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:`AUTHOR`
196      The email address used to contact the original author or authors in
197      order to send patches and forward bugs.
198
199   :term:`AUTO_LIBNAME_PKGS`
200      When the :ref:`ref-classes-debian` class is inherited,
201      which is the default behavior, :term:`AUTO_LIBNAME_PKGS` specifies which
202      packages should be checked for libraries and renamed according to
203      Debian library package naming.
204
205      The default value is "${PACKAGES}", which causes the
206      :ref:`ref-classes-debian` class to act on all packages that are
207      explicitly generated by the recipe.
208
209   :term:`AUTOREV`
210      When :term:`SRCREV` is set to the value of this variable, it specifies to
211      use the latest source revision in the repository. Here is an example::
212
213         SRCREV = "${AUTOREV}"
214
215      If you use the previous statement to retrieve the latest version of
216      software, you need to be sure :term:`PV` contains
217      ``${``\ :term:`SRCPV`\ ``}``. For example, suppose you have a kernel
218      recipe that inherits the :ref:`ref-classes-kernel` class and you
219      use the previous statement. In this example, ``${SRCPV}`` does not
220      automatically get into :term:`PV`. Consequently, you need to change
221      :term:`PV` in your recipe so that it does contain ``${SRCPV}``.
222
223      For more information see the
224      ":ref:`dev-manual/packages:automatically incrementing a package version number`"
225      section in the Yocto Project Development Tasks Manual.
226
227   :term:`AUTO_SYSLINUXMENU`
228      Enables creating an automatic menu for the syslinux bootloader. You
229      must set this variable in your recipe. The
230      :ref:`ref-classes-syslinux` class checks this variable.
231
232   :term:`AVAILTUNES`
233      The list of defined CPU and Application Binary Interface (ABI)
234      tunings (i.e. "tunes") available for use by the OpenEmbedded build
235      system.
236
237      The list simply presents the tunes that are available. Not all tunes
238      may be compatible with a particular machine configuration, or with
239      each other in a
240      :ref:`Multilib <dev-manual/libraries:combining multiple versions of library files into one image>`
241      configuration.
242
243      To add a tune to the list, be sure to append it with spaces using the
244      "+=" BitBake operator. Do not simply replace the list by using the
245      "=" operator. See the
246      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:basic syntax`" section in the BitBake
247      User Manual for more information.
248
249   :term:`AZ_SAS`
250      Azure Storage Shared Access Signature, when using the
251      :ref:`Azure Storage fetcher (az://) <bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
252      This variable can be defined to be used by the fetcher to authenticate
253      and gain access to non-public artifacts::
254
255         AZ_SAS = ""se=2021-01-01&sp=r&sv=2018-11-09&sr=c&skoid=<skoid>&sig=<signature>""
256
257      For more information see Microsoft's Azure Storage documentation at
258      https://docs.microsoft.com/en-us/azure/storage/common/storage-sas-overview
259
260   :term:`B`
261      The directory within the :term:`Build Directory` in which the
262      OpenEmbedded build system places generated objects during a recipe's
263      build process. By default, this directory is the same as the
264      :term:`S` directory, which is defined as::
265
266         S = "${WORKDIR}/${BP}"
267
268      You can separate the (:term:`S`) directory and the directory pointed to
269      by the :term:`B` variable. Most Autotools-based recipes support
270      separating these directories. The build system defaults to using
271      separate directories for ``gcc`` and some kernel recipes.
272
273   :term:`BAD_RECOMMENDATIONS`
274      Lists "recommended-only" packages to not install. Recommended-only
275      packages are packages installed only through the
276      :term:`RRECOMMENDS` variable. You can prevent any
277      of these "recommended" packages from being installed by listing them
278      with the :term:`BAD_RECOMMENDATIONS` variable::
279
280         BAD_RECOMMENDATIONS = "package_name package_name package_name ..."
281
282      You can set this variable globally in your ``local.conf`` file or you
283      can attach it to a specific image recipe by using the recipe name
284      override::
285
286         BAD_RECOMMENDATIONS:pn-target_image = "package_name"
287
288      It is important to realize that if you choose to not install packages
289      using this variable and some other packages are dependent on them
290      (i.e. listed in a recipe's :term:`RDEPENDS`
291      variable), the OpenEmbedded build system ignores your request and
292      will install the packages to avoid dependency errors.
293
294      This variable is supported only when using the IPK and RPM
295      packaging backends. DEB is not supported.
296
297      See the :term:`NO_RECOMMENDATIONS` and the
298      :term:`PACKAGE_EXCLUDE` variables for related
299      information.
300
301   :term:`BASE_LIB`
302      The library directory name for the CPU or Application Binary
303      Interface (ABI) tune. The :term:`BASE_LIB` applies only in the Multilib
304      context. See the ":ref:`dev-manual/libraries:combining multiple versions of library files into one image`"
305      section in the Yocto Project Development Tasks Manual for information
306      on Multilib.
307
308      The :term:`BASE_LIB` variable is defined in the machine include files in
309      the :term:`Source Directory`. If Multilib is not
310      being used, the value defaults to "lib".
311
312   :term:`BASE_WORKDIR`
313      Points to the base of the work directory for all recipes. The default
314      value is "${TMPDIR}/work".
315
316   :term:`BB_ALLOWED_NETWORKS`
317      Specifies a space-delimited list of hosts that the fetcher is allowed
318      to use to obtain the required source code. Following are
319      considerations surrounding this variable:
320
321      -  This host list is only used if :term:`BB_NO_NETWORK` is either not set
322         or set to "0".
323
324      -  There is limited support for wildcard matching against the beginning of
325         host names. For example, the following setting matches
326         ``git.gnu.org``, ``ftp.gnu.org``, and ``foo.git.gnu.org``::
327
328            BB_ALLOWED_NETWORKS = "*.gnu.org"
329
330         .. note::
331
332            The use of the "``*``" character only works at the beginning of
333            a host name and it must be isolated from the remainder of the
334            host name. You cannot use the wildcard character in any other
335            location of the name or combined with the front part of the
336            name.
337
338            For example, ``*.foo.bar`` is supported, while ``*aa.foo.bar``
339            is not.
340
341      -  Mirrors not in the host list are skipped and logged in debug.
342
343      -  Attempts to access networks not in the host list cause a failure.
344
345      Using :term:`BB_ALLOWED_NETWORKS` in conjunction with
346      :term:`PREMIRRORS` is very useful. Adding the host
347      you want to use to :term:`PREMIRRORS` results in the source code being
348      fetched from an allowed location and avoids raising an error when a
349      host that is not allowed is in a :term:`SRC_URI`
350      statement. This is because the fetcher does not attempt to use the
351      host listed in :term:`SRC_URI` after a successful fetch from the
352      :term:`PREMIRRORS` occurs.
353
354   :term:`BB_BASEHASH_IGNORE_VARS`
355      See :term:`bitbake:BB_BASEHASH_IGNORE_VARS` in the BitBake manual.
356
357   :term:`BB_CACHEDIR`
358      See :term:`bitbake:BB_CACHEDIR` in the BitBake manual.
359
360   :term:`BB_CHECK_SSL_CERTS`
361      See :term:`bitbake:BB_CHECK_SSL_CERTS` in the BitBake manual.
362
363   :term:`BB_CONSOLELOG`
364      See :term:`bitbake:BB_CONSOLELOG` in the BitBake manual.
365
366   :term:`BB_CURRENTTASK`
367      See :term:`bitbake:BB_CURRENTTASK` in the BitBake manual.
368
369   :term:`BB_DANGLINGAPPENDS_WARNONLY`
370      Defines how BitBake handles situations where an append file
371      (``.bbappend``) has no corresponding recipe file (``.bb``). This
372      condition often occurs when layers get out of sync (e.g. ``oe-core``
373      bumps a recipe version and the old recipe no longer exists and the
374      other layer has not been updated to the new version of the recipe
375      yet).
376
377      The default fatal behavior is safest because it is the sane reaction
378      given something is out of sync. It is important to realize when your
379      changes are no longer being applied.
380
381      You can change the default behavior by setting this variable to "1",
382      "yes", or "true" in your ``local.conf`` file, which is located in the
383      :term:`Build Directory`: Here is an example::
384
385         BB_DANGLINGAPPENDS_WARNONLY = "1"
386
387   :term:`BB_DEFAULT_TASK`
388      See :term:`bitbake:BB_DEFAULT_TASK` in the BitBake manual.
389
390   :term:`BB_DEFAULT_UMASK`
391      See :term:`bitbake:BB_DEFAULT_UMASK` in the BitBake manual.
392
393   :term:`BB_DISKMON_DIRS`
394      Monitors disk space and available inodes during the build and allows
395      you to control the build based on these parameters.
396
397      Disk space monitoring is disabled by default. To enable monitoring,
398      add the :term:`BB_DISKMON_DIRS` variable to your ``conf/local.conf`` file
399      found in the :term:`Build Directory`. Use the
400      following form:
401
402      .. code-block:: none
403
404         BB_DISKMON_DIRS = "action,dir,threshold [...]"
405
406         where:
407
408            action is:
409               ABORT:     Immediately stop the build when
410                          a threshold is broken.
411               STOPTASKS: Stop the build after the currently
412                          executing tasks have finished when
413                          a threshold is broken.
414               WARN:      Issue a warning but continue the
415                          build when a threshold is broken.
416                          Subsequent warnings are issued as
417                          defined by the BB_DISKMON_WARNINTERVAL
418                          variable, which must be defined in
419                          the conf/local.conf file.
420
421            dir is:
422               Any directory you choose. You can specify one or
423               more directories to monitor by separating the
424               groupings with a space.  If two directories are
425               on the same device, only the first directory
426               is monitored.
427
428            threshold is:
429               Either the minimum available disk space,
430               the minimum number of free inodes, or
431               both.  You must specify at least one.  To
432               omit one or the other, simply omit the value.
433               Specify the threshold using G, M, K for Gbytes,
434               Mbytes, and Kbytes, respectively. If you do
435               not specify G, M, or K, Kbytes is assumed by
436               default.  Do not use GB, MB, or KB.
437
438      Here are some examples::
439
440         BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K"
441         BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G"
442         BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
443
444      The first example works only if you also provide the
445      :term:`BB_DISKMON_WARNINTERVAL`
446      variable in the ``conf/local.conf``. This example causes the build
447      system to immediately stop when either the disk space in
448      ``${TMPDIR}`` drops below 1 Gbyte or the available free inodes drops
449      below 100 Kbytes. Because two directories are provided with the
450      variable, the build system also issue a warning when the disk space
451      in the ``${SSTATE_DIR}`` directory drops below 1 Gbyte or the number
452      of free inodes drops below 100 Kbytes. Subsequent warnings are issued
453      during intervals as defined by the :term:`BB_DISKMON_WARNINTERVAL`
454      variable.
455
456      The second example stops the build after all currently executing
457      tasks complete when the minimum disk space in the ``${TMPDIR}``
458      directory drops below 1 Gbyte. No disk monitoring occurs for the free
459      inodes in this case.
460
461      The final example immediately stops the build when the number of
462      free inodes in the ``${TMPDIR}`` directory drops below 100 Kbytes. No
463      disk space monitoring for the directory itself occurs in this case.
464
465   :term:`BB_DISKMON_WARNINTERVAL`
466      Defines the disk space and free inode warning intervals. To set these
467      intervals, define the variable in your ``conf/local.conf`` file in
468      the :term:`Build Directory`.
