term:`Initramfs` recipe. Setting the variable there when the data is not
4775      needed avoids a potential dependency loop.
4776
4777   :term:`KFEATURE_DESCRIPTION`
4778      Provides a short description of a configuration fragment. You use
4779      this variable in the ``.scc`` file that describes a configuration
4780      fragment file. Here is the variable used in a file named ``smp.scc``
4781      to describe SMP being enabled::
4782
4783          define KFEATURE_DESCRIPTION "Enable SMP"
4784
4785   :term:`KMACHINE`
4786      The machine as known by the kernel. Sometimes the machine name used
4787      by the kernel does not match the machine name used by the
4788      OpenEmbedded build system. For example, the machine name that the
4789      OpenEmbedded build system understands as ``core2-32-intel-common``
4790      goes by a different name in the Linux Yocto kernel. The kernel
4791      understands that machine as ``intel-core2-32``. For cases like these,
4792      the :term:`KMACHINE` variable maps the kernel machine name to the
4793      OpenEmbedded build system machine name.
4794
4795      These mappings between different names occur in the Yocto Linux
4796      Kernel's ``meta`` branch. As an example take a look in the
4797      ``common/recipes-kernel/linux/linux-yocto_3.19.bbappend`` file::
4798
4799         LINUX_VERSION:core2-32-intel-common = "3.19.0"
4800         COMPATIBLE_MACHINE:core2-32-intel-common = "${MACHINE}"
4801         SRCREV_meta:core2-32-intel-common = "8897ef68b30e7426bc1d39895e71fb155d694974"
4802         SRCREV_machine:core2-32-intel-common = "43b9eced9ba8a57add36af07736344dcc383f711"
4803         KMACHINE:core2-32-intel-common = "intel-core2-32"
4804         KBRANCH:core2-32-intel-common = "standard/base"
4805         KERNEL_FEATURES:append:core2-32-intel-common = " ${KERNEL_FEATURES_INTEL_COMMON}"
4806
4807      The :term:`KMACHINE` statement says
4808      that the kernel understands the machine name as "intel-core2-32".
4809      However, the OpenEmbedded build system understands the machine as
4810      "core2-32-intel-common".
4811
4812   :term:`KTYPE`
4813      Defines the kernel type to be used in assembling the configuration.
4814      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4815      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4816      section in the
4817      Yocto Project Linux Kernel Development Manual for more information on
4818      kernel types.
4819
4820      You define the :term:`KTYPE` variable in the
4821      :ref:`kernel-dev/advanced:bsp descriptions`. The
4822      value you use must match the value used for the
4823      :term:`LINUX_KERNEL_TYPE` value used by the
4824      kernel recipe.
4825
4826   :term:`LABELS`
4827      Provides a list of targets for automatic configuration.
4828
4829      See the :ref:`ref-classes-grub-efi` class for more
4830      information on how this variable is used.
4831
4832   :term:`LAYERDEPENDS`
4833      Lists the layers, separated by spaces, on which this recipe depends.
4834      Optionally, you can specify a specific layer version for a dependency
4835      by adding it to the end of the layer name. Here is an example::
4836
4837         LAYERDEPENDS_mylayer = "anotherlayer (=3)"
4838
4839      In this previous example,
4840      version 3 of "anotherlayer" is compared against
4841      :term:`LAYERVERSION`\ ``_anotherlayer``.
4842
4843      An error is produced if any dependency is missing or the version
4844      numbers (if specified) do not match exactly. This variable is used in
4845      the ``conf/layer.conf`` file and must be suffixed with the name of
4846      the specific layer (e.g. ``LAYERDEPENDS_mylayer``).
4847
4848   :term:`LAYERDIR`
4849      When used inside the ``layer.conf`` configuration file, this variable
4850      provides the path of the current layer. This variable is not
4851      available outside of ``layer.conf`` and references are expanded
4852      immediately when parsing of the file completes.
4853
4854   :term:`LAYERDIR_RE`
4855      See :term:`bitbake:LAYERDIR_RE` in the BitBake manual.
4856
4857   :term:`LAYERRECOMMENDS`
4858      Lists the layers, separated by spaces, recommended for use with this
4859      layer.
4860
4861      Optionally, you can specify a specific layer version for a
4862      recommendation by adding the version to the end of the layer name.
4863      Here is an example::
4864
4865         LAYERRECOMMENDS_mylayer = "anotherlayer (=3)"
4866
4867      In this previous example, version 3 of "anotherlayer" is compared
4868      against ``LAYERVERSION_anotherlayer``.
4869
4870      This variable is used in the ``conf/layer.conf`` file and must be
4871      suffixed with the name of the specific layer (e.g.
4872      ``LAYERRECOMMENDS_mylayer``).
4873
4874   :term:`LAYERSERIES_COMPAT`
4875      See :term:`bitbake:LAYERSERIES_COMPAT` in the BitBake manual.
4876
4877   :term:`LAYERVERSION`
4878      Optionally specifies the version of a layer as a single number. You
4879      can use this within :term:`LAYERDEPENDS` for
4880      another layer in order to depend on a specific version of the layer.
4881      This variable is used in the ``conf/layer.conf`` file and must be
4882      suffixed with the name of the specific layer (e.g.
4883      ``LAYERVERSION_mylayer``).
4884
4885   :term:`LD`
4886      The minimal command and arguments used to run the linker.
4887
4888   :term:`LDFLAGS`
4889      Specifies the flags to pass to the linker. This variable is exported
4890      to an environment variable and thus made visible to the software
4891      being built during the compilation step.
4892
4893      Default initialization for :term:`LDFLAGS` varies depending on what is
4894      being built:
4895
4896      -  :term:`TARGET_LDFLAGS` when building for the
4897         target
4898
4899      -  :term:`BUILD_LDFLAGS` when building for the
4900         build host (i.e. ``-native``)
4901
4902      -  :term:`BUILDSDK_LDFLAGS` when building for
4903         an SDK (i.e. ``nativesdk-``)
4904
4905   :term:`LEAD_SONAME`
4906      Specifies the lead (or primary) compiled library file (i.e. ``.so``)
4907      that the :ref:`ref-classes-debian` class applies its
4908      naming policy to given a recipe that packages multiple libraries.
4909
4910      This variable works in conjunction with the :ref:`ref-classes-debian`
4911      class.
4912
4913   :term:`LIC_FILES_CHKSUM`
4914      Checksums of the license text in the recipe source code.
4915
4916      This variable tracks changes in license text of the source code
4917      files. If the license text is changed, it will trigger a build
4918      failure, which gives the developer an opportunity to review any
4919      license change.
4920
4921      This variable must be defined for all recipes (unless
4922      :term:`LICENSE` is set to "CLOSED").
4923
4924      For more information, see the ":ref:`dev-manual/licenses:tracking license changes`"
4925      section in the Yocto Project Development Tasks Manual.
4926
4927   :term:`LICENSE`
4928      The list of source licenses for the recipe. Follow these rules:
4929
4930      -  Do not use spaces within individual license names.
4931
4932      -  Separate license names using \| (pipe) when there is a choice
4933         between licenses.
4934
4935      -  Separate license names using & (ampersand) when there are
4936         multiple licenses for different parts of the source.
4937
4938      -  You can use spaces between license names.
4939
4940      -  For standard licenses, use the names of the files in
4941         ``meta/files/common-licenses/`` or the
4942         :term:`SPDXLICENSEMAP` flag names defined in
4943         ``meta/conf/licenses.conf``.
4944
4945      Here are some examples::
4946
4947         LICENSE = "LGPL-2.1-only | GPL-3.0-only"
4948         LICENSE = "MPL-1.0 & LGPL-2.1-only"
4949         LICENSE = "GPL-2.0-or-later"
4950
4951      The first example is from the
4952      recipes for Qt, which the user may choose to distribute under either
4953      the LGPL version 2.1 or GPL version 3. The second example is from
4954      Cairo where two licenses cover different parts of the source code.
4955      The final example is from ``sysstat``, which presents a single
4956      license.
4957
4958      You can also specify licenses on a per-package basis to handle
4959      situations where components of the output have different licenses.
4960      For example, a piece of software whose code is licensed under GPLv2
4961      but has accompanying documentation licensed under the GNU Free
4962      Documentation License 1.2 could be specified as follows::
4963
4964         LICENSE = "GFDL-1.2 & GPL-2.0-only"
4965         LICENSE:${PN} = "GPL-2.0.only"
4966         LICENSE:${PN}-doc = "GFDL-1.2"
4967
4968   :term:`LICENSE_CREATE_PACKAGE`
4969      Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
4970      build system to create an extra package (i.e.
4971      ``${``\ :term:`PN`\ ``}-lic``) for each recipe and to add
4972      those packages to the
4973      :term:`RRECOMMENDS`\ ``:${PN}``.
4974
4975      The ``${PN}-lic`` package installs a directory in
4976      ``/usr/share/licenses`` named ``${PN}``, which is the recipe's base
4977      name, and installs files in that directory that contain license and
4978      copyright information (i.e. copies of the appropriate license files
4979      from ``meta/common-licenses`` that match the licenses specified in
4980      the :term:`LICENSE` variable of the recipe metadata
4981      and copies of files marked in
4982      :term:`LIC_FILES_CHKSUM` as containing
4983      license text).
4984
4985      For related information on providing license text, see the
4986      :term:`COPY_LIC_DIRS` variable, the
4987      :term:`COPY_LIC_MANIFEST` variable, and the
4988      ":ref:`dev-manual/licenses:providing license text`"
4989      section in the Yocto Project Development Tasks Manual.
4990
4991   :term:`LICENSE_FLAGS`
4992      Specifies additional flags for a recipe you must allow through
4993      :term:`LICENSE_FLAGS_ACCEPTED` in
4994      order for the recipe to be built. When providing multiple flags,
4995      separate them with spaces.
4996
4997      This value is independent of :term:`LICENSE` and is
4998      typically used to mark recipes that might require additional licenses
4999      in order to be used in a commercial product. For more information,
5000      see the
5001      ":ref:`dev-manual/licenses:enabling commercially licensed recipes`"
5002      section in the Yocto Project Development Tasks Manual.
5003
5004   :term:`LICENSE_FLAGS_ACCEPTED`
5005      Lists license flags that when specified in
5006      :term:`LICENSE_FLAGS` within a recipe should not
5007      prevent that recipe from being built.  For more information, see the
5008      ":ref:`dev-manual/licenses:enabling commercially licensed recipes`"
5009      section in the Yocto Project Development Tasks Manual.
5010
5011   :term:`LICENSE_FLAGS_DETAILS`
5012      Adds details about a flag in :term:`LICENSE_FLAGS`. This way,
5013      if such a flag is not accepted through :term:`LICENSE_FLAGS_ACCEPTED`,
5014      the error message will be more informative, containing the specified
5015      extra details.
5016
5017      For example, a recipe with an EULA may set::
5018
5019         LICENSE_FLAGS = "FooBar-EULA"
5020         LICENSE_FLAGS_DETAILS[FooBar-EULA] = "For further details, see https://example.com/eula."
5021
5022      If ``Foobar-EULA`` isn't in :term:`LICENSE_FLAGS_ACCEPTED`, the
5023      error message is more useful::
5024
5025        Has a restricted license 'FooBar-EULA' which is not listed in your LICENSE_FLAGS_ACCEPTED.
5026        For further details, see https://example.com/eula.
5027
5028   :term:`LICENSE_PATH`
5029      Path to additional licenses used during the build. By default, the
5030      OpenEmbedded build system uses :term:`COMMON_LICENSE_DIR` to define the
5031      directory that holds common license text used during the build. The
5032      :term:`LICENSE_PATH` variable allows you to extend that location to other
5033      areas that have additional licenses::
5034
5035         LICENSE_PATH += "path-to-additional-common-licenses"
5036
5037   :term:`LINUX_KERNEL_TYPE`
5038      Defines the kernel type to be used in assembling the configuration.
5039      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
5040      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
5041      section in the
5042      Yocto Project Linux Kernel Development Manual for more information on
5043      kernel types.
5044
5045      If you do not specify a :term:`LINUX_KERNEL_TYPE`, it defaults to
5046      "standard". Together with :term:`KMACHINE`, the
5047      :term:`LINUX_KERNEL_TYPE` variable defines the search arguments used by
5048      the kernel tools to find the appropriate description within the
5049      kernel :term:`Metadata` with which to build out the sources
5050      and configuration.
5051
5052   :term:`LINUX_VERSION`
5053      The Linux version from ``kernel.org`` on which the Linux kernel image
5054      being built using the OpenEmbedded build system is based. You define
5055      this variable in the kernel recipe. For example, the
5056      ``linux-yocto-3.4.bb`` kernel recipe found in
5057      ``meta/recipes-kernel/linux`` defines the variables as follows::
5058
5059         LINUX_VERSION ?= "3.4.24"
5060
5061      The :term:`LINUX_VERSION` variable is used to define :term:`PV`
5062      for the recipe::
5063
5064         PV = "${LINUX_VERSION}+git${SRCPV}"
5065
5066   :term:`LINUX_VERSION_EXTENSION`
5067      A string extension compiled into the version string of the Linux
5068      kernel built with the OpenEmbedded build system. You define this
5069      variable in the kernel recipe. For example, the linux-yocto kernel
5070      recipes all define the variable as follows::
5071
5072         LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
5073
5074      Defining this variable essentially sets the Linux kernel
5075      configuration item ``CONFIG_LOCALVERSION``, which is visible through
5076      the ``uname`` command. Here is an example that shows the extension
5077      assuming it was set as previously shown::
5078
5079         $ uname -r
5080         3.7.0-rc8-custom
5081
5082   :term:`LOG_DIR`
5083      Specifies the directory to which the OpenEmbedded build system writes
5084      overall log files. The default directory is ``${TMPDIR}/log``.
5085
5086      For the directory containing logs specific to each task, see the
5087      :term:`T` variable.
5088
5089   :term:`MACHINE`
5090      Specifies the target device for which the image is built. You define
5091      :term:`MACHINE` in the ``local.conf`` file found in the
5092      :term:`Build Directory`. By default, :term:`MACHINE` is set to
5093      "qemux86", which is an x86-based architecture machine to be emulated
5094      using QEMU::
5095
5096         MACHINE ?= "qemux86"
5097
5098      The variable corresponds to a machine configuration file of the same
5099      name, through which machine-specific configurations are set. Thus,
5100      when :term:`MACHINE` is set to "qemux86", the corresponding
5101      ``qemux86.conf`` machine configuration file can be found in
5102      the :term:`Source Directory` in
5103      ``meta/conf/machine``.
5104
5105      The list of machines supported by the Yocto Project as shipped
5106      include the following::
5107
5108         MACHINE ?= "qemuarm"
5109         MACHINE ?= "qemuarm64"
5110         MACHINE ?= "qemumips"
5111         MACHINE ?= "qemumips64"
5112         MACHINE ?= "qemuppc"
5113         MACHINE ?= "qemux86"
5114         MACHINE ?= "qemux86-64"
5115         MACHINE ?= "genericx86"
5116         MACHINE ?= "genericx86-64"
5117         MACHINE ?= "beaglebone"
5118
5119      The last five are Yocto Project reference hardware
5120      boards, which are provided in the ``meta-yocto-bsp`` layer.
5121
5122      .. note::
5123
5124         Adding additional Board Support Package (BSP) layers to your
5125         configuration adds new possible settings for :term:`MACHINE`.
5126
5127   :term:`MACHINE_ARCH`
5128      Specifies the name of the machine-specific architecture. This
5129      variable is set automatically from :term:`MACHINE` or
5130      :term:`TUNE_PKGARCH`. You should not hand-edit
5131      the :term:`MACHINE_ARCH` variable.
5132
5133   :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
5134      A list of required machine-specific packages to install as part of
5135      the image being built. The build process depends on these packages
5136      being present. Furthermore, because this is a "machine-essential"
5137      variable, the list of packages are essential for the machine to boot.
5138      The impact of this variable affects images based on
5139      ``packagegroup-core-boot``, including the ``core-image-minimal``
5140      image.
5141
5142      This variable is similar to the
5143      :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` variable with the exception
5144      that the image being built has a build dependency on the variable's
5145      list of packages. In other words, the image will not build if a file
5146      in this list is not found.
5147
5148      As an example, suppose the machine for which you are building
5149      requires ``example-init`` to be run during boot to initialize the
5150      hardware. In this case, you would use the following in the machine's
5151      ``.conf`` configuration file::
5152
5153         MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
5154
5155   :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS`
5156      A list of recommended machine-specific packages to install as part of
5157      the image being built. The build process does not depend on these
5158      packages being present. However, because this is a
5159      "machine-essential" variable, the list of packages are essential for
5160      the machine to boot. The impact of this variable affects images based
5161      on ``packagegroup-core-boot``, including the ``core-image-minimal``
5162      image.
5163
5164      This variable is similar to the :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
5165      variable with the exception that the image being built does not have
5166      a build dependency on the variable's list of packages. In other
5167      words, the image will still build if a package in this list is not
5168      found. Typically, this variable is used to handle essential kernel
5169      modules, whose functionality may be selected to be built into the
5170      kernel rather than as a module, in which case a package will not be
5171      produced.
5172
5173      Consider an example where you have a custom kernel where a specific
5174      touchscreen driver is required for the machine to be usable. However,
5175      the driver can be built as a module or into the kernel depending on
5176      the kernel configuration. If the driver is built as a module, you
5177      want it to be installed. But, when the driver is built into the
5178      kernel, you still want the build to succeed. This variable sets up a
5179      "recommends" relationship so that in the latter case, the build will
5180      not fail due to the missing package. To accomplish this, assuming the
5181      package for the module was called ``kernel-module-ab123``, you would
5182      use the following in the machine's ``.conf`` configuration file::
5183
5184         MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
5185
5186      .. note::
5187
5188         In this example, the ``kernel-module-ab123`` recipe needs to
5189         explicitly set its :term:`PACKAGES` variable to ensure that BitBake
5190         does not use the kernel recipe's :term:`PACKAGES_DYNAMIC` variable to
5191         satisfy the dependency.
5192
5193      Some examples of these machine essentials are flash, screen,
5194      keyboard, mouse, or touchscreen drivers (depending on the machine).
5195
5196   :term:`MACHINE_EXTRA_RDEPENDS`
5197      A list of machine-specific packages to install as part of the image
5198      being built that are not essential for the machine to boot. However,
5199      the build process for more fully-featured images depends on the
5200      packages being present.
5201
5202      This variable affects all images based on ``packagegroup-base``,
5203      which does not include the ``core-image-minimal`` or
5204      ``core-image-full-cmdline`` images.
5205
5206      The variable is similar to the :term:`MACHINE_EXTRA_RRECOMMENDS` variable
5207      with the exception that the image being built has a build dependency
5208      on the variable's list of packages. In other words, the image will
5209      not build if a file in this list is not found.
5210
5211      An example is a machine that has WiFi capability but is not essential
5212      for the machine to boot the image. However, if you are building a
5213      more fully-featured image, you want to enable the WiFi. The package
5214      containing the firmware for the WiFi hardware is always expected to
5215      exist, so it is acceptable for the build process to depend upon
5216      finding the package. In this case, assuming the package for the
5217      firmware was called ``wifidriver-firmware``, you would use the
5218      following in the ``.conf`` file for the machine::
5219
5220         MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
5221
5222   :term:`MACHINE_EXTRA_RRECOMMENDS`
5223      A list of machine-specific packages to install as part of the image
5224      being built that are not essential for booting the machine. The image
5225      being built has no build dependency on this list of packages.
5226
5227      This variable affects only images based on ``packagegroup-base``,
5228      which does not include the ``core-image-minimal`` or
5229      ``core-image-full-cmdline`` images.
5230
5231      This variable is similar to the :term:`MACHINE_EXTRA_RDEPENDS` variable
5232      with the exception that the image being built does not have a build
5233      dependency on the variable's list of packages. In other words, the
5234      image will build if a file in this list is not found.
5235
5236      An example is a machine that has WiFi capability but is not essential
5237      For the machine to boot the image. However, if you are building a
5238      more fully-featured image, you want to enable WiFi. In this case, the
5239      package containing the WiFi kernel module will not be produced if the
5240      WiFi driver is built into the kernel, in which case you still want
5241      the build to succeed instead of failing as a result of the package
5242      not being found. To accomplish this, assuming the package for the
5243      module was called ``kernel-module-examplewifi``, you would use the
5244      following in the ``.conf`` file for the machine::
5245
5246         MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
5247
5248   :term:`MACHINE_FEATURES`
5249      Specifies the list of hardware features the
5250      :term:`MACHINE` is capable of supporting. For related
5251      information on enabling features, see the
5252      :term:`DISTRO_FEATURES`,
5253      :term:`COMBINED_FEATURES`, and
5254      :term:`IMAGE_FEATURES` variables.
5255
5256      For a list of hardware features supported by the Yocto Project as
5257      shipped, see the ":ref:`ref-features-machine`" section.
5258
5259   :term:`MACHINE_FEATURES_BACKFILL`
5260      A list of space-separated features to be added to
5261      :term:`MACHINE_FEATURES` if not also present in
5262      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`.
5263
5264      This variable is set in the ``meta/conf/bitbake.conf`` file. It is not
5265      intended to be user-configurable. It is best to just reference the
5266      variable to see which machine features are being
5267      :ref:`backfilled <ref-features-backfill>` for all machine configurations.
5268
5269   :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`
5270      A list of space-separated features from :term:`MACHINE_FEATURES_BACKFILL`
5271      that should not be :ref:`backfilled <ref-features-backfill>` (i.e. added
5272      to :term:`MACHINE_FEATURES`) during the build.
5273
5274      This corresponds to an opt-out mechanism. When new default machine
5275      features are introduced, machine definition maintainers can review
5276      (`consider`) them and decide to exclude them from the
5277      :ref:`backfilled <ref-features-backfill>` features. Therefore, the
5278      combination of :term:`MACHINE_FEATURES_BACKFILL` and
5279      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED` makes it possible to
5280      add new default features without breaking existing machine definitions.
5281
5282   :term:`MACHINEOVERRIDES`
5283      A colon-separated list of overrides that apply to the current
5284      machine. By default, this list includes the value of
5285      :term:`MACHINE`.
5286
5287      You can extend :term:`MACHINEOVERRIDES` to add extra overrides that
5288      should apply to a machine. For example, all machines emulated in QEMU
5289      (e.g. ``qemuarm``, ``qemux86``, and so forth) include a file named
5290      ``meta/conf/machine/include/qemu.inc`` that prepends the following
5291      override to :term:`MACHINEOVERRIDES`::
5292
5293         MACHINEOVERRIDES =. "qemuall:"
5294
5295      This
5296      override allows variables to be overridden for all machines emulated
5297      in QEMU, like in the following example from the ``connman-conf``
5298      recipe::
5299
5300         SRC_URI:append:qemuall = " file://wired.config \
5301             file://wired-setup \
5302             "
5303
5304      The underlying mechanism behind
5305      :term:`MACHINEOVERRIDES` is simply that it is included in the default
5306      value of :term:`OVERRIDES`.
5307
5308   :term:`MAINTAINER`
5309      The email address of the distribution maintainer.
5310
5311   :term:`MESON_BUILDTYPE`
5312      Value of the Meson ``--buildtype`` argument used by the
5313      :ref:`ref-classes-meson` class. It defaults to ``debug`` if
5314      :term:`DEBUG_BUILD` is set to "1", and ``plain`` otherwise.
5315
5316      See `Meson build options <https://mesonbuild.com/Builtin-options.html>`__
5317      for the values you could set in a recipe. Values such as ``plain``,
5318      ``debug``, ``debugoptimized``, ``release`` and ``minsize`` allow
5319      you to specify the inclusion of debugging symbols and the compiler
5320      optimizations (none, performance or size).
5321
5322   :term:`MESON_TARGET`
5323      A variable for the :ref:`ref-classes-meson` class, allowing to choose
5324      a Meson target to build in :ref:`ref-tasks-compile`.  Otherwise, the
5325      default targets are built.
5326
5327   :term:`METADATA_BRANCH`
5328      The branch currently checked out for the OpenEmbedded-Core layer (path
5329      determined by :term:`COREBASE`).
5330
5331   :term:`METADATA_REVISION`
5332      The revision currently checked out for the OpenEmbedded-Core layer (path
5333      determined by :term:`COREBASE`).
5334
5335   :term:`MIME_XDG_PACKAGES`
5336      The current implementation of the :ref:`ref-classes-mime-xdg`
5337      class cannot detect ``.desktop`` files installed through absolute
5338      symbolic links. Use this setting to make the class create post-install
5339      and post-remove scripts for these packages anyway, to invoke the
5340      ``update-destop-database`` command.
5341
5342   :term:`MIRRORS`
5343      Specifies additional paths from which the OpenEmbedded build system
5344      gets source code. When the build system searches for source code, it
5345      first tries the local download directory. If that location fails, the
5346      build system tries locations defined by
5347      :term:`PREMIRRORS`, the upstream source, and then
5348      locations specified by :term:`MIRRORS` in that order.
5349
5350      The default value for :term:`MIRRORS` is defined in the
5351      ``meta/classes-global/mirrors.bbclass`` file in the core metadata layer.
5352
5353   :term:`MLPREFIX`
5354      Specifies a prefix has been added to :term:`PN` to create a
5355      special version of a recipe or package (i.e. a Multilib version). The
5356      variable is used in places where the prefix needs to be added to or
5357      removed from a name (e.g. the :term:`BPN` variable).
5358      :term:`MLPREFIX` gets set when a prefix has been added to :term:`PN`.
5359
5360      .. note::
5361
5362         The "ML" in :term:`MLPREFIX` stands for "MultiLib". This representation
5363         is historical and comes from a time when ":ref:`ref-classes-nativesdk`"
5364         was a suffix rather than a prefix on the recipe name. When
5365         ":ref:`ref-classes-nativesdk`" was turned into a prefix, it made sense
5366         to set :term:`MLPREFIX` for it as well.
5367
5368      To help understand when :term:`MLPREFIX` might be needed, consider when
5369      :term:`BBCLASSEXTEND` is used to provide a :ref:`ref-classes-nativesdk`
5370      version of a recipe in addition to the target version. If that recipe
5371      declares build-time dependencies on tasks in other recipes by using
5372      :term:`DEPENDS`, then a dependency on "foo" will automatically get
5373      rewritten to a dependency on "nativesdk-foo". However, dependencies like
5374      the following will not get rewritten automatically::
5375
5376         do_foo[depends] += "recipe:do_foo"
5377
5378      If you want such a dependency to also get transformed, you can do the
5379      following::
5380
5381         do_foo[depends] += "${MLPREFIX}recipe:do_foo"
5382
5383   :term:`module_autoload`
5384      This variable has been replaced by the :term:`KERNEL_MODULE_AUTOLOAD`
5385      variable. You should replace all occurrences of :term:`module_autoload`
5386      with additions to :term:`KERNEL_MODULE_AUTOLOAD`, for example::
5387
5388         module_autoload_rfcomm = "rfcomm"
5389
5390      should now be replaced with::
5391
5392         KERNEL_MODULE_AUTOLOAD += "rfcomm"
5393
5394      See the :term:`KERNEL_MODULE_AUTOLOAD` variable for more information.
5395
5396   :term:`module_conf`
5397      Specifies `modprobe.d <https://linux.die.net/man/5/modprobe.d>`__
5398      syntax lines for inclusion in the ``/etc/modprobe.d/modname.conf``
5399      file.
5400
5401      You can use this variable anywhere that it can be recognized by the
5402      kernel recipe or out-of-tree kernel module recipe (e.g. a machine
5403      configuration file, a distribution configuration file, an append file
5404      for the recipe, or the recipe itself). If you use this variable, you
5405      must also be sure to list the module name in the
5406      :term:`KERNEL_MODULE_PROBECONF`
5407      variable.
5408
5409      Here is the general syntax::
5410
5411         module_conf_module_name = "modprobe.d-syntax"
5412
5413      You must use the kernel module name override.
5414
5415      Run ``man modprobe.d`` in the shell to find out more information on
5416      the exact syntax you want to provide with :term:`module_conf`.
5417
5418      Including :term:`module_conf` causes the OpenEmbedded build system to
5419      populate the ``/etc/modprobe.d/modname.conf`` file with
5420      ``modprobe.d`` syntax lines. Here is an example that adds the options
5421      ``arg1`` and ``arg2`` to a module named ``mymodule``::
5422
5423         module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
5424
5425      For information on how to specify kernel modules to auto-load on
5426      boot, see the :term:`KERNEL_MODULE_AUTOLOAD` variable.