469
470      If you are going to use the :term:`BB_DISKMON_WARNINTERVAL` variable, you
471      must also use the :term:`BB_DISKMON_DIRS`
472      variable and define its action as "WARN". During the build,
473      subsequent warnings are issued each time disk space or number of free
474      inodes further reduces by the respective interval.
475
476      If you do not provide a :term:`BB_DISKMON_WARNINTERVAL` variable and you
477      do use :term:`BB_DISKMON_DIRS` with the "WARN" action, the disk
478      monitoring interval defaults to the following::
479
480         BB_DISKMON_WARNINTERVAL = "50M,5K"
481
482      When specifying the variable in your configuration file, use the
483      following form:
484
485      .. code-block:: none
486
487         BB_DISKMON_WARNINTERVAL = "disk_space_interval,disk_inode_interval"
488
489         where:
490
491            disk_space_interval is:
492               An interval of memory expressed in either
493               G, M, or K for Gbytes, Mbytes, or Kbytes,
494               respectively. You cannot use GB, MB, or KB.
495
496            disk_inode_interval is:
497               An interval of free inodes expressed in either
498               G, M, or K for Gbytes, Mbytes, or Kbytes,
499               respectively. You cannot use GB, MB, or KB.
500
501      Here is an example::
502
503         BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K"
504         BB_DISKMON_WARNINTERVAL = "50M,5K"
505
506      These variables cause the
507      OpenEmbedded build system to issue subsequent warnings each time the
508      available disk space further reduces by 50 Mbytes or the number of
509      free inodes further reduces by 5 Kbytes in the ``${SSTATE_DIR}``
510      directory. Subsequent warnings based on the interval occur each time
511      a respective interval is reached beyond the initial warning (i.e. 1
512      Gbytes and 100 Kbytes).
513
514   :term:`BB_ENV_PASSTHROUGH`
515      See :term:`bitbake:BB_ENV_PASSTHROUGH` in the BitBake manual.
516
517   :term:`BB_ENV_PASSTHROUGH_ADDITIONS`
518      See :term:`bitbake:BB_ENV_PASSTHROUGH_ADDITIONS` in the BitBake manual.
519
520   :term:`BB_FETCH_PREMIRRORONLY`
521      See :term:`bitbake:BB_FETCH_PREMIRRORONLY` in the BitBake manual.
522
523   :term:`BB_FILENAME`
524      See :term:`bitbake:BB_FILENAME` in the BitBake manual.
525
526   :term:`BB_GENERATE_MIRROR_TARBALLS`
527      Causes tarballs of the source control repositories (e.g. Git
528      repositories), including metadata, to be placed in the
529      :term:`DL_DIR` directory.
530
531      For performance reasons, creating and placing tarballs of these
532      repositories is not the default action by the OpenEmbedded build
533      system::
534
535         BB_GENERATE_MIRROR_TARBALLS = "1"
536
537      Set this variable in your
538      ``local.conf`` file in the :term:`Build Directory`.
539
540      Once you have the tarballs containing your source files, you can
541      clean up your :term:`DL_DIR` directory by deleting any Git or other
542      source control work directories.
543
544   :term:`BB_GENERATE_SHALLOW_TARBALLS`
545      See :term:`bitbake:BB_GENERATE_SHALLOW_TARBALLS` in the BitBake manual.
546
547   :term:`BB_GIT_SHALLOW`
548      See :term:`bitbake:BB_GIT_SHALLOW` in the BitBake manual.
549
550   :term:`BB_GIT_SHALLOW_DEPTH`
551      See :term:`bitbake:BB_GIT_SHALLOW_DEPTH` in the BitBake manual.
552
553   :term:`BB_HASHCHECK_FUNCTION`
554      See :term:`bitbake:BB_HASHCHECK_FUNCTION` in the BitBake manual.
555
556   :term:`BB_HASHCONFIG_IGNORE_VARS`
557      See :term:`bitbake:BB_HASHCONFIG_IGNORE_VARS` in the BitBake manual.
558
559   :term:`BB_HASHSERVE`
560      See :term:`bitbake:BB_HASHSERVE` in the BitBake manual.
561
562   :term:`BB_HASHSERVE_UPSTREAM`
563      See :term:`bitbake:BB_HASHSERVE_UPSTREAM` in the BitBake manual.
564
565   :term:`BB_INVALIDCONF`
566      See :term:`bitbake:BB_INVALIDCONF` in the BitBake manual.
567
568   :term:`BB_LOGCONFIG`
569      See :term:`bitbake:BB_LOGCONFIG` in the BitBake manual.
570
571   :term:`BB_LOGFMT`
572      See :term:`bitbake:BB_LOGFMT` in the BitBake manual.
573
574   :term:`BB_MULTI_PROVIDER_ALLOWED`
575      See :term:`bitbake:BB_MULTI_PROVIDER_ALLOWED` in the BitBake manual.
576
577   :term:`BB_NICE_LEVEL`
578      See :term:`bitbake:BB_NICE_LEVEL` in the BitBake manual.
579
580   :term:`BB_NO_NETWORK`
581      See :term:`bitbake:BB_NO_NETWORK` in the BitBake manual.
582
583   :term:`BB_NUMBER_PARSE_THREADS`
584      See :term:`bitbake:BB_NUMBER_PARSE_THREADS` in the BitBake manual.
585
586   :term:`BB_NUMBER_THREADS`
587      The maximum number of tasks BitBake should run in parallel at any one
588      time. The OpenEmbedded build system automatically configures this
589      variable to be equal to the number of cores on the build system. For
590      example, a system with a dual core processor that also uses
591      hyper-threading causes the :term:`BB_NUMBER_THREADS` variable to default
592      to "4".
593
594      For single socket systems (i.e. one CPU), you should not have to
595      override this variable to gain optimal parallelism during builds.
596      However, if you have very large systems that employ multiple physical
597      CPUs, you might want to make sure the :term:`BB_NUMBER_THREADS` variable
598      is not set higher than "20".
599
600      For more information on speeding up builds, see the
601      ":ref:`dev-manual/speeding-up-build:speeding up a build`"
602      section in the Yocto Project Development Tasks Manual.
603
604      On the other hand, if your goal is to limit the amount of system
605      resources consumed by BitBake tasks, setting :term:`BB_NUMBER_THREADS`
606      to a number lower than the number of CPU threads in your machine
607      won't be sufficient. That's because each package will still be built
608      and installed through a number of parallel jobs specified by the
609      :term:`PARALLEL_MAKE` variable, which is by default the number of CPU
610      threads in your system, and is not impacted by the
611      :term:`BB_NUMBER_THREADS` value.
612
613      So, if you set :term:`BB_NUMBER_THREADS` to "1" but don't set
614      :term:`PARALLEL_MAKE`, most of your system resources will be consumed
615      anyway.
616
617      Therefore, if you intend to reduce the load of your build system by
618      setting :term:`BB_NUMBER_THREADS` to a relatively low value compared
619      to the number of CPU threads on your system, you should also set
620      :term:`PARALLEL_MAKE` to a similarly low value.
621
622      An alternative to using :term:`BB_NUMBER_THREADS` to keep the usage
623      of build system resources under control is to use the smarter
624      :term:`BB_PRESSURE_MAX_CPU`, :term:`BB_PRESSURE_MAX_IO` or
625      :term:`BB_PRESSURE_MAX_MEMORY` controls. They will prevent BitBake
626      from starting new tasks as long as thresholds are exceeded. Anyway,
627      as with :term:`BB_NUMBER_THREADS`, such controls won't prevent the
628      tasks already being run from using all CPU threads on the system
629      if :term:`PARALLEL_MAKE` is not set to a low value.
630
631   :term:`BB_ORIGENV`
632      See :term:`bitbake:BB_ORIGENV` in the BitBake manual.
633
634   :term:`BB_PRESERVE_ENV`
635      See :term:`bitbake:BB_PRESERVE_ENV` in the BitBake manual.
636
637   :term:`BB_PRESSURE_MAX_CPU`
638      See :term:`bitbake:BB_PRESSURE_MAX_CPU` in the BitBake manual.
639
640   :term:`BB_PRESSURE_MAX_IO`
641      See :term:`bitbake:BB_PRESSURE_MAX_IO` in the BitBake manual.
642
643   :term:`BB_PRESSURE_MAX_MEMORY`
644      See :term:`bitbake:BB_PRESSURE_MAX_MEMORY` in the BitBake manual.
645
646   :term:`BB_RUNFMT`
647      See :term:`bitbake:BB_RUNFMT` in the BitBake manual.
648
649   :term:`BB_RUNTASK`
650      See :term:`bitbake:BB_RUNTASK` in the BitBake manual.
651
652   :term:`BB_SCHEDULER`
653      See :term:`bitbake:BB_SCHEDULER` in the BitBake manual.
654
655   :term:`BB_SCHEDULERS`
656      See :term:`bitbake:BB_SCHEDULERS` in the BitBake manual.
657
658   :term:`BB_SERVER_TIMEOUT`
659      Specifies the time (in seconds) after which to unload the BitBake
660      server due to inactivity. Set :term:`BB_SERVER_TIMEOUT` to determine how
661      long the BitBake server stays resident between invocations.
662
663      For example, the following statement in your ``local.conf`` file
664      instructs the server to be unloaded after 20 seconds of inactivity::
665
666         BB_SERVER_TIMEOUT = "20"
667
668      If you want the server to never be unloaded,
669      set :term:`BB_SERVER_TIMEOUT` to "-1".
670
671   :term:`BB_SETSCENE_DEPVALID`
672      See :term:`bitbake:BB_SETSCENE_DEPVALID` in the BitBake manual.
673
674   :term:`BB_SIGNATURE_EXCLUDE_FLAGS`
675      See :term:`bitbake:BB_SIGNATURE_EXCLUDE_FLAGS` in the BitBake manual.
676
677   :term:`BB_SIGNATURE_HANDLER`
678      See :term:`bitbake:BB_SIGNATURE_HANDLER` in the BitBake manual.
679
680   :term:`BB_SRCREV_POLICY`
681      See :term:`bitbake:BB_SRCREV_POLICY` in the BitBake manual.
682
683   :term:`BB_STRICT_CHECKSUM`
684      See :term:`bitbake:BB_STRICT_CHECKSUM` in the BitBake manual.
685
686   :term:`BB_TASK_IONICE_LEVEL`
687      See :term:`bitbake:BB_TASK_IONICE_LEVEL` in the BitBake manual.
688
689   :term:`BB_TASK_NICE_LEVEL`
690      See :term:`bitbake:BB_TASK_NICE_LEVEL` in the BitBake manual.
691
692   :term:`BB_TASKHASH`
693      See :term:`bitbake:BB_TASKHASH` in the BitBake manual.
694
695   :term:`BB_VERBOSE_LOGS`
696      See :term:`bitbake:BB_VERBOSE_LOGS` in the BitBake manual.
697
698   :term:`BB_WORKERCONTEXT`
699      See :term:`bitbake:BB_WORKERCONTEXT` in the BitBake manual.
700
701   :term:`BBCLASSEXTEND`
702      Allows you to extend a recipe so that it builds variants of the
703      software. There are common variants for recipes as "natives" like
704      ``quilt-native``, which is a copy of Quilt built to run on the build
705      system; "crosses" such as ``gcc-cross``, which is a compiler built to
706      run on the build machine but produces binaries that run on the target
707      :term:`MACHINE`; ":ref:`ref-classes-nativesdk`", which
708      targets the SDK machine instead of :term:`MACHINE`; and "mulitlibs" in
709      the form "``multilib:``\ multilib_name".
710
711      To build a different variant of the recipe with a minimal amount of
712      code, it usually is as simple as adding the following to your recipe::
713
714         BBCLASSEXTEND =+ "native nativesdk"
715         BBCLASSEXTEND =+ "multilib:multilib_name"
716
717      .. note::
718
719         Internally, the :term:`BBCLASSEXTEND` mechanism generates recipe
720         variants by rewriting variable values and applying overrides such
721         as ``:class-native``. For example, to generate a native version of
722         a recipe, a :term:`DEPENDS` on "foo" is rewritten
723         to a :term:`DEPENDS` on "foo-native".
724
725         Even when using :term:`BBCLASSEXTEND`, the recipe is only parsed once.
726         Parsing once adds some limitations. For example, it is not
727         possible to include a different file depending on the variant,
728         since ``include`` statements are processed when the recipe is
729         parsed.
730
731   :term:`BBDEBUG`
732      See :term:`bitbake:BBDEBUG` in the BitBake manual.
733
734   :term:`BBFILE_COLLECTIONS`
735      Lists the names of configured layers. These names are used to find
736      the other ``BBFILE_*`` variables. Typically, each layer will append
737      its name to this variable in its ``conf/layer.conf`` file.
738
739   :term:`BBFILE_PATTERN`
740      Variable that expands to match files from
741      :term:`BBFILES` in a particular layer. This variable
742      is used in the ``conf/layer.conf`` file and must be suffixed with the
743      name of the specific layer (e.g. ``BBFILE_PATTERN_emenlow``).
744
745   :term:`BBFILE_PRIORITY`
746      Assigns the priority for recipe files in each layer.
747
748      This variable is useful in situations where the same recipe appears
749      in more than one layer. Setting this variable allows you to
750      prioritize a layer against other layers that contain the same recipe
751      --- effectively letting you control the precedence for the multiple
752      layers. The precedence established through this variable stands
753      regardless of a recipe's version (:term:`PV` variable). For
754      example, a layer that has a recipe with a higher :term:`PV` value but for
755      which the :term:`BBFILE_PRIORITY` is set to have a lower precedence still
756      has a lower precedence.
757
758      A larger value for the :term:`BBFILE_PRIORITY` variable results in a
759      higher precedence. For example, the value 6 has a higher precedence
760      than the value 5. If not specified, the :term:`BBFILE_PRIORITY` variable
761      is set based on layer dependencies (see the :term:`LAYERDEPENDS` variable
762      for more information. The default priority, if unspecified for a
763      layer with no dependencies, is the lowest defined priority + 1 (or 1
764      if no priorities are defined).
765
766      .. tip::
767
768         You can use the command ``bitbake-layers show-layers``
769         to list all configured layers along with their priorities.
770
771   :term:`BBFILES`
772      A space-separated list of recipe files BitBake uses to build
773      software.
774
775      When specifying recipe files, you can pattern match using Python's
776      `glob <https://docs.python.org/3/library/glob.html>`__ syntax.
777      For details on the syntax, see the documentation by following the
778      previous link.
779
780   :term:`BBFILES_DYNAMIC`
781      Activates content when identified layers are present. You identify
782      the layers by the collections that the layers define.
783
784      Use the :term:`BBFILES_DYNAMIC` variable to avoid ``.bbappend`` files
785      whose corresponding ``.bb`` file is in a layer that attempts to
786      modify other layers through ``.bbappend`` but does not want to
787      introduce a hard dependency on those other layers.
788
789      Use the following form for :term:`BBFILES_DYNAMIC`:
790      ``collection_name:filename_pattern``.
791
792      The following example identifies two collection names and two
793      filename patterns::
794
795         BBFILES_DYNAMIC += " \
796            clang-layer:${LAYERDIR}/bbappends/meta-clang/*/*/*.bbappend \
797            core:${LAYERDIR}/bbappends/openembedded-core/meta/*/*/*.bbappend \
798            "
799
800      This next example shows an error message that occurs because invalid
801      entries are found, which cause parsing to fail:
802
803      .. code-block:: none
804
805         ERROR: BBFILES_DYNAMIC entries must be of the form <collection name>:<filename pattern>, not:
806             /work/my-layer/bbappends/meta-security-isafw/*/*/*.bbappend
807             /work/my-layer/bbappends/openembedded-core/meta/*/*/*.bbappend
808
809   :term:`BBINCLUDED`
810      See :term:`bitbake:BBINCLUDED` in the BitBake manual.
811
812   :term:`BBINCLUDELOGS`
813      Variable that controls how BitBake displays logs on build failure.
814
815   :term:`BBINCLUDELOGS_LINES`
816      If :term:`BBINCLUDELOGS` is set, specifies the
817      maximum number of lines from the task log file to print when
818      reporting a failed task. If you do not set :term:`BBINCLUDELOGS_LINES`,
819      the entire log is printed.
820
821   :term:`BBLAYERS`
822      Lists the layers to enable during the build. This variable is defined
823      in the ``bblayers.conf`` configuration file in the :term:`Build Directory`.
824      Here is an example::
825
826         BBLAYERS = " \
827             /home/scottrif/poky/meta \
828             /home/scottrif/poky/meta-poky \
829             /home/scottrif/poky/meta-yocto-bsp \
830             /home/scottrif/poky/meta-mykernel \
831             "
832
833      This example enables four layers, one of which is a custom,
834      user-defined layer named ``meta-mykernel``.
835
836   :term:`BBLAYERS_FETCH_DIR`
837      See :term:`bitbake:BBLAYERS_FETCH_DIR` in the BitBake manual.
838
839   :term:`BBMASK`
840      Prevents BitBake from processing recipes and recipe append files.
841
842      You can use the :term:`BBMASK` variable to "hide" these ``.bb`` and
843      ``.bbappend`` files. BitBake ignores any recipe or recipe append
844      files that match any of the expressions. It is as if BitBake does not
845      see them at all. Consequently, matching files are not parsed or
846      otherwise used by BitBake.
847
848      The values you provide are passed to Python's regular expression
849      compiler. Consequently, the syntax follows Python's Regular
850      Expression (re) syntax. The expressions are compared against the full
851      paths to the files. For complete syntax information, see Python's
852      documentation at https://docs.python.org/3/library/re.html#regular-expression-syntax.
853
854      The following example uses a complete regular expression to tell
855      BitBake to ignore all recipe and recipe append files in the
856      ``meta-ti/recipes-misc/`` directory::
857
858         BBMASK = "meta-ti/recipes-misc/"
859
860      If you want to mask out multiple directories or recipes, you can
861      specify multiple regular expression fragments. This next example
862      masks out multiple directories and individual recipes::
863
864         BBMASK += "/meta-ti/recipes-misc/ meta-ti/recipes-ti/packagegroup/"
865         BBMASK += "/meta-oe/recipes-support/"
866         BBMASK += "/meta-foo/.*/openldap"
867         BBMASK += "opencv.*\.bbappend"
868         BBMASK += "lzma"
869
870      .. note::
871
872         When specifying a directory name, use the trailing slash character
873         to ensure you match just that directory name.
874
875   :term:`BBMULTICONFIG`
876      Specifies each additional separate configuration when you are
877      building targets with multiple configurations. Use this variable in
878      your ``conf/local.conf`` configuration file. Specify a
879      multiconfigname for each configuration file you are using. For
880      example, the following line specifies three configuration files::
881
882         BBMULTICONFIG = "configA configB configC"
883
884      Each configuration file you use must reside in a ``multiconfig``
885      subdirectory of a configuration directory within a layer, or
886      within the :term:`Build Directory` (e.g.
887      ``build_directory/conf/multiconfig/configA.conf`` or
888      ``mylayer/conf/multiconfig/configB.conf``).
889
890      For information on how to use :term:`BBMULTICONFIG` in an environment
891      that supports building targets with multiple configurations, see the
892      ":ref:`dev-manual/building:building images for multiple targets using multiple configurations`"
893      section in the Yocto Project Development Tasks Manual.
894
895   :term:`BBPATH`
896      See :term:`bitbake:BBPATH` in the BitBake manual.
897
898   :term:`BBSERVER`
899      If defined in the BitBake environment, :term:`BBSERVER` points to the
900      BitBake remote server.
901
902      Use the following format to export the variable to the BitBake
903      environment::
904
905         export BBSERVER=localhost:$port
906
907      By default, :term:`BBSERVER` also appears in :term:`BB_BASEHASH_IGNORE_VARS`.
908      Consequently, :term:`BBSERVER` is excluded from checksum and dependency
909      data.
910
911   :term:`BBTARGETS`
912      See :term:`bitbake:BBTARGETS` in the BitBake manual.
913
914   :term:`BINCONFIG`
915      When inheriting the :ref:`ref-classes-binconfig-disabled` class, this
916      variable specifies binary configuration scripts to disable in favor of
917      using ``pkg-config`` to query the information. The
918      :ref:`ref-classes-binconfig-disabled` class will modify the specified
919      scripts to return an error so that calls to them can be easily found
920      and replaced.
921
922      To add multiple scripts, separate them by spaces. Here is an example
923      from the ``libpng`` recipe::
924
925         BINCONFIG = "${bindir}/libpng-config ${bindir}/libpng16-config"
926
927   :term:`BINCONFIG_GLOB`
928      When inheriting the :ref:`ref-classes-binconfig` class,
929      this variable specifies a wildcard for configuration scripts that
930      need editing. The scripts are edited to correct any paths that have
931      been set up during compilation so that they are correct for use when
932      installed into the sysroot and called by the build processes of other
933      recipes.
934
935      .. note::
936
937         The :term:`BINCONFIG_GLOB` variable uses
938         `shell globbing <https://tldp.org/LDP/abs/html/globbingref.html>`__,
939         which is recognition and expansion of wildcards during pattern
940         matching. Shell globbing is very similar to
941         `fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__
942         and `glob <https://docs.python.org/3/library/glob.html>`__.
943
944      For more information on how this variable works, see
945      ``meta/classes-recipe/binconfig.bbclass`` in the :term:`Source Directory`.
946      You can also find general
947      information on the class in the
948      ":ref:`ref-classes-binconfig`" section.
949
950   :term:`BITBAKE_UI`
951      See :term:`bitbake:BITBAKE_UI` in the BitBake manual.
952
953   :term:`BP`
954      The base recipe name and version but without any special recipe name
955      suffix (i.e. ``-native``, ``lib64-``, and so forth). :term:`BP` is
956      comprised of the following::
957
958         ${BPN}-${PV}
959
960   :term:`BPN`
961      This variable is a version of the :term:`PN` variable with
962      common prefixes and suffixes removed, such as ``nativesdk-``,
963      ``-cross``, ``-native``, and multilib's ``lib64-`` and ``lib32-``.
964      The exact lists of prefixes and suffixes removed are specified by the
965      :term:`MLPREFIX` and
966      :term:`SPECIAL_PKGSUFFIX` variables,
967      respectively.
968
969   :term:`BUGTRACKER`
970      Specifies a URL for an upstream bug tracking website for a recipe.
971      The OpenEmbedded build system does not use this variable. Rather, the
972      variable is a useful pointer in case a bug in the software being
973      built needs to be manually reported.