5427
5428   :term:`MODULE_TARBALL_DEPLOY`
5429      Controls creation of the ``modules-*.tgz`` file. Set this variable to
5430      "0" to disable creation of this file, which contains all of the
5431      kernel modules resulting from a kernel build.
5432
5433   :term:`MODULE_TARBALL_LINK_NAME`
5434      The link name of the kernel module tarball. This variable is set in
5435      the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
5436
5437         MODULE_TARBALL_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
5438
5439      The value
5440      of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the
5441      same file, has the following value::
5442
5443         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
5444
5445      See the :term:`MACHINE` variable for additional information.
5446
5447   :term:`MODULE_TARBALL_NAME`
5448      The base name of the kernel module tarball. This variable is set in
5449      the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
5450
5451         MODULE_TARBALL_NAME ?= "${KERNEL_ARTIFACT_NAME}"
5452
5453      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
5454
5455   :term:`MOUNT_BASE`
5456      On non-systemd systems (where ``udev-extraconf`` is being used),
5457      specifies the base directory for auto-mounting filesystems. The
5458      default value is "/run/media".
5459
5460   :term:`MULTIMACH_TARGET_SYS`
5461      Uniquely identifies the type of the target system for which packages
5462      are being built. This variable allows output for different types of
5463      target systems to be put into different subdirectories of the same
5464      output directory.
5465
5466      The default value of this variable is::
5467
5468         ${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}
5469
5470      Some classes (e.g.  :ref:`ref-classes-cross-canadian`) modify the
5471      :term:`MULTIMACH_TARGET_SYS` value.
5472
5473      See the :term:`STAMP` variable for an example. See the
5474      :term:`STAGING_DIR_TARGET` variable for more information.
5475
5476   :term:`NATIVELSBSTRING`
5477      A string identifying the host distribution. Strings consist of the
5478      host distributor ID followed by the release, as reported by the
5479      ``lsb_release`` tool or as read from ``/etc/lsb-release``. For
5480      example, when running a build on Ubuntu 12.10, the value is
5481      "Ubuntu-12.10". If this information is unable to be determined, the
5482      value resolves to "Unknown".
5483
5484      This variable is used by default to isolate native shared state
5485      packages for different distributions (e.g. to avoid problems with
5486      ``glibc`` version incompatibilities). Additionally, the variable is
5487      checked against
5488      :term:`SANITY_TESTED_DISTROS` if that
5489      variable is set.
5490
5491   :term:`NM`
5492      The minimal command and arguments to run ``nm``.
5493
5494   :term:`NO_GENERIC_LICENSE`
5495      Avoids QA errors when you use a non-common, non-CLOSED license in a
5496      recipe. There are packages, such as the linux-firmware package, with many
5497      licenses that are not in any way common. Also, new licenses are added
5498      occasionally to avoid introducing a lot of common license files,
5499      which are only applicable to a specific package.
5500      :term:`NO_GENERIC_LICENSE` is used to allow copying a license that does
5501      not exist in common licenses.
5502
5503      The following example shows how to add :term:`NO_GENERIC_LICENSE` to a
5504      recipe::
5505
5506         NO_GENERIC_LICENSE[license_name] = "license_file_in_fetched_source"
5507
5508      Here is an example that
5509      uses the ``LICENSE.Abilis.txt`` file as the license from the fetched
5510      source::
5511
5512         NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt"
5513
5514   :term:`NO_RECOMMENDATIONS`
5515      Prevents installation of all "recommended-only" packages.
5516      Recommended-only packages are packages installed only through the
5517      :term:`RRECOMMENDS` variable). Setting the
5518      :term:`NO_RECOMMENDATIONS` variable to "1" turns this feature on::
5519
5520         NO_RECOMMENDATIONS = "1"
5521
5522      You can set this variable globally in your ``local.conf`` file or you
5523      can attach it to a specific image recipe by using the recipe name
5524      override::
5525
5526         NO_RECOMMENDATIONS:pn-target_image = "1"
5527
5528      It is important to realize that if you choose to not install packages
5529      using this variable and some other packages are dependent on them
5530      (i.e. listed in a recipe's :term:`RDEPENDS`
5531      variable), the OpenEmbedded build system ignores your request and
5532      will install the packages to avoid dependency errors.
5533
5534      .. note::
5535
5536         Some recommended packages might be required for certain system
5537         functionality, such as kernel modules. It is up to you to add
5538         packages with the :term:`IMAGE_INSTALL` variable.
5539
5540      This variable is only supported when using the IPK and RPM
5541      packaging backends. DEB is not supported.
5542
5543      See the :term:`BAD_RECOMMENDATIONS` and
5544      the :term:`PACKAGE_EXCLUDE` variables for
5545      related information.
5546
5547   :term:`NOAUTOPACKAGEDEBUG`
5548      Disables auto package from splitting ``.debug`` files. If a recipe
5549      requires ``FILES:${PN}-dbg`` to be set manually, the
5550      :term:`NOAUTOPACKAGEDEBUG` can be defined allowing you to define the
5551      content of the debug package. For example::
5552
5553         NOAUTOPACKAGEDEBUG = "1"
5554         FILES:${PN}-dev = "${includedir}/${QT_DIR_NAME}/Qt/*"
5555         FILES:${PN}-dbg = "/usr/src/debug/"
5556         FILES:${QT_BASE_NAME}-demos-doc = "${docdir}/${QT_DIR_NAME}/qch/qt.qch"
5557
5558   :term:`NON_MULTILIB_RECIPES`
5559      A list of recipes that should not be built for multilib. OE-Core's
5560      ``multilib.conf`` file defines a reasonable starting point for this
5561      list with::
5562
5563         NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot"
5564
5565   :term:`OBJCOPY`
5566      The minimal command and arguments to run ``objcopy``.
5567
5568   :term:`OBJDUMP`
5569      The minimal command and arguments to run ``objdump``.
5570
5571   :term:`OE_BINCONFIG_EXTRA_MANGLE`
5572      When inheriting the :ref:`ref-classes-binconfig` class,
5573      this variable specifies additional arguments passed to the "sed"
5574      command. The sed command alters any paths in configuration scripts
5575      that have been set up during compilation. Inheriting this class
5576      results in all paths in these scripts being changed to point into the
5577      ``sysroots/`` directory so that all builds that use the script will
5578      use the correct directories for the cross compiling layout.
5579
5580      See the ``meta/classes-recipe/binconfig.bbclass`` in the
5581      :term:`Source Directory` for details on how this class
5582      applies these additional sed command arguments.
5583
5584   :term:`OECMAKE_GENERATOR`
5585      A variable for the :ref:`ref-classes-cmake` class, allowing to choose
5586      which back-end will be generated by CMake to build an application.
5587
5588      By default, this variable is set to ``Ninja``, which is faster than GNU
5589      make, but if building is broken with Ninja, a recipe can use this
5590      variable to use GNU make instead::
5591
5592         OECMAKE_GENERATOR = "Unix Makefiles"
5593
5594   :term:`OE_IMPORTS`
5595      An internal variable used to tell the OpenEmbedded build system what
5596      Python modules to import for every Python function run by the system.
5597
5598      .. note::
5599
5600         Do not set this variable. It is for internal use only.
5601
5602   :term:`OE_INIT_ENV_SCRIPT`
5603      The name of the build environment setup script for the purposes of
5604      setting up the environment within the extensible SDK. The default
5605      value is "oe-init-build-env".
5606
5607      If you use a custom script to set up your build environment, set the
5608      :term:`OE_INIT_ENV_SCRIPT` variable to its name.
5609
5610   :term:`OE_TERMINAL`
5611      Controls how the OpenEmbedded build system spawns interactive
5612      terminals on the host development system (e.g. using the BitBake
5613      command with the ``-c devshell`` command-line option). For more
5614      information, see the ":ref:`dev-manual/development-shell:using a development shell`" section in
5615      the Yocto Project Development Tasks Manual.
5616
5617      You can use the following values for the :term:`OE_TERMINAL` variable:
5618
5619      - auto
5620      - gnome
5621      - xfce
5622      - rxvt
5623      - screen
5624      - konsole
5625      - none
5626
5627   :term:`OEROOT`
5628      The directory from which the top-level build environment setup script
5629      is sourced. The Yocto Project provides a top-level build environment
5630      setup script: :ref:`structure-core-script`. When you run this
5631      script, the :term:`OEROOT` variable resolves to the directory that
5632      contains the script.
5633
5634      For additional information on how this variable is used, see the
5635      initialization script.
5636
5637   :term:`OEQA_REPRODUCIBLE_TEST_PACKAGE`
5638      Set the package manager(s) for build reproducibility testing.
5639      See :yocto_git:`reproducible.py </poky/tree/meta/lib/oeqa/selftest/cases/reproducible.py>`
5640      and :doc:`/test-manual/reproducible-builds`.
5641
5642   :term:`OEQA_REPRODUCIBLE_TEST_TARGET`
5643      Set build target for build reproducibility testing. By default
5644      all available recipes are compiled with "bitbake world", see also :term:`EXCLUDE_FROM_WORLD`
5645      and :doc:`/test-manual/reproducible-builds`.
5646
5647   :term:`OEQA_REPRODUCIBLE_TEST_SSTATE_TARGETS`
5648      Set build targets which can be rebuilt using :ref:`shared state <overview-manual/concepts:shared state cache>`
5649      when running build reproducibility tests. See :doc:`/test-manual/reproducible-builds`.
5650
5651   :term:`OLDEST_KERNEL`
5652      Declares the oldest version of the Linux kernel that the produced
5653      binaries must support. This variable is passed into the build of the
5654      Embedded GNU C Library (``glibc``).
5655
5656      The default for this variable comes from the
5657      ``meta/conf/bitbake.conf`` configuration file. You can override this
5658      default by setting the variable in a custom distribution
5659      configuration file.
5660
5661   :term:`OVERLAYFS_ETC_DEVICE`
5662      When the :ref:`ref-classes-overlayfs-etc` class is
5663      inherited, specifies the device to be mounted for the read/write
5664      layer of ``/etc``. There is no default, so you must set this if you
5665      wish to enable :ref:`ref-classes-overlayfs-etc`, for
5666      example, assuming ``/dev/mmcblk0p2`` was the desired device::
5667
5668         OVERLAYFS_ETC_DEVICE = "/dev/mmcblk0p2"
5669
5670   :term:`OVERLAYFS_ETC_EXPOSE_LOWER`
5671      When the :ref:`ref-classes-overlayfs-etc` class is
5672      inherited, if set to "1" then a read-only access to the original
5673      ``/etc`` content will be provided as a ``lower/`` subdirectory of
5674      :term:`OVERLAYFS_ETC_MOUNT_POINT`. The default value is "0".
5675
5676   :term:`OVERLAYFS_ETC_FSTYPE`
5677      When the :ref:`ref-classes-overlayfs-etc` class is
5678      inherited, specifies the file system type for the read/write
5679      layer of ``/etc``. There is no default, so you must set this if you
5680      wish to enable :ref:`ref-classes-overlayfs-etc`,
5681      for example, assuming the file system is ext4::
5682
5683         OVERLAYFS_ETC_FSTYPE = "ext4"
5684
5685   :term:`OVERLAYFS_ETC_MOUNT_OPTIONS`
5686      When the :ref:`ref-classes-overlayfs-etc` class is
5687      inherited, specifies the mount options for the read-write layer.
5688      The default value is "defaults".
5689
5690   :term:`OVERLAYFS_ETC_MOUNT_POINT`
5691      When the :ref:`ref-classes-overlayfs-etc` class is
5692      inherited, specifies the parent mount path for the filesystem layers.
5693      There is no default, so you must set this if you wish to enable
5694      :ref:`ref-classes-overlayfs-etc`, for example if the desired path is
5695      "/data"::
5696
5697         OVERLAYFS_ETC_MOUNT_POINT = "/data"
5698
5699   :term:`OVERLAYFS_ETC_USE_ORIG_INIT_NAME`
5700      When the :ref:`ref-classes-overlayfs-etc` class is inherited, controls
5701      how the generated init will be named. For more information, see the
5702      :ref:`ref-classes-overlayfs-etc` class documentation. The default value
5703      is "1".
5704
5705   :term:`OVERLAYFS_MOUNT_POINT`
5706      When inheriting the :ref:`ref-classes-overlayfs` class,
5707      specifies mount point(s) to be used. For example::
5708
5709         OVERLAYFS_MOUNT_POINT[data] = "/data"
5710
5711      The assumes you have a ``data.mount`` systemd unit defined elsewhere in
5712      your BSP (e.g. in ``systemd-machine-units`` recipe) and it is installed
5713      into the image. For more information see :ref:`ref-classes-overlayfs`.
5714
5715      .. note::
5716
5717         Although the :ref:`ref-classes-overlayfs` class is
5718         inherited by individual recipes, :term:`OVERLAYFS_MOUNT_POINT`
5719         should be set in your machine configuration.
5720
5721   :term:`OVERLAYFS_QA_SKIP`
5722      When inheriting the :ref:`ref-classes-overlayfs` class,
5723      provides the ability to disable QA checks for particular overlayfs
5724      mounts. For example::
5725
5726         OVERLAYFS_QA_SKIP[data] = "mount-configured"
5727
5728      .. note::
5729
5730         Although the :ref:`ref-classes-overlayfs` class is
5731         inherited by individual recipes, :term:`OVERLAYFS_QA_SKIP`
5732         should be set in your machine configuration.
5733
5734   :term:`OVERLAYFS_WRITABLE_PATHS`
5735      When inheriting the :ref:`ref-classes-overlayfs` class,
5736      specifies writable paths used at runtime for the recipe. For
5737      example::
5738
5739         OVERLAYFS_WRITABLE_PATHS[data] = "/usr/share/my-custom-application"
5740
5741   :term:`OVERRIDES`
5742      A colon-separated list of overrides that currently apply. Overrides
5743      are a BitBake mechanism that allows variables to be selectively
5744      overridden at the end of parsing. The set of overrides in
5745      :term:`OVERRIDES` represents the "state" during building, which includes
5746      the current recipe being built, the machine for which it is being
5747      built, and so forth.
5748
5749      As an example, if the string "an-override" appears as an element in
5750      the colon-separated list in :term:`OVERRIDES`, then the following
5751      assignment will override ``FOO`` with the value "overridden" at the
5752      end of parsing::
5753
5754         FOO:an-override = "overridden"
5755
5756      See the
5757      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
5758      section in the BitBake User Manual for more information on the
5759      overrides mechanism.
5760
5761      The default value of :term:`OVERRIDES` includes the values of the
5762      :term:`CLASSOVERRIDE`,
5763      :term:`MACHINEOVERRIDES`, and
5764      :term:`DISTROOVERRIDES` variables. Another
5765      important override included by default is ``pn-${PN}``. This override
5766      allows variables to be set for a single recipe within configuration
5767      (``.conf``) files. Here is an example::
5768
5769         FOO:pn-myrecipe = "myrecipe-specific value"
5770
5771      .. note::
5772
5773         An easy way to see what overrides apply is to search for :term:`OVERRIDES`
5774         in the output of the ``bitbake -e`` command. See the
5775         ":ref:`dev-manual/debugging:viewing variable values`" section in the Yocto
5776         Project Development Tasks Manual for more information.
5777
5778   :term:`P`
5779      The recipe name and version. :term:`P` is comprised of the following::
5780
5781         ${PN}-${PV}
5782
5783   :term:`P4DIR`
5784      See :term:`bitbake:P4DIR` in the BitBake manual.
5785
5786   :term:`PACKAGE_ADD_METADATA`
5787      This variable defines additional metadata to add to packages.
5788
5789      You may find you need to inject additional metadata into packages.
5790      This variable allows you to do that by setting the injected data as
5791      the value. Multiple fields can be added by splitting the content with
5792      the literal separator "\n".
5793
5794      The suffixes '_IPK', '_DEB', or '_RPM' can be applied to the variable
5795      to do package type specific settings. It can also be made package
5796      specific by using the package name as a suffix.
5797
5798      You can find out more about applying this variable in the
5799      ":ref:`dev-manual/packages:adding custom metadata to packages`"
5800      section in the Yocto Project Development Tasks Manual.
5801
5802   :term:`PACKAGE_ARCH`
5803      The architecture of the resulting package or packages.
5804
5805      By default, the value of this variable is set to
5806      :term:`TUNE_PKGARCH` when building for the
5807      target, :term:`BUILD_ARCH` when building for the
5808      build host, and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building for the
5809      SDK.
5810
5811      .. note::
5812
5813         See :term:`SDK_ARCH` for more information.
5814
5815      However, if your recipe's output packages are built specific to the
5816      target machine rather than generally for the architecture of the
5817      machine, you should set :term:`PACKAGE_ARCH` to the value of
5818      :term:`MACHINE_ARCH` in the recipe as follows::
5819
5820         PACKAGE_ARCH = "${MACHINE_ARCH}"
5821
5822   :term:`PACKAGE_ARCHS`
5823      Specifies a list of architectures compatible with the target machine.
5824      This variable is set automatically and should not normally be
5825      hand-edited. Entries are separated using spaces and listed in order
5826      of priority. The default value for :term:`PACKAGE_ARCHS` is "all any
5827      noarch ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
5828
5829   :term:`PACKAGE_BEFORE_PN`
5830      Enables easily adding packages to :term:`PACKAGES` before ``${PN}`` so
5831      that those added packages can pick up files that would normally be
5832      included in the default package.
5833
5834   :term:`PACKAGE_CLASSES`
5835      This variable, which is set in the ``local.conf`` configuration file
5836      found in the ``conf`` folder of the
5837      :term:`Build Directory`, specifies the package manager the
5838      OpenEmbedded build system uses when packaging data.
5839
5840      You can provide one or more of the following arguments for the
5841      variable::
5842
5843         PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
5844
5845      The build system uses only the first argument in the list as the
5846      package manager when creating your image or SDK. However, packages
5847      will be created using any additional packaging classes you specify.
5848      For example, if you use the following in your ``local.conf`` file::
5849
5850         PACKAGE_CLASSES ?= "package_ipk"
5851
5852      The OpenEmbedded build system uses
5853      the IPK package manager to create your image or SDK.
5854
5855      For information on packaging and build performance effects as a
5856      result of the package manager in use, see the
5857      ":ref:`ref-classes-package`" section.
5858
5859   :term:`PACKAGE_DEBUG_SPLIT_STYLE`
5860      Determines how to split up and package debug and source information
5861      when creating debugging packages to be used with the GNU Project
5862      Debugger (GDB). In general, based on the value of this variable,
5863      you can combine the source and debug info in a single package,
5864      you can break out the source into a separate package that can be
5865      installed independently, or you can choose to not have the source
5866      packaged at all.
5867
5868      The possible values of :term:`PACKAGE_DEBUG_SPLIT_STYLE` variable:
5869
5870      -  "``.debug``": All debugging and source info is placed in a single
5871         ``*-dbg`` package; debug symbol files are placed next to the
5872         binary in a ``.debug`` directory so that, if a binary is installed
5873         into ``/bin``, the corresponding debug symbol file is installed
5874         in ``/bin/.debug``. Source files are installed in the same ``*-dbg``
5875         package under ``/usr/src/debug``.
5876
5877      -  "``debug-file-directory``": As above, all debugging and source info
5878         is placed in a single ``*-dbg`` package; debug symbol files are
5879         placed entirely under the directory ``/usr/lib/debug`` and separated
5880         by the path from where the binary is installed, so that if a binary
5881         is installed in ``/bin``, the corresponding debug symbols are installed
5882         in ``/usr/lib/debug/bin``, and so on. As above, source is installed
5883         in the same package under ``/usr/src/debug``.
5884
5885      -  "``debug-with-srcpkg``": Debugging info is placed in the standard
5886         ``*-dbg`` package as with the ``.debug`` value, while source is
5887         placed in a separate ``*-src`` package, which can be installed
5888         independently.  This is the default setting for this variable,
5889         as defined in Poky's ``bitbake.conf`` file.
5890
5891      -  "``debug-without-src``": The same behavior as with the ``.debug``
5892         setting, but no source is packaged at all.
5893
5894      .. note::
5895
5896         Much of the above package splitting can be overridden via
5897         use of the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable.
5898
5899      You can find out more about debugging using GDB by reading the
5900      ":ref:`dev-manual/debugging:debugging with the gnu project debugger (gdb) remotely`" section
5901      in the Yocto Project Development Tasks Manual.
5902
5903   :term:`PACKAGE_EXCLUDE`
5904      Lists packages that should not be installed into an image. For
5905      example::
5906
5907         PACKAGE_EXCLUDE = "package_name package_name package_name ..."
5908
5909      You can set this variable globally in your ``local.conf`` file or you
5910      can attach it to a specific image recipe by using the recipe name
5911      override::
5912
5913         PACKAGE_EXCLUDE:pn-target_image = "package_name"
5914
5915      If you choose to not install a package using this variable and some
5916      other package is dependent on it (i.e. listed in a recipe's
5917      :term:`RDEPENDS` variable), the OpenEmbedded build
5918      system generates a fatal installation error. Because the build system
5919      halts the process with a fatal error, you can use the variable with
5920      an iterative development process to remove specific components from a
5921      system.
5922
5923      This variable is supported only when using the IPK and RPM
5924      packaging backends. DEB is not supported.
5925
5926      See the :term:`NO_RECOMMENDATIONS` and the
5927      :term:`BAD_RECOMMENDATIONS` variables for
5928      related information.
5929
5930   :term:`PACKAGE_EXCLUDE_COMPLEMENTARY`
5931      Prevents specific packages from being installed when you are
5932      installing complementary packages.
5933
5934      You might find that you want to prevent installing certain packages
5935      when you are installing complementary packages. For example, if you
5936      are using :term:`IMAGE_FEATURES` to install
5937      ``dev-pkgs``, you might not want to install all packages from a
5938      particular multilib. If you find yourself in this situation, you can
5939      use the :term:`PACKAGE_EXCLUDE_COMPLEMENTARY` variable to specify regular
5940      expressions to match the packages you want to exclude.
5941
5942   :term:`PACKAGE_EXTRA_ARCHS`
5943      Specifies the list of architectures compatible with the device CPU.
5944      This variable is useful when you build for several different devices
5945      that use miscellaneous processors such as XScale and ARM926-EJS.
5946
5947   :term:`PACKAGE_FEED_ARCHS`
5948      Optionally specifies the package architectures used as part of the
5949      package feed URIs during the build. When used, the
5950      :term:`PACKAGE_FEED_ARCHS` variable is appended to the final package feed
5951      URI, which is constructed using the
5952      :term:`PACKAGE_FEED_URIS` and
5953      :term:`PACKAGE_FEED_BASE_PATHS`
5954      variables.
5955
5956      .. note::
5957
5958         You can use the :term:`PACKAGE_FEED_ARCHS`
5959         variable to allow specific package architectures. If you do
5960         not need to allow specific architectures, which is a common
5961         case, you can omit this variable. Omitting the variable results in
5962         all available architectures for the current machine being included
5963         into remote package feeds.
5964
5965      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5966      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5967      defined in your ``local.conf`` file::
5968
5969         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5970                              https://example.com/packagerepos/updates"
5971         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5972         PACKAGE_FEED_ARCHS = "all core2-64"
5973
5974      Given these settings, the resulting package feeds are as follows:
5975
5976      .. code-block:: none
5977
5978         https://example.com/packagerepos/release/rpm/all
5979         https://example.com/packagerepos/release/rpm/core2-64
5980         https://example.com/packagerepos/release/rpm-dev/all
5981         https://example.com/packagerepos/release/rpm-dev/core2-64
5982         https://example.com/packagerepos/updates/rpm/all
5983         https://example.com/packagerepos/updates/rpm/core2-64
5984         https://example.com/packagerepos/updates/rpm-dev/all
5985         https://example.com/packagerepos/updates/rpm-dev/core2-64
5986
5987   :term:`PACKAGE_FEED_BASE_PATHS`
5988      Specifies the base path used when constructing package feed URIs. The
5989      :term:`PACKAGE_FEED_BASE_PATHS` variable makes up the middle portion of a
5990      package feed URI used by the OpenEmbedded build system. The base path
5991      lies between the :term:`PACKAGE_FEED_URIS`
5992      and :term:`PACKAGE_FEED_ARCHS` variables.
5993
5994      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5995      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5996      defined in your ``local.conf`` file::
5997
5998         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5999                              https://example.com/packagerepos/updates"
6000         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
6001         PACKAGE_FEED_ARCHS = "all core2-64"
6002
6003      Given these settings, the resulting package feeds are as follows:
6004
6005      .. code-block:: none
6006
6007         https://example.com/packagerepos/release/rpm/all
6008         https://example.com/packagerepos/release/rpm/core2-64
6009         https://example.com/packagerepos/release/rpm-dev/all
6010         https://example.com/packagerepos/release/rpm-dev/core2-64
6011         https://example.com/packagerepos/updates/rpm/all
6012         https://example.com/packagerepos/updates/rpm/core2-64
6013         https://example.com/packagerepos/updates/rpm-dev/all
6014         https://example.com/packagerepos/updates/rpm-dev/core2-64
6015
6016   :term:`PACKAGE_FEED_URIS`
6017      Specifies the front portion of the package feed URI used by the
6018      OpenEmbedded build system. Each final package feed URI is comprised
6019      of :term:`PACKAGE_FEED_URIS`,
6020      :term:`PACKAGE_FEED_BASE_PATHS`, and
6021      :term:`PACKAGE_FEED_ARCHS` variables.
6022
6023      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
6024      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
6025      defined in your ``local.conf`` file::
6026
6027         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
6028                              https://example.com/packagerepos/updates"
6029         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
6030         PACKAGE_FEED_ARCHS = "all core2-64"
6031
6032      Given these settings, the resulting package feeds are as follows:
6033
6034      .. code-block:: none
6035
6036         https://example.com/packagerepos/release/rpm/all
6037         https://example.com/packagerepos/release/rpm/core2-64
6038         https://example.com/packagerepos/release/rpm-dev/all
6039         https://example.com/packagerepos/release/rpm-dev/core2-64
6040         https://example.com/packagerepos/updates/rpm/all
6041         https://example.com/packagerepos/updates/rpm/core2-64
6042         https://example.com/packagerepos/updates/rpm-dev/all
6043         https://example.com/packagerepos/updates/rpm-dev/core2-64
6044
6045   :term:`PACKAGE_INSTALL`
6046      The final list of packages passed to the package manager for
6047      installation into the image.
6048
6049      Because the package manager controls actual installation of all
6050      packages, the list of packages passed using :term:`PACKAGE_INSTALL` is
6051      not the final list of packages that are actually installed. This
6052      variable is internal to the image construction code. Consequently, in
6053      general, you should use the
6054      :term:`IMAGE_INSTALL` variable to specify
6055      packages for installation. The exception to this is when working with
6056      the :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
6057      image. When working with an initial RAM filesystem (:term:`Initramfs`) image,
6058      use the :term:`PACKAGE_INSTALL` variable. For information on creating an
6059      :term:`Initramfs`, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
6060      in the Yocto Project Development Tasks Manual.
6061
6062   :term:`PACKAGE_INSTALL_ATTEMPTONLY`
6063      Specifies a list of packages the OpenEmbedded build system attempts
6064      to install when creating an image. If a listed package fails to
6065      install, the build system does not generate an error. This variable
6066      is generally not user-defined.
6067
6068   :term:`PACKAGE_PREPROCESS_FUNCS`
6069      Specifies a list of functions run to pre-process the
6070      :term:`PKGD` directory prior to splitting the files out
6071      to individual packages.
6072
6073   :term:`PACKAGE_WRITE_DEPS`
6074      Specifies a list of dependencies for post-installation and
6075      pre-installation scripts on native/cross tools. If your
6076      post-installation or pre-installation script can execute at root filesystem
6077      creation time rather than on the target but depends on a native tool
6078      in order to execute, you need to list the tools in
6079      :term:`PACKAGE_WRITE_DEPS`.
6080
6081      For information on running post-installation scripts, see the
6082      ":ref:`dev-manual/new-recipe:post-installation scripts`"
6083      section in the Yocto Project Development Tasks Manual.
6084
6085   :term:`PACKAGECONFIG`
6086      This variable provides a means of enabling or disabling features of a
6087      recipe on a per-recipe basis. :term:`PACKAGECONFIG` blocks are defined in
6088      recipes when you specify features and then arguments that define
6089      feature behaviors. Here is the basic block structure (broken over
6090      multiple lines for readability)::
6091
6092         PACKAGECONFIG ??= "f1 f2 f3 ..."
6093         PACKAGECONFIG[f1] = "\
6094             --with-f1, \
6095             --without-f1, \
6096             build-deps-for-f1, \
6097             runtime-deps-for-f1, \
6098             runtime-recommends-for-f1, \
6099             packageconfig-conflicts-for-f1"
6100         PACKAGECONFIG[f2] = "\
6101              ... and so on and so on ...