974
975   :term:`BUILD_ARCH`
976      Specifies the architecture of the build host (e.g. ``i686``). The
977      OpenEmbedded build system sets the value of :term:`BUILD_ARCH` from the
978      machine name reported by the ``uname`` command.
979
980   :term:`BUILD_AS_ARCH`
981      Specifies the architecture-specific assembler flags for the build
982      host. By default, the value of :term:`BUILD_AS_ARCH` is empty.
983
984   :term:`BUILD_CC_ARCH`
985      Specifies the architecture-specific C compiler flags for the build
986      host. By default, the value of :term:`BUILD_CC_ARCH` is empty.
987
988   :term:`BUILD_CCLD`
989      Specifies the linker command to be used for the build host when the C
990      compiler is being used as the linker. By default, :term:`BUILD_CCLD`
991      points to GCC and passes as arguments the value of
992      :term:`BUILD_CC_ARCH`, assuming
993      :term:`BUILD_CC_ARCH` is set.
994
995   :term:`BUILD_CFLAGS`
996      Specifies the flags to pass to the C compiler when building for the
997      build host. When building in the ``-native`` context,
998      :term:`CFLAGS` is set to the value of this variable by
999      default.
1000
1001   :term:`BUILD_CPPFLAGS`
1002      Specifies the flags to pass to the C preprocessor (i.e. to both the C
1003      and the C++ compilers) when building for the build host. When
1004      building in the ``-native`` context, :term:`CPPFLAGS`
1005      is set to the value of this variable by default.
1006
1007   :term:`BUILD_CXXFLAGS`
1008      Specifies the flags to pass to the C++ compiler when building for the
1009      build host. When building in the ``-native`` context,
1010      :term:`CXXFLAGS` is set to the value of this variable
1011      by default.
1012
1013   :term:`BUILD_FC`
1014      Specifies the Fortran compiler command for the build host. By
1015      default, :term:`BUILD_FC` points to Gfortran and passes as arguments the
1016      value of :term:`BUILD_CC_ARCH`, assuming
1017      :term:`BUILD_CC_ARCH` is set.
1018
1019   :term:`BUILD_LD`
1020      Specifies the linker command for the build host. By default,
1021      :term:`BUILD_LD` points to the GNU linker (ld) and passes as arguments
1022      the value of :term:`BUILD_LD_ARCH`, assuming
1023      :term:`BUILD_LD_ARCH` is set.
1024
1025   :term:`BUILD_LD_ARCH`
1026      Specifies architecture-specific linker flags for the build host. By
1027      default, the value of :term:`BUILD_LD_ARCH` is empty.
1028
1029   :term:`BUILD_LDFLAGS`
1030      Specifies the flags to pass to the linker when building for the build
1031      host. When building in the ``-native`` context,
1032      :term:`LDFLAGS` is set to the value of this variable
1033      by default.
1034
1035   :term:`BUILD_OPTIMIZATION`
1036      Specifies the optimization flags passed to the C compiler when
1037      building for the build host or the SDK. The flags are passed through
1038      the :term:`BUILD_CFLAGS` and
1039      :term:`BUILDSDK_CFLAGS` default values.
1040
1041      The default value of the :term:`BUILD_OPTIMIZATION` variable is "-O2
1042      -pipe".
1043
1044   :term:`BUILD_OS`
1045      Specifies the operating system in use on the build host (e.g.
1046      "linux"). The OpenEmbedded build system sets the value of
1047      :term:`BUILD_OS` from the OS reported by the ``uname`` command --- the
1048      first word, converted to lower-case characters.
1049
1050   :term:`BUILD_PREFIX`
1051      The toolchain binary prefix used for native recipes. The OpenEmbedded
1052      build system uses the :term:`BUILD_PREFIX` value to set the
1053      :term:`TARGET_PREFIX` when building for :ref:`ref-classes-native` recipes.
1054
1055   :term:`BUILD_STRIP`
1056      Specifies the command to be used to strip debugging symbols from
1057      binaries produced for the build host. By default, :term:`BUILD_STRIP`
1058      points to
1059      ``${``\ :term:`BUILD_PREFIX`\ ``}strip``.
1060
1061   :term:`BUILD_SYS`
1062      Specifies the system, including the architecture and the operating
1063      system, to use when building for the build host (i.e. when building
1064      :ref:`ref-classes-native` recipes).
1065
1066      The OpenEmbedded build system automatically sets this variable based
1067      on :term:`BUILD_ARCH`,
1068      :term:`BUILD_VENDOR`, and
1069      :term:`BUILD_OS`. You do not need to set the
1070      :term:`BUILD_SYS` variable yourself.
1071
1072   :term:`BUILD_VENDOR`
1073      Specifies the vendor name to use when building for the build host.
1074      The default value is an empty string ("").
1075
1076   :term:`BUILDDIR`
1077      Points to the location of the :term:`Build Directory`. You can define
1078      this directory indirectly through the :ref:`structure-core-script` script
1079      by passing in a :term:`Build Directory` path when you run the script. If
1080      you run the script and do not provide a :term:`Build Directory` path, the
1081      :term:`BUILDDIR` defaults to ``build`` in the current directory.
1082
1083   :term:`BUILDHISTORY_COMMIT`
1084      When inheriting the :ref:`ref-classes-buildhistory` class, this variable
1085      specifies whether or not to commit the build history output in a local
1086      Git repository. If set to "1", this local repository will be maintained
1087      automatically by the :ref:`ref-classes-buildhistory` class and a commit
1088      will be created on every build for changes to each top-level subdirectory
1089      of the build history output (images, packages, and sdk). If you want to
1090      track changes to build history over time, you should set this value to
1091      "1".
1092
1093      By default, the :ref:`ref-classes-buildhistory` class
1094      enables committing the buildhistory output in a local Git repository::
1095
1096         BUILDHISTORY_COMMIT ?= "1"
1097
1098   :term:`BUILDHISTORY_COMMIT_AUTHOR`
1099      When inheriting the :ref:`ref-classes-buildhistory`
1100      class, this variable specifies the author to use for each Git commit.
1101      In order for the :term:`BUILDHISTORY_COMMIT_AUTHOR` variable to work, the
1102      :term:`BUILDHISTORY_COMMIT` variable must
1103      be set to "1".
1104
1105      Git requires that the value you provide for the
1106      :term:`BUILDHISTORY_COMMIT_AUTHOR` variable takes the form of "name
1107      email@host". Providing an email address or host that is not valid
1108      does not produce an error.
1109
1110      By default, the :ref:`ref-classes-buildhistory` class sets the variable
1111      as follows::
1112
1113         BUILDHISTORY_COMMIT_AUTHOR ?= "buildhistory <buildhistory@${DISTRO}>"
1114
1115   :term:`BUILDHISTORY_DIR`
1116      When inheriting the :ref:`ref-classes-buildhistory`
1117      class, this variable specifies the directory in which build history
1118      information is kept. For more information on how the variable works,
1119      see the :ref:`ref-classes-buildhistory` class.
1120
1121      By default, the :ref:`ref-classes-buildhistory` class sets the directory
1122      as follows::
1123
1124         BUILDHISTORY_DIR ?= "${TOPDIR}/buildhistory"
1125
1126   :term:`BUILDHISTORY_FEATURES`
1127      When inheriting the :ref:`ref-classes-buildhistory`
1128      class, this variable specifies the build history features to be
1129      enabled. For more information on how build history works, see the
1130      ":ref:`dev-manual/build-quality:maintaining build output quality`"
1131      section in the Yocto Project Development Tasks Manual.
1132
1133      You can specify these features in the form of a space-separated list:
1134
1135      -  *image:* Analysis of the contents of images, which includes the
1136         list of installed packages among other things.
1137
1138      -  *package:* Analysis of the contents of individual packages.
1139
1140      -  *sdk:* Analysis of the contents of the software development kit
1141         (SDK).
1142
1143      -  *task:* Save output file signatures for
1144         :ref:`shared state <overview-manual/concepts:shared state cache>`
1145         (sstate) tasks.
1146         This saves one file per task and lists the SHA-256 checksums for
1147         each file staged (i.e. the output of the task).
1148
1149      By default, the :ref:`ref-classes-buildhistory` class enables the
1150      following features::
1151
1152         BUILDHISTORY_FEATURES ?= "image package sdk"
1153
1154   :term:`BUILDHISTORY_IMAGE_FILES`
1155      When inheriting the :ref:`ref-classes-buildhistory`
1156      class, this variable specifies a list of paths to files copied from
1157      the image contents into the build history directory under an
1158      "image-files" directory in the directory for the image, so that you
1159      can track the contents of each file. The default is to copy
1160      ``/etc/passwd`` and ``/etc/group``, which allows you to monitor for
1161      changes in user and group entries. You can modify the list to include
1162      any file. Specifying an invalid path does not produce an error.
1163      Consequently, you can include files that might not always be present.
1164
1165      By default, the :ref:`ref-classes-buildhistory` class provides paths to
1166      the following files::
1167
1168         BUILDHISTORY_IMAGE_FILES ?= "/etc/passwd /etc/group"
1169
1170   :term:`BUILDHISTORY_PATH_PREFIX_STRIP`
1171      When inheriting the :ref:`ref-classes-buildhistory`
1172      class, this variable specifies a common path prefix that should be
1173      stripped off the beginning of paths in the task signature list when the
1174      ``task`` feature is active in :term:`BUILDHISTORY_FEATURES`. This can be
1175      useful when build history is populated from multiple sources that may not
1176      all use the same top level directory.
1177
1178      By default, the :ref:`ref-classes-buildhistory` class sets the variable
1179      as follows::
1180
1181         BUILDHISTORY_PATH_PREFIX_STRIP ?= ""
1182
1183      In this case, no prefixes will be stripped.
1184
1185   :term:`BUILDHISTORY_PUSH_REPO`
1186      When inheriting the :ref:`ref-classes-buildhistory` class, this variable
1187      optionally specifies a remote repository to which build history pushes
1188      Git changes. In order for :term:`BUILDHISTORY_PUSH_REPO` to work,
1189      :term:`BUILDHISTORY_COMMIT` must be set to "1".
1190
1191      The repository should correspond to a remote address that specifies a
1192      repository as understood by Git, or alternatively to a remote name
1193      that you have set up manually using ``git remote`` within the local
1194      repository.
1195
1196      By default, the :ref:`ref-classes-buildhistory` class sets the variable
1197      as follows::
1198
1199         BUILDHISTORY_PUSH_REPO ?= ""
1200
1201   :term:`BUILDNAME`
1202      See :term:`bitbake:BUILDNAME` in the BitBake manual.
1203
1204   :term:`BUILDSDK_CFLAGS`
1205      Specifies the flags to pass to the C compiler when building for the
1206      SDK. When building in the ``nativesdk-`` context,
1207      :term:`CFLAGS` is set to the value of this variable by
1208      default.
1209
1210   :term:`BUILDSDK_CPPFLAGS`
1211      Specifies the flags to pass to the C pre-processor (i.e. to both the
1212      C and the C++ compilers) when building for the SDK. When building in
1213      the ``nativesdk-`` context, :term:`CPPFLAGS` is set
1214      to the value of this variable by default.
1215
1216   :term:`BUILDSDK_CXXFLAGS`
1217      Specifies the flags to pass to the C++ compiler when building for the
1218      SDK. When building in the ``nativesdk-`` context,
1219      :term:`CXXFLAGS` is set to the value of this variable
1220      by default.