6102
6103      The :term:`PACKAGECONFIG` variable itself specifies a space-separated
6104      list of the features to enable. Following the features, you can
6105      determine the behavior of each feature by providing up to six
6106      order-dependent arguments, which are separated by commas. You can
6107      omit any argument you like but must retain the separating commas. The
6108      order is important and specifies the following:
6109
6110      #. Extra arguments that should be added to :term:`PACKAGECONFIG_CONFARGS`
6111         if the feature is enabled.
6112
6113      #. Extra arguments that should be added to :term:`PACKAGECONFIG_CONFARGS`
6114         if the feature is disabled.
6115
6116      #. Additional build dependencies (:term:`DEPENDS`)
6117         that should be added if the feature is enabled.
6118
6119      #. Additional runtime dependencies (:term:`RDEPENDS`)
6120         that should be added if the feature is enabled.
6121
6122      #. Additional runtime recommendations
6123         (:term:`RRECOMMENDS`) that should be added if
6124         the feature is enabled.
6125
6126      #. Any conflicting (that is, mutually exclusive) :term:`PACKAGECONFIG`
6127         settings for this feature.
6128
6129      Consider the following :term:`PACKAGECONFIG` block taken from the
6130      ``librsvg`` recipe. In this example the feature is ``gtk``, which has
6131      three arguments that determine the feature's behavior::
6132
6133         PACKAGECONFIG[gtk] = "--with-gtk3,--without-gtk3,gtk+3"
6134
6135      The
6136      ``--with-gtk3`` and ``gtk+3`` arguments apply only if the feature is
6137      enabled. In this case, ``--with-gtk3`` is added to the configure
6138      script argument list and ``gtk+3`` is added to :term:`DEPENDS`. On the
6139      other hand, if the feature is disabled say through a ``.bbappend``
6140      file in another layer, then the second argument ``--without-gtk3`` is
6141      added to the configure script instead.
6142
6143      The basic :term:`PACKAGECONFIG` structure previously described holds true
6144      regardless of whether you are creating a block or changing a block.
6145      When creating a block, use the structure inside your recipe.
6146
6147      If you want to change an existing :term:`PACKAGECONFIG` block, you can do
6148      so one of two ways:
6149
6150      -  *Append file:* Create an append file named
6151         ``recipename.bbappend`` in your layer and override the value of
6152         :term:`PACKAGECONFIG`. You can either completely override the
6153         variable::
6154
6155            PACKAGECONFIG = "f4 f5"
6156
6157         Or, you can just append the variable::
6158
6159            PACKAGECONFIG:append = " f4"
6160
6161      -  *Configuration file:* This method is identical to changing the
6162         block through an append file except you edit your ``local.conf``
6163         or ``mydistro.conf`` file. As with append files previously
6164         described, you can either completely override the variable::
6165
6166            PACKAGECONFIG:pn-recipename = "f4 f5"
6167
6168         Or, you can just amend the variable::
6169
6170            PACKAGECONFIG:append:pn-recipename = " f4"
6171
6172      Consider the following example of a :ref:`ref-classes-cmake` recipe with a systemd service
6173      in which :term:`PACKAGECONFIG` is used to transform the systemd service
6174      into a feature that can be easily enabled or disabled via :term:`PACKAGECONFIG`::
6175
6176         example.c
6177         example.service
6178         CMakeLists.txt
6179
6180      The ``CMakeLists.txt`` file contains::
6181
6182         if(WITH_SYSTEMD)
6183            install(FILES ${PROJECT_SOURCE_DIR}/example.service DESTINATION /etc/systemd/systemd)
6184         endif(WITH_SYSTEMD)
6185
6186      In order to enable the installation of ``example.service`` we need to
6187      ensure that ``-DWITH_SYSTEMD=ON`` is passed to the ``cmake`` command
6188      execution.  Recipes that have ``CMakeLists.txt`` generally inherit the
6189      :ref:`ref-classes-cmake` class, that runs ``cmake`` with
6190      :term:`EXTRA_OECMAKE`, which :term:`PACKAGECONFIG_CONFARGS` will be
6191      appended to.  Now, knowing that :term:`PACKAGECONFIG_CONFARGS` is
6192      automatically filled with either the first or second element of
6193      :term:`PACKAGECONFIG` flag value, the recipe would be like::
6194
6195         inherit cmake
6196         PACKAGECONFIG = "systemd"
6197         PACKAGECONFIG[systemd] = "-DWITH_SYSTEMD=ON,-DWITH_SYSTEMD=OFF"
6198
6199      A side note to this recipe is to check if ``systemd`` is in fact the used :term:`INIT_MANAGER`
6200      or not::
6201
6202         PACKAGECONFIG = "${@'systemd' if d.getVar('INIT_MANAGER') == 'systemd' else ''}"
6203
6204   :term:`PACKAGECONFIG_CONFARGS`
6205      A space-separated list of configuration options generated from the
6206      :term:`PACKAGECONFIG` setting.
6207
6208      Classes such as :ref:`ref-classes-autotools` and :ref:`ref-classes-cmake`
6209      use :term:`PACKAGECONFIG_CONFARGS` to pass :term:`PACKAGECONFIG` options
6210      to ``configure`` and ``cmake``, respectively. If you are using
6211      :term:`PACKAGECONFIG` but not a class that handles the
6212      :ref:`ref-tasks-configure` task, then you need to use
6213      :term:`PACKAGECONFIG_CONFARGS` appropriately.
6214
6215   :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY`
6216      For recipes inheriting the :ref:`ref-classes-packagegroup` class, setting
6217      :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY` to "1" specifies that the
6218      normal complementary packages (i.e. ``-dev``, ``-dbg``, and so forth)
6219      should not be automatically created by the ``packagegroup`` recipe,
6220      which is the default behavior.
6221
6222   :term:`PACKAGES`
6223      The list of packages the recipe creates. The default value is the
6224      following::
6225
6226         ${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
6227
6228      During packaging, the :ref:`ref-tasks-package` task
6229      goes through :term:`PACKAGES` and uses the :term:`FILES`
6230      variable corresponding to each package to assign files to the
6231      package. If a file matches the :term:`FILES` variable for more than one
6232      package in :term:`PACKAGES`, it will be assigned to the earliest
6233      (leftmost) package.
6234
6235      Packages in the variable's list that are empty (i.e. where none of
6236      the patterns in ``FILES:``\ pkg match any files installed by the
6237      :ref:`ref-tasks-install` task) are not generated,
6238      unless generation is forced through the
6239      :term:`ALLOW_EMPTY` variable.
6240
6241   :term:`PACKAGES_DYNAMIC`
6242      A promise that your recipe satisfies runtime dependencies for
6243      optional modules that are found in other recipes.
6244      :term:`PACKAGES_DYNAMIC` does not actually satisfy the dependencies, it
6245      only states that they should be satisfied. For example, if a hard,
6246      runtime dependency (:term:`RDEPENDS`) of another
6247      package is satisfied at build time through the :term:`PACKAGES_DYNAMIC`
6248      variable, but a package with the module name is never actually
6249      produced, then the other package will be broken. Thus, if you attempt
6250      to include that package in an image, you will get a dependency
6251      failure from the packaging system during the
6252      :ref:`ref-tasks-rootfs` task.
6253
6254      Typically, if there is a chance that such a situation can occur and
6255      the package that is not created is valid without the dependency being
6256      satisfied, then you should use :term:`RRECOMMENDS`
6257      (a soft runtime dependency) instead of :term:`RDEPENDS`.
6258
6259      For an example of how to use the :term:`PACKAGES_DYNAMIC` variable when
6260      you are splitting packages, see the
6261      ":ref:`dev-manual/packages:handling optional module packaging`"
6262      section in the Yocto Project Development Tasks Manual.
6263
6264   :term:`PACKAGESPLITFUNCS`
6265      Specifies a list of functions run to perform additional splitting of
6266      files into individual packages. Recipes can either prepend to this
6267      variable or prepend to the ``populate_packages`` function in order to
6268      perform additional package splitting. In either case, the function
6269      should set :term:`PACKAGES`,
6270      :term:`FILES`, :term:`RDEPENDS` and
6271      other packaging variables appropriately in order to perform the
6272      desired splitting.
6273
6274   :term:`PARALLEL_MAKE`
6275
6276      Extra options passed to the build tool command (``make``,
6277      ``ninja`` or more specific build engines, like the Go language one)
6278      during the :ref:`ref-tasks-compile` task, to specify parallel compilation
6279      on the local build host. This variable is usually in the form "-j x",
6280      where x represents the maximum number of parallel threads such engines
6281      can run.
6282
6283      .. note::
6284
6285         For software compiled by ``make``, in order for :term:`PARALLEL_MAKE`
6286         to be effective, ``make`` must be called with
6287         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
6288         way to ensure this is to use the ``oe_runmake`` function.
6289
6290      By default, the OpenEmbedded build system automatically sets this
6291      variable to be equal to the number of cores the build system uses.
6292
6293      .. note::
6294
6295         If the software being built experiences dependency issues during
6296         the :ref:`ref-tasks-compile` task that result in race conditions, you can clear
6297         the :term:`PARALLEL_MAKE` variable within the recipe as a workaround. For
6298         information on addressing race conditions, see the
6299         ":ref:`dev-manual/debugging:debugging parallel make races`"
6300         section in the Yocto Project Development Tasks Manual.
6301
6302      For single socket systems (i.e. one CPU), you should not have to
6303      override this variable to gain optimal parallelism during builds.
6304      However, if you have very large systems that employ multiple physical
6305      CPUs, you might want to make sure the :term:`PARALLEL_MAKE` variable is
6306      not set higher than "-j 20".
6307
6308      For more information on speeding up builds, see the
6309      ":ref:`dev-manual/speeding-up-build:speeding up a build`"
6310      section in the Yocto Project Development Tasks Manual.
6311
6312   :term:`PARALLEL_MAKEINST`
6313      Extra options passed to the build tool install command
6314      (``make install``, ``ninja install`` or more specific ones)
6315      during the :ref:`ref-tasks-install` task in order to specify
6316      parallel installation. This variable defaults to the value of
6317      :term:`PARALLEL_MAKE`.
6318
6319      .. note::
6320
6321         For software compiled by ``make``, in order for :term:`PARALLEL_MAKEINST`
6322         to be effective, ``make`` must be called with
6323         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
6324         way to ensure this is to use the ``oe_runmake`` function.
6325
6326         If the software being built experiences dependency issues during
6327         the :ref:`ref-tasks-install` task that result in race conditions, you can
6328         clear the :term:`PARALLEL_MAKEINST` variable within the recipe as a
6329         workaround. For information on addressing race conditions, see the
6330         ":ref:`dev-manual/debugging:debugging parallel make races`"
6331         section in the Yocto Project Development Tasks Manual.
6332
6333   :term:`PATCHRESOLVE`
6334      Determines the action to take when a patch fails. You can set this
6335      variable to one of two values: "noop" and "user".
6336
6337      The default value of "noop" causes the build to simply fail when the
6338      OpenEmbedded build system cannot successfully apply a patch. Setting
6339      the value to "user" causes the build system to launch a shell and
6340      places you in the right location so that you can manually resolve the
6341      conflicts.
6342
6343      Set this variable in your ``local.conf`` file.
6344
6345   :term:`PATCHTOOL`
6346      Specifies the utility used to apply patches for a recipe during the
6347      :ref:`ref-tasks-patch` task. You can specify one of
6348      three utilities: "patch", "quilt", or "git". The default utility used
6349      is "quilt" except for the quilt-native recipe itself. Because the
6350      quilt tool is not available at the time quilt-native is being
6351      patched, it uses "patch".
6352
6353      If you wish to use an alternative patching tool, set the variable in
6354      the recipe using one of the following::
6355
6356         PATCHTOOL = "patch"
6357         PATCHTOOL = "quilt"
6358         PATCHTOOL = "git"
6359
6360   :term:`PE`
6361      The epoch of the recipe. By default, this variable is unset. The
6362      variable is used to make upgrades possible when the versioning scheme
6363      changes in some backwards incompatible way.
6364
6365      :term:`PE` is the default value of the :term:`PKGE` variable.
6366
6367   :term:`PEP517_WHEEL_PATH`
6368      When used by recipes that inherit the :ref:`ref-classes-python_pep517`
6369      class, denotes the path to ``dist/`` (short for distribution) where the
6370      binary archive ``wheel`` is built.
6371
6372   :term:`PERSISTENT_DIR`
6373      See :term:`bitbake:PERSISTENT_DIR` in the BitBake manual.
6374
6375   :term:`PF`
6376      Specifies the recipe or package name and includes all version and
6377      revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
6378      ``bash-4.2-r1/``). This variable is comprised of the following:
6379      ${:term:`PN`}-${:term:`EXTENDPE`}${:term:`PV`}-${:term:`PR`}
6380
6381   :term:`PIXBUF_PACKAGES`
6382      When inheriting the :ref:`ref-classes-pixbufcache`
6383      class, this variable identifies packages that contain the pixbuf
6384      loaders used with ``gdk-pixbuf``. By default, the
6385      :ref:`ref-classes-pixbufcache` class assumes that
6386      the loaders are in the recipe's main package (i.e.
6387      ``${``\ :term:`PN`\ ``}``). Use this variable if the
6388      loaders you need are in a package other than that main package.
6389
6390   :term:`PKG`
6391      The name of the resulting package created by the OpenEmbedded build
6392      system.
6393
6394      .. note::
6395
6396         When using the :term:`PKG` variable, you must use a package name override.
6397
6398      For example, when the :ref:`ref-classes-debian` class renames the output
6399      package, it does so by setting ``PKG:packagename``.
6400
6401   :term:`PKG_CONFIG_PATH`
6402      The path to ``pkg-config`` files for the current build context.
6403      ``pkg-config`` reads this variable from the environment.
6404
6405   :term:`PKGD`
6406      Points to the destination directory for files to be packaged before
6407      they are split into individual packages. This directory defaults to
6408      the following::
6409
6410         ${WORKDIR}/package
6411
6412      Do not change this default.
6413
6414   :term:`PKGDATA_DIR`
6415      Points to a shared, global-state directory that holds data generated
6416      during the packaging process. During the packaging process, the
6417      :ref:`ref-tasks-packagedata` task packages data
6418      for each recipe and installs it into this temporary, shared area.
6419      This directory defaults to the following, which you should not
6420      change::
6421
6422         ${STAGING_DIR_HOST}/pkgdata
6423
6424      For examples of how this data is used, see the
6425      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6426      section in the Yocto Project Overview and Concepts Manual and the
6427      ":ref:`dev-manual/debugging:viewing package information with \`\`oe-pkgdata-util\`\``"
6428      section in the Yocto Project Development Tasks Manual. For more
6429      information on the shared, global-state directory, see
6430      :term:`STAGING_DIR_HOST`.
6431
6432   :term:`PKGDEST`
6433      Points to the parent directory for files to be packaged after they
6434      have been split into individual packages. This directory defaults to
6435      the following::
6436
6437         ${WORKDIR}/packages-split
6438
6439      Under this directory, the build system creates directories for each
6440      package specified in :term:`PACKAGES`. Do not change
6441      this default.
6442
6443   :term:`PKGDESTWORK`
6444      Points to a temporary work area where the
6445      :ref:`ref-tasks-package` task saves package metadata.
6446      The :term:`PKGDESTWORK` location defaults to the following::
6447
6448         ${WORKDIR}/pkgdata
6449
6450      Do not change this default.
6451
6452      The :ref:`ref-tasks-packagedata` task copies the
6453      package metadata from :term:`PKGDESTWORK` to
6454      :term:`PKGDATA_DIR` to make it available globally.
6455
6456   :term:`PKGE`
6457      The epoch of the package(s) built by the recipe. By default, :term:`PKGE`
6458      is set to :term:`PE`.
6459
6460   :term:`PKGR`
6461      The revision of the package(s) built by the recipe. By default,
6462      :term:`PKGR` is set to :term:`PR`.
6463
6464   :term:`PKGV`
6465      The version of the package(s) built by the recipe. By default,
6466      :term:`PKGV` is set to :term:`PV`.
6467
6468   :term:`PN`
6469      This variable can have two separate functions depending on the
6470      context: a recipe name or a resulting package name.
6471
6472      :term:`PN` refers to a recipe name in the context of a file used by the
6473      OpenEmbedded build system as input to create a package. The name is
6474      normally extracted from the recipe file name. For example, if the
6475      recipe is named ``expat_2.0.1.bb``, then the default value of :term:`PN`
6476      will be "expat".
6477
6478      The variable refers to a package name in the context of a file
6479      created or produced by the OpenEmbedded build system.
6480
6481      If applicable, the :term:`PN` variable also contains any special suffix
6482      or prefix. For example, using ``bash`` to build packages for the
6483      native machine, :term:`PN` is ``bash-native``. Using ``bash`` to build
6484      packages for the target and for Multilib, :term:`PN` would be ``bash``
6485      and ``lib64-bash``, respectively.
6486
6487   :term:`POPULATE_SDK_POST_HOST_COMMAND`
6488      Specifies a list of functions to call once the OpenEmbedded build
6489      system has created the host part of the SDK. You can specify
6490      functions separated by spaces::
6491
6492          POPULATE_SDK_POST_HOST_COMMAND += "function"
6493
6494      If you need to pass the SDK path to a command within a function, you
6495      can use ``${SDK_DIR}``, which points to the parent directory used by
6496      the OpenEmbedded build system when creating SDK output. See the
6497      :term:`SDK_DIR` variable for more information.
6498
6499   :term:`POPULATE_SDK_POST_TARGET_COMMAND`
6500      Specifies a list of functions to call once the OpenEmbedded build
6501      system has created the target part of the SDK. You can specify
6502      functions separated by spaces::
6503
6504         POPULATE_SDK_POST_TARGET_COMMAND += "function"
6505
6506      If you need to pass the SDK path to a command within a function, you
6507      can use ``${SDK_DIR}``, which points to the parent directory used by
6508      the OpenEmbedded build system when creating SDK output. See the
6509      :term:`SDK_DIR` variable for more information.
6510
6511   :term:`PR`
6512      The revision of the recipe. The default value for this variable is
6513      "r0". Subsequent revisions of the recipe conventionally have the
6514      values "r1", "r2", and so forth. When :term:`PV` increases,
6515      :term:`PR` is conventionally reset to "r0".
6516
6517      .. note::
6518
6519         The OpenEmbedded build system does not need the aid of :term:`PR`
6520         to know when to rebuild a recipe. The build system uses the task
6521         :ref:`input checksums <overview-manual/concepts:checksums (signatures)>` along with the
6522         :ref:`stamp <structure-build-tmp-stamps>` and
6523         :ref:`overview-manual/concepts:shared state cache`
6524         mechanisms.
6525
6526      The :term:`PR` variable primarily becomes significant when a package
6527      manager dynamically installs packages on an already built image. In
6528      this case, :term:`PR`, which is the default value of
6529      :term:`PKGR`, helps the package manager distinguish which
6530      package is the most recent one in cases where many packages have the
6531      same :term:`PV` (i.e. :term:`PKGV`). A component having many packages with
6532      the same :term:`PV` usually means that the packages all install the same
6533      upstream version, but with later (:term:`PR`) version packages including
6534      packaging fixes.
6535
6536      .. note::
6537
6538         :term:`PR` does not need to be increased for changes that do not change the
6539         package contents or metadata.
6540
6541      Because manually managing :term:`PR` can be cumbersome and error-prone,
6542      an automated solution exists. See the
6543      ":ref:`dev-manual/packages:working with a pr service`" section
6544      in the Yocto Project Development Tasks Manual for more information.
6545
6546   :term:`PREFERRED_PROVIDER`
6547      If multiple recipes provide the same item, this variable determines
6548      which recipe is preferred and thus provides the item (i.e. the
6549      preferred provider). You should always suffix this variable with the
6550      name of the provided item. And, you should define the variable using
6551      the preferred recipe's name (:term:`PN`). Here is a common
6552      example::
6553
6554         PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
6555
6556      In the previous example, multiple recipes are providing "virtual/kernel".
6557      The :term:`PREFERRED_PROVIDER` variable is set with the name (:term:`PN`) of
6558      the recipe you prefer to provide "virtual/kernel".
6559
6560      Here are more examples::
6561
6562         PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
6563         PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
6564
6565      For more
6566      information, see the ":ref:`dev-manual/new-recipe:using virtual providers`"
6567      section in the Yocto Project Development Tasks Manual.
6568
6569      .. note::
6570
6571         If you use a ``virtual/\*`` item with :term:`PREFERRED_PROVIDER`, then any
6572         recipe that :term:`PROVIDES` that item but is not selected (defined)
6573         by :term:`PREFERRED_PROVIDER` is prevented from building, which is usually
6574         desirable since this mechanism is designed to select between mutually
6575         exclusive alternative providers.
6576
6577   :term:`PREFERRED_PROVIDERS`
6578      See :term:`bitbake:PREFERRED_PROVIDERS` in the BitBake manual.
6579
6580   :term:`PREFERRED_VERSION`
6581      If there are multiple versions of a recipe available, this variable
6582      determines which version should be given preference. You must always
6583      suffix the variable with the :term:`PN` you want to select (`python` in
6584      the first example below), and you should specify the :term:`PV`
6585      accordingly (`3.4.0` in the example).
6586
6587      The :term:`PREFERRED_VERSION` variable supports limited wildcard use
6588      through the "``%``" character. You can use the character to match any
6589      number of characters, which can be useful when specifying versions
6590      that contain long revision numbers that potentially change. Here are
6591      two examples::
6592
6593         PREFERRED_VERSION_python = "3.4.0"
6594         PREFERRED_VERSION_linux-yocto = "5.0%"
6595
6596      .. note::
6597
6598         The use of the "%" character is limited in that it only works at the end of the
6599         string. You cannot use the wildcard character in any other
6600         location of the string.
6601
6602      The specified version is matched against :term:`PV`, which
6603      does not necessarily match the version part of the recipe's filename.
6604      For example, consider two recipes ``foo_1.2.bb`` and ``foo_git.bb``
6605      where ``foo_git.bb`` contains the following assignment::
6606
6607         PV = "1.1+git${SRCPV}"
6608
6609      In this case, the correct way to select
6610      ``foo_git.bb`` is by using an assignment such as the following::
6611
6612         PREFERRED_VERSION_foo = "1.1+git%"
6613
6614      Compare that previous example
6615      against the following incorrect example, which does not work::
6616
6617         PREFERRED_VERSION_foo = "git"
6618
6619      Sometimes the :term:`PREFERRED_VERSION` variable can be set by
6620      configuration files in a way that is hard to change. You can use
6621      :term:`OVERRIDES` to set a machine-specific
6622      override. Here is an example::
6623
6624         PREFERRED_VERSION_linux-yocto:qemux86 = "5.0%"
6625
6626      Although not recommended, worst case, you can also use the
6627      "forcevariable" override, which is the strongest override possible.
6628      Here is an example::
6629
6630         PREFERRED_VERSION_linux-yocto:forcevariable = "5.0%"
6631
6632      .. note::
6633
6634         The ``:forcevariable`` override is not handled specially. This override
6635         only works because the default value of :term:`OVERRIDES` includes "forcevariable".
6636
6637      If a recipe with the specified version is not available, a warning
6638      message will be shown. See :term:`REQUIRED_VERSION` if you want this
6639      to be an error instead.
6640
6641   :term:`PREMIRRORS`
6642      Specifies additional paths from which the OpenEmbedded build system
6643      gets source code. When the build system searches for source code, it
6644      first tries the local download directory. If that location fails, the
6645      build system tries locations defined by :term:`PREMIRRORS`, the upstream
6646      source, and then locations specified by
6647      :term:`MIRRORS` in that order.
6648
6649      The default value for :term:`PREMIRRORS` is defined in the
6650      ``meta/classes-global/mirrors.bbclass`` file in the core metadata layer.
6651
6652      Typically, you could add a specific server for the build system to
6653      attempt before any others by adding something like the following to
6654      the ``local.conf`` configuration file in the
6655      :term:`Build Directory`::
6656
6657         PREMIRRORS:prepend = "\
6658             git://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6659             ftp://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6660             http://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6661             https://.*/.* &YOCTO_DL_URL;/mirror/sources/"
6662
6663      These changes cause the
6664      build system to intercept Git, FTP, HTTP, and HTTPS requests and
6665      direct them to the ``http://`` sources mirror. You can use
6666      ``file://`` URLs to point to local directories or network shares as
6667      well.
6668
6669   :term:`PRIORITY`
6670      Indicates the importance of a package.
6671
6672      :term:`PRIORITY` is considered to be part of the distribution policy
6673      because the importance of any given recipe depends on the purpose for
6674      which the distribution is being produced. Thus, :term:`PRIORITY` is not
6675      normally set within recipes.
6676
6677      You can set :term:`PRIORITY` to "required", "standard", "extra", and
6678      "optional", which is the default.
6679
6680   :term:`PRIVATE_LIBS`
6681      Specifies libraries installed within a recipe that should be ignored
6682      by the OpenEmbedded build system's shared library resolver. This
6683      variable is typically used when software being built by a recipe has
6684      its own private versions of a library normally provided by another
6685      recipe. In this case, you would not want the package containing the
6686      private libraries to be set as a dependency on other unrelated
6687      packages that should instead depend on the package providing the
6688      standard version of the library.
6689
6690      Libraries specified in this variable should be specified by their
6691      file name. For example, from the Firefox recipe in meta-browser::
6692
6693         PRIVATE_LIBS = "libmozjs.so \
6694                         libxpcom.so \
6695                         libnspr4.so \
6696                         libxul.so \
6697                         libmozalloc.so \
6698                         libplc4.so \
6699                         libplds4.so"
6700
6701      For more information, see the
6702      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6703      section in the Yocto Project Overview and Concepts Manual.
6704
6705   :term:`PROVIDES`
6706      A list of aliases by which a particular recipe can be known. By
6707      default, a recipe's own :term:`PN` is implicitly already in its
6708      :term:`PROVIDES` list and therefore does not need to mention that it
6709      provides itself. If a recipe uses :term:`PROVIDES`, the additional
6710      aliases are synonyms for the recipe and can be useful for satisfying
6711      dependencies of other recipes during the build as specified by
6712      :term:`DEPENDS`.
6713
6714      Consider the following example :term:`PROVIDES` statement from the recipe
6715      file ``eudev_3.2.9.bb``::
6716
6717         PROVIDES += "udev"
6718
6719      The :term:`PROVIDES` statement
6720      results in the "eudev" recipe also being available as simply "udev".
6721
6722      .. note::
6723
6724         A recipe's own recipe name (:term:`PN`) is always implicitly prepended
6725         to :term:`PROVIDES`, so while using "+=" in the above example may not be
6726         strictly necessary it is recommended to avoid confusion.
6727
6728      In addition to providing recipes under alternate names, the
6729      :term:`PROVIDES` mechanism is also used to implement virtual targets. A
6730      virtual target is a name that corresponds to some particular
6731      functionality (e.g. a Linux kernel). Recipes that provide the
6732      functionality in question list the virtual target in :term:`PROVIDES`.
6733      Recipes that depend on the functionality in question can include the
6734      virtual target in :term:`DEPENDS` to leave the choice of provider open.
6735
6736      Conventionally, virtual targets have names on the form
6737      "virtual/function" (e.g. "virtual/kernel"). The slash is simply part
6738      of the name and has no syntactical significance.
6739
6740      The :term:`PREFERRED_PROVIDER` variable is
6741      used to select which particular recipe provides a virtual target.
6742
6743      .. note::
6744
6745         A corresponding mechanism for virtual runtime dependencies
6746         (packages) exists. However, the mechanism does not depend on any
6747         special functionality beyond ordinary variable assignments. For
6748         example, ``VIRTUAL-RUNTIME_dev_manager`` refers to the package of
6749         the component that manages the ``/dev`` directory.
6750
6751         Setting the "preferred provider" for runtime dependencies is as
6752         simple as using the following assignment in a configuration file::
6753
6754                 VIRTUAL-RUNTIME_dev_manager = "udev"
6755
6756
6757   :term:`PRSERV_HOST`
6758      The network based :term:`PR` service host and port.
6759
6760      The ``conf/templates/default/local.conf.sample.extended`` configuration
6761      file in the :term:`Source Directory` shows how the :term:`PRSERV_HOST`
6762      variable is set::
6763
6764         PRSERV_HOST = "localhost:0"
6765
6766      You must
6767      set the variable if you want to automatically start a local :ref:`PR
6768      service <dev-manual/packages:working with a pr service>`. You can
6769      set :term:`PRSERV_HOST` to other values to use a remote PR service.
6770
6771
6772   :term:`PSEUDO_IGNORE_PATHS`
6773      A comma-separated (without spaces) list of path prefixes that should be ignored
6774      by pseudo when monitoring and recording file operations, in order to avoid
6775      problems with files being written to outside of the pseudo context and
6776      reduce pseudo's overhead. A path is ignored if it matches any prefix in the list
6777      and can include partial directory (or file) names.
6778
6779
6780   :term:`PTEST_ENABLED`
6781      Specifies whether or not :ref:`Package
6782      Test <dev-manual/packages:testing packages with ptest>` (ptest)
6783      functionality is enabled when building a recipe. You should not set
6784      this variable directly. Enabling and disabling building Package Tests
6785      at build time should be done by adding "ptest" to (or removing it
6786      from) :term:`DISTRO_FEATURES`.
6787
6788   :term:`PV`
6789      The version of the recipe. The version is normally extracted from the
6790      recipe filename. For example, if the recipe is named
6791      ``expat_2.0.1.bb``, then the default value of :term:`PV` will be "2.0.1".
6792      :term:`PV` is generally not overridden within a recipe unless it is
6793      building an unstable (i.e. development) version from a source code
6794      repository (e.g. Git or Subversion).
6795
6796      :term:`PV` is the default value of the :term:`PKGV` variable.
6797
6798   :term:`PYPI_PACKAGE`
6799      When inheriting the :ref:`ref-classes-pypi` class, specifies the
6800      `PyPI <https://pypi.org/>`__ package name to be built. The default value
6801      is set based upon :term:`BPN` (stripping any "python-" or "python3-"
6802      prefix off if present), however for some packages it will need to be set
6803      explicitly if that will not match the package name (e.g. where the
6804      package name has a prefix, underscores, uppercase letters etc.)
6805
6806   :term:`PYTHON_ABI`
6807      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
6808      class, denotes the Application Binary Interface (ABI) currently in use
6809      for Python. By default, the ABI is "m". You do not have to set this
6810      variable as the OpenEmbedded build system sets it for you.
6811
6812      The OpenEmbedded build system uses the ABI to construct directory
6813      names used when installing the Python headers and libraries in
6814      sysroot (e.g. ``.../python3.3m/...``).
6815
6816   :term:`QA_EMPTY_DIRS`
6817      Specifies a list of directories that are expected to be empty when
6818      packaging; if ``empty-dirs`` appears in :term:`ERROR_QA` or
6819      :term:`WARN_QA` these will be checked and an error or warning
6820      (respectively) will be produced.
6821
6822      The default :term:`QA_EMPTY_DIRS` value is set in
6823      :ref:`insane.bbclass <ref-classes-insane>`.
6824
6825   :term:`QA_EMPTY_DIRS_RECOMMENDATION`
6826      Specifies a recommendation for why a directory must be empty,
6827      which will be included in the error message if a specific directory
6828      is found to contain files. Must be overridden with the directory
6829      path to match on.
6830
6831      If no recommendation is specified for a directory, then the default
6832      "but it is expected to be empty" will be used.
6833
6834      An example message shows if files were present in '/dev'::
6835
6836         QA_EMPTY_DIRS_RECOMMENDATION:/dev = "but all devices must be created at runtime"
6837
6838   :term:`RANLIB`
6839      The minimal command and arguments to run ``ranlib``.
6840
6841   :term:`RCONFLICTS`
6842      The list of packages that conflict with packages. Note that packages
6843      will not be installed if conflicting packages are not first removed.
6844
6845      Like all package-controlling variables, you must always use them in
6846      conjunction with a package name override. Here is an example::
6847
6848         RCONFLICTS:${PN} = "another_conflicting_package_name"
6849
6850      BitBake, which the OpenEmbedded build system uses, supports
6851      specifying versioned dependencies. Although the syntax varies
6852      depending on the packaging format, BitBake hides these differences
6853      from you. Here is the general syntax to specify versions with the
6854      :term:`RCONFLICTS` variable::
6855
6856         RCONFLICTS:${PN} = "package (operator version)"
6857
6858      For ``operator``, you can specify the following:
6859
6860      - =
6861      - <
6862      - >
6863      - <=
6864      - >=
6865
6866      For example, the following sets up a dependency on version 1.2 or
6867      greater of the package ``foo``::
6868
6869         RCONFLICTS:${PN} = "foo (>= 1.2)"
6870
6871   :term:`RDEPENDS`
6872      Lists runtime dependencies of a package. These dependencies are other
6873      packages that must be installed in order for the package to function
6874      correctly. As an example, the following assignment declares that the
6875      package ``foo`` needs the packages ``bar`` and ``baz`` to be
6876      installed::
6877
6878         RDEPENDS:foo = "bar baz"
6879
6880      The most common types of package
6881      runtime dependencies are automatically detected and added. Therefore,
6882      most recipes do not need to set :term:`RDEPENDS`. For more information,
6883      see the
6884      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6885      section in the Yocto Project Overview and Concepts Manual.
6886
6887      The practical effect of the above :term:`RDEPENDS` assignment is that
6888      ``bar`` and ``baz`` will be declared as dependencies inside the
6889      package ``foo`` when it is written out by one of the
6890      :ref:`do_package_write_* <ref-tasks-package_write_deb>` tasks.
6891      Exactly how this is done depends on which package format is used,
6892      which is determined by
6893      :term:`PACKAGE_CLASSES`. When the
6894      corresponding package manager installs the package, it will know to
6895      also install the packages on which it depends.
6896
6897      To ensure that the packages ``bar`` and ``baz`` get built, the
6898      previous :term:`RDEPENDS` assignment also causes a task dependency to be
6899      added. This dependency is from the recipe's
6900      :ref:`ref-tasks-build` (not to be confused with
6901      :ref:`ref-tasks-compile`) task to the
6902      :ref:`do_package_write_* <ref-tasks-package_write_deb>` task of the recipes that build ``bar`` and
6903      ``baz``.
6904
6905      The names of the packages you list within :term:`RDEPENDS` must be the
6906      names of other packages --- they cannot be recipe names. Although
6907      package names and recipe names usually match, the important point
6908      here is that you are providing package names within the :term:`RDEPENDS`
6909      variable. For an example of the default list of packages created from
6910      a recipe, see the :term:`PACKAGES` variable.
6911
6912      Because the :term:`RDEPENDS` variable applies to packages being built,
6913      you should always use the variable in a form with an attached package
6914      name (remember that a single recipe can build multiple packages). For
6915      example, suppose you are building a development package that depends
6916      on the ``perl`` package. In this case, you would use the following
6917      :term:`RDEPENDS` statement::
6918
6919         RDEPENDS:${PN}-dev += "perl"
6920
6921      In the example,
6922      the development package depends on the ``perl`` package. Thus, the
6923      :term:`RDEPENDS` variable has the ``${PN}-dev`` package name as part of
6924      the variable.
6925
6926      .. note::
6927
6928         ``RDEPENDS:${PN}-dev`` includes ``${``\ :term:`PN`\ ``}``
6929         by default. This default is set in the BitBake configuration file
6930         (``meta/conf/bitbake.conf``). Be careful not to accidentally remove
6931         ``${PN}`` when modifying ``RDEPENDS:${PN}-dev``. Use the "+=" operator
6932         rather than the "=" operator.
6933
6934      The package names you use with :term:`RDEPENDS` must appear as they would
6935      in the :term:`PACKAGES` variable. The :term:`PKG` variable
6936      allows a different name to be used for the final package (e.g. the
6937      :ref:`ref-classes-debian` class uses this to rename
6938      packages), but this final package name cannot be used with
6939      :term:`RDEPENDS`, which makes sense as :term:`RDEPENDS` is meant to be
6940      independent of the package format used.
6941
6942      BitBake, which the OpenEmbedded build system uses, supports
6943      specifying versioned dependencies. Although the syntax varies
6944      depending on the packaging format, BitBake hides these differences
6945      from you. Here is the general syntax to specify versions with the
6946      :term:`RDEPENDS` variable::
6947
6948         RDEPENDS:${PN} = "package (operator version)"
6949
6950      For ``operator``, you can specify the following:
6951
6952      - =
6953      - <
6954      - >
6955      - <=
6956      - >=
6957
6958      For version, provide the version number.
6959
6960      .. note::
6961
6962         You can use :term:`EXTENDPKGV` to provide a full package version
6963         specification.
6964
6965      For example, the following sets up a dependency on version 1.2 or
6966      greater of the package ``foo``::
6967
6968         RDEPENDS:${PN} = "foo (>= 1.2)"
6969
6970      For information on build-time dependencies, see the :term:`DEPENDS`
6971      variable. You can also see the
6972      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
6973      ":ref:`bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
6974      BitBake User Manual for additional information on tasks and dependencies.
6975
6976   :term:`RECIPE_MAINTAINER`
6977      This variable defines the name and e-mail address of the maintainer of a
6978      recipe. Such information can be used by human users submitted changes,
6979      and by automated tools to send notifications, for example about
6980      vulnerabilities or source updates.
6981
6982      The variable can be defined in a global distribution :oe_git:`maintainers.inc
6983      </openembedded-core/tree/meta/conf/distro/include/maintainers.inc>` file::
6984
6985          meta/conf/distro/include/maintainers.inc:RECIPE_MAINTAINER:pn-sysvinit = "Ross Burton <ross.burton@arm.com>"
6986
6987      It can also be directly defined in a recipe,
6988      for example in the ``libgpiod`` one::
6989
6990          RECIPE_MAINTAINER = "Bartosz Golaszewski <brgl@bgdev.pl>"
6991
6992   :term:`RECIPE_NO_UPDATE_REASON`
6993      If a recipe should not be replaced by a more recent upstream version,
6994      putting the reason why in this variable in a recipe allows
6995      ``devtool check-upgrade-status`` command to display it, as explained
6996      in the ":ref:`ref-manual/devtool-reference:checking on the upgrade status of a recipe`"
6997      section.
6998
6999   :term:`RECIPE_SYSROOT`
7000      This variable points to the directory that holds all files populated from
7001      recipes specified in :term:`DEPENDS`. As the name indicates,
7002      think of this variable as a custom root (``/``) for the recipe that will be
7003      used by the compiler in order to find headers and other files needed to complete
7004      its job.
7005
7006      This variable is related to :term:`STAGING_DIR_HOST` or :term:`STAGING_DIR_TARGET`
7007      according to the type of the recipe and the build target.
7008
7009      To better understand this variable, consider the following examples:
7010
7011      -  For ``#include <header.h>``, ``header.h`` should be in ``"${RECIPE_SYSROOT}/usr/include"``
7012
7013      -  For ``-lexample``, ``libexample.so`` should be in ``"${RECIPE_SYSROOT}/lib"``
7014         or other library sysroot directories.
7015
7016      The default value is ``"${WORKDIR}/recipe-sysroot"``.
7017      Do not modify it.
7018
7019   :term:`RECIPE_SYSROOT_NATIVE`
7020      This is similar to :term:`RECIPE_SYSROOT` but the populated files are from
7021      ``-native`` recipes. This allows a recipe built for the target machine to
7022      use ``native`` tools.
7023
7024      This variable is related to :term:`STAGING_DIR_NATIVE`.
7025
7026      The default value is ``"${WORKDIR}/recipe-sysroot-native"``.
7027      Do not modify it.
7028
7029   :term:`REPODIR`
7030      See :term:`bitbake:REPODIR` in the BitBake manual.
7031
7032   :term:`REQUIRED_DISTRO_FEATURES`
7033      When inheriting the :ref:`ref-classes-features_check`
7034      class, this variable identifies distribution features that must exist
7035      in the current configuration in order for the OpenEmbedded build
7036      system to build the recipe. In other words, if the
7037      :term:`REQUIRED_DISTRO_FEATURES` variable lists a feature that does not
7038      appear in :term:`DISTRO_FEATURES` within the current configuration, then
7039      the recipe will be skipped, and if the build system attempts to build
7040      the recipe then an error will be triggered.
7041
7042   :term:`REQUIRED_VERSION`
7043      If there are multiple versions of a recipe available, this variable
7044      determines which version should be given preference.
7045      :term:`REQUIRED_VERSION` works in exactly the same manner as
7046      :term:`PREFERRED_VERSION`, except that if the specified version is not
7047      available then an error message is shown and the build fails
7048      immediately.
7049
7050      If both :term:`REQUIRED_VERSION` and :term:`PREFERRED_VERSION` are set
7051      for the same recipe, the :term:`REQUIRED_VERSION` value applies.
7052
7053   :term:`RM_WORK_EXCLUDE`
7054      With :ref:`ref-classes-rm-work` enabled, this variable
7055      specifies a list of recipes whose work directories should not be removed.
7056      See the ":ref:`ref-classes-rm-work`" section for more details.
7057
7058   :term:`ROOT_HOME`
7059      Defines the root home directory. By default, this directory is set as
7060      follows in the BitBake configuration file::
7061
7062         ROOT_HOME ??= "/home/root"
7063
7064      .. note::
7065
7066         This default value is likely used because some embedded solutions
7067         prefer to have a read-only root filesystem and prefer to keep
7068         writeable data in one place.
7069
7070      You can override the default by setting the variable in any layer or
7071      in the ``local.conf`` file. Because the default is set using a "weak"
7072      assignment (i.e. "??="), you can use either of the following forms to
7073      define your override::
7074
7075         ROOT_HOME = "/root"
7076         ROOT_HOME ?= "/root"
7077
7078      These
7079      override examples use ``/root``, which is probably the most commonly
7080      used override.
7081
7082   :term:`ROOTFS`
7083      Indicates a filesystem image to include as the root filesystem.
7084
7085      The :term:`ROOTFS` variable is an optional variable used with the
7086      :ref:`ref-classes-image-live` class.
7087
7088   :term:`ROOTFS_POSTINSTALL_COMMAND`
7089      Specifies a list of functions to call after the OpenEmbedded build
7090      system has installed packages. You can specify functions separated by
7091      spaces::
7092
7093         ROOTFS_POSTINSTALL_COMMAND += "function"
7094
7095      If you need to pass the root filesystem path to a command within a
7096      function, you can use ``${IMAGE_ROOTFS}``, which points to the
7097      directory that becomes the root filesystem image. See the
7098      :term:`IMAGE_ROOTFS` variable for more
7099      information.
7100
7101   :term:`ROOTFS_POSTPROCESS_COMMAND`
7102      Specifies a list of functions to call once the OpenEmbedded build
7103      system has created the root filesystem. You can specify functions
7104      separated by spaces::
7105
7106         ROOTFS_POSTPROCESS_COMMAND += "function"
7107
7108      If you need to pass the root filesystem path to a command within a
7109      function, you can use ``${IMAGE_ROOTFS}``, which points to the
7110      directory that becomes the root filesystem image. See the
7111      :term:`IMAGE_ROOTFS` variable for more
7112      information.
7113
7114   :term:`ROOTFS_POSTUNINSTALL_COMMAND`
7115      Specifies a list of functions to call after the OpenEmbedded build
7116      system has removed unnecessary packages. When runtime package
7117      management is disabled in the image, several packages are removed
7118      including ``base-passwd``, ``shadow``, and ``update-alternatives``.
7119      You can specify functions separated by spaces::
7120
7121         ROOTFS_POSTUNINSTALL_COMMAND += "function"
7122
7123      If you need to pass the root filesystem path to a command within a
7124      function, you can use ``${IMAGE_ROOTFS}``, which points to the
7125      directory that becomes the root filesystem image. See the
7126      :term:`IMAGE_ROOTFS` variable for more
7127      information.
7128
7129   :term:`ROOTFS_PREPROCESS_COMMAND`
7130      Specifies a list of functions to call before the OpenEmbedded build
7131      system has created the root filesystem. You can specify functions
7132      separated by spaces::
7133
7134         ROOTFS_PREPROCESS_COMMAND += "function"
7135
7136      If you need to pass the root filesystem path to a command within a
7137      function, you can use ``${IMAGE_ROOTFS}``, which points to the
7138      directory that becomes the root filesystem image. See the
7139      :term:`IMAGE_ROOTFS` variable for more
7140      information.
7141
7142   :term:`RPROVIDES`
7143      A list of package name aliases that a package also provides. These
7144      aliases are useful for satisfying runtime dependencies of other
7145      packages both during the build and on the target (as specified by
7146      :term:`RDEPENDS`).
7147
7148      .. note::
7149
7150         A package's own name is implicitly already in its :term:`RPROVIDES` list.
7151
7152      As with all package-controlling variables, you must always use the
7153      variable in conjunction with a package name override. Here is an
7154      example::
7155
7156         RPROVIDES:${PN} = "widget-abi-2"
7157
7158   :term:`RRECOMMENDS`
7159      A list of packages that extends the usability of a package being
7160      built. The package being built does not depend on this list of
7161      packages in order to successfully build, but rather uses them for
7162      extended usability. To specify runtime dependencies for packages, see
7163      the :term:`RDEPENDS` variable.
7164
7165      The package manager will automatically install the :term:`RRECOMMENDS`
7166      list of packages when installing the built package. However, you can
7167      prevent listed packages from being installed by using the
7168      :term:`BAD_RECOMMENDATIONS`,
7169      :term:`NO_RECOMMENDATIONS`, and
7170      :term:`PACKAGE_EXCLUDE` variables.
7171
7172      Packages specified in :term:`RRECOMMENDS` need not actually be produced.
7173      However, there must be a recipe providing each package, either
7174      through the :term:`PACKAGES` or
7175      :term:`PACKAGES_DYNAMIC` variables or the
7176      :term:`RPROVIDES` variable, or an error will occur
7177      during the build. If such a recipe does exist and the package is not
7178      produced, the build continues without error.
7179
7180      Because the :term:`RRECOMMENDS` variable applies to packages being built,
7181      you should always attach an override to the variable to specify the
7182      particular package whose usability is being extended. For example,
7183      suppose you are building a development package that is extended to
7184      support wireless functionality. In this case, you would use the
7185      following::
7186
7187         RRECOMMENDS:${PN}-dev += "wireless_package_name"
7188
7189      In the
7190      example, the package name (``${PN}-dev``) must appear as it would in
7191      the :term:`PACKAGES` namespace before any renaming of the output package
7192      by classes such as :ref:`ref-classes-debian`.
7193
7194      BitBake, which the OpenEmbedded build system uses, supports
7195      specifying versioned recommends. Although the syntax varies depending
7196      on the packaging format, BitBake hides these differences from you.
7197      Here is the general syntax to specify versions with the
7198      :term:`RRECOMMENDS` variable::
7199
7200         RRECOMMENDS:${PN} = "package (operator version)"
7201
7202      For ``operator``, you can specify the following:
7203
7204      - =
7205      - <
7206      - >
7207      - <=
7208      - >=
7209
7210      For example, the following sets up a recommend on version 1.2 or
7211      greater of the package ``foo``::
7212
7213         RRECOMMENDS:${PN} = "foo (>= 1.2)"
7214
7215   :term:`RREPLACES`
7216      A list of packages replaced by a package. The package manager uses
7217      this variable to determine which package should be installed to
7218      replace other package(s) during an upgrade. In order to also have the
7219      other package(s) removed at the same time, you must add the name of
7220      the other package to the :term:`RCONFLICTS` variable.
7221
7222      As with all package-controlling variables, you must use this variable
7223      in conjunction with a package name override. Here is an example::
7224
7225         RREPLACES:${PN} = "other_package_being_replaced"
7226
7227      BitBake, which the OpenEmbedded build system uses, supports
7228      specifying versioned replacements. Although the syntax varies
7229      depending on the packaging format, BitBake hides these differences
7230      from you. Here is the general syntax to specify versions with the
7231      :term:`RREPLACES` variable::
7232
7233         RREPLACES:${PN} = "package (operator version)"
7234
7235      For ``operator``, you can specify the following:
7236
7237      - =
7238      - <
7239      - >
7240      - <=
7241      - >=
7242
7243      For example, the following sets up a replacement using version 1.2
7244      or greater of the package ``foo``::
7245
7246          RREPLACES:${PN} = "foo (>= 1.2)"
7247
7248   :term:`RSUGGESTS`
7249      A list of additional packages that you can suggest for installation
7250      by the package manager at the time a package is installed. Not all
7251      package managers support this functionality.
7252
7253      As with all package-controlling variables, you must always use this
7254      variable in conjunction with a package name override. Here is an
7255      example::
7256
7257         RSUGGESTS:${PN} = "useful_package another_package"
7258
7259   :term:`RUST_CHANNEL`
7260      Specifies which version of Rust to build - "stable", "beta" or "nightly".
7261      The default value is "stable". Set this at your own risk, as values other
7262      than "stable" are not guaranteed to work at a given time.
7263
7264   :term:`S`
7265      The location in the :term:`Build Directory` where
7266      unpacked recipe source code resides. By default, this directory is
7267      ``${``\ :term:`WORKDIR`\ ``}/${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
7268      where ``${BPN}`` is the base recipe name and ``${PV}`` is the recipe
7269      version. If the source tarball extracts the code to a directory named
7270      anything other than ``${BPN}-${PV}``, or if the source code is
7271      fetched from an SCM such as Git or Subversion, then you must set
7272      :term:`S` in the recipe so that the OpenEmbedded build system knows where
7273      to find the unpacked source.
7274
7275      As an example, assume a :term:`Source Directory`
7276      top-level folder named ``poky`` and a default :term:`Build Directory` at
7277      ``poky/build``. In this case, the work directory the build system
7278      uses to keep the unpacked recipe for ``db`` is the following::
7279
7280         poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
7281
7282      The unpacked source code resides in the ``db-5.1.19`` folder.
7283
7284      This next example assumes a Git repository. By default, Git
7285      repositories are cloned to ``${WORKDIR}/git`` during
7286      :ref:`ref-tasks-fetch`. Since this path is different
7287      from the default value of :term:`S`, you must set it specifically so the
7288      source can be located::
7289
7290         SRC_URI = "git://path/to/repo.git;branch=main"
7291         S = "${WORKDIR}/git"
7292
7293   :term:`SANITY_REQUIRED_UTILITIES`
7294      Specifies a list of command-line utilities that should be checked for
7295      during the initial sanity checking process when running BitBake. If
7296      any of the utilities are not installed on the build host, then
7297      BitBake immediately exits with an error.
7298
7299   :term:`SANITY_TESTED_DISTROS`
7300      A list of the host distribution identifiers that the build system has
7301      been tested against. Identifiers consist of the host distributor ID
7302      followed by the release, as reported by the ``lsb_release`` tool or
7303      as read from ``/etc/lsb-release``. Separate the list items with
7304      explicit newline characters (``\n``). If :term:`SANITY_TESTED_DISTROS` is
7305      not empty and the current value of
7306      :term:`NATIVELSBSTRING` does not appear in the
7307      list, then the build system reports a warning that indicates the
7308      current host distribution has not been tested as a build host.
7309
7310   :term:`SDK_ARCH`
7311      The target architecture for the SDK. Typically, you do not directly
7312      set this variable. Instead, use :term:`SDKMACHINE`.
7313
7314   :term:`SDK_ARCHIVE_TYPE`
7315      Specifies the type of archive to create for the SDK. Valid values:
7316
7317      - ``tar.xz`` (default)
7318      - ``zip``
7319
7320      Only one archive type can be specified.
7321
7322   :term:`SDK_BUILDINFO_FILE`
7323      When using the :ref:`ref-classes-image-buildinfo` class,
7324      specifies the file in the SDK to write the build information into. The
7325      default value is "``/buildinfo``".
7326
7327   :term:`SDK_CUSTOM_TEMPLATECONF`
7328      When building the extensible SDK, if :term:`SDK_CUSTOM_TEMPLATECONF` is set to
7329      "1" and a ``conf/templateconf.cfg`` file exists in the :term:`Build Directory`
7330      (:term:`TOPDIR`) then this will be copied into the SDK.
7331
7332   :term:`SDK_DEPLOY`
7333      The directory set up and used by the
7334      :ref:`populate_sdk_base <ref-classes-populate-sdk>` class to which the
7335      SDK is deployed. The :ref:`populate_sdk_base <ref-classes-populate-sdk>`
7336      class defines :term:`SDK_DEPLOY` as follows::
7337
7338         SDK_DEPLOY = "${TMPDIR}/deploy/sdk"
7339
7340   :term:`SDK_DIR`
7341      The parent directory used by the OpenEmbedded build system when
7342      creating SDK output. The
7343      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class defines
7344      the variable as follows::
7345
7346         SDK_DIR = "${WORKDIR}/sdk"
7347
7348      .. note::
7349
7350         The :term:`SDK_DIR` directory is a temporary directory as it is part of
7351         :term:`WORKDIR`. The final output directory is :term:`SDK_DEPLOY`.
7352
7353   :term:`SDK_EXT_TYPE`
7354      Controls whether or not shared state artifacts are copied into the
7355      extensible SDK. The default value of "full" copies all of the
7356      required shared state artifacts into the extensible SDK. The value
7357      "minimal" leaves these artifacts out of the SDK.
7358
7359      .. note::
7360
7361         If you set the variable to "minimal", you need to ensure
7362         :term:`SSTATE_MIRRORS` is set in the SDK's configuration to enable the
7363         artifacts to be fetched as needed.
7364
7365   :term:`SDK_HOST_MANIFEST`
7366      The manifest file for the host part of the SDK. This file lists all
7367      the installed packages that make up the host part of the SDK. The
7368      file contains package information on a line-per-package basis as
7369      follows::
7370
7371         packagename packagearch version
7372
7373      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
7374      defines the manifest file as follows::
7375
7376         SDK_HOST_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.host.manifest"
7377
7378      The location is derived using the :term:`SDK_DEPLOY` and
7379      :term:`TOOLCHAIN_OUTPUTNAME` variables.
7380
7381   :term:`SDK_INCLUDE_PKGDATA`
7382      When set to "1", specifies to include the packagedata for all recipes
7383      in the "world" target in the extensible SDK. Including this data
7384      allows the ``devtool search`` command to find these recipes in search
7385      results, as well as allows the ``devtool add`` command to map
7386      dependencies more effectively.
7387
7388      .. note::
7389
7390         Enabling the :term:`SDK_INCLUDE_PKGDATA`
7391         variable significantly increases build time because all of world
7392         needs to be built. Enabling the variable also slightly increases
7393         the size of the extensible SDK.
7394
7395   :term:`SDK_INCLUDE_TOOLCHAIN`
7396      When set to "1", specifies to include the toolchain in the extensible
7397      SDK. Including the toolchain is useful particularly when
7398      :term:`SDK_EXT_TYPE` is set to "minimal" to keep
7399      the SDK reasonably small but you still want to provide a usable
7400      toolchain. For example, suppose you want to use the toolchain from an
7401      IDE or from other tools and you do not want to perform additional
7402      steps to install the toolchain.
7403
7404      The :term:`SDK_INCLUDE_TOOLCHAIN` variable defaults to "0" if
7405      :term:`SDK_EXT_TYPE` is set to "minimal", and defaults to "1" if
7406      :term:`SDK_EXT_TYPE` is set to "full".
7407
7408   :term:`SDK_NAME`
7409      The base name for SDK output files. The default value (as set in
7410      ``meta-poky/conf/distro/poky.conf``) is derived from the
7411      :term:`DISTRO`,
7412      :term:`TCLIBC`,
7413      :term:`SDKMACHINE`,
7414      :term:`IMAGE_BASENAME`,
7415      :term:`TUNE_PKGARCH`, and
7416      :term:`MACHINE` variables::
7417
7418         SDK_NAME = "${DISTRO}-${TCLIBC}-${SDKMACHINE}-${IMAGE_BASENAME}-${TUNE_PKGARCH}-${MACHINE}"
7419
7420   :term:`SDK_OS`
7421      Specifies the operating system for which the SDK will be built. The
7422      default value is the value of :term:`BUILD_OS`.
7423
7424   :term:`SDK_OUTPUT`
7425      The location used by the OpenEmbedded build system when creating SDK
7426      output. The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>`
7427      class defines the variable as follows::
7428
7429         SDK_DIR = "${WORKDIR}/sdk"
7430         SDK_OUTPUT = "${SDK_DIR}/image"
7431         SDK_DEPLOY = "${DEPLOY_DIR}/sdk"
7432
7433      .. note::
7434
7435         The :term:`SDK_OUTPUT` directory is a temporary directory as it is part of
7436         :term:`WORKDIR` by way of :term:`SDK_DIR`. The final output directory is
7437         :term:`SDK_DEPLOY`.