1221
1222   :term:`BUILDSDK_LDFLAGS`
1223      Specifies the flags to pass to the linker when building for the SDK.
1224      When building in the ``nativesdk-`` context,
1225      :term:`LDFLAGS` is set to the value of this variable
1226      by default.
1227
1228   :term:`BUILDSTATS_BASE`
1229      Points to the location of the directory that holds build statistics
1230      when you use and enable the :ref:`ref-classes-buildstats` class. The
1231      :term:`BUILDSTATS_BASE` directory defaults to
1232      ``${``\ :term:`TMPDIR`\ ``}/buildstats/``.
1233
1234   :term:`BUSYBOX_SPLIT_SUID`
1235      For the BusyBox recipe, specifies whether to split the output
1236      executable file into two parts: one for features that require
1237      ``setuid root``, and one for the remaining features (i.e. those that
1238      do not require ``setuid root``).
1239
1240      The :term:`BUSYBOX_SPLIT_SUID` variable defaults to "1", which results in
1241      splitting the output executable file. Set the variable to "0" to get
1242      a single output executable file.
1243
1244   :term:`BZRDIR`
1245      See :term:`bitbake:BZRDIR` in the BitBake manual.
1246
1247   :term:`CACHE`
1248      Specifies the directory BitBake uses to store a cache of the
1249      :term:`Metadata` so it does not need to be parsed every time
1250      BitBake is started.
1251
1252   :term:`CC`
1253      The minimal command and arguments used to run the C compiler.
1254
1255   :term:`CFLAGS`
1256      Specifies the flags to pass to the C compiler. This variable is
1257      exported to an environment variable and thus made visible to the
1258      software being built during the compilation step.
1259
1260      Default initialization for :term:`CFLAGS` varies depending on what is
1261      being built:
1262
1263      -  :term:`TARGET_CFLAGS` when building for the
1264         target
1265
1266      -  :term:`BUILD_CFLAGS` when building for the
1267         build host (i.e. ``-native``)
1268
1269      -  :term:`BUILDSDK_CFLAGS` when building for
1270         an SDK (i.e. ``nativesdk-``)
1271
1272   :term:`CLASSOVERRIDE`
1273      An internal variable specifying the special class override that
1274      should currently apply (e.g. "class-target", "class-native", and so
1275      forth). The classes that use this variable (e.g.
1276      :ref:`ref-classes-native`, :ref:`ref-classes-nativesdk`, and so forth)
1277      set the variable to appropriate values.
1278
1279      .. note::
1280
1281         :term:`CLASSOVERRIDE` gets its default "class-target" value from the
1282         ``bitbake.conf`` file.
1283
1284      As an example, the following override allows you to install extra
1285      files, but only when building for the target::
1286
1287         do_install:append:class-target() {
1288             install my-extra-file ${D}${sysconfdir}
1289         }
1290
1291      Here is an example where ``FOO`` is set to
1292      "native" when building for the build host, and to "other" when not
1293      building for the build host::
1294
1295         FOO:class-native = "native"
1296         FOO = "other"
1297
1298      The underlying mechanism behind :term:`CLASSOVERRIDE` is simply
1299      that it is included in the default value of
1300      :term:`OVERRIDES`.
1301
1302   :term:`CLEANBROKEN`
1303      If set to "1" within a recipe, :term:`CLEANBROKEN` specifies that the
1304      ``make clean`` command does not work for the software being built.
1305      Consequently, the OpenEmbedded build system will not try to run
1306      ``make clean`` during the :ref:`ref-tasks-configure`
1307      task, which is the default behavior.
1308
1309   :term:`COMBINED_FEATURES`
1310      Provides a list of hardware features that are enabled in both
1311      :term:`MACHINE_FEATURES` and
1312      :term:`DISTRO_FEATURES`. This select list of
1313      features contains features that make sense to be controlled both at
1314      the machine and distribution configuration level. For example, the
1315      "bluetooth" feature requires hardware support but should also be
1316      optional at the distribution level, in case the hardware supports
1317      Bluetooth but you do not ever intend to use it.
1318
1319   :term:`COMMERCIAL_AUDIO_PLUGINS`
1320      This variable is specific to the :yocto_git:`GStreamer recipes
1321      </poky/tree/meta/recipes-multimedia/gstreamer/gstreamer1.0-meta-base.bb>`.
1322      It allows to build the GStreamer `"ugly"
1323      <https://github.com/GStreamer/gst-plugins-ugly>`__  and
1324      `"bad" <https://github.com/GStreamer/gst-plugins-bad>`__ audio plugins.
1325
1326      See the :ref:`dev-manual/licenses:other variables related to commercial licenses`
1327      section for usage details.
1328
1329   :term:`COMMERCIAL_VIDEO_PLUGINS`
1330      This variable is specific to the :yocto_git:`GStreamer recipes
1331      </poky/tree/meta/recipes-multimedia/gstreamer/gstreamer1.0-meta-base.bb>`.
1332      It allows to build the GStreamer `"ugly"
1333      <https://github.com/GStreamer/gst-plugins-ugly>`__  and
1334      `"bad" <https://github.com/GStreamer/gst-plugins-bad>`__ video plugins.
1335
1336      See the :ref:`dev-manual/licenses:other variables related to commercial licenses`
1337      section for usage details.
1338
1339   :term:`COMMON_LICENSE_DIR`
1340      Points to ``meta/files/common-licenses`` in the
1341      :term:`Source Directory`, which is where generic license
1342      files reside.
1343
1344   :term:`COMPATIBLE_HOST`
1345      A regular expression that resolves to one or more hosts (when the
1346      recipe is native) or one or more targets (when the recipe is
1347      non-native) with which a recipe is compatible. The regular expression
1348      is matched against :term:`HOST_SYS`. You can use the
1349      variable to stop recipes from being built for classes of systems with
1350      which the recipes are not compatible. Stopping these builds is
1351      particularly useful with kernels. The variable also helps to increase
1352      parsing speed since the build system skips parsing recipes not
1353      compatible with the current system.
1354
1355   :term:`COMPATIBLE_MACHINE`
1356      A regular expression that resolves to one or more target machines
1357      with which a recipe is compatible. The regular expression is matched
1358      against :term:`MACHINEOVERRIDES`. You can use
1359      the variable to stop recipes from being built for machines with which
1360      the recipes are not compatible. Stopping these builds is particularly
1361      useful with kernels. The variable also helps to increase parsing
1362      speed since the build system skips parsing recipes not compatible
1363      with the current machine.
1364
1365   :term:`COMPLEMENTARY_GLOB`
1366      Defines wildcards to match when installing a list of complementary
1367      packages for all the packages explicitly (or implicitly) installed in
1368      an image.
1369
1370      The :term:`COMPLEMENTARY_GLOB` variable uses Unix filename pattern matching
1371      (`fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__),
1372      which is similar to the Unix style pathname pattern expansion
1373      (`glob <https://docs.python.org/3/library/glob.html>`__).
1374
1375      The resulting list of complementary packages is associated with an
1376      item that can be added to
1377      :term:`IMAGE_FEATURES`. An example usage of
1378      this is the "dev-pkgs" item that when added to :term:`IMAGE_FEATURES`
1379      will install -dev packages (containing headers and other development
1380      files) for every package in the image.
1381
1382      To add a new feature item pointing to a wildcard, use a variable flag
1383      to specify the feature item name and use the value to specify the
1384      wildcard. Here is an example::
1385
1386         COMPLEMENTARY_GLOB[dev-pkgs] = '*-dev'
1387
1388      .. note::
1389
1390         When installing complementary packages, recommends relationships
1391         (set via :term:`RRECOMMENDS`) are always ignored.
1392
1393   :term:`COMPONENTS_DIR`
1394      Stores sysroot components for each recipe. The OpenEmbedded build
1395      system uses :term:`COMPONENTS_DIR` when constructing recipe-specific
1396      sysroots for other recipes.
1397
1398      The default is
1399      "``${``\ :term:`STAGING_DIR`\ ``}-components``."
1400      (i.e.
1401      "``${``\ :term:`TMPDIR`\ ``}/sysroots-components``").
1402
1403   :term:`CONF_VERSION`
1404      Tracks the version of the local configuration file (i.e.
1405      ``local.conf``). The value for :term:`CONF_VERSION` increments each time
1406      ``build/conf/`` compatibility changes.
1407
1408   :term:`CONFFILES`
1409      Identifies editable or configurable files that are part of a package.
1410      If the Package Management System (PMS) is being used to update
1411      packages on the target system, it is possible that configuration
1412      files you have changed after the original installation and that you
1413      now want to remain unchanged are overwritten. In other words,
1414      editable files might exist in the package that you do not want reset
1415      as part of the package update process. You can use the :term:`CONFFILES`
1416      variable to list the files in the package that you wish to prevent
1417      the PMS from overwriting during this update process.
1418
1419      To use the :term:`CONFFILES` variable, provide a package name override
1420      that identifies the resulting package. Then, provide a
1421      space-separated list of files. Here is an example::
1422
1423         CONFFILES:${PN} += "${sysconfdir}/file1 \
1424             ${sysconfdir}/file2 ${sysconfdir}/file3"
1425
1426      There is a relationship between the :term:`CONFFILES` and :term:`FILES`
1427      variables. The files listed within :term:`CONFFILES` must be a subset of
1428      the files listed within :term:`FILES`. Because the configuration files
1429      you provide with :term:`CONFFILES` are simply being identified so that
1430      the PMS will not overwrite them, it makes sense that the files must
1431      already be included as part of the package through the :term:`FILES`
1432      variable.
1433
1434      .. note::
1435
1436         When specifying paths as part of the :term:`CONFFILES` variable, it is
1437         good practice to use appropriate path variables.
1438         For example, ``${sysconfdir}`` rather than ``/etc`` or ``${bindir}``
1439         rather than ``/usr/bin``. You can find a list of these variables at
1440         the top of the ``meta/conf/bitbake.conf`` file in the
1441         :term:`Source Directory`.
1442
1443   :term:`CONFIG_INITRAMFS_SOURCE`
1444      Identifies the initial RAM filesystem (:term:`Initramfs`) source files. The
1445      OpenEmbedded build system receives and uses this kernel Kconfig
1446      variable as an environment variable. By default, the variable is set
1447      to null ("").
1448
1449      The :term:`CONFIG_INITRAMFS_SOURCE` can be either a single cpio archive
1450      with a ``.cpio`` suffix or a space-separated list of directories and
1451      files for building the :term:`Initramfs` image. A cpio archive should contain
1452      a filesystem archive to be used as an :term:`Initramfs` image. Directories
1453      should contain a filesystem layout to be included in the :term:`Initramfs`
1454      image. Files should contain entries according to the format described
1455      by the ``usr/gen_init_cpio`` program in the kernel tree.
1456
1457      If you specify multiple directories and files, the :term:`Initramfs` image
1458      will be the aggregate of all of them.
1459
1460      For information on creating an :term:`Initramfs`, see the
1461      ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
1462      in the Yocto Project Development Tasks Manual.
1463
1464   :term:`CONFIG_SITE`
1465      A list of files that contains ``autoconf`` test results relevant to
1466      the current build. This variable is used by the Autotools utilities
1467      when running ``configure``.
1468
1469   :term:`CONFIGURE_FLAGS`
1470      The minimal arguments for GNU configure.
1471
1472   :term:`CONFLICT_DISTRO_FEATURES`
1473      When inheriting the :ref:`ref-classes-features_check`
1474      class, this variable identifies distribution features that would be
1475      in conflict should the recipe be built. In other words, if the
1476      :term:`CONFLICT_DISTRO_FEATURES` variable lists a feature that also
1477      appears in :term:`DISTRO_FEATURES` within the current configuration, then
1478      the recipe will be skipped, and if the build system attempts to build
1479      the recipe then an error will be triggered.
1480
1481   :term:`CONVERSION_CMD`
1482      This variable is used for storing image conversion commands.
1483      Image conversion can convert an image into different objects like:
1484
1485      -   Compressed version of the image
1486
1487      -   Checksums for the image
1488
1489      An example of :term:`CONVERSION_CMD` from :ref:`ref-classes-image_types`
1490      class is::
1491
1492         CONVERSION_CMD:lzo = "lzop -9 ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}"
1493
1494   :term:`COPY_LIC_DIRS`
1495      If set to "1" along with the
1496      :term:`COPY_LIC_MANIFEST` variable, the
1497      OpenEmbedded build system copies into the image the license files,
1498      which are located in ``/usr/share/common-licenses``, for each
1499      package. The license files are placed in directories within the image
1500      itself during build time.
1501
1502      .. note::
1503
1504         The :term:`COPY_LIC_DIRS` does not offer a path for adding licenses for
1505         newly installed packages to an image, which might be most suitable for
1506         read-only filesystems that cannot be upgraded. See the
1507         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1508         You can also reference the ":ref:`dev-manual/licenses:providing license text`"
1509         section in the Yocto Project Development Tasks Manual for
1510         information on providing license text.
1511
1512   :term:`COPY_LIC_MANIFEST`
1513      If set to "1", the OpenEmbedded build system copies the license
1514      manifest for the image to
1515      ``/usr/share/common-licenses/license.manifest`` within the image
1516      itself during build time.
1517
1518      .. note::
1519
1520         The :term:`COPY_LIC_MANIFEST` does not offer a path for adding licenses for
1521         newly installed packages to an image, which might be most suitable for
1522         read-only filesystems that cannot be upgraded. See the
1523         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1524         You can also reference the ":ref:`dev-manual/licenses:providing license text`"
1525         section in the Yocto Project Development Tasks Manual for
1526         information on providing license text.
1527
1528   :term:`COPYLEFT_LICENSE_EXCLUDE`
1529      A space-separated list of licenses to exclude from the source archived by
1530      the :ref:`ref-classes-archiver` class. In other words, if a license in a
1531      recipe's :term:`LICENSE` value is in the value of
1532      :term:`COPYLEFT_LICENSE_EXCLUDE`, then its source is not archived by the
1533      class.
1534
1535      .. note::
1536
1537         The :term:`COPYLEFT_LICENSE_EXCLUDE` variable takes precedence over the
1538         :term:`COPYLEFT_LICENSE_INCLUDE` variable.
1539
1540      The default value, which is "CLOSED Proprietary", for
1541      :term:`COPYLEFT_LICENSE_EXCLUDE` is set by the
1542      :ref:`ref-classes-copyleft_filter` class, which
1543      is inherited by the :ref:`ref-classes-archiver` class.
1544
1545   :term:`COPYLEFT_LICENSE_INCLUDE`
1546      A space-separated list of licenses to include in the source archived
1547      by the :ref:`ref-classes-archiver` class. In other
1548      words, if a license in a recipe's :term:`LICENSE`
1549      value is in the value of :term:`COPYLEFT_LICENSE_INCLUDE`, then its
1550      source is archived by the class.
1551
1552      The default value is set by the :ref:`ref-classes-copyleft_filter` class,
1553      which is inherited by the :ref:`ref-classes-archiver` class. The default
1554      value includes "GPL*", "LGPL*", and "AGPL*".
1555
1556   :term:`COPYLEFT_PN_EXCLUDE`
1557      A list of recipes to exclude in the source archived by the
1558      :ref:`ref-classes-archiver` class. The :term:`COPYLEFT_PN_EXCLUDE`
1559      variable overrides the license inclusion and exclusion caused through the
1560      :term:`COPYLEFT_LICENSE_INCLUDE` and :term:`COPYLEFT_LICENSE_EXCLUDE`
1561      variables, respectively.
1562
1563      The default value, which is "" indicating to not explicitly exclude
1564      any recipes by name, for :term:`COPYLEFT_PN_EXCLUDE` is set by the
1565      :ref:`ref-classes-copyleft_filter` class, which is inherited by the
1566      :ref:`ref-classes-archiver` class.
1567
1568   :term:`COPYLEFT_PN_INCLUDE`
1569      A list of recipes to include in the source archived by the
1570      :ref:`ref-classes-archiver` class. The :term:`COPYLEFT_PN_INCLUDE`
1571      variable overrides the license inclusion and exclusion caused through the
1572      :term:`COPYLEFT_LICENSE_INCLUDE` and :term:`COPYLEFT_LICENSE_EXCLUDE`
1573      variables, respectively.
1574
1575      The default value, which is "" indicating to not explicitly include
1576      any recipes by name, for :term:`COPYLEFT_PN_INCLUDE` is set by the
1577      :ref:`ref-classes-copyleft_filter` class, which is inherited by the
1578      :ref:`ref-classes-archiver` class.
1579
1580   :term:`COPYLEFT_RECIPE_TYPES`
1581      A space-separated list of recipe types to include in the source
1582      archived by the :ref:`archiver <ref-classes-archiver>` class.
1583      Recipe types are ``target``, :ref:`ref-classes-native`,
1584      :ref:`ref-classes-nativesdk`, :ref:`ref-classes-cross`,
1585      :ref:`ref-classes-crosssdk`, and :ref:`ref-classes-cross-canadian`.
1586
1587      The default value, which is "target*", for :term:`COPYLEFT_RECIPE_TYPES`
1588      is set by the :ref:`ref-classes-copyleft_filter` class, which is
1589      inherited by the :ref:`ref-classes-archiver` class.
1590
1591   :term:`CORE_IMAGE_EXTRA_INSTALL`
1592      Specifies the list of packages to be added to the image. You should
1593      only set this variable in the ``local.conf`` configuration file found
1594      in the :term:`Build Directory`.
1595
1596      This variable replaces ``POKY_EXTRA_INSTALL``, which is no longer
1597      supported.
1598
1599   :term:`COREBASE`
1600      Specifies the parent directory of the OpenEmbedded-Core Metadata
1601      layer (i.e. ``meta``).
1602
1603      It is an important distinction that :term:`COREBASE` points to the parent
1604      of this layer and not the layer itself. Consider an example where you
1605      have cloned the Poky Git repository and retained the ``poky`` name
1606      for your local copy of the repository. In this case, :term:`COREBASE`
1607      points to the ``poky`` folder because it is the parent directory of
1608      the ``poky/meta`` layer.
1609
1610   :term:`COREBASE_FILES`
1611      Lists files from the :term:`COREBASE` directory that
1612      should be copied other than the layers listed in the
1613      ``bblayers.conf`` file. The :term:`COREBASE_FILES` variable allows
1614      to copy metadata from the OpenEmbedded build system
1615      into the extensible SDK.
1616
1617      Explicitly listing files in :term:`COREBASE` is needed because it
1618      typically contains build directories and other files that should not
1619      normally be copied into the extensible SDK. Consequently, the value
1620      of :term:`COREBASE_FILES` is used in order to only copy the files that
1621      are actually needed.
1622
1623   :term:`CPP`
1624      The minimal command and arguments used to run the C preprocessor.
1625
1626   :term:`CPPFLAGS`
1627      Specifies the flags to pass to the C pre-processor (i.e. to both the
1628      C and the C++ compilers). This variable is exported to an environment
1629      variable and thus made visible to the software being built during the
1630      compilation step.
1631
1632      Default initialization for :term:`CPPFLAGS` varies depending on what is
1633      being built:
1634
1635      -  :term:`TARGET_CPPFLAGS` when building for
1636         the target
1637
1638      -  :term:`BUILD_CPPFLAGS` when building for the
1639         build host (i.e. ``-native``)
1640
1641      -  :term:`BUILDSDK_CPPFLAGS` when building
1642         for an SDK (i.e. ``nativesdk-``)
1643
1644   :term:`CROSS_COMPILE`
1645      The toolchain binary prefix for the target tools. The
1646      :term:`CROSS_COMPILE` variable is the same as the
1647      :term:`TARGET_PREFIX` variable.
1648
1649      .. note::
1650
1651         The OpenEmbedded build system sets the :term:`CROSS_COMPILE`
1652         variable only in certain contexts (e.g. when building for kernel
1653         and kernel module recipes).
1654
1655   :term:`CVE_CHECK_IGNORE`
1656      The list of CVE IDs which are ignored. Here is
1657      an example from the :oe_layerindex:`Python3 recipe</layerindex/recipe/23823>`::
1658
1659         # This is windows only issue.
1660         CVE_CHECK_IGNORE += "CVE-2020-15523"
1661
1662   :term:`CVE_CHECK_SHOW_WARNINGS`
1663      Specifies whether or not the :ref:`ref-classes-cve-check`
1664      class should generate warning messages on the console when unpatched
1665      CVEs are found. The default is "1", but you may wish to set it to "0" if
1666      you are already examining/processing the logs after the build has
1667      completed and thus do not need the warning messages.
1668
1669   :term:`CVE_CHECK_SKIP_RECIPE`
1670      The list of package names (:term:`PN`) for which
1671      CVEs (Common Vulnerabilities and Exposures) are ignored.
1672
1673   :term:`CVE_DB_UPDATE_INTERVAL`
1674      Specifies the CVE database update interval in seconds, as used by
1675      ``cve-update-db-native``. The default value is "86400" i.e. once a day
1676      (24*60*60). If the value is set to "0" then the update will be forced
1677      every time. Alternatively, a negative value e.g. "-1" will disable
1678      updates entirely.
1679
1680   :term:`CVE_PRODUCT`
1681      In a recipe, defines the name used to match the recipe name
1682      against the name in the upstream `NIST CVE database <https://nvd.nist.gov/>`__.
1683
1684      The default is ${:term:`BPN`} (except for recipes that inherit the
1685      :ref:`ref-classes-pypi` class where it is set based upon
1686      :term:`PYPI_PACKAGE`). If it does not match the name in the NIST CVE
1687      database or matches with multiple entries in the database, the default
1688      value needs to be changed.
1689
1690      Here is an example from the :oe_layerindex:`Berkeley DB recipe </layerindex/recipe/544>`::
1691
1692         CVE_PRODUCT = "oracle_berkeley_db berkeley_db"
1693
1694      Sometimes the product name is not specific enough, for example
1695      "tar" has been matching CVEs for the GNU ``tar`` package and also
1696      the ``node-tar`` node.js extension. To avoid this problem, use the
1697      vendor name as a prefix. The syntax for this is::
1698
1699         CVE_PRODUCT = "vendor:package"
1700
1701   :term:`CVE_VERSION`
1702      In a recipe, defines the version used to match the recipe version
1703      against the version in the `NIST CVE database <https://nvd.nist.gov/>`__
1704      when usign :ref:`ref-classes-cve-check`.