7438
7439   :term:`SDK_PACKAGE_ARCHS`
7440      Specifies a list of architectures compatible with the SDK machine.
7441      This variable is set automatically and should not normally be
7442      hand-edited. Entries are separated using spaces and listed in order
7443      of priority. The default value for :term:`SDK_PACKAGE_ARCHS` is "all any
7444      noarch ${SDK_ARCH}-${SDKPKGSUFFIX}".
7445
7446   :term:`SDK_POSTPROCESS_COMMAND`
7447      Specifies a list of functions to call once the OpenEmbedded build
7448      system creates the SDK. You can specify functions separated by
7449      spaces:
7450
7451         SDK_POSTPROCESS_COMMAND += "function"
7452
7453      If you need to pass an SDK path to a command within a function, you
7454      can use ``${SDK_DIR}``, which points to the parent directory used by
7455      the OpenEmbedded build system when creating SDK output. See the
7456      :term:`SDK_DIR` variable for more information.
7457
7458   :term:`SDK_PREFIX`
7459      The toolchain binary prefix used for
7460      :ref:`ref-classes-nativesdk` recipes. The
7461      OpenEmbedded build system uses the :term:`SDK_PREFIX` value to set the
7462      :term:`TARGET_PREFIX` when building
7463      ``nativesdk`` recipes. The default value is "${SDK_SYS}-".
7464
7465   :term:`SDK_RECRDEP_TASKS`
7466      A list of shared state tasks added to the extensible SDK. By default,
7467      the following tasks are added:
7468
7469      - :ref:`ref-tasks-populate_lic`
7470      - :ref:`ref-tasks-package_qa`
7471      - :ref:`ref-tasks-populate_sysroot`
7472      - :ref:`ref-tasks-deploy`
7473
7474      Despite the default value of "" for the
7475      :term:`SDK_RECRDEP_TASKS` variable, the above four tasks are always added
7476      to the SDK. To specify tasks beyond these four, you need to use the
7477      :term:`SDK_RECRDEP_TASKS` variable (e.g. you are defining additional
7478      tasks that are needed in order to build
7479      :term:`SDK_TARGETS`).
7480
7481   :term:`SDK_SYS`
7482      Specifies the system, including the architecture and the operating
7483      system, for which the SDK will be built.
7484
7485      The OpenEmbedded build system automatically sets this variable based
7486      on :term:`SDK_ARCH`,
7487      :term:`SDK_VENDOR`, and
7488      :term:`SDK_OS`. You do not need to set the :term:`SDK_SYS`
7489      variable yourself.
7490
7491   :term:`SDK_TARGET_MANIFEST`
7492      The manifest file for the target part of the SDK. This file lists all
7493      the installed packages that make up the target part of the SDK. The
7494      file contains package information on a line-per-package basis as
7495      follows::
7496
7497         packagename packagearch version
7498
7499      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
7500      defines the manifest file as follows::
7501
7502         SDK_TARGET_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.target.manifest"
7503
7504      The location is derived using the :term:`SDK_DEPLOY` and
7505      :term:`TOOLCHAIN_OUTPUTNAME` variables.
7506
7507   :term:`SDK_TARGETS`
7508      A list of targets to install from shared state as part of the
7509      standard or extensible SDK installation. The default value is "${PN}"
7510      (i.e. the image from which the SDK is built).
7511
7512      The :term:`SDK_TARGETS` variable is an internal variable and typically
7513      would not be changed.
7514
7515   :term:`SDK_TITLE`
7516      The title to be printed when running the SDK installer. By default,
7517      this title is based on the :term:`DISTRO_NAME` or
7518      :term:`DISTRO` variable and is set in the
7519      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
7520      follows::
7521
7522         SDK_TITLE ??= "${@d.getVar('DISTRO_NAME') or d.getVar('DISTRO')} SDK"
7523
7524      For the default distribution "poky",
7525      :term:`SDK_TITLE` is set to "Poky (Yocto Project Reference Distro)".
7526
7527      For information on how to change this default title, see the
7528      ":ref:`sdk-manual/appendix-customizing:changing the extensible sdk installer title`"
7529      section in the Yocto Project Application Development and the
7530      Extensible Software Development Kit (eSDK) manual.
7531
7532   :term:`SDK_TOOLCHAIN_LANGS`
7533      Specifies programming languages to support in the SDK, as a
7534      space-separated list. Currently supported items are ``rust`` and ``go``.
7535
7536   :term:`SDK_UPDATE_URL`
7537      An optional URL for an update server for the extensible SDK. If set,
7538      the value is used as the default update server when running
7539      ``devtool sdk-update`` within the extensible SDK.
7540
7541   :term:`SDK_VENDOR`
7542      Specifies the name of the SDK vendor.
7543
7544   :term:`SDK_VERSION`
7545      Specifies the version of the SDK. The Poky distribution configuration file
7546      (``/meta-poky/conf/distro/poky.conf``) sets the default
7547      :term:`SDK_VERSION` as follows::
7548
7549         SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"
7550
7551      For additional information, see the
7552      :term:`DISTRO_VERSION` and
7553      :term:`METADATA_REVISION` variables.
7554
7555   :term:`SDK_ZIP_OPTIONS`
7556      Specifies extra options to pass to the ``zip`` command when zipping the SDK
7557      (i.e. when :term:`SDK_ARCHIVE_TYPE` is set to "zip"). The default value is
7558      "-y".
7559
7560   :term:`SDKEXTPATH`
7561      The default installation directory for the Extensible SDK. By
7562      default, this directory is based on the :term:`DISTRO`
7563      variable and is set in the
7564      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
7565      follows::
7566
7567         SDKEXTPATH ??= "~/${@d.getVar('DISTRO')}_sdk"
7568
7569      For the
7570      default distribution "poky", the :term:`SDKEXTPATH` is set to "poky_sdk".
7571
7572      For information on how to change this default directory, see the
7573      ":ref:`sdk-manual/appendix-customizing:changing the default sdk installation directory`"
7574      section in the Yocto Project Application Development and the
7575      Extensible Software Development Kit (eSDK) manual.
7576
7577   :term:`SDKIMAGE_FEATURES`
7578      Equivalent to :term:`IMAGE_FEATURES`. However, this variable applies to
7579      the SDK generated from an image using the following command::
7580
7581         $ bitbake -c populate_sdk imagename
7582
7583   :term:`SDKMACHINE`
7584      The machine for which the SDK is built. In other words, the SDK is built
7585      such that it runs on the target you specify with the :term:`SDKMACHINE`
7586      value. The value points to a corresponding ``.conf`` file under
7587      ``conf/machine-sdk/`` in the enabled layers, for example ``aarch64``,
7588      ``i586``, ``i686``, ``ppc64``, ``ppc64le``, and ``x86_64`` are
7589      :oe_git:`available in OpenEmbedded-Core </openembedded-core/tree/meta/conf/machine-sdk>`.
7590
7591      The variable defaults to :term:`BUILD_ARCH` so that SDKs are built for the
7592      architecture of the build machine.
7593
7594      .. note::
7595
7596         You cannot set the :term:`SDKMACHINE`
7597         variable in your distribution configuration file. If you do, the
7598         configuration will not take effect.
7599
7600   :term:`SDKPATH`
7601      Defines the path offered to the user for installation of the SDK that
7602      is generated by the OpenEmbedded build system. The path appears as
7603      the default location for installing the SDK when you run the SDK's
7604      installation script. You can override the offered path when you run
7605      the script.
7606
7607   :term:`SDKTARGETSYSROOT`
7608      The full path to the sysroot used for cross-compilation within an SDK
7609      as it will be when installed into the default
7610      :term:`SDKPATH`.
7611
7612   :term:`SECTION`
7613      The section in which packages should be categorized. Package
7614      management utilities can make use of this variable.
7615
7616   :term:`SELECTED_OPTIMIZATION`
7617      Specifies the optimization flags passed to the C compiler when
7618      building for the target. The flags are passed through the default
7619      value of the :term:`TARGET_CFLAGS` variable.
7620
7621      The :term:`SELECTED_OPTIMIZATION` variable takes the value of
7622      :term:`FULL_OPTIMIZATION` unless :term:`DEBUG_BUILD` = "1", in which
7623      case the value of :term:`DEBUG_OPTIMIZATION` is used.
7624
7625   :term:`SERIAL_CONSOLES`
7626      Defines a serial console (TTY) to enable using
7627      :wikipedia:`getty <Getty_(Unix)>`. Provide a value that specifies the
7628      baud rate followed by the TTY device name separated by a semicolon.
7629      Use spaces to separate multiple devices::
7630
7631         SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
7632
7633   :term:`SETUPTOOLS_BUILD_ARGS`
7634      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7635      class, this variable can be used to specify additional arguments to be
7636      passed to ``setup.py build`` in the ``setuptools3_do_compile()`` task.
7637
7638   :term:`SETUPTOOLS_INSTALL_ARGS`
7639      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7640      class, this variable can be used to specify additional arguments to be
7641      passed to ``setup.py install`` in the ``setuptools3_do_install()`` task.
7642
7643   :term:`SETUPTOOLS_SETUP_PATH`
7644      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7645      class, this variable should be used to specify the directory in which
7646      the ``setup.py`` file is located if it is not at the root of the source
7647      tree (as specified by :term:`S`). For example, in a recipe where the
7648      sources are fetched from a Git repository and ``setup.py`` is in a
7649      ``python/pythonmodule`` subdirectory, you would have this::
7650
7651         S = "${WORKDIR}/git"
7652         SETUPTOOLS_SETUP_PATH = "${S}/python/pythonmodule"
7653
7654   :term:`SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS`
7655      A list of recipe dependencies that should not be used to determine
7656      signatures of tasks from one recipe when they depend on tasks from
7657      another recipe. For example::
7658
7659         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
7660
7661      In the previous example, ``intone`` depends on ``mplayer2``.
7662
7663      You can use the special token ``"*"`` on the left-hand side of the
7664      dependency to match all recipes except the one on the right-hand
7665      side. Here is an example::
7666
7667         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "*->quilt-native"
7668
7669      In the previous example, all recipes except ``quilt-native`` ignore
7670      task signatures from the ``quilt-native`` recipe when determining
7671      their task signatures.
7672
7673      Use of this variable is one mechanism to remove dependencies that
7674      affect task signatures and thus force rebuilds when a recipe changes.
7675
7676      .. note::
7677
7678         If you add an inappropriate dependency for a recipe relationship,
7679         the software might break during runtime if the interface of the
7680         second recipe was changed after the first recipe had been built.
7681
7682   :term:`SIGGEN_EXCLUDERECIPES_ABISAFE`
7683      A list of recipes that are completely stable and will never change.
7684      The ABI for the recipes in the list are presented by output from the
7685      tasks run to build the recipe. Use of this variable is one way to
7686      remove dependencies from one recipe on another that affect task
7687      signatures and thus force rebuilds when the recipe changes.
7688
7689      .. note::
7690
7691         If you add an inappropriate variable to this list, the software
7692         might break at runtime if the interface of the recipe was changed
7693         after the other had been built.
7694
7695   :term:`SITEINFO_BITS`
7696      Specifies the number of bits for the target system CPU. The value
7697      should be either "32" or "64".
7698
7699   :term:`SITEINFO_ENDIANNESS`
7700      Specifies the endian byte order of the target system. The value
7701      should be either "le" for little-endian or "be" for big-endian.
7702
7703   :term:`SKIP_FILEDEPS`
7704      Enables removal of all files from the "Provides" section of an RPM
7705      package. Removal of these files is required for packages containing
7706      prebuilt binaries and libraries such as ``libstdc++`` and ``glibc``.
7707
7708      To enable file removal, set the variable to "1" in your
7709      ``conf/local.conf`` configuration file in your:
7710      :term:`Build Directory`::
7711
7712         SKIP_FILEDEPS = "1"
7713
7714   :term:`SKIP_RECIPE`
7715      Used to prevent the OpenEmbedded build system from building a given
7716      recipe. Specify the :term:`PN` value as a variable flag (``varflag``)
7717      and provide a reason, which will be reported when attempting to
7718      build the recipe.
7719
7720      To prevent a recipe from being built, use the :term:`SKIP_RECIPE`
7721      variable in your ``local.conf`` file or distribution configuration.
7722      Here is an example which prevents ``myrecipe`` from being built::
7723
7724         SKIP_RECIPE[myrecipe] = "Not supported by our organization."
7725
7726   :term:`SOC_FAMILY`
7727      A colon-separated list grouping together machines based upon the same
7728      family of SoC (System On Chip). You typically set this variable in a
7729      common ``.inc`` file that you include in the configuration files of all
7730      the machines.
7731
7732      .. note::
7733
7734         You must include ``conf/machine/include/soc-family.inc`` for this
7735         variable to appear in :term:`MACHINEOVERRIDES`.
7736
7737   :term:`SOLIBS`
7738      Defines the suffix for shared libraries used on the target platform.
7739      By default, this suffix is ".so.*" for all Linux-based systems and is
7740      defined in the ``meta/conf/bitbake.conf`` configuration file.
7741
7742      You will see this variable referenced in the default values of
7743      ``FILES:${PN}``.
7744
7745   :term:`SOLIBSDEV`
7746      Defines the suffix for the development symbolic link (symlink) for
7747      shared libraries on the target platform. By default, this suffix is
7748      ".so" for Linux-based systems and is defined in the
7749      ``meta/conf/bitbake.conf`` configuration file.
7750
7751      You will see this variable referenced in the default values of
7752      ``FILES:${PN}-dev``.
7753
7754   :term:`SOURCE_DATE_EPOCH`
7755      This defines a date expressed in number of seconds since
7756      the UNIX EPOCH (01 Jan 1970 00:00:00 UTC), which is used by
7757      multiple build systems to force a timestamp in built binaries.
7758      Many upstream projects already support this variable.
7759
7760      You will find more details in the `official specifications
7761      <https://reproducible-builds.org/specs/source-date-epoch/>`__.
7762
7763      A value for each recipe is computed from the sources by
7764      :oe_git:`meta/lib/oe/reproducible.py </openembedded-core/tree/meta/lib/oe/reproducible.py>`.
7765
7766      If a recipe wishes to override the default behavior, it should set its
7767      own :term:`SOURCE_DATE_EPOCH` value::
7768
7769          SOURCE_DATE_EPOCH = "1613559011"
7770
7771   :term:`SOURCE_MIRROR_FETCH`
7772      When you are fetching files to create a mirror of sources (i.e.
7773      creating a source mirror), setting :term:`SOURCE_MIRROR_FETCH` to "1" in
7774      your ``local.conf`` configuration file ensures the source for all
7775      recipes are fetched regardless of whether or not a recipe is
7776      compatible with the configuration. A recipe is considered
7777      incompatible with the currently configured machine when either or
7778      both the :term:`COMPATIBLE_MACHINE`
7779      variable and :term:`COMPATIBLE_HOST` variables
7780      specify compatibility with a machine other than that of the current
7781      machine or host.
7782
7783      .. note::
7784
7785         Do not set the :term:`SOURCE_MIRROR_FETCH`
7786         variable unless you are creating a source mirror. In other words,
7787         do not set the variable during a normal build.
7788
7789   :term:`SOURCE_MIRROR_URL`
7790      Defines your own :term:`PREMIRRORS` from which to
7791      first fetch source before attempting to fetch from the upstream
7792      specified in :term:`SRC_URI`.
7793
7794      To use this variable, you must globally inherit the
7795      :ref:`ref-classes-own-mirrors` class and then provide
7796      the URL to your mirrors. Here is the general syntax::
7797
7798         INHERIT += "own-mirrors"
7799         SOURCE_MIRROR_URL = "http://example.com/my_source_mirror"
7800
7801      .. note::
7802
7803         You can specify only a single URL in :term:`SOURCE_MIRROR_URL`.
7804
7805   :term:`SPDX_ARCHIVE_PACKAGED`
7806      This option allows to add to :term:`SPDX` output compressed archives
7807      of the files in the generated target packages.
7808
7809      Such archives are available in
7810      ``tmp/deploy/spdx/MACHINE/packages/packagename.tar.zst``
7811      under the :term:`Build Directory`.
7812
7813      Enable this option as follows::
7814
7815         SPDX_ARCHIVE_PACKAGED = "1"
7816
7817      According to our tests on release 4.1 "langdale", building
7818      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling this
7819      option multiplied the size of the ``tmp/deploy/spdx`` directory by a
7820      factor of 13 (+1.6 GiB for this image), compared to just using the
7821      :ref:`ref-classes-create-spdx` class with no option.
7822
7823      Note that this option doesn't increase the size of :term:`SPDX`
7824      files in ``tmp/deploy/images/MACHINE``.
7825
7826   :term:`SPDX_ARCHIVE_SOURCES`
7827      This option allows to add to :term:`SPDX` output compressed archives
7828      of the sources for packages installed on the target. It currently
7829      only works when :term:`SPDX_INCLUDE_SOURCES` is set.
7830
7831      This is one way of fulfilling "source code access" license
7832      requirements.
7833
7834      Such source archives are available in
7835      ``tmp/deploy/spdx/MACHINE/recipes/recipe-packagename.tar.zst``
7836      under the :term:`Build Directory`.
7837
7838      Enable this option as follows::
7839
7840         SPDX_INCLUDE_SOURCES = "1"
7841         SPDX_ARCHIVE_SOURCES = "1"
7842
7843      According to our tests on release 4.1 "langdale", building
7844      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling
7845      these options multiplied the size of the ``tmp/deploy/spdx``
7846      directory by a factor of 11 (+1.4 GiB for this image),
7847      compared to just using the :ref:`ref-classes-create-spdx`
7848      class with no option.
7849
7850      Note that using this option only marginally increases the size
7851      of the :term:`SPDX` output in ``tmp/deploy/images/MACHINE/``
7852      (+ 0.07\% with the tested image), compared to just enabling
7853      :term:`SPDX_INCLUDE_SOURCES`.
7854
7855   :term:`SPDX_CUSTOM_ANNOTATION_VARS`
7856      This option allows to associate `SPDX annotations
7857      <https://spdx.github.io/spdx-spec/v2.3/annotations/>`__ to a recipe,
7858      using the values of variables in the recipe::
7859
7860         ANNOTATION1 = "First annotation for recipe"
7861         ANNOTATION2 = "Second annotation for recipe"
7862         SPDX_CUSTOM_ANNOTATION_VARS = "ANNOTATION1 ANNOTATION2"
7863
7864      This will add a new block to the recipe ``.sdpx.json`` output::
7865
7866         "annotations": [
7867           {
7868             "annotationDate": "2023-04-18T08:32:12Z",
7869             "annotationType": "OTHER",
7870             "annotator": "Tool: oe-spdx-creator - 1.0",
7871             "comment": "ANNOTATION1=First annotation for recipe"
7872           },
7873           {
7874             "annotationDate": "2023-04-18T08:32:12Z",
7875             "annotationType": "OTHER",
7876             "annotator": "Tool: oe-spdx-creator - 1.0",
7877             "comment": "ANNOTATION2=Second annotation for recipe"
7878           }
7879         ],
7880
7881   :term:`SPDX_INCLUDE_SOURCES`
7882      This option allows to add a description of the source files used to build
7883      the host tools and the target packages, to the ``spdx.json`` files in
7884      ``tmp/deploy/spdx/MACHINE/recipes/`` under the :term:`Build Directory`.
7885      As a consequence, the ``spdx.json`` files under the ``by-namespace`` and
7886      ``packages`` subdirectories in ``tmp/deploy/spdx/MACHINE`` are also
7887      modified to include references to such source file descriptions.
7888
7889      Enable this option as follows::
7890
7891         SPDX_INCLUDE_SOURCES = "1"
7892
7893      According to our tests on release 4.1 "langdale", building
7894      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling
7895      this option multiplied the total size of the ``tmp/deploy/spdx``
7896      directory by a factor of 3  (+291 MiB for this image),
7897      and the size of the ``IMAGE-MACHINE.spdx.tar.zst`` in
7898      ``tmp/deploy/images/MACHINE`` by a factor of 130 (+15 MiB for this
7899      image), compared to just using the :ref:`ref-classes-create-spdx` class
7900      with no option.
7901
7902   :term:`SPDX_PRETTY`
7903      This option makes the SPDX output more human-readable, using
7904      identation and newlines, instead of the default output in a
7905      single line::
7906
7907         SPDX_PRETTY = "1"
7908
7909      The generated SPDX files are approximately 20% bigger, but
7910      this option is recommended if you want to inspect the SPDX
7911      output files with a text editor.
7912
7913   :term:`SPDXLICENSEMAP`
7914      Maps commonly used license names to their SPDX counterparts found in
7915      ``meta/files/common-licenses/``. For the default :term:`SPDXLICENSEMAP`
7916      mappings, see the ``meta/conf/licenses.conf`` file.
7917
7918      For additional information, see the :term:`LICENSE`
7919      variable.
7920
7921   :term:`SPECIAL_PKGSUFFIX`
7922      A list of prefixes for :term:`PN` used by the OpenEmbedded
7923      build system to create variants of recipes or packages. The list
7924      specifies the prefixes to strip off during certain circumstances such
7925      as the generation of the :term:`BPN` variable.
7926
7927   :term:`SPL_BINARY`
7928      The file type for the Secondary Program Loader (SPL). Some devices
7929      use an SPL from which to boot (e.g. the BeagleBone development
7930      board). For such cases, you can declare the file type of the SPL
7931      binary in the ``u-boot.inc`` include file, which is used in the
7932      U-Boot recipe.
7933
7934      The SPL file type is set to "null" by default in the ``u-boot.inc``
7935      file as follows::
7936
7937         # Some versions of u-boot build an SPL (Second Program Loader) image that
7938         # should be packaged along with the u-boot binary as well as placed in the
7939         # deploy directory. For those versions they can set the following variables
7940         # to allow packaging the SPL.
7941         SPL_BINARY ?= ""
7942         SPL_BINARYNAME ?= "${@os.path.basename(d.getVar("SPL_BINARY"))}"
7943         SPL_IMAGE ?= "${SPL_BINARYNAME}-${MACHINE}-${PV}-${PR}"
7944         SPL_SYMLINK ?= "${SPL_BINARYNAME}-${MACHINE}"
7945
7946      The :term:`SPL_BINARY` variable helps form
7947      various ``SPL_*`` variables used by the OpenEmbedded build system.
7948
7949      See the BeagleBone machine configuration example in the
7950      ":ref:`dev-manual/layers:adding a layer using the \`\`bitbake-layers\`\` script`"
7951      section in the Yocto Project Board Support Package Developer's Guide
7952      for additional information.
7953
7954   :term:`SPL_MKIMAGE_DTCOPTS`
7955      Options for the device tree compiler passed to ``mkimage -D`` feature
7956      while creating a FIT image with the :ref:`ref-classes-uboot-sign`
7957      class. If :term:`SPL_MKIMAGE_DTCOPTS` is not set then the
7958      :ref:`ref-classes-uboot-sign` class will not pass the ``-D`` option
7959      to ``mkimage``.
7960
7961      The default value is set to "" by the :ref:`ref-classes-uboot-config`
7962      class.
7963
7964   :term:`SPL_SIGN_ENABLE`
7965      Enable signing of the U-Boot FIT image. The default value is "0".
7966      This variable is used by the :ref:`ref-classes-uboot-sign` class.
7967
7968   :term:`SPL_SIGN_KEYDIR`
7969      Location of the directory containing the RSA key and certificate used for
7970      signing the U-Boot FIT image, used by the :ref:`ref-classes-uboot-sign`
7971      class.
7972
7973   :term:`SPL_SIGN_KEYNAME`
7974      The name of keys used by the :ref:`ref-classes-kernel-fitimage` class
7975      for signing U-Boot FIT image stored in the :term:`SPL_SIGN_KEYDIR`
7976      directory. If we have for example a ``dev.key`` key and a ``dev.crt``
7977      certificate stored in the :term:`SPL_SIGN_KEYDIR` directory, you will
7978      have to set :term:`SPL_SIGN_KEYNAME` to ``dev``.
7979
7980   :term:`SPLASH`
7981      This variable, used by the :ref:`ref-classes-image` class, allows
7982      to choose splashscreen applications. Set it to the names of packages
7983      for such applications to use. This variable is set by default to
7984      ``psplash``.
7985
7986   :term:`SPLASH_IMAGES`
7987      This variable, used by the ``psplash`` recipe, allows to customize
7988      the default splashscreen image.
7989
7990      Specified images in PNG format are converted to ``.h`` files by the recipe,
7991      and are included in the ``psplash`` binary, so you won't find them in
7992      the root filesystem.
7993
7994      To make such a change, it is recommended to customize the
7995      ``psplash`` recipe in a custom layer. Here is an example structure for
7996      an ``ACME`` board::
7997
7998          meta-acme/recipes-core/psplash
7999          ├── files
8000          │   └── logo-acme.png
8001          └── psplash_%.bbappend
8002
8003      And here are the contents of the ``psplash_%.bbappend`` file in
8004      this example::
8005
8006          SPLASH_IMAGES = "file://logo-acme.png;outsuffix=default"
8007          FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
8008
8009      You could even add specific configuration options for ``psplash``,
8010      for example::
8011
8012          EXTRA_OECONF += "--disable-startup-msg --enable-img-fullscreen"
8013
8014      For information on append files, see the
8015      ":ref:`dev-manual/layers:appending other layers metadata with your layer`"
8016      section.
8017
8018   :term:`SRCREV_FORMAT`
8019      See :term:`bitbake:SRCREV_FORMAT` in the BitBake manual.
8020
8021   :term:`SRC_URI`
8022
8023      See the BitBake manual for the initial description for this variable:
8024      :term:`bitbake:SRC_URI`.
8025
8026      The following features are added by OpenEmbedded and the Yocto Project.
8027
8028      There are standard and recipe-specific options. Here are standard ones:
8029
8030      -  ``apply`` --- whether to apply the patch or not. The default
8031         action is to apply the patch.
8032
8033      -  ``striplevel`` --- which striplevel to use when applying the
8034         patch. The default level is 1.
8035
8036      -  ``patchdir`` --- specifies the directory in which the patch should
8037         be applied. The default is ``${``\ :term:`S`\ ``}``.
8038
8039      Here are options specific to recipes building code from a revision
8040      control system:
8041
8042      -  ``mindate`` --- apply the patch only if
8043         :term:`SRCDATE` is equal to or greater than
8044         ``mindate``.
8045
8046      -  ``maxdate`` --- apply the patch only if :term:`SRCDATE` is not later
8047         than ``maxdate``.
8048
8049      -  ``minrev`` --- apply the patch only if :term:`SRCREV` is equal to or
8050         greater than ``minrev``.
8051
8052      -  ``maxrev`` --- apply the patch only if :term:`SRCREV` is not later
8053         than ``maxrev``.
8054
8055      -  ``rev`` --- apply the patch only if :term:`SRCREV` is equal to
8056         ``rev``.
8057
8058      -  ``notrev`` --- apply the patch only if :term:`SRCREV` is not equal to
8059         ``rev``.
8060
8061      .. note::
8062
8063         If you want the build system to pick up files specified through
8064         a :term:`SRC_URI` statement from your append file, you need to be
8065         sure to extend the :term:`FILESPATH` variable by also using the
8066         :term:`FILESEXTRAPATHS` variable from within your append file.
8067
8068   :term:`SRC_URI_OVERRIDES_PACKAGE_ARCH`
8069      By default, the OpenEmbedded build system automatically detects
8070      whether :term:`SRC_URI` contains files that are machine-specific. If so,
8071      the build system automatically changes :term:`PACKAGE_ARCH`. Setting this
8072      variable to "0" disables this behavior.
8073
8074   :term:`SRCDATE`
8075      The date of the source code used to build the package. This variable
8076      applies only if the source was fetched from a Source Code Manager
8077      (SCM).
8078
8079   :term:`SRCPV`
8080      Returns the version string of the current package. This string is
8081      used to help define the value of :term:`PV`.
8082
8083      The :term:`SRCPV` variable is defined in the ``meta/conf/bitbake.conf``
8084      configuration file in the :term:`Source Directory` as
8085      follows::
8086
8087         SRCPV = "${@bb.fetch2.get_srcrev(d)}"
8088
8089      Recipes that need to define :term:`PV` do so with the help of the
8090      :term:`SRCPV`. For example, the ``ofono`` recipe (``ofono_git.bb``)
8091      located in ``meta/recipes-connectivity`` in the Source Directory
8092      defines :term:`PV` as follows::
8093
8094         PV = "0.12-git${SRCPV}"
8095
8096   :term:`SRCREV`
8097      The revision of the source code used to build the package. This
8098      variable applies to Subversion, Git, Mercurial, and Bazaar only. Note
8099      that if you want to build a fixed revision and you want to avoid
8100      performing a query on the remote repository every time BitBake parses
8101      your recipe, you should specify a :term:`SRCREV` that is a full revision
8102      identifier (e.g. the full SHA hash in git) and not just a tag.
8103
8104      .. note::
8105
8106         For information on limitations when inheriting the latest revision
8107         of software using :term:`SRCREV`, see the :term:`AUTOREV` variable
8108         description and the
8109         ":ref:`dev-manual/packages:automatically incrementing a package version number`"
8110         section, which is in the Yocto Project Development Tasks Manual.
8111
8112   :term:`SRCTREECOVEREDTASKS`
8113      A list of tasks that are typically not relevant (and therefore skipped)
8114      when building using the :ref:`ref-classes-externalsrc`
8115      class. The default value as set in that class file is the set of tasks
8116      that are rarely needed when using external source::
8117
8118         SRCTREECOVEREDTASKS ?= "do_patch do_unpack do_fetch"
8119
8120      The notable exception is when processing external kernel source as
8121      defined in the :ref:`ref-classes-kernel-yocto` class file (formatted for
8122      aesthetics)::
8123
8124         SRCTREECOVEREDTASKS += "\
8125           do_validate_branches \
8126           do_kernel_configcheck \
8127           do_kernel_checkout \
8128           do_fetch \
8129           do_unpack \
8130           do_patch \
8131         "
8132
8133      See the associated :term:`EXTERNALSRC` and :term:`EXTERNALSRC_BUILD`
8134      variables for more information.
8135
8136   :term:`SSTATE_DIR`
8137      The directory for the shared state cache.
8138
8139   :term:`SSTATE_EXCLUDEDEPS_SYSROOT`
8140      This variable allows to specify indirect dependencies to exclude
8141      from sysroots, for example to avoid the situations when a dependency on
8142      any ``-native`` recipe will pull in all dependencies of that recipe
8143      in the recipe sysroot. This behaviour might not always be wanted,
8144      for example when that ``-native`` recipe depends on build tools
8145      that are not relevant for the current recipe.
8146
8147      This way, irrelevant dependencies are ignored, which could have
8148      prevented the reuse of prebuilt artifacts stored in the Shared
8149      State Cache.
8150
8151      :term:`SSTATE_EXCLUDEDEPS_SYSROOT` is evaluated as two regular
8152      expressions of recipe and dependency to ignore. An example
8153      is the rule in :oe_git:`meta/conf/layer.conf </openembedded-core/tree/meta/conf/layer.conf>`::
8154
8155         # Nothing needs to depend on libc-initial
8156         # base-passwd/shadow-sysroot don't need their dependencies
8157         SSTATE_EXCLUDEDEPS_SYSROOT += "\
8158             .*->.*-initial.* \
8159             .*(base-passwd|shadow-sysroot)->.* \
8160         "
8161
8162      The ``->`` substring represents the dependency between
8163      the two regular expressions.
8164
8165   :term:`SSTATE_MIRROR_ALLOW_NETWORK`
8166      If set to "1", allows fetches from mirrors that are specified in
8167      :term:`SSTATE_MIRRORS` to work even when
8168      fetching from the network is disabled by setting :term:`BB_NO_NETWORK` to
8169      "1". Using the :term:`SSTATE_MIRROR_ALLOW_NETWORK` variable is useful if
8170      you have set :term:`SSTATE_MIRRORS` to point to an internal server for
8171      your shared state cache, but you want to disable any other fetching
8172      from the network.
8173
8174   :term:`SSTATE_MIRRORS`
8175      Configures the OpenEmbedded build system to search other mirror
8176      locations for prebuilt cache data objects before building out the
8177      data. This variable works like fetcher :term:`MIRRORS`
8178      and :term:`PREMIRRORS` and points to the cache
8179      locations to check for the shared state (sstate) objects.
8180
8181      You can specify a filesystem directory or a remote URL such as HTTP
8182      or FTP. The locations you specify need to contain the shared state
8183      cache (sstate-cache) results from previous builds. The sstate-cache
8184      you point to can also be from builds on other machines.
8185
8186      When pointing to sstate build artifacts on another machine that uses
8187      a different GCC version for native builds, you must configure
8188      :term:`SSTATE_MIRRORS` with a regular expression that maps local search
8189      paths to server paths. The paths need to take into account
8190      :term:`NATIVELSBSTRING` set by the :ref:`ref-classes-uninative` class.
8191      For example, the following maps the local search path ``universal-4.9``
8192      to the server-provided path server_url_sstate_path::
8193
8194         SSTATE_MIRRORS ?= "file://universal-4.9/(.*) https://server_url_sstate_path/universal-4.8/\1"
8195
8196      If a mirror uses the same structure as
8197      :term:`SSTATE_DIR`, you need to add "PATH" at the
8198      end as shown in the examples below. The build system substitutes the
8199      correct path within the directory structure::
8200
8201         SSTATE_MIRRORS ?= "\
8202             file://.* https://someserver.tld/share/sstate/PATH;downloadfilename=PATH \
8203             file://.* file:///some-local-dir/sstate/PATH"
8204
8205      The Yocto Project actually shares the cache data objects built by its
8206      autobuilder::
8207
8208         SSTATE_MIRRORS ?= "file://.* http://cdn.jsdelivr.net/yocto/sstate/all/PATH;downloadfilename=PATH"
8209
8210      As such binary artifacts are built for the generic QEMU machines
8211      supported by the various Poky releases, they are less likely to be
8212      reusable in real projects building binaries optimized for a specific
8213      CPU family.
8214
8215   :term:`SSTATE_SCAN_FILES`
8216      Controls the list of files the OpenEmbedded build system scans for
8217      hardcoded installation paths. The variable uses a space-separated
8218      list of filenames (not paths) with standard wildcard characters
8219      allowed.
8220
8221      During a build, the OpenEmbedded build system creates a shared state
8222      (sstate) object during the first stage of preparing the sysroots.
8223      That object is scanned for hardcoded paths for original installation
8224      locations. The list of files that are scanned for paths is controlled
8225      by the :term:`SSTATE_SCAN_FILES` variable. Typically, recipes add files
8226      they want to be scanned to the value of :term:`SSTATE_SCAN_FILES` rather
8227      than the variable being comprehensively set. The
8228      :ref:`ref-classes-sstate` class specifies the default list of files.
8229
8230      For details on the process, see the :ref:`ref-classes-staging` class.
8231
8232   :term:`STAGING_BASE_LIBDIR_NATIVE`
8233      Specifies the path to the ``/lib`` subdirectory of the sysroot
8234      directory for the build host.
8235
8236   :term:`STAGING_BASELIBDIR`
8237      Specifies the path to the ``/lib`` subdirectory of the sysroot
8238      directory for the target for which the current recipe is being built
8239      (:term:`STAGING_DIR_HOST`).
8240
8241   :term:`STAGING_BINDIR`
8242      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
8243      directory for the target for which the current recipe is being built
8244      (:term:`STAGING_DIR_HOST`).
8245
8246   :term:`STAGING_BINDIR_CROSS`
8247      Specifies the path to the directory containing binary configuration
8248      scripts. These scripts provide configuration information for other
8249      software that wants to make use of libraries or include files
8250      provided by the software associated with the script.
8251
8252      .. note::
8253
8254         This style of build configuration has been largely replaced by
8255         ``pkg-config``. Consequently, if ``pkg-config`` is supported by the
8256         library to which you are linking, it is recommended you use
8257         ``pkg-config`` instead of a provided configuration script.
8258
8259   :term:`STAGING_BINDIR_NATIVE`
8260      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
8261      directory for the build host.
8262
8263   :term:`STAGING_DATADIR`
8264      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
8265      directory for the target for which the current recipe is being built
8266      (:term:`STAGING_DIR_HOST`).
8267
8268   :term:`STAGING_DATADIR_NATIVE`
8269      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
8270      directory for the build host.
8271
8272   :term:`STAGING_DIR`
8273      Helps construct the ``recipe-sysroots`` directory, which is used
8274      during packaging.
8275
8276      For information on how staging for recipe-specific sysroots occurs,
8277      see the :ref:`ref-tasks-populate_sysroot`
8278      task, the ":ref:`sdk-manual/extensible:sharing files between recipes`"
8279      section in the Yocto Project Development Tasks Manual, the
8280      ":ref:`overview-manual/concepts:configuration, compilation, and staging`"
8281      section in the Yocto Project Overview and Concepts Manual, and the
8282      :term:`SYSROOT_DIRS` variable.
8283
8284      .. note::
8285
8286         Recipes should never write files directly under the :term:`STAGING_DIR`
8287         directory because the OpenEmbedded build system manages the
8288         directory automatically. Instead, files should be installed to
8289         ``${``\ :term:`D`\ ``}`` within your recipe's :ref:`ref-tasks-install`
8290         task and then the OpenEmbedded build system will stage a subset of
8291         those files into the sysroot.
8292
8293   :term:`STAGING_DIR_HOST`
8294      Specifies the path to the sysroot directory for the system on which
8295      the component is built to run (the system that hosts the component).
8296      For most recipes, this sysroot is the one in which that recipe's
8297      :ref:`ref-tasks-populate_sysroot` task copies
8298      files. Exceptions include ``-native`` recipes, where the
8299      :ref:`ref-tasks-populate_sysroot` task instead uses
8300      :term:`STAGING_DIR_NATIVE`. Depending on
8301      the type of recipe and the build target, :term:`STAGING_DIR_HOST` can
8302      have the following values:
8303
8304      -  For recipes building for the target machine, the value is
8305         "${:term:`STAGING_DIR`}/${:term:`MACHINE`}".
8306
8307      -  For native recipes building for the build host, the value is empty
8308         given the assumption that when building for the build host, the
8309         build host's own directories should be used.
8310
8311         .. note::
8312
8313            ``-native`` recipes are not installed into host paths like such
8314            as ``/usr``. Rather, these recipes are installed into
8315            :term:`STAGING_DIR_NATIVE`. When compiling ``-native`` recipes,
8316            standard build environment variables such as
8317            :term:`CPPFLAGS` and
8318            :term:`CFLAGS` are set up so that both host paths
8319            and :term:`STAGING_DIR_NATIVE` are searched for libraries and
8320            headers using, for example, GCC's ``-isystem`` option.
8321
8322            Thus, the emphasis is that the ``STAGING_DIR*`` variables
8323            should be viewed as input variables by tasks such as
8324            :ref:`ref-tasks-configure`,
8325            :ref:`ref-tasks-compile`, and
8326            :ref:`ref-tasks-install`. Having the real system
8327            root correspond to :term:`STAGING_DIR_HOST` makes conceptual sense
8328            for ``-native`` recipes, as they make use of host headers and
8329            libraries.
8330
8331      Check :term:`RECIPE_SYSROOT` and :term:`RECIPE_SYSROOT_NATIVE`.
8332
8333   :term:`STAGING_DIR_NATIVE`
8334      Specifies the path to the sysroot directory used when building
8335      components that run on the build host itself.
8336
8337      The default value is ``"${RECIPE_SYSROOT_NATIVE}"``,
8338      check :term:`RECIPE_SYSROOT_NATIVE`.
8339
8340   :term:`STAGING_DIR_TARGET`
8341      Specifies the path to the sysroot used for the system for which the
8342      component generates code. For components that do not generate code,
8343      which is the majority, :term:`STAGING_DIR_TARGET` is set to match
8344      :term:`STAGING_DIR_HOST`.
8345
8346      Some recipes build binaries that can run on the target system but those
8347      binaries in turn generate code for another different system (e.g.
8348      :ref:`ref-classes-cross-canadian` recipes). Using terminology from GNU,
8349      the primary system is referred to as the "HOST" and the secondary, or
8350      different, system is referred to as the "TARGET". Thus, the binaries
8351      run on the "HOST" system and generate binaries for the "TARGET"
8352      system. The :term:`STAGING_DIR_HOST` variable points to the sysroot used
8353      for the "HOST" system, while :term:`STAGING_DIR_TARGET` points to the
8354      sysroot used for the "TARGET" system.
8355
8356   :term:`STAGING_ETCDIR_NATIVE`
8357      Specifies the path to the ``/etc`` subdirectory of the sysroot
8358      directory for the build host.
8359
8360   :term:`STAGING_EXECPREFIXDIR`
8361      Specifies the path to the ``/usr`` subdirectory of the sysroot
8362      directory for the target for which the current recipe is being built
8363      (:term:`STAGING_DIR_HOST`).
8364
8365   :term:`STAGING_INCDIR`
8366      Specifies the path to the ``/usr/include`` subdirectory of the
8367      sysroot directory for the target for which the current recipe being
8368      built (:term:`STAGING_DIR_HOST`).
8369
8370   :term:`STAGING_INCDIR_NATIVE`
8371      Specifies the path to the ``/usr/include`` subdirectory of the
8372      sysroot directory for the build host.
8373
8374   :term:`STAGING_KERNEL_BUILDDIR`
8375      Points to the directory containing the kernel build artifacts.
8376      Recipes building software that needs to access kernel build artifacts
8377      (e.g. ``systemtap-uprobes``) can look in the directory specified with
8378      the :term:`STAGING_KERNEL_BUILDDIR` variable to find these artifacts
8379      after the kernel has been built.
8380
8381   :term:`STAGING_KERNEL_DIR`
8382      The directory with kernel headers that are required to build
8383      out-of-tree modules.
8384
8385   :term:`STAGING_LIBDIR`
8386      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
8387      directory for the target for which the current recipe is being built
8388      (:term:`STAGING_DIR_HOST`).
8389
8390   :term:`STAGING_LIBDIR_NATIVE`
8391      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
8392      directory for the build host.
8393
8394   :term:`STAMP`
8395      Specifies the base path used to create recipe stamp files. The path
8396      to an actual stamp file is constructed by evaluating this string and
8397      then appending additional information. Currently, the default
8398      assignment for :term:`STAMP` as set in the ``meta/conf/bitbake.conf``
8399      file is::
8400
8401         STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
8402
8403      For information on how BitBake uses stamp files to determine if a
8404      task should be rerun, see the
8405      ":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`"
8406      section in the Yocto Project Overview and Concepts Manual.
8407
8408      See :term:`STAMPS_DIR`,
8409      :term:`MULTIMACH_TARGET_SYS`,
8410      :term:`PN`, :term:`EXTENDPE`,
8411      :term:`PV`, and :term:`PR` for related variable
8412      information.
8413
8414   :term:`STAMPCLEAN`
8415      See :term:`bitbake:STAMPCLEAN` in the BitBake manual.
8416
8417   :term:`STAMPS_DIR`
8418      Specifies the base directory in which the OpenEmbedded build system
8419      places stamps. The default directory is ``${TMPDIR}/stamps``.
8420
8421   :term:`STRIP`
8422      The minimal command and arguments to run ``strip``, which is used to
8423      strip symbols.
8424
8425   :term:`SUMMARY`
8426      The short (72 characters or less) summary of the binary package for
8427      packaging systems such as ``opkg``, ``rpm``, or ``dpkg``. By default,
8428      :term:`SUMMARY` is used to define the
8429      :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
8430      not set in the recipe.
8431
8432   :term:`SVNDIR`
8433      The directory in which files checked out of a Subversion system are
8434      stored.
8435
8436   :term:`SYSLINUX_DEFAULT_CONSOLE`
8437      Specifies the kernel boot default console. If you want to use a
8438      console other than the default, set this variable in your recipe as
8439      follows where "X" is the console number you want to use::
8440
8441         SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
8442
8443      The :ref:`ref-classes-syslinux` class initially sets
8444      this variable to null but then checks for a value later.
8445
8446   :term:`SYSLINUX_OPTS`
8447      Lists additional options to add to the syslinux file. You need to set
8448      this variable in your recipe. If you want to list multiple options,
8449      separate the options with a semicolon character (``;``).
8450
8451      The :ref:`ref-classes-syslinux` class uses this variable
8452      to create a set of options.
8453
8454   :term:`SYSLINUX_SERIAL`
8455      Specifies the alternate serial port or turns it off. To turn off
8456      serial, set this variable to an empty string in your recipe. The
8457      variable's default value is set in the
8458      :ref:`ref-classes-syslinux` class as follows::
8459
8460         SYSLINUX_SERIAL ?= "0 115200"
8461
8462      The class checks for and uses the variable as needed.
8463
8464   :term:`SYSLINUX_SERIAL_TTY`
8465      Specifies the alternate console=tty... kernel boot argument. The
8466      variable's default value is set in the :ref:`ref-classes-syslinux`
8467      class as follows::
8468
8469         SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
8470
8471      The class checks for and uses the variable as needed.
8472
8473   :term:`SYSLINUX_SPLASH`
8474      An ``.LSS`` file used as the background for the VGA boot menu when
8475      you use the boot menu. You need to set this variable in your recipe.
8476
8477      The :ref:`ref-classes-syslinux` class checks for this
8478      variable and if found, the OpenEmbedded build system installs the
8479      splash screen.
8480
8481   :term:`SYSROOT_DESTDIR`
8482      Points to the temporary directory under the work directory (default
8483      "``${``\ :term:`WORKDIR`\ ``}/sysroot-destdir``")
8484      where the files populated into the sysroot are assembled during the
8485      :ref:`ref-tasks-populate_sysroot` task.
8486
8487   :term:`SYSROOT_DIRS`
8488      Directories that are staged into the sysroot by the
8489      :ref:`ref-tasks-populate_sysroot` task. By
8490      default, the following directories are staged::
8491
8492         SYSROOT_DIRS = " \
8493             ${includedir} \
8494             ${libdir} \
8495             ${base_libdir} \
8496             ${nonarch_base_libdir} \
8497             ${datadir} \
8498             /sysroot-only \
8499             "
8500
8501   :term:`SYSROOT_DIRS_IGNORE`
8502      Directories that are not staged into the sysroot by the
8503      :ref:`ref-tasks-populate_sysroot` task. You
8504      can use this variable to exclude certain subdirectories of
8505      directories listed in :term:`SYSROOT_DIRS` from
8506      staging. By default, the following directories are not staged::
8507
8508         SYSROOT_DIRS_IGNORE = " \
8509             ${mandir} \
8510             ${docdir} \
8511             ${infodir} \
8512             ${datadir}/X11/locale \
8513             ${datadir}/applications \
8514             ${datadir}/bash-completion \
8515             ${datadir}/fonts \
8516             ${datadir}/gtk-doc/html \
8517             ${datadir}/installed-tests \
8518             ${datadir}/locale \
8519             ${datadir}/pixmaps \
8520             ${datadir}/terminfo \
8521             ${libdir}/${BPN}/ptest \
8522             "
8523
8524      Consider the following example in which you need to manipulate this variable.
8525      Assume you have a recipe ``A`` that provides a shared library ``.so.*`` that is
8526      installed into a custom folder other than "``${libdir}``"
8527      or "``${base_libdir}``", let's say "``/opt/lib``".
8528
8529      .. note::
8530
8531         This is not a recommended way to deal with shared libraries, but this
8532         is just to show the usefulness of setting :term:`SYSROOT_DIRS`.
8533
8534      When a recipe ``B`` :term:`DEPENDS` on ``A``, it means what is in
8535      :term:`SYSROOT_DIRS` will be copied from :term:`D` of the recipe ``B``
8536      into ``B``'s :term:`SYSROOT_DESTDIR` that is "``${WORKDIR}/sysroot-destdir``".
8537
8538      Now, since ``/opt/lib`` is not in :term:`SYSROOT_DIRS`, it will never be copied to
8539      ``A``'s :term:`RECIPE_SYSROOT`, which is "``${WORKDIR}/recipe-sysroot``". So,
8540      the linking process will fail.
8541
8542      To fix this, you need to add ``/opt/lib`` to :term:`SYSROOT_DIRS`::
8543
8544         SYSROOT_DIRS:append = " /opt/lib"
8545
8546      .. note::
8547         Even after setting ``/opt/lib`` to :term:`SYSROOT_DIRS`, the linking process will still fail
8548         because the linker does not know that location, since :term:`TARGET_LDFLAGS`
8549         doesn't contain it (if your recipe is for the target). Therefore, so you should add::
8550
8551            TARGET_LDFLAGS:append = " -L${RECIPE_SYSROOT}/opt/lib"
8552
8553   :term:`SYSROOT_DIRS_NATIVE`
8554      Extra directories staged into the sysroot by the
8555      :ref:`ref-tasks-populate_sysroot` task for
8556      ``-native`` recipes, in addition to those specified in
8557      :term:`SYSROOT_DIRS`. By default, the following
8558      extra directories are staged::
8559
8560         SYSROOT_DIRS_NATIVE = " \
8561             ${bindir} \
8562             ${sbindir} \
8563             ${base_bindir} \
8564             ${base_sbindir} \
8565             ${libexecdir} \
8566             ${sysconfdir} \
8567             ${localstatedir} \
8568             "
8569
8570      .. note::
8571
8572         Programs built by ``-native`` recipes run directly from the sysroot
8573         (:term:`STAGING_DIR_NATIVE`), which is why additional directories
8574         containing program executables and supporting files need to be staged.
8575
8576   :term:`SYSROOT_PREPROCESS_FUNCS`
8577      A list of functions to execute after files are staged into the
8578      sysroot. These functions are usually used to apply additional
8579      processing on the staged files, or to stage additional files.
8580
8581   :term:`SYSTEMD_AUTO_ENABLE`
8582      When inheriting the :ref:`ref-classes-systemd` class,
8583      this variable specifies whether the specified service in
8584      :term:`SYSTEMD_SERVICE` should start
8585      automatically or not. By default, the service is enabled to
8586      automatically start at boot time. The default setting is in the
8587      :ref:`ref-classes-systemd` class as follows::
8588
8589         SYSTEMD_AUTO_ENABLE ??= "enable"
8590
8591      You can disable the service by setting the variable to "disable".
8592
8593   :term:`SYSTEMD_BOOT_CFG`
8594      When :term:`EFI_PROVIDER` is set to
8595      "systemd-boot", the :term:`SYSTEMD_BOOT_CFG` variable specifies the
8596      configuration file that should be used. By default, the
8597      :ref:`ref-classes-systemd-boot` class sets the
8598      :term:`SYSTEMD_BOOT_CFG` as follows::
8599
8600         SYSTEMD_BOOT_CFG ?= "${S}/loader.conf"
8601
8602      For information on Systemd-boot, see the `Systemd-boot
8603      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8604
8605   :term:`SYSTEMD_BOOT_ENTRIES`
8606      When :term:`EFI_PROVIDER` is set to
8607      "systemd-boot", the :term:`SYSTEMD_BOOT_ENTRIES` variable specifies a
8608      list of entry files (``*.conf``) to install that contain one boot
8609      entry per file. By default, the :ref:`ref-classes-systemd-boot` class
8610      sets the :term:`SYSTEMD_BOOT_ENTRIES` as follows::
8611
8612          SYSTEMD_BOOT_ENTRIES ?= ""
8613
8614      For information on Systemd-boot, see the `Systemd-boot
8615      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8616
8617   :term:`SYSTEMD_BOOT_TIMEOUT`
8618      When :term:`EFI_PROVIDER` is set to
8619      "systemd-boot", the :term:`SYSTEMD_BOOT_TIMEOUT` variable specifies the
8620      boot menu timeout in seconds. By default, the
8621      :ref:`ref-classes-systemd-boot` class sets the
8622      :term:`SYSTEMD_BOOT_TIMEOUT` as follows::
8623
8624         SYSTEMD_BOOT_TIMEOUT ?= "10"
8625
8626      For information on Systemd-boot, see the `Systemd-boot
8627      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8628
8629   :term:`SYSTEMD_DEFAULT_TARGET`
8630
8631      This variable allows to set the default unit that systemd starts at bootup.
8632      Usually, this is either ``multi-user.target`` or ``graphical.target``.
8633      This works by creating a ``default.target`` symbolic link to the chosen systemd
8634      target file.
8635
8636      See `systemd's documentation
8637      <https://www.freedesktop.org/software/systemd/man/systemd.special.html>`__
8638      for details.
8639
8640      For example, this variable is used in the :oe_git:`core-image-minimal-xfce.bb
8641      </meta-openembedded/tree/meta-xfce/recipes-core/images/core-image-minimal-xfce.bb>`
8642      recipe::
8643
8644          SYSTEMD_DEFAULT_TARGET = "graphical.target"
8645
8646   :term:`SYSTEMD_PACKAGES`
8647      When inheriting the :ref:`ref-classes-systemd` class,
8648      this variable locates the systemd unit files when they are not found
8649      in the main recipe's package. By default, the :term:`SYSTEMD_PACKAGES`
8650      variable is set such that the systemd unit files are assumed to
8651      reside in the recipes main package::
8652
8653         SYSTEMD_PACKAGES ?= "${PN}"
8654
8655      If these unit files are not in this recipe's main package, you need
8656      to use :term:`SYSTEMD_PACKAGES` to list the package or packages in which
8657      the build system can find the systemd unit files.
8658
8659   :term:`SYSTEMD_SERVICE`
8660      When inheriting the :ref:`ref-classes-systemd` class,
8661      this variable specifies the systemd service name for a package.
8662
8663      Multiple services can be specified, each one separated by a space.
8664
8665      When you specify this file in your recipe, use a package name
8666      override to indicate the package to which the value applies. Here is
8667      an example from the connman recipe::
8668
8669         SYSTEMD_SERVICE:${PN} = "connman.service"
8670
8671      The package overrides that can be specified are directly related to the value of
8672      :term:`SYSTEMD_PACKAGES`. Overrides not included in :term:`SYSTEMD_PACKAGES`
8673      will be silently ignored.
8674
8675   :term:`SYSVINIT_ENABLED_GETTYS`
8676      When using :ref:`SysVinit <dev-manual/new-recipe:enabling system services>`,
8677      specifies a space-separated list of the virtual terminals that should
8678      run a :wikipedia:`getty <Getty_(Unix)>` (allowing login), assuming
8679      :term:`USE_VT` is not set to "0".
8680
8681      The default value for :term:`SYSVINIT_ENABLED_GETTYS` is "1" (i.e. only
8682      run a getty on the first virtual terminal).
8683
8684   :term:`T`
8685      This variable points to a directory were BitBake places temporary
8686      files, which consist mostly of task logs and scripts, when building a
8687      particular recipe. The variable is typically set as follows::
8688
8689         T = "${WORKDIR}/temp"
8690
8691      The :term:`WORKDIR` is the directory into which
8692      BitBake unpacks and builds the recipe. The default ``bitbake.conf``
8693      file sets this variable.
8694
8695      The :term:`T` variable is not to be confused with the
8696      :term:`TMPDIR` variable, which points to the root of
8697      the directory tree where BitBake places the output of an entire
8698      build.
8699
8700   :term:`TARGET_ARCH`
8701      The target machine's architecture. The OpenEmbedded build system
8702      supports many architectures. Here is an example list of architectures
8703      supported. This list is by no means complete as the architecture is
8704      configurable:
8705
8706      - arm
8707      - i586
8708      - x86_64
8709      - powerpc
8710      - powerpc64
8711      - mips
8712      - mipsel
8713
8714      For additional information on machine architectures, see the
8715      :term:`TUNE_ARCH` variable.
8716
8717   :term:`TARGET_AS_ARCH`
8718      Specifies architecture-specific assembler flags for the target
8719      system. :term:`TARGET_AS_ARCH` is initialized from
8720      :term:`TUNE_ASARGS` by default in the BitBake
8721      configuration file (``meta/conf/bitbake.conf``)::
8722
8723         TARGET_AS_ARCH = "${TUNE_ASARGS}"
8724
8725   :term:`TARGET_CC_ARCH`
8726      Specifies architecture-specific C compiler flags for the target
8727      system. :term:`TARGET_CC_ARCH` is initialized from
8728      :term:`TUNE_CCARGS` by default.
8729
8730      .. note::
8731
8732         It is a common workaround to append :term:`LDFLAGS` to
8733         :term:`TARGET_CC_ARCH` in recipes that build software for the target that
8734         would not otherwise respect the exported :term:`LDFLAGS` variable.
8735
8736   :term:`TARGET_CC_KERNEL_ARCH`
8737      This is a specific kernel compiler flag for a CPU or Application
8738      Binary Interface (ABI) tune. The flag is used rarely and only for
8739      cases where a userspace :term:`TUNE_CCARGS` is not
8740      compatible with the kernel compilation. The :term:`TARGET_CC_KERNEL_ARCH`
8741      variable allows the kernel (and associated modules) to use a
8742      different configuration. See the
8743      ``meta/conf/machine/include/arm/feature-arm-thumb.inc`` file in the
8744      :term:`Source Directory` for an example.