1705
1706      The default is ${:term:`PV`} but if recipes use custom version numbers
1707      which do not map to upstream software component release versions and the versions
1708      used in the CVE database, then this variable can be used to set the
1709      version number for :ref:`ref-classes-cve-check`. Example::
1710
1711          CVE_VERSION = "2.39"
1712
1713   :term:`CVSDIR`
1714      The directory in which files checked out under the CVS system are
1715      stored.
1716
1717   :term:`CXX`
1718      The minimal command and arguments used to run the C++ compiler.
1719
1720   :term:`CXXFLAGS`
1721      Specifies the flags to pass to the C++ compiler. This variable is
1722      exported to an environment variable and thus made visible to the
1723      software being built during the compilation step.
1724
1725      Default initialization for :term:`CXXFLAGS` varies depending on what is
1726      being built:
1727
1728      -  :term:`TARGET_CXXFLAGS` when building for
1729         the target
1730
1731      -  :term:`BUILD_CXXFLAGS` when building for the
1732         build host (i.e. ``-native``)
1733
1734      -  :term:`BUILDSDK_CXXFLAGS` when building
1735         for an SDK (i.e. ``nativesdk-``)
1736
1737   :term:`D`
1738      The destination directory. The location in the :term:`Build Directory`
1739      where components are installed by the
1740      :ref:`ref-tasks-install` task. This location defaults
1741      to::
1742
1743         ${WORKDIR}/image
1744
1745      .. note::
1746
1747         Tasks that read from or write to this directory should run under
1748         :ref:`fakeroot <overview-manual/concepts:fakeroot and pseudo>`.
1749
1750   :term:`DATE`
1751      The date the build was started. Dates appear using the year, month,
1752      and day (YMD) format (e.g. "20150209" for February 9th, 2015).
1753
1754   :term:`DATETIME`
1755      The date and time on which the current build started. The format is
1756      suitable for timestamps.
1757
1758   :term:`DEBIAN_NOAUTONAME`
1759      When the :ref:`ref-classes-debian` class is inherited,
1760      which is the default behavior, :term:`DEBIAN_NOAUTONAME` specifies a
1761      particular package should not be renamed according to Debian library
1762      package naming. You must use the package name as an override when you
1763      set this variable. Here is an example from the ``fontconfig`` recipe::
1764
1765         DEBIAN_NOAUTONAME:fontconfig-utils = "1"
1766
1767   :term:`DEBIANNAME`
1768      When the :ref:`ref-classes-debian` class is inherited,
1769      which is the default behavior, :term:`DEBIANNAME` allows you to override
1770      the library name for an individual package. Overriding the library
1771      name in these cases is rare. You must use the package name as an
1772      override when you set this variable. Here is an example from the
1773      ``dbus`` recipe::
1774
1775         DEBIANNAME:${PN} = "dbus-1"
1776
1777   :term:`DEBUG_BUILD`
1778      Specifies to build packages with debugging information. This
1779      influences the value of the :term:`SELECTED_OPTIMIZATION` variable.
1780
1781   :term:`DEBUG_OPTIMIZATION`
1782      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
1783      compiling a system for debugging. This variable defaults to "-O
1784      -fno-omit-frame-pointer ${DEBUG_FLAGS} -pipe".
1785
1786   :term:`DEBUG_PREFIX_MAP`
1787      Allows to set C compiler options, such as ``-fdebug-prefix-map``,
1788      ``-fmacro-prefix-map``, and ``-ffile-prefix-map``, which allow to
1789      replace build-time paths by install-time ones in the debugging sections
1790      of binaries.  This makes compiler output files location independent,
1791      at the cost of having to pass an extra command to tell the debugger
1792      where source files are.
1793
1794      This is used by the Yocto Project to guarantee
1795      :doc:`/test-manual/reproducible-builds` even when the source code of
1796      a package uses the ``__FILE__`` or ``assert()`` macros. See the
1797      `reproducible-builds.org <https://reproducible-builds.org/docs/build-path/>`__
1798      website for details.
1799
1800      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1801      not intended to be user-configurable.
1802
1803   :term:`DEFAULT_PREFERENCE`
1804      Specifies a weak bias for recipe selection priority.
1805
1806      The most common usage of this is variable is to set it to "-1" within
1807      a recipe for a development version of a piece of software. Using the
1808      variable in this way causes the stable version of the recipe to build
1809      by default in the absence of :term:`PREFERRED_VERSION` being used to
1810      build the development version.
1811
1812      .. note::
1813
1814         The bias provided by :term:`DEFAULT_PREFERENCE` is weak and is overridden
1815         by :term:`BBFILE_PRIORITY` if that variable is different between two
1816         layers that contain different versions of the same recipe.
1817
1818   :term:`DEFAULTTUNE`
1819      The default CPU and Application Binary Interface (ABI) tunings (i.e.
1820      the "tune") used by the OpenEmbedded build system. The
1821      :term:`DEFAULTTUNE` helps define
1822      :term:`TUNE_FEATURES`.
1823
1824      The default tune is either implicitly or explicitly set by the
1825      machine (:term:`MACHINE`). However, you can override
1826      the setting using available tunes as defined with
1827      :term:`AVAILTUNES`.
1828
1829   :term:`DEPENDS`
1830      Lists a recipe's build-time dependencies. These are dependencies on
1831      other recipes whose contents (e.g. headers and shared libraries) are
1832      needed by the recipe at build time.
1833
1834      As an example, consider a recipe ``foo`` that contains the following
1835      assignment::
1836
1837          DEPENDS = "bar"
1838
1839      The practical effect of the previous assignment is that all files
1840      installed by bar will be available in the appropriate staging sysroot,
1841      given by the :term:`STAGING_DIR* <STAGING_DIR>` variables, by the time
1842      the :ref:`ref-tasks-configure` task for ``foo`` runs. This mechanism is
1843      implemented by having :ref:`ref-tasks-configure` depend on the
1844      :ref:`ref-tasks-populate_sysroot` task of each recipe listed in
1845      :term:`DEPENDS`, through a
1846      ``[``\ :ref:`deptask <bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]``
1847      declaration in the :ref:`ref-classes-base` class.
1848
1849      .. note::
1850
1851         It seldom is necessary to reference, for example, :term:`STAGING_DIR_HOST`
1852         explicitly. The standard classes and build-related variables are
1853         configured to automatically use the appropriate staging sysroots.
1854
1855      As another example, :term:`DEPENDS` can also be used to add utilities
1856      that run on the build machine during the build. For example, a recipe
1857      that makes use of a code generator built by the recipe ``codegen``
1858      might have the following::
1859
1860         DEPENDS = "codegen-native"
1861
1862      For more
1863      information, see the :ref:`ref-classes-native` class and
1864      the :term:`EXTRANATIVEPATH` variable.
1865
1866      .. note::
1867
1868         -  :term:`DEPENDS` is a list of recipe names. Or, to be more precise,
1869            it is a list of :term:`PROVIDES` names, which
1870            usually match recipe names. Putting a package name such as
1871            "foo-dev" in :term:`DEPENDS` does not make sense. Use "foo"
1872            instead, as this will put files from all the packages that make
1873            up ``foo``, which includes those from ``foo-dev``, into the
1874            sysroot.
1875
1876         -  One recipe having another recipe in :term:`DEPENDS` does not by
1877            itself add any runtime dependencies between the packages
1878            produced by the two recipes. However, as explained in the
1879            ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
1880            section in the Yocto Project Overview and Concepts Manual,
1881            runtime dependencies will often be added automatically, meaning
1882            :term:`DEPENDS` alone is sufficient for most recipes.
1883
1884         -  Counterintuitively, :term:`DEPENDS` is often necessary even for
1885            recipes that install precompiled components. For example, if
1886            ``libfoo`` is a precompiled library that links against
1887            ``libbar``, then linking against ``libfoo`` requires both
1888            ``libfoo`` and ``libbar`` to be available in the sysroot.
1889            Without a :term:`DEPENDS` from the recipe that installs ``libfoo``
1890            to the recipe that installs ``libbar``, other recipes might
1891            fail to link against ``libfoo``.
1892
1893      For information on runtime dependencies, see the :term:`RDEPENDS`
1894      variable. You can also see the
1895      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
1896      ":ref:`bitbake-user-manual/bitbake-user-manual-execution:dependencies`"
1897      sections in the BitBake User Manual for additional information on tasks
1898      and dependencies.
1899
1900   :term:`DEPLOY_DIR`
1901      Points to the general area that the OpenEmbedded build system uses to
1902      place images, packages, SDKs, and other output files that are ready
1903      to be used outside of the build system. By default, this directory
1904      resides within the :term:`Build Directory` as ``${TMPDIR}/deploy``.
1905
1906      For more information on the structure of the Build Directory, see
1907      ":ref:`ref-manual/structure:the build directory --- \`\`build/\`\``" section.
1908      For more detail on the contents of the ``deploy`` directory, see the
1909      ":ref:`overview-manual/concepts:images`",
1910      ":ref:`overview-manual/concepts:package feeds`", and
1911      ":ref:`overview-manual/concepts:application development sdk`" sections all in the
1912      Yocto Project Overview and Concepts Manual.
1913
1914   :term:`DEPLOY_DIR_DEB`
1915      Points to the area that the OpenEmbedded build system uses to place
1916      Debian packages that are ready to be used outside of the build
1917      system. This variable applies only when :term:`PACKAGE_CLASSES` contains
1918      ":ref:`ref-classes-package_deb`".
1919
1920      The BitBake configuration file initially defines the
1921      :term:`DEPLOY_DIR_DEB` variable as a sub-folder of
1922      :term:`DEPLOY_DIR`::
1923
1924         DEPLOY_DIR_DEB = "${DEPLOY_DIR}/deb"
1925
1926      The :ref:`ref-classes-package_deb` class uses the
1927      :term:`DEPLOY_DIR_DEB` variable to make sure the
1928      :ref:`ref-tasks-package_write_deb` task
1929      writes Debian packages into the appropriate folder. For more
1930      information on how packaging works, see the
1931      ":ref:`overview-manual/concepts:package feeds`" section
1932      in the Yocto Project Overview and Concepts Manual.
1933
1934   :term:`DEPLOY_DIR_IMAGE`
1935      Points to the area that the OpenEmbedded build system uses to place
1936      images and other associated output files that are ready to be
1937      deployed onto the target machine. The directory is machine-specific
1938      as it contains the ``${MACHINE}`` name. By default, this directory
1939      resides within the :term:`Build Directory` as
1940      ``${DEPLOY_DIR}/images/${MACHINE}/``.
1941
1942      It must not be used directly in recipes when deploying files. Instead,
1943      it's only useful when a recipe needs to "read" a file already deployed
1944      by a dependency. So, it should be filled with the contents of
1945      :term:`DEPLOYDIR` by the :ref:`ref-classes-deploy` class or with the
1946      contents of :term:`IMGDEPLOYDIR` by the :ref:`ref-classes-image` class.
1947
1948      For more information on the structure of the :term:`Build Directory`, see
1949      ":ref:`ref-manual/structure:the build directory --- \`\`build/\`\``" section.
1950      For more detail on the contents of the ``deploy`` directory, see the
1951      ":ref:`overview-manual/concepts:images`" and
1952      ":ref:`overview-manual/concepts:application development sdk`" sections both in
1953      the Yocto Project Overview and Concepts Manual.