8745
8746   :term:`TARGET_CFLAGS`
8747      Specifies the flags to pass to the C compiler when building for the
8748      target. When building in the target context,
8749      :term:`CFLAGS` is set to the value of this variable by
8750      default.
8751
8752      Additionally, the SDK's environment setup script sets the :term:`CFLAGS`
8753      variable in the environment to the :term:`TARGET_CFLAGS` value so that
8754      executables built using the SDK also have the flags applied.
8755
8756   :term:`TARGET_CPPFLAGS`
8757      Specifies the flags to pass to the C pre-processor (i.e. to both the
8758      C and the C++ compilers) when building for the target. When building
8759      in the target context, :term:`CPPFLAGS` is set to the
8760      value of this variable by default.
8761
8762      Additionally, the SDK's environment setup script sets the
8763      :term:`CPPFLAGS` variable in the environment to the :term:`TARGET_CPPFLAGS`
8764      value so that executables built using the SDK also have the flags
8765      applied.
8766
8767   :term:`TARGET_CXXFLAGS`
8768      Specifies the flags to pass to the C++ compiler when building for the
8769      target. When building in the target context,
8770      :term:`CXXFLAGS` is set to the value of this variable
8771      by default.
8772
8773      Additionally, the SDK's environment setup script sets the
8774      :term:`CXXFLAGS` variable in the environment to the :term:`TARGET_CXXFLAGS`
8775      value so that executables built using the SDK also have the flags
8776      applied.
8777
8778   :term:`TARGET_FPU`
8779      Specifies the method for handling FPU code. For FPU-less targets,
8780      which include most ARM CPUs, the variable must be set to "soft". If
8781      not, the kernel emulation gets used, which results in a performance
8782      penalty.
8783
8784   :term:`TARGET_LD_ARCH`
8785      Specifies architecture-specific linker flags for the target system.
8786      :term:`TARGET_LD_ARCH` is initialized from
8787      :term:`TUNE_LDARGS` by default in the BitBake
8788      configuration file (``meta/conf/bitbake.conf``)::
8789
8790         TARGET_LD_ARCH = "${TUNE_LDARGS}"
8791
8792   :term:`TARGET_LDFLAGS`
8793      Specifies the flags to pass to the linker when building for the
8794      target. When building in the target context,
8795      :term:`LDFLAGS` is set to the value of this variable
8796      by default.
8797
8798      Additionally, the SDK's environment setup script sets the
8799      :term:`LDFLAGS` variable in the environment to the
8800      :term:`TARGET_LDFLAGS` value so that executables built using the SDK also
8801      have the flags applied.
8802
8803   :term:`TARGET_OS`
8804      Specifies the target's operating system. The variable can be set to
8805      "linux" for glibc-based systems (GNU C Library) and to "linux-musl"
8806      for musl libc. For ARM/EABI targets, the possible values are
8807      "linux-gnueabi" and "linux-musleabi".
8808
8809   :term:`TARGET_PREFIX`
8810      Specifies the prefix used for the toolchain binary target tools.
8811
8812      Depending on the type of recipe and the build target,
8813      :term:`TARGET_PREFIX` is set as follows:
8814
8815      -  For recipes building for the target machine, the value is
8816         "${:term:`TARGET_SYS`}-".
8817
8818      -  For native recipes, the build system sets the variable to the
8819         value of :term:`BUILD_PREFIX`.
8820
8821      -  For native SDK recipes (:ref:`ref-classes-nativesdk`),
8822         the build system sets the variable to the value of :term:`SDK_PREFIX`.
8823
8824   :term:`TARGET_SYS`
8825      Specifies the system, including the architecture and the operating
8826      system, for which the build is occurring in the context of the
8827      current recipe.
8828
8829      The OpenEmbedded build system automatically sets this variable based
8830      on :term:`TARGET_ARCH`,
8831      :term:`TARGET_VENDOR`, and
8832      :term:`TARGET_OS` variables.
8833
8834      .. note::
8835
8836         You do not need to set the :term:`TARGET_SYS` variable yourself.
8837
8838      Consider these two examples:
8839
8840      -  Given a native recipe on a 32-bit, x86 machine running Linux, the
8841         value is "i686-linux".
8842
8843      -  Given a recipe being built for a little-endian, MIPS target
8844         running Linux, the value might be "mipsel-linux".
8845
8846   :term:`TARGET_VENDOR`
8847      Specifies the name of the target vendor.
8848
8849   :term:`TCLIBC`
8850      Specifies the GNU standard C library (``libc``) variant to use during
8851      the build process.
8852
8853      You can select "glibc", "musl", "newlib", or "baremetal".
8854
8855   :term:`TCLIBCAPPEND`
8856      Specifies a suffix to be appended onto the :term:`TMPDIR` value. The
8857      suffix identifies the ``libc`` variant for building. When you are
8858      building for multiple variants with the same :term:`Build Directory`,
8859      this mechanism ensures that output for different ``libc`` variants is
8860      kept separate to avoid potential conflicts.
8861
8862      In the ``defaultsetup.conf`` file, the default value of
8863      :term:`TCLIBCAPPEND` is "-${TCLIBC}". However, distros such as poky,
8864      which normally only support one ``libc`` variant, set
8865      :term:`TCLIBCAPPEND` to "" in their distro configuration file resulting
8866      in no suffix being applied.
8867
8868   :term:`TCMODE`
8869      Specifies the toolchain selector. :term:`TCMODE` controls the
8870      characteristics of the generated packages and images by telling the
8871      OpenEmbedded build system which toolchain profile to use. By default,
8872      the OpenEmbedded build system builds its own internal toolchain. The
8873      variable's default value is "default", which uses that internal
8874      toolchain.
8875
8876      .. note::
8877
8878         If :term:`TCMODE` is set to a value other than "default", then it is your
8879         responsibility to ensure that the toolchain is compatible with the
8880         default toolchain. Using older or newer versions of these
8881         components might cause build problems. See
8882         :doc:`Release Information </migration-guides/index>` for your
8883         version of the Yocto Project, to find the specific components with
8884         which the toolchain must be compatible.
8885
8886      The :term:`TCMODE` variable is similar to :term:`TCLIBC`,
8887      which controls the variant of the GNU standard C library (``libc``)
8888      used during the build process: ``glibc`` or ``musl``.
8889
8890      With additional layers, it is possible to use a pre-compiled external
8891      toolchain. One example is the Sourcery G++ Toolchain. The support for
8892      this toolchain resides in the separate Mentor Graphics
8893      ``meta-sourcery`` layer at
8894      https://github.com/MentorEmbedded/meta-sourcery/.
8895
8896      The layer's ``README`` file contains information on how to use the
8897      Sourcery G++ Toolchain as an external toolchain. You will have to
8898      add the layer to your ``bblayers.conf`` file and then set the
8899      :term:`EXTERNAL_TOOLCHAIN` variable in your ``local.conf`` file to
8900      the location of the toolchain.
8901
8902      The fundamentals used for this example apply to any external
8903      toolchain. You can use ``meta-sourcery`` as a template for adding
8904      support for other external toolchains.
8905
8906      In addition to toolchain configuration, you will also need a
8907      corresponding toolchain recipe file. This recipe file needs to package
8908      up any pre-built objects in the toolchain such as ``libgcc``,
8909      ``libstdcc++``, any locales, and ``libc``.
8910
8911   :term:`TC_CXX_RUNTIME`
8912      Specifies the C/C++ STL and runtime variant to use during
8913      the build process. Default value is 'gnu'
8914
8915      You can select "gnu", "llvm", or "android".
8916
8917   :term:`TEMPLATECONF`
8918      Specifies the directory used by the build system to find templates
8919      from which to build the ``bblayers.conf`` and ``local.conf`` files.
8920      Use this variable if you wish to customize such files, and the default
8921      BitBake targets shown when sourcing the ``oe-init-build-env`` script.
8922
8923      For details, see the
8924      :ref:`dev-manual/custom-template-configuration-directory:creating a custom template configuration directory`
8925      section in the Yocto Project Development Tasks manual.
8926
8927      .. note::
8928
8929         You must set this variable in the external environment in order
8930         for it to work.
8931
8932   :term:`TEST_EXPORT_DIR`
8933      The location the OpenEmbedded build system uses to export tests when
8934      the :term:`TEST_EXPORT_ONLY` variable is set
8935      to "1".
8936
8937      The :term:`TEST_EXPORT_DIR` variable defaults to
8938      ``"${TMPDIR}/testimage/${PN}"``.
8939
8940   :term:`TEST_EXPORT_ONLY`
8941      Specifies to export the tests only. Set this variable to "1" if you
8942      do not want to run the tests but you want them to be exported in a
8943      manner that you to run them outside of the build system.
8944
8945   :term:`TEST_LOG_DIR`
8946      Holds the SSH log and the boot log for QEMU machines. The
8947      :term:`TEST_LOG_DIR` variable defaults to ``"${WORKDIR}/testimage"``.
8948
8949      .. note::
8950
8951         Actual test results reside in the task log (``log.do_testimage``),
8952         which is in the ``${WORKDIR}/temp/`` directory.
8953
8954   :term:`TEST_POWERCONTROL_CMD`
8955      For automated hardware testing, specifies the command to use to
8956      control the power of the target machine under test. Typically, this
8957      command would point to a script that performs the appropriate action
8958      (e.g. interacting with a web-enabled power strip). The specified
8959      command should expect to receive as the last argument "off", "on" or
8960      "cycle" specifying to power off, on, or cycle (power off and then
8961      power on) the device, respectively.
8962
8963   :term:`TEST_POWERCONTROL_EXTRA_ARGS`
8964      For automated hardware testing, specifies additional arguments to
8965      pass through to the command specified in
8966      :term:`TEST_POWERCONTROL_CMD`. Setting
8967      :term:`TEST_POWERCONTROL_EXTRA_ARGS` is optional. You can use it if you
8968      wish, for example, to separate the machine-specific and
8969      non-machine-specific parts of the arguments.
8970
8971   :term:`TEST_QEMUBOOT_TIMEOUT`
8972      The time in seconds allowed for an image to boot before automated
8973      runtime tests begin to run against an image. The default timeout
8974      period to allow the boot process to reach the login prompt is 500
8975      seconds. You can specify a different value in the ``local.conf``
8976      file.
8977
8978      For more information on testing images, see the
8979      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8980      section in the Yocto Project Development Tasks Manual.
8981
8982   :term:`TEST_SERIALCONTROL_CMD`
8983      For automated hardware testing, specifies the command to use to
8984      connect to the serial console of the target machine under test. This
8985      command simply needs to connect to the serial console and forward
8986      that connection to standard input and output as any normal terminal
8987      program does.
8988
8989      For example, to use the Picocom terminal program on serial device
8990      ``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows::
8991
8992         TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
8993
8994   :term:`TEST_SERIALCONTROL_EXTRA_ARGS`
8995      For automated hardware testing, specifies additional arguments to
8996      pass through to the command specified in
8997      :term:`TEST_SERIALCONTROL_CMD`. Setting
8998      :term:`TEST_SERIALCONTROL_EXTRA_ARGS` is optional. You can use it if you
8999      wish, for example, to separate the machine-specific and
9000      non-machine-specific parts of the command.
9001
9002   :term:`TEST_SERVER_IP`
9003      The IP address of the build machine (host machine). This IP address
9004      is usually automatically detected. However, if detection fails, this
9005      variable needs to be set to the IP address of the build machine (i.e.
9006      where the build is taking place).
9007
9008      .. note::
9009
9010         The :term:`TEST_SERVER_IP` variable is only used for a small number of
9011         tests such as the "dnf" test suite, which needs to download packages
9012         from ``WORKDIR/oe-rootfs-repo``.
9013
9014   :term:`TEST_SUITES`
9015      An ordered list of tests (modules) to run against an image when
9016      performing automated runtime testing.
9017
9018      The OpenEmbedded build system provides a core set of tests that can
9019      be used against images.
9020
9021      .. note::
9022
9023         Currently, there is only support for running these tests under
9024         QEMU.
9025
9026      Tests include ``ping``, ``ssh``, ``df`` among others. You can add
9027      your own tests to the list of tests by appending :term:`TEST_SUITES` as
9028      follows::
9029
9030         TEST_SUITES:append = " mytest"
9031
9032      Alternatively, you can
9033      provide the "auto" option to have all applicable tests run against
9034      the image::
9035
9036         TEST_SUITES:append = " auto"
9037
9038      Using this option causes the
9039      build system to automatically run tests that are applicable to the
9040      image. Tests that are not applicable are skipped.
9041
9042      The order in which tests are run is important. Tests that depend on
9043      another test must appear later in the list than the test on which
9044      they depend. For example, if you append the list of tests with two
9045      tests (``test_A`` and ``test_B``) where ``test_B`` is dependent on
9046      ``test_A``, then you must order the tests as follows::
9047
9048         TEST_SUITES = "test_A test_B"
9049
9050      For more information on testing images, see the
9051      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
9052      section in the Yocto Project Development Tasks Manual.
9053
9054   :term:`TEST_TARGET`
9055      Specifies the target controller to use when running tests against a
9056      test image. The default controller to use is "qemu"::
9057
9058         TEST_TARGET = "qemu"
9059
9060      A target controller is a class that defines how an image gets
9061      deployed on a target and how a target is started. A layer can extend
9062      the controllers by adding a module in the layer's
9063      ``/lib/oeqa/controllers`` directory and by inheriting the
9064      ``BaseTarget`` class, which is an abstract class that cannot be used
9065      as a value of :term:`TEST_TARGET`.
9066
9067      You can provide the following arguments with :term:`TEST_TARGET`:
9068
9069      -  *"qemu":* Boots a QEMU image and runs the tests. See the
9070         ":ref:`dev-manual/runtime-testing:enabling runtime tests on qemu`" section
9071         in the Yocto Project Development Tasks Manual for more
9072         information.
9073
9074      -  *"simpleremote":* Runs the tests on target hardware that is
9075         already up and running. The hardware can be on the network or it
9076         can be a device running an image on QEMU. You must also set
9077         :term:`TEST_TARGET_IP` when you use
9078         "simpleremote".
9079
9080         .. note::
9081
9082            This argument is defined in
9083            ``meta/lib/oeqa/controllers/simpleremote.py``.
9084
9085      For information on running tests on hardware, see the
9086      ":ref:`dev-manual/runtime-testing:enabling runtime tests on hardware`"
9087      section in the Yocto Project Development Tasks Manual.
9088
9089   :term:`TEST_TARGET_IP`
9090      The IP address of your hardware under test. The :term:`TEST_TARGET_IP`
9091      variable has no effect when :term:`TEST_TARGET` is
9092      set to "qemu".
9093
9094      When you specify the IP address, you can also include a port. Here is
9095      an example::
9096
9097         TEST_TARGET_IP = "192.168.1.4:2201"
9098
9099      Specifying a port is
9100      useful when SSH is started on a non-standard port or in cases when
9101      your hardware under test is behind a firewall or network that is not
9102      directly accessible from your host and you need to do port address
9103      translation.
9104
9105   :term:`TESTIMAGE_AUTO`
9106      Automatically runs the series of automated tests for images when an
9107      image is successfully built. Setting :term:`TESTIMAGE_AUTO` to "1" causes
9108      any image that successfully builds to automatically boot under QEMU.
9109      Using the variable also adds in dependencies so that any SDK for
9110      which testing is requested is automatically built first.
9111
9112      These tests are written in Python making use of the ``unittest``
9113      module, and the majority of them run commands on the target system
9114      over ``ssh``. You can set this variable to "1" in your ``local.conf``
9115      file in the :term:`Build Directory` to have the
9116      OpenEmbedded build system automatically run these tests after an
9117      image successfully builds:
9118
9119         TESTIMAGE_AUTO = "1"
9120
9121      For more information
9122      on enabling, running, and writing these tests, see the
9123      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
9124      section in the Yocto Project Development Tasks Manual and the
9125      ":ref:`ref-classes-testimage`" section.
9126
9127   :term:`THISDIR`
9128      The directory in which the file BitBake is currently parsing is
9129      located. Do not manually set this variable.
9130
9131   :term:`TIME`
9132      The time the build was started. Times appear using the hour, minute,
9133      and second (HMS) format (e.g. "140159" for one minute and fifty-nine
9134      seconds past 1400 hours).
9135
9136   :term:`TMPDIR`
9137      This variable is the base directory the OpenEmbedded build system
9138      uses for all build output and intermediate files (other than the
9139      shared state cache). By default, the :term:`TMPDIR` variable points to
9140      ``tmp`` within the :term:`Build Directory`.
9141
9142      If you want to establish this directory in a location other than the
9143      default, you can uncomment and edit the following statement in the
9144      ``conf/local.conf`` file in the :term:`Source Directory`::
9145
9146         #TMPDIR = "${TOPDIR}/tmp"
9147
9148      An example use for this scenario is to set :term:`TMPDIR` to a local disk,
9149      which does not use NFS, while having the :term:`Build Directory` use NFS.
9150
9151      The filesystem used by :term:`TMPDIR` must have standard filesystem
9152      semantics (i.e. mixed-case files are unique, POSIX file locking, and
9153      persistent inodes). Due to various issues with NFS and bugs in some
9154      implementations, NFS does not meet this minimum requirement.
9155      Consequently, :term:`TMPDIR` cannot be on NFS.
9156
9157   :term:`TOOLCHAIN_HOST_TASK`
9158      This variable lists packages the OpenEmbedded build system uses when
9159      building an SDK, which contains a cross-development environment. The
9160      packages specified by this variable are part of the toolchain set
9161      that runs on the :term:`SDKMACHINE`, and each
9162      package should usually have the prefix ``nativesdk-``. For example,
9163      consider the following command when building an SDK::
9164
9165         $ bitbake -c populate_sdk imagename
9166
9167      In this case, a default list of packages is
9168      set in this variable, but you can add additional packages to the
9169      list. See the
9170      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
9171      in the Yocto Project Application Development and the Extensible
9172      Software Development Kit (eSDK) manual for more information.
9173
9174      For background information on cross-development toolchains in the
9175      Yocto Project development environment, see the
9176      ":ref:`sdk-manual/intro:the cross-development toolchain`"
9177      section in the Yocto Project Overview and Concepts Manual. For
9178      information on setting up a cross-development environment, see the
9179      :doc:`/sdk-manual/index` manual.
9180
9181      Note that this variable applies to building an SDK, not an eSDK,
9182      in which case the :term:`TOOLCHAIN_HOST_TASK_ESDK` setting should be
9183      used instead.
9184
9185   :term:`TOOLCHAIN_HOST_TASK_ESDK`
9186      This variable allows to extend what is installed in the host
9187      portion of an eSDK. This is similar to :term:`TOOLCHAIN_HOST_TASK`
9188      applying to SDKs.
9189
9190   :term:`TOOLCHAIN_OPTIONS`
9191      This variable holds extra options passed to the compiler and the linker
9192      for non ``-native`` recipes as they have to point to their custom
9193      ``sysroot`` folder pointed to by :term:`RECIPE_SYSROOT`::
9194
9195         TOOLCHAIN_OPTIONS = " --sysroot=${RECIPE_SYSROOT}"
9196
9197      Native recipes don't need this variable to be set, as they are
9198      built for the host machine with the native compiler.
9199
9200   :term:`TOOLCHAIN_OUTPUTNAME`
9201      This variable defines the name used for the toolchain output. The
9202      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class sets
9203      the :term:`TOOLCHAIN_OUTPUTNAME` variable as follows::
9204
9205         TOOLCHAIN_OUTPUTNAME ?= "${SDK_NAME}-toolchain-${SDK_VERSION}"
9206
9207      See
9208      the :term:`SDK_NAME` and
9209      :term:`SDK_VERSION` variables for additional
9210      information.
9211
9212   :term:`TOOLCHAIN_TARGET_TASK`
9213      This variable lists packages the OpenEmbedded build system uses when
9214      it creates the target part of an SDK (i.e. the part built for the
9215      target hardware), which includes libraries and headers. Use this
9216      variable to add individual packages to the part of the SDK that runs
9217      on the target. See the
9218      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
9219      in the Yocto Project Application Development and the Extensible
9220      Software Development Kit (eSDK) manual for more information.
9221
9222      For background information on cross-development toolchains in the
9223      Yocto Project development environment, see the
9224      ":ref:`sdk-manual/intro:the cross-development toolchain`"
9225      section in the Yocto Project Overview and Concepts Manual. For
9226      information on setting up a cross-development environment, see the
9227      :doc:`/sdk-manual/index` manual.
9228
9229   :term:`TOPDIR`
9230      See :term:`bitbake:TOPDIR` in the BitBake manual.
9231
9232   :term:`TRANSLATED_TARGET_ARCH`
9233      A sanitized version of :term:`TARGET_ARCH`. This
9234      variable is used where the architecture is needed in a value where
9235      underscores are not allowed, for example within package filenames. In
9236      this case, dash characters replace any underscore characters used in
9237      :term:`TARGET_ARCH`.
9238
9239      Do not edit this variable.
9240
9241   :term:`TUNE_ARCH`
9242      The GNU canonical architecture for a specific architecture (i.e.
9243      ``arm``, ``armeb``, ``mips``, ``mips64``, and so forth). BitBake uses
9244      this value to setup configuration.
9245
9246      :term:`TUNE_ARCH` definitions are specific to a given architecture. The
9247      definitions can be a single static definition, or can be dynamically
9248      adjusted. You can see details for a given CPU family by looking at
9249      the architecture's ``README`` file. For example, the
9250      ``meta/conf/machine/include/mips/README`` file in the
9251      :term:`Source Directory` provides information for
9252      :term:`TUNE_ARCH` specific to the ``mips`` architecture.
9253
9254      :term:`TUNE_ARCH` is tied closely to
9255      :term:`TARGET_ARCH`, which defines the target
9256      machine's architecture. The BitBake configuration file
9257      (``meta/conf/bitbake.conf``) sets :term:`TARGET_ARCH` as follows::
9258
9259         TARGET_ARCH = "${TUNE_ARCH}"
9260
9261      The following list, which is by no means complete since architectures
9262      are configurable, shows supported machine architectures:
9263
9264      - arm
9265      - i586
9266      - x86_64
9267      - powerpc
9268      - powerpc64
9269      - mips
9270      - mipsel
9271
9272   :term:`TUNE_ASARGS`
9273      Specifies architecture-specific assembler flags for the target
9274      system. The set of flags is based on the selected tune features.
9275      :term:`TUNE_ASARGS` is set using the tune include files, which are
9276      typically under ``meta/conf/machine/include/`` and are influenced
9277      through :term:`TUNE_FEATURES`. For example, the
9278      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
9279      for the x86 architecture as follows::
9280
9281         TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
9282
9283      .. note::
9284
9285         Board Support Packages (BSPs) select the tune. The selected tune,
9286         in turn, affects the tune variables themselves (i.e. the tune can
9287         supply its own set of flags).
9288
9289   :term:`TUNE_CCARGS`
9290      Specifies architecture-specific C compiler flags for the target
9291      system. The set of flags is based on the selected tune features.
9292      :term:`TUNE_CCARGS` is set using the tune include files, which are
9293      typically under ``meta/conf/machine/include/`` and are influenced
9294      through :term:`TUNE_FEATURES`.
9295
9296      .. note::
9297
9298         Board Support Packages (BSPs) select the tune. The selected tune,
9299         in turn, affects the tune variables themselves (i.e. the tune can
9300         supply its own set of flags).
9301
9302   :term:`TUNE_FEATURES`
9303      Features used to "tune" a compiler for optimal use given a specific
9304      processor. The features are defined within the tune files and allow
9305      arguments (i.e. ``TUNE_*ARGS``) to be dynamically generated based on
9306      the features.
9307
9308      The OpenEmbedded build system verifies the features to be sure they
9309      are not conflicting and that they are supported.
9310
9311      The BitBake configuration file (``meta/conf/bitbake.conf``) defines
9312      :term:`TUNE_FEATURES` as follows::
9313
9314         TUNE_FEATURES ??= "${TUNE_FEATURES:tune-${DEFAULTTUNE}}"
9315
9316      See the :term:`DEFAULTTUNE` variable for more information.
9317
9318   :term:`TUNE_LDARGS`
9319      Specifies architecture-specific linker flags for the target system.
9320      The set of flags is based on the selected tune features.
9321      :term:`TUNE_LDARGS` is set using the tune include files, which are
9322      typically under ``meta/conf/machine/include/`` and are influenced
9323      through :term:`TUNE_FEATURES`. For example, the
9324      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
9325      for the x86 architecture as follows::
9326
9327         TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
9328
9329      .. note::
9330
9331         Board Support Packages (BSPs) select the tune. The selected tune,
9332         in turn, affects the tune variables themselves (i.e. the tune can
9333         supply its own set of flags).
9334
9335   :term:`TUNE_PKGARCH`
9336      The package architecture understood by the packaging system to define
9337      the architecture, ABI, and tuning of output packages. The specific
9338      tune is defined using the "_tune" override as follows::
9339
9340         TUNE_PKGARCH:tune-tune = "tune"
9341
9342      These tune-specific package architectures are defined in the machine
9343      include files. Here is an example of the "core2-32" tuning as used in
9344      the ``meta/conf/machine/include/x86/tune-core2.inc`` file::
9345
9346         TUNE_PKGARCH:tune-core2-32 = "core2-32"
9347
9348   :term:`TUNECONFLICTS[feature]`
9349      Specifies CPU or Application Binary Interface (ABI) tuning features
9350      that conflict with feature.
9351
9352      Known tuning conflicts are specified in the machine include files in
9353      the :term:`Source Directory`. Here is an example from
9354      the ``meta/conf/machine/include/mips/arch-mips.inc`` include file
9355      that lists the "o32" and "n64" features as conflicting with the "n32"
9356      feature::
9357
9358         TUNECONFLICTS[n32] = "o32 n64"
9359
9360   :term:`TUNEVALID[feature]`
9361      Specifies a valid CPU or Application Binary Interface (ABI) tuning
9362      feature. The specified feature is stored as a flag. Valid features
9363      are specified in the machine include files (e.g.
9364      ``meta/conf/machine/include/arm/arch-arm.inc``). Here is an example
9365      from that file::
9366
9367         TUNEVALID[bigendian] = "Enable big-endian mode."
9368
9369      See the machine include files in the :term:`Source Directory`
9370      for these features.
9371
9372   :term:`UBOOT_BINARY`
9373      Specifies the name of the binary build by U-Boot.
9374
9375   :term:`UBOOT_CONFIG`
9376      Configures one or more U-Boot configurations to build. Each
9377      configuration can define the :term:`UBOOT_MACHINE` and optionally the
9378      :term:`IMAGE_FSTYPES` and the :term:`UBOOT_BINARY`.
9379
9380      Here is an example from the ``meta-freescale`` layer. ::
9381
9382         UBOOT_CONFIG ??= "sdcard-ifc-secure-boot sdcard-ifc sdcard-qspi lpuart qspi secure-boot nor"
9383         UBOOT_CONFIG[nor] = "ls1021atwr_nor_defconfig"
9384         UBOOT_CONFIG[sdcard-ifc] = "ls1021atwr_sdcard_ifc_defconfig,,u-boot-with-spl-pbl.bin"
9385         UBOOT_CONFIG[sdcard-qspi] = "ls1021atwr_sdcard_qspi_defconfig,,u-boot-with-spl-pbl.bin"
9386         UBOOT_CONFIG[lpuart] = "ls1021atwr_nor_lpuart_defconfig"
9387         UBOOT_CONFIG[qspi] = "ls1021atwr_qspi_defconfig"
9388         UBOOT_CONFIG[secure-boot] = "ls1021atwr_nor_SECURE_BOOT_defconfig"
9389         UBOOT_CONFIG[sdcard-ifc-secure-boot] = "ls1021atwr_sdcard_ifc_SECURE_BOOT_defconfig,,u-boot-with-spl-pbl.bin"
9390
9391      In this example, all possible seven configurations are selected. Each
9392      configuration specifies "..._defconfig" as :term:`UBOOT_MACHINE`, and
9393      the "sd..." configurations define an individual name for
9394      :term:`UBOOT_BINARY`. No configuration defines a second parameter for
9395      :term:`IMAGE_FSTYPES` to use for the U-Boot image.
9396
9397      For more information on how the :term:`UBOOT_CONFIG` is handled, see the
9398      :ref:`ref-classes-uboot-config` class.
9399
9400   :term:`UBOOT_DTB_LOADADDRESS`
9401      Specifies the load address for the dtb image used by U-Boot. During FIT
9402      image creation, the :term:`UBOOT_DTB_LOADADDRESS` variable is used in
9403      :ref:`ref-classes-kernel-fitimage` class to specify the load address to be
9404      used in creating the dtb sections of Image Tree Source for the FIT image.
9405
9406   :term:`UBOOT_DTBO_LOADADDRESS`
9407      Specifies the load address for the dtbo image used by U-Boot.  During FIT
9408      image creation, the :term:`UBOOT_DTBO_LOADADDRESS` variable is used in
9409      :ref:`ref-classes-kernel-fitimage` class to specify the load address to be
9410      used in creating the dtbo sections of Image Tree Source for the FIT image.
9411
9412   :term:`UBOOT_ENTRYPOINT`
9413      Specifies the entry point for the U-Boot image. During U-Boot image
9414      creation, the :term:`UBOOT_ENTRYPOINT` variable is passed as a
9415      command-line parameter to the ``uboot-mkimage`` utility.
9416
9417      To pass a 64 bit address for FIT image creation, you will need to set:
9418      -  The :term:`FIT_ADDRESS_CELLS` variable for FIT image creation.
9419      -  The :term:`UBOOT_FIT_ADDRESS_CELLS` variable for U-Boot FIT image creation.
9420
9421      This variable is used by the :ref:`ref-classes-kernel-fitimage`,
9422      :ref:`ref-classes-kernel-uimage`, :ref:`ref-classes-kernel`,
9423      :ref:`ref-classes-uboot-config` and :ref:`ref-classes-uboot-sign`
9424      classes.
9425
9426   :term:`UBOOT_FIT_ADDRESS_CELLS`
9427      Specifies the value of the ``#address-cells`` value for the
9428      description of the U-Boot FIT image.
9429
9430      The default value is set to "1" by the :ref:`ref-classes-uboot-sign`
9431      class, which corresponds to 32 bit addresses.
9432
9433      For platforms that need to set 64 bit addresses in
9434      :term:`UBOOT_LOADADDRESS` and :term:`UBOOT_ENTRYPOINT`, you need to
9435      set this value to "2", as two 32 bit values (cells) will be needed
9436      to represent such addresses.
9437
9438      Here is an example setting "0x400000000" as a load address::
9439
9440         UBOOT_FIT_ADDRESS_CELLS = "2"
9441         UBOOT_LOADADDRESS= "0x04 0x00000000"
9442
9443      See `more details about #address-cells <https://elinux.org/Device_Tree_Usage#How_Addressing_Works>`__.
9444
9445   :term:`UBOOT_FIT_DESC`
9446      Specifies the description string encoded into a U-Boot fitImage. The default
9447      value is set by the :ref:`ref-classes-uboot-sign` class as follows::
9448
9449         UBOOT_FIT_DESC ?= "U-Boot fitImage for ${DISTRO_NAME}/${PV}/${MACHINE}"
9450
9451   :term:`UBOOT_FIT_GENERATE_KEYS`
9452      Decides whether to generate the keys for signing the U-Boot fitImage if
9453      they don't already exist. The keys are created in :term:`SPL_SIGN_KEYDIR`.
9454      The default value is "0".
9455
9456      Enable this as follows::
9457
9458         UBOOT_FIT_GENERATE_KEYS = "1"
9459
9460      This variable is used in the :ref:`ref-classes-uboot-sign` class.
9461
9462   :term:`UBOOT_FIT_HASH_ALG`
9463      Specifies the hash algorithm used in creating the U-Boot FIT Image.
9464      It is set by default to ``sha256`` by the :ref:`ref-classes-uboot-sign`
9465      class.
9466
9467   :term:`UBOOT_FIT_KEY_GENRSA_ARGS`
9468      Arguments to ``openssl genrsa`` for generating a RSA private key for
9469      signing the U-Boot FIT image. The default value of this variable
9470      is set to "-F4" by the :ref:`ref-classes-uboot-sign` class.
9471
9472   :term:`UBOOT_FIT_KEY_REQ_ARGS`
9473      Arguments to ``openssl req`` for generating a certificate for signing
9474      the U-Boot FIT image. The default value is "-batch -new" by the
9475      :ref:`ref-classes-uboot-sign` class, "batch" for
9476      non interactive mode and "new" for generating new keys.
9477
9478   :term:`UBOOT_FIT_KEY_SIGN_PKCS`
9479      Format for the public key certificate used for signing the U-Boot FIT
9480      image. The default value is set to "x509" by the
9481      :ref:`ref-classes-uboot-sign` class.
9482
9483   :term:`UBOOT_FIT_SIGN_ALG`
9484      Specifies the signature algorithm used in creating the U-Boot FIT Image.
9485      This variable is set by default to "rsa2048" by the
9486      :ref:`ref-classes-uboot-sign` class.
9487
9488   :term:`UBOOT_FIT_SIGN_NUMBITS`
9489      Size of the private key used in signing the U-Boot FIT image, in number
9490      of bits. The default value for this variable is set to "2048"
9491      by the :ref:`ref-classes-uboot-sign` class.
9492
9493   :term:`UBOOT_FITIMAGE_ENABLE`
9494      This variable allows to generate a FIT image for U-Boot, which is one
9495      of the ways to implement a verified boot process.
9496
9497      Its default value is "0", so set it to "1" to enable this functionality::
9498
9499         UBOOT_FITIMAGE_ENABLE = "1"
9500
9501      See the :ref:`ref-classes-uboot-sign` class for details.
9502
9503   :term:`UBOOT_LOADADDRESS`
9504      Specifies the load address for the U-Boot image. During U-Boot image
9505      creation, the :term:`UBOOT_LOADADDRESS` variable is passed as a
9506      command-line parameter to the ``uboot-mkimage`` utility.
9507
9508      To pass a 64 bit address, you will also need to set:
9509
9510      -  The :term:`FIT_ADDRESS_CELLS` variable for FIT image creation.
9511      -  The :term:`UBOOT_FIT_ADDRESS_CELLS` variable for U-Boot FIT image creation.
9512
9513      This variable is used by the :ref:`ref-classes-kernel-fitimage`,
9514      :ref:`ref-classes-kernel-uimage`, :ref:`ref-classes-kernel`,
9515      :ref:`ref-classes-uboot-config` and :ref:`ref-classes-uboot-sign`
9516      classes.
9517
9518   :term:`UBOOT_LOCALVERSION`
9519      Appends a string to the name of the local version of the U-Boot
9520      image. For example, assuming the version of the U-Boot image built
9521      was "2013.10", the full version string reported by U-Boot would be
9522      "2013.10-yocto" given the following statement::
9523
9524         UBOOT_LOCALVERSION = "-yocto"
9525
9526   :term:`UBOOT_MACHINE`
9527      Specifies the value passed on the ``make`` command line when building
9528      a U-Boot image. The value indicates the target platform
9529      configuration. You typically set this variable from the machine
9530      configuration file (i.e. ``conf/machine/machine_name.conf``).
9531
9532      Please see the "Selection of Processor Architecture and Board Type"
9533      section in the U-Boot README for valid values for this variable.
9534
9535   :term:`UBOOT_MAKE_TARGET`
9536      Specifies the target called in the ``Makefile``. The default target
9537      is "all".
9538
9539   :term:`UBOOT_MKIMAGE`
9540      Specifies the name of the mkimage command as used by the
9541      :ref:`ref-classes-kernel-fitimage` class to assemble
9542      the FIT image. This can be used to substitute an alternative command, wrapper
9543      script or function if desired. The default is "uboot-mkimage".
9544
9545   :term:`UBOOT_MKIMAGE_DTCOPTS`
9546      Options for the device tree compiler passed to ``mkimage -D`` feature
9547      while creating a FIT image with the :ref:`ref-classes-kernel-fitimage`
9548      class. If :term:`UBOOT_MKIMAGE_DTCOPTS` is not set then the
9549      :ref:`ref-classes-kernel-fitimage` class will not pass the ``-D`` option
9550      to ``mkimage``.
9551
9552      This variable is also used by the :ref:`ref-classes-uboot-sign` class.
9553
9554   :term:`UBOOT_MKIMAGE_KERNEL_TYPE`
9555      Specifies the type argument for the kernel as passed to ``uboot-mkimage``.
9556      The default value is "kernel".
9557
9558   :term:`UBOOT_MKIMAGE_SIGN`
9559      Specifies the name of the mkimage command as used by the
9560      :ref:`ref-classes-kernel-fitimage` class to sign
9561      the FIT image after it has been assembled (if enabled). This can be used
9562      to substitute an alternative command, wrapper script or function if
9563      desired. The default is "${:term:`UBOOT_MKIMAGE`}".
9564
9565   :term:`UBOOT_MKIMAGE_SIGN_ARGS`
9566      Optionally specifies additional arguments for the
9567      :ref:`ref-classes-kernel-fitimage` class to pass to the
9568      mkimage command when signing the FIT image.
9569
9570   :term:`UBOOT_RD_ENTRYPOINT`
9571      Specifies the entrypoint for the RAM disk image. During FIT image
9572      creation, the :term:`UBOOT_RD_ENTRYPOINT` variable is used in
9573      :ref:`ref-classes-kernel-fitimage` class to specify the entrypoint to be
9574      used in creating the Image Tree Source for the FIT image.
9575
9576   :term:`UBOOT_RD_LOADADDRESS`
9577      Specifies the load address for the RAM disk image. During FIT image
9578      creation, the :term:`UBOOT_RD_LOADADDRESS` variable is used in
9579      :ref:`ref-classes-kernel-fitimage` class to specify the load address to
9580      be used in creating the Image Tree Source for the FIT image.
9581
9582   :term:`UBOOT_SIGN_ENABLE`
9583      Enable signing of FIT image. The default value is "0".
9584
9585      This variable is used by the :ref:`ref-classes-kernel-fitimage`,
9586      :ref:`ref-classes-uboot-config` and :ref:`ref-classes-uboot-sign`
9587      classes.
9588
9589   :term:`UBOOT_SIGN_KEYDIR`
9590      Location of the directory containing the RSA key and certificate used for
9591      signing FIT image, used by the :ref:`ref-classes-kernel-fitimage` and
9592      :ref:`ref-classes-uboot-sign` classes.
9593
9594   :term:`UBOOT_SIGN_KEYNAME`
9595      The name of keys used by the :ref:`ref-classes-kernel-fitimage` class
9596      for signing U-Boot FIT image stored in the :term:`UBOOT_SIGN_KEYDIR`
9597      directory. If we have for example a ``dev.key`` key and a ``dev.crt``
9598      certificate stored in the :term:`UBOOT_SIGN_KEYDIR` directory, you will
9599      have to set :term:`UBOOT_SIGN_KEYNAME` to ``dev``.
9600
9601   :term:`UBOOT_SUFFIX`
9602      Points to the generated U-Boot extension. For example, ``u-boot.sb``
9603      has a ``.sb`` extension.
9604
9605      The default U-Boot extension is ``.bin``
9606
9607   :term:`UBOOT_TARGET`
9608      Specifies the target used for building U-Boot. The target is passed
9609      directly as part of the "make" command (e.g. SPL and AIS). If you do
9610      not specifically set this variable, the OpenEmbedded build process
9611      passes and uses "all" for the target during the U-Boot building
9612      process.
9613
9614   :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`
9615      Specifies a list of options that, if reported by the configure script
9616      as being invalid, should not generate a warning during the
9617      :ref:`ref-tasks-configure` task. Normally, invalid
9618      configure options are simply not passed to the configure script (e.g.
9619      should be removed from :term:`EXTRA_OECONF` or
9620      :term:`PACKAGECONFIG_CONFARGS`).
9621      However, there are common options that are passed to all
9622      configure scripts at a class level, but might not be valid for some
9623      configure scripts. Therefore warnings about these options are useless.
9624      For these cases, the options are added to :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`.
9625
9626      The configure arguments check that uses
9627      :term:`UNKNOWN_CONFIGURE_OPT_IGNORE` is part of the
9628      :ref:`ref-classes-insane` class and is only enabled if the
9629      recipe inherits the :ref:`ref-classes-autotools` class.
9630
9631   :term:`UPDATERCPN`
9632      For recipes inheriting the
9633      :ref:`ref-classes-update-rc.d` class, :term:`UPDATERCPN`
9634      specifies the package that contains the initscript that is enabled.
9635
9636      The default value is "${PN}". Given that almost all recipes that
9637      install initscripts package them in the main package for the recipe,
9638      you rarely need to set this variable in individual recipes.
9639
9640   :term:`UPSTREAM_CHECK_COMMITS`
9641      You can perform a per-recipe check for what the latest upstream
9642      source code version is by calling ``devtool latest-version recipe``. If
9643      the recipe source code is provided from Git repositories, but
9644      releases are not identified by Git tags, set :term:`UPSTREAM_CHECK_COMMITS`
9645      to ``1`` in the recipe, and the OpenEmbedded build system
9646      will compare the latest commit with the one currently specified
9647      by the recipe (:term:`SRCREV`)::
9648
9649         UPSTREAM_CHECK_COMMITS = "1"
9650
9651   :term:`UPSTREAM_CHECK_GITTAGREGEX`
9652      You can perform a per-recipe check for what the latest upstream
9653      source code version is by calling ``devtool latest-version recipe``. If
9654      the recipe source code is provided from Git repositories, the
9655      OpenEmbedded build system determines the latest upstream version by
9656      picking the latest tag from the list of all repository tags.
9657
9658      You can use the :term:`UPSTREAM_CHECK_GITTAGREGEX` variable to provide a
9659      regular expression to filter only the relevant tags should the
9660      default filter not work correctly::
9661
9662         UPSTREAM_CHECK_GITTAGREGEX = "git_tag_regex"
9663
9664   :term:`UPSTREAM_CHECK_REGEX`
9665      Use the :term:`UPSTREAM_CHECK_REGEX` variable to specify a different
9666      regular expression instead of the default one when the package
9667      checking system is parsing the page found using
9668      :term:`UPSTREAM_CHECK_URI`::
9669
9670         UPSTREAM_CHECK_REGEX = "package_regex"
9671
9672   :term:`UPSTREAM_CHECK_URI`
9673      You can perform a per-recipe check for what the latest upstream
9674      source code version is by calling ``devtool latest-version recipe``. If
9675      the source code is provided from tarballs, the latest version is
9676      determined by fetching the directory listing where the tarball is and
9677      attempting to find a later tarball. When this approach does not work,
9678      you can use :term:`UPSTREAM_CHECK_URI` to provide a different URI that
9679      contains the link to the latest tarball::
9680
9681         UPSTREAM_CHECK_URI = "recipe_url"
9682
9683   :term:`UPSTREAM_VERSION_UNKNOWN`
9684      You can perform a per-recipe check for what the latest upstream
9685      source code version is by calling ``devtool latest-version recipe``.
9686      If no combination of the :term:`UPSTREAM_CHECK_URI`, :term:`UPSTREAM_CHECK_REGEX`,
9687      :term:`UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
9688      the recipe allows to determine what the latest upstream version is,
9689      you can set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1`` in the recipe
9690      to acknowledge that the check cannot be performed::
9691
9692         UPSTREAM_VERSION_UNKNOWN = "1"
9693
9694   :term:`USE_DEVFS`
9695      Determines if ``devtmpfs`` is used for ``/dev`` population. The
9696      default value used for :term:`USE_DEVFS` is "1" when no value is
9697      specifically set. Typically, you would set :term:`USE_DEVFS` to "0" for a
9698      statically populated ``/dev`` directory.
9699
9700      See the ":ref:`dev-manual/device-manager:selecting a device manager`" section in
9701      the Yocto Project Development Tasks Manual for information on how to
9702      use this variable.
9703
9704   :term:`USE_VT`
9705      When using
9706      :ref:`SysVinit <dev-manual/new-recipe:enabling system services>`,
9707      determines whether or not to run a :wikipedia:`getty <Getty_(Unix)>`
9708      on any virtual terminals in order to enable logging in through those
9709      terminals.
9710
9711      The default value used for :term:`USE_VT` is "1" when no default value is
9712      specifically set. Typically, you would set :term:`USE_VT` to "0" in the
9713      machine configuration file for machines that do not have a graphical
9714      display attached and therefore do not need virtual terminal
9715      functionality.
9716
9717   :term:`USER_CLASSES`
9718      A list of classes to globally inherit. These classes are used by the
9719      OpenEmbedded build system to enable extra features.
9720
9721      Classes inherited using :term:`USER_CLASSES` must be located in the
9722      ``classes-global/`` or ``classes/`` subdirectories.
9723
9724      The default list is set in your ``local.conf`` file::
9725
9726         USER_CLASSES ?= "buildstats"
9727
9728      For more information, see
9729      ``meta-poky/conf/templates/default/local.conf.sample`` in the
9730      :term:`Source Directory`.
9731
9732   :term:`USERADD_ERROR_DYNAMIC`
9733      If set to ``error``, forces the OpenEmbedded build system to produce
9734      an error if the user identification (``uid``) and group
9735      identification (``gid``) values are not defined in any of the files
9736      listed in :term:`USERADD_UID_TABLES` and
9737      :term:`USERADD_GID_TABLES`. If set to
9738      ``warn``, a warning will be issued instead.
9739
9740      The default behavior for the build system is to dynamically apply
9741      ``uid`` and ``gid`` values. Consequently, the
9742      :term:`USERADD_ERROR_DYNAMIC` variable is by default not set. If you plan
9743      on using statically assigned ``gid`` and ``uid`` values, you should
9744      set the :term:`USERADD_ERROR_DYNAMIC` variable in your ``local.conf``
9745      file as follows::
9746
9747         USERADD_ERROR_DYNAMIC = "error"
9748
9749      Overriding the
9750      default behavior implies you are going to also take steps to set
9751      static ``uid`` and ``gid`` values through use of the
9752      :term:`USERADDEXTENSION`,
9753      :term:`USERADD_UID_TABLES`, and
9754      :term:`USERADD_GID_TABLES` variables.
9755
9756      .. note::
9757
9758         There is a difference in behavior between setting
9759         :term:`USERADD_ERROR_DYNAMIC` to ``error`` and setting it to ``warn``.
9760         When it is set to ``warn``, the build system will report a warning for
9761         every undefined ``uid`` and ``gid`` in any recipe. But when it is set
9762         to ``error``, it will only report errors for recipes that are actually
9763         built.
9764         This saves you from having to add static IDs for recipes that you
9765         know will never be built.
9766
9767   :term:`USERADD_GID_TABLES`
9768      Specifies a password file to use for obtaining static group
9769      identification (``gid``) values when the OpenEmbedded build system
9770      adds a group to the system during package installation.
9771
9772      When applying static group identification (``gid``) values, the
9773      OpenEmbedded build system looks in :term:`BBPATH` for a
9774      ``files/group`` file and then applies those ``uid`` values. Set the
9775      variable as follows in your ``local.conf`` file::
9776
9777
9778         USERADD_GID_TABLES = "files/group"
9779
9780      .. note::
9781
9782         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
9783         causes the build system to use static ``gid`` values.
9784
9785   :term:`USERADD_PACKAGES`
9786      When inheriting the :ref:`ref-classes-useradd` class,
9787      this variable specifies the individual packages within the recipe
9788      that require users and/or groups to be added.
9789
9790      You must set this variable if the recipe inherits the class. For
9791      example, the following enables adding a user for the main package in
9792      a recipe::
9793
9794         USERADD_PACKAGES = "${PN}"
9795
9796      .. note::
9797
9798         It follows that if you are going to use the :term:`USERADD_PACKAGES`
9799         variable, you need to set one or more of the :term:`USERADD_PARAM`,
9800         :term:`GROUPADD_PARAM`, or :term:`GROUPMEMS_PARAM` variables.
9801
9802   :term:`USERADD_PARAM`
9803      When inheriting the :ref:`ref-classes-useradd` class,
9804      this variable specifies for a package what parameters should pass to
9805      the ``useradd`` command if you add a user to the system when the
9806      package is installed.
9807
9808      Here is an example from the ``dbus`` recipe::
9809
9810         USERADD_PARAM:${PN} = "--system --home ${localstatedir}/lib/dbus \
9811                                --no-create-home --shell /bin/false \
9812                                --user-group messagebus"
9813
9814      For information on the
9815      standard Linux shell command ``useradd``, see
9816      https://linux.die.net/man/8/useradd.
9817
9818   :term:`USERADD_UID_TABLES`
9819      Specifies a password file to use for obtaining static user
9820      identification (``uid``) values when the OpenEmbedded build system
9821      adds a user to the system during package installation.
9822
9823      When applying static user identification (``uid``) values, the
9824      OpenEmbedded build system looks in :term:`BBPATH` for a
9825      ``files/passwd`` file and then applies those ``uid`` values. Set the
9826      variable as follows in your ``local.conf`` file::
9827
9828         USERADD_UID_TABLES = "files/passwd"
9829
9830      .. note::
9831
9832         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
9833         causes the build system to use static ``uid`` values.
9834
9835   :term:`USERADDEXTENSION`
9836      When set to "useradd-staticids", causes the OpenEmbedded build system
9837      to base all user and group additions on a static ``passwd`` and
9838      ``group`` files found in :term:`BBPATH`.
9839
9840      To use static user identification (``uid``) and group identification
9841      (``gid``) values, set the variable as follows in your ``local.conf``
9842      file: USERADDEXTENSION = "useradd-staticids"
9843
9844      .. note::
9845
9846         Setting this variable to use static ``uid`` and ``gid``
9847         values causes the OpenEmbedded build system to employ the
9848         :ref:`ref-classes-useradd` class.
9849
9850      If you use static ``uid`` and ``gid`` information, you must also
9851      specify the ``files/passwd`` and ``files/group`` files by setting the
9852      :term:`USERADD_UID_TABLES` and
9853      :term:`USERADD_GID_TABLES` variables.
9854      Additionally, you should also set the
9855      :term:`USERADD_ERROR_DYNAMIC` variable.
9856
9857   :term:`VOLATILE_LOG_DIR`
9858      Specifies the persistence of the target's ``/var/log`` directory,
9859      which is used to house postinstall target log files.
9860
9861      By default, :term:`VOLATILE_LOG_DIR` is set to "yes", which means the
9862      file is not persistent. You can override this setting by setting the
9863      variable to "no" to make the log directory persistent.
9864
9865   :term:`VOLATILE_TMP_DIR`
9866      Specifies the persistence of the target's ``/tmp`` directory.
9867
9868      By default, :term:`VOLATILE_TMP_DIR` is set to "yes", in which case
9869      ``/tmp`` links to a directory which resides in RAM in a ``tmpfs``
9870      filesystem.
9871
9872      If instead, you want the ``/tmp`` directory to be persistent, set the
9873      variable to "no" to make it a regular directory in the root filesystem.
9874
9875      This supports both sysvinit and systemd based systems.
9876
9877   :term:`WARN_QA`
9878      Specifies the quality assurance checks whose failures are reported as
9879      warnings by the OpenEmbedded build system. You set this variable in
9880      your distribution configuration file. For a list of the checks you
9881      can control with this variable, see the
9882      ":ref:`ref-classes-insane`" section.
9883
9884   :term:`WATCHDOG_TIMEOUT`
9885      Specifies the timeout in seconds used by the ``watchdog`` recipe and
9886      also by ``systemd`` during reboot. The default is 60 seconds.
9887
9888   :term:`WIRELESS_DAEMON`
9889      For ``connman`` and ``packagegroup-base``, specifies the wireless
9890      daemon to use. The default is "wpa-supplicant" (note that the value
9891      uses a dash and not an underscore).
9892
9893   :term:`WKS_FILE`
9894      Specifies the location of the Wic kickstart file that is used by the
9895      OpenEmbedded build system to create a partitioned image
9896      (``image.wic``). For information on how to create a partitioned
9897      image, see the
9898      ":ref:`dev-manual/wic:creating partitioned images using wic`"
9899      section in the Yocto Project Development Tasks Manual. For details on
9900      the kickstart file format, see the ":doc:`/ref-manual/kickstart`" Chapter.
9901
9902   :term:`WKS_FILE_DEPENDS`
9903      When placed in the recipe that builds your image, this variable lists
9904      build-time dependencies. The :term:`WKS_FILE_DEPENDS` variable is only
9905      applicable when Wic images are active (i.e. when
9906      :term:`IMAGE_FSTYPES` contains entries related
9907      to Wic). If your recipe does not create Wic images, the variable has
9908      no effect.
9909
9910      The :term:`WKS_FILE_DEPENDS` variable is similar to the
9911      :term:`DEPENDS` variable. When you use the variable in
9912      your recipe that builds the Wic image, dependencies you list in the
9913      :term:`WKS_FILE_DEPENDS` variable are added to the :term:`DEPENDS` variable.
9914
9915      With the :term:`WKS_FILE_DEPENDS` variable, you have the possibility to
9916      specify a list of additional dependencies (e.g. native tools,
9917      bootloaders, and so forth), that are required to build Wic images.
9918      Here is an example::
9919
9920         WKS_FILE_DEPENDS = "some-native-tool"
9921
9922      In the
9923      previous example, some-native-tool would be replaced with an actual
9924      native tool on which the build would depend.
9925
9926   :term:`WKS_FILES`
9927      Specifies a list of candidate Wic kickstart files to be used by the
9928      OpenEmbedded build system to create a partitioned image. Only the
9929      first one that is found, from left to right, will be used.
9930
9931      This is only useful when there are multiple ``.wks`` files that can be
9932      used to produce an image. A typical case is when multiple layers are
9933      used for different hardware platforms, each supplying a different
9934      ``.wks`` file. In this case, you specify all possible ones through
9935      :term:`WKS_FILES`.
9936
9937      If only one ``.wks`` file is used, set :term:`WKS_FILE` instead.
9938
9939   :term:`WORKDIR`
9940      The pathname of the work directory in which the OpenEmbedded build
9941      system builds a recipe. This directory is located within the
9942      :term:`TMPDIR` directory structure and is specific to
9943      the recipe being built and the system for which it is being built.
9944
9945      The :term:`WORKDIR` directory is defined as follows::
9946
9947         ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
9948
9949      The actual directory depends on several things:
9950
9951      -  :term:`TMPDIR`: The top-level build output directory
9952      -  :term:`MULTIMACH_TARGET_SYS`: The target system identifier
9953      -  :term:`PN`: The recipe name
9954      -  :term:`EXTENDPE`: The epoch --- if :term:`PE` is not specified, which
9955         is usually the case for most recipes, then :term:`EXTENDPE` is blank.
9956      -  :term:`PV`: The recipe version
9957      -  :term:`PR`: The recipe revision
9958
9959      As an example, assume a Source Directory top-level folder name
9960      ``poky``, a default :term:`Build Directory` at ``poky/build``, and a
9961      ``qemux86-poky-linux`` machine target system. Furthermore, suppose
9962      your recipe is named ``foo_1.3.0-r0.bb``. In this case, the work
9963      directory the build system uses to build the package would be as
9964      follows::
9965
9966         poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
9967
9968   :term:`XSERVER`
9969      Specifies the packages that should be installed to provide an X
9970      server and drivers for the current machine, assuming your image
9971      directly includes ``packagegroup-core-x11-xserver`` or, perhaps
9972      indirectly, includes "x11-base" in
9973      :term:`IMAGE_FEATURES`.
9974
9975      The default value of :term:`XSERVER`, if not specified in the machine
9976      configuration, is "xserver-xorg xf86-video-fbdev xf86-input-evdev".
9977
9978   :term:`XZ_THREADS`
9979      Specifies the number of parallel threads that should be used when
9980      using xz compression.
9981
9982      By default this scales with core count, but is never set less than 2
9983      to ensure that multi-threaded mode is always used so that the output
9984      file contents are deterministic. Builds will work with a value of 1
9985      but the output will differ compared to the output from the compression
9986      generated when more than one thread is used.
9987
9988      On systems where many tasks run in parallel, setting a limit to this
9989      can be helpful in controlling system resource usage.
9990
9991   :term:`XZ_MEMLIMIT`
9992      Specifies the maximum memory the xz compression should use as a percentage
9993      of system memory. If unconstrained the xz compressor can use large amounts of
9994      memory and become problematic with parallelism elsewhere in the build.
9995      "50%" has been found to be a good value.
9996
9997   :term:`ZSTD_THREADS`
9998      Specifies the number of parallel threads that should be used when
9999      using ZStandard compression.
10000
10001      By default this scales with core count, but is never set less than 2
10002      to ensure that multi-threaded mode is always used so that the output
10003      file contents are deterministic. Builds will work with a value of 1
10004      but the output will differ compared to the output from the compression
10005      generated when more than one thread is used.
10006
10007      On systems where many tasks run in parallel, setting a limit to this
10008      can be helpful in controlling system resource usage.
10009