1954
1955   :term:`DEPLOY_DIR_IPK`
1956      Points to the area that the OpenEmbedded build system uses to place
1957      IPK packages that are ready to be used outside of the build system.
1958      This variable applies only when :term:`PACKAGE_CLASSES` contains
1959      ":ref:`ref-classes-package_ipk`".
1960
1961      The BitBake configuration file initially defines this variable as a
1962      sub-folder of :term:`DEPLOY_DIR`::
1963
1964         DEPLOY_DIR_IPK = "${DEPLOY_DIR}/ipk"
1965
1966      The :ref:`ref-classes-package_ipk` class uses the :term:`DEPLOY_DIR_IPK`
1967      variable to make sure the :ref:`ref-tasks-package_write_ipk` task
1968      writes IPK packages into the appropriate folder. For more information
1969      on how packaging works, see the
1970      ":ref:`overview-manual/concepts:package feeds`" section
1971      in the Yocto Project Overview and Concepts Manual.
1972
1973   :term:`DEPLOY_DIR_RPM`
1974      Points to the area that the OpenEmbedded build system uses to place
1975      RPM packages that are ready to be used outside of the build system.
1976      This variable applies only when :term:`PACKAGE_CLASSES` contains
1977      ":ref:`ref-classes-package_rpm`".
1978
1979      The BitBake configuration file initially defines this variable as a
1980      sub-folder of :term:`DEPLOY_DIR`::
1981
1982         DEPLOY_DIR_RPM = "${DEPLOY_DIR}/rpm"
1983
1984      The :ref:`ref-classes-package_rpm` class uses the
1985      :term:`DEPLOY_DIR_RPM` variable to make sure the
1986      :ref:`ref-tasks-package_write_rpm` task
1987      writes RPM packages into the appropriate folder. For more information
1988      on how packaging works, see the
1989      ":ref:`overview-manual/concepts:package feeds`" section
1990      in the Yocto Project Overview and Concepts Manual.
1991
1992   :term:`DEPLOYDIR`
1993      When inheriting the :ref:`ref-classes-deploy` class, the
1994      :term:`DEPLOYDIR` points to a temporary work area for deployed files that
1995      is set in the :ref:`ref-classes-deploy` class as follows::
1996
1997         DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
1998
1999      Recipes inheriting the :ref:`ref-classes-deploy` class should copy files to be
2000      deployed into :term:`DEPLOYDIR`, and the class will take care of copying
2001      them into :term:`DEPLOY_DIR_IMAGE`
2002      afterwards.
2003
2004   :term:`DESCRIPTION`
2005      The package description used by package managers. If not set,
2006      :term:`DESCRIPTION` takes the value of the :term:`SUMMARY`
2007      variable.
2008
2009   :term:`DEV_PKG_DEPENDENCY`
2010      Provides an easy way for recipes to disable or adjust the runtime recommendation
2011      (:term:`RRECOMMENDS`) of the ``${PN}-dev`` package on the main
2012      (``${PN}``) package.
2013
2014   :term:`DISABLE_STATIC`
2015      Used in order to disable static linking by default (in order to save
2016      space, since static libraries are often unused in embedded systems.)
2017      The default value is " --disable-static", however it can be set to ""
2018      in order to enable static linking if desired. Certain recipes do this
2019      individually, and also there is a
2020      ``meta/conf/distro/include/no-static-libs.inc`` include file that
2021      disables static linking for a number of recipes. Some software
2022      packages or build tools (such as CMake) have explicit support for
2023      enabling / disabling static linking, and in those cases
2024      :term:`DISABLE_STATIC` is not used.
2025
2026   :term:`DISTRO`
2027      The short name of the distribution. For information on the long name
2028      of the distribution, see the :term:`DISTRO_NAME`
2029      variable.
2030
2031      The :term:`DISTRO` variable corresponds to a distribution configuration
2032      file whose root name is the same as the variable's argument and whose
2033      filename extension is ``.conf``. For example, the distribution
2034      configuration file for the Poky distribution is named ``poky.conf``
2035      and resides in the ``meta-poky/conf/distro`` directory of the
2036      :term:`Source Directory`.
2037
2038      Within that ``poky.conf`` file, the :term:`DISTRO` variable is set as
2039      follows::
2040
2041         DISTRO = "poky"
2042
2043      Distribution configuration files are located in a ``conf/distro``
2044      directory within the :term:`Metadata` that contains the
2045      distribution configuration. The value for :term:`DISTRO` must not contain
2046      spaces, and is typically all lower-case.
2047
2048      .. note::
2049
2050         If the :term:`DISTRO` variable is blank, a set of default configurations
2051         are used, which are specified within
2052         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
2053
2054   :term:`DISTRO_CODENAME`
2055      Specifies a codename for the distribution being built.
2056
2057   :term:`DISTRO_EXTRA_RDEPENDS`
2058      Specifies a list of distro-specific packages to add to all images.
2059      This variable takes effect through ``packagegroup-base`` so the
2060      variable only really applies to the more full-featured images that
2061      include ``packagegroup-base``. You can use this variable to keep
2062      distro policy out of generic images. As with all other distro
2063      variables, you set this variable in the distro ``.conf`` file.
2064
2065   :term:`DISTRO_EXTRA_RRECOMMENDS`
2066      Specifies a list of distro-specific packages to add to all images if
2067      the packages exist. The packages might not exist or be empty (e.g.
2068      kernel modules). The list of packages are automatically installed but
2069      you can remove them.
2070
2071   :term:`DISTRO_FEATURES`
2072      The software support you want in your distribution for various
2073      features. You define your distribution features in the distribution
2074      configuration file.
2075
2076      In most cases, the presence or absence of a feature in
2077      :term:`DISTRO_FEATURES` is translated to the appropriate option supplied
2078      to the configure script during the
2079      :ref:`ref-tasks-configure` task for recipes that
2080      optionally support the feature. For example, specifying "x11" in
2081      :term:`DISTRO_FEATURES`, causes every piece of software built for the
2082      target that can optionally support X11 to have its X11 support
2083      enabled.
2084
2085      .. note::
2086
2087         Just enabling :term:`DISTRO_FEATURES` alone doesn't
2088         enable feature support for packages. Mechanisms such as making
2089         :term:`PACKAGECONFIG` track :term:`DISTRO_FEATURES` are used
2090         to enable/disable package features.
2091
2092      Two more examples are Bluetooth and NFS support. For a more complete
2093      list of features that ships with the Yocto Project and that you can
2094      provide with this variable, see the ":ref:`ref-features-distro`" section.
2095
2096   :term:`DISTRO_FEATURES_BACKFILL`
2097      A space-separated list of features to be added to :term:`DISTRO_FEATURES`
2098      if not also present in :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`.
2099
2100      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
2101      not intended to be user-configurable. It is best to just reference
2102      the variable to see which distro features are being
2103      :ref:`backfilled <ref-features-backfill>` for all distro configurations.
2104
2105   :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`
2106      A space-separated list of features from :term:`DISTRO_FEATURES_BACKFILL`
2107      that should not be :ref:`backfilled <ref-features-backfill>` (i.e. added
2108      to :term:`DISTRO_FEATURES`) during the build.
2109
2110      This corresponds to an opt-out mechanism. When new default distro
2111      features are introduced, distribution maintainers can review (`consider`)
2112      them and decide to exclude them from the
2113      :ref:`backfilled <ref-features-backfill>` features. Therefore, the
2114      combination of :term:`DISTRO_FEATURES_BACKFILL` and
2115      :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED` makes it possible to
2116      add new default features without breaking existing distributions.
2117
2118
2119   :term:`DISTRO_FEATURES_DEFAULT`
2120      A convenience variable that gives you the default list of distro
2121      features with the exception of any features specific to the C library
2122      (``libc``).
2123
2124      When creating a custom distribution, you might find it useful to be
2125      able to reuse the default
2126      :term:`DISTRO_FEATURES` options without the
2127      need to write out the full set. Here is an example that uses
2128      :term:`DISTRO_FEATURES_DEFAULT` from a custom distro configuration file::
2129
2130         DISTRO_FEATURES ?= "${DISTRO_FEATURES_DEFAULT} myfeature"
2131
2132   :term:`DISTRO_FEATURES_FILTER_NATIVE`
2133      Specifies a list of features that if present in the target
2134      :term:`DISTRO_FEATURES` value should be
2135      included in :term:`DISTRO_FEATURES` when building native recipes. This
2136      variable is used in addition to the features filtered using the
2137      :term:`DISTRO_FEATURES_NATIVE`
2138      variable.
2139
2140   :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
2141      Specifies a list of features that if present in the target
2142      :term:`DISTRO_FEATURES` value should be included in
2143      :term:`DISTRO_FEATURES` when building :ref:`ref-classes-nativesdk`
2144      recipes. This variable is used in addition to the features filtered using
2145      the :term:`DISTRO_FEATURES_NATIVESDK` variable.
2146
2147   :term:`DISTRO_FEATURES_NATIVE`
2148      Specifies a list of features that should be included in
2149      :term:`DISTRO_FEATURES` when building native
2150      recipes. This variable is used in addition to the features filtered
2151      using the
2152      :term:`DISTRO_FEATURES_FILTER_NATIVE`
2153      variable.
2154
2155   :term:`DISTRO_FEATURES_NATIVESDK`
2156      Specifies a list of features that should be included in
2157      :term:`DISTRO_FEATURES` when building
2158      :ref:`ref-classes-nativesdk` recipes. This variable is used
2159      in addition to the features filtered using the
2160      :term:`DISTRO_FEATURES_FILTER_NATIVESDK` variable.
2161
2162   :term:`DISTRO_NAME`
2163      The long name of the distribution. For information on the short name
2164      of the distribution, see the :term:`DISTRO` variable.
2165
2166      The :term:`DISTRO_NAME` variable corresponds to a distribution
2167      configuration file whose root name is the same as the variable's
2168      argument and whose filename extension is ``.conf``. For example, the
2169      distribution configuration file for the Poky distribution is named
2170      ``poky.conf`` and resides in the ``meta-poky/conf/distro`` directory
2171      of the :term:`Source Directory`.
2172
2173      Within that ``poky.conf`` file, the :term:`DISTRO_NAME` variable is set
2174      as follows::
2175
2176         DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
2177
2178      Distribution configuration files are located in a ``conf/distro``
2179      directory within the :term:`Metadata` that contains the
2180      distribution configuration.
2181
2182      .. note::
2183
2184         If the :term:`DISTRO_NAME` variable is blank, a set of default
2185         configurations are used, which are specified within
2186         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
2187
2188   :term:`DISTRO_VERSION`
2189      The version of the distribution.
2190
2191   :term:`DISTROOVERRIDES`
2192      A colon-separated list of overrides specific to the current
2193      distribution. By default, this list includes the value of
2194      :term:`DISTRO`.
2195
2196      You can extend :term:`DISTROOVERRIDES` to add extra overrides that should
2197      apply to the distribution.
2198
2199      The underlying mechanism behind :term:`DISTROOVERRIDES` is simply that it
2200      is included in the default value of
2201      :term:`OVERRIDES`.
2202
2203   :term:`DL_DIR`
2204      The central download directory used by the build process to store
2205      downloads. By default, :term:`DL_DIR` gets files suitable for mirroring
2206      for everything except Git repositories. If you want tarballs of Git
2207      repositories, use the
2208      :term:`BB_GENERATE_MIRROR_TARBALLS`
2209      variable.
2210
2211      You can set this directory by defining the :term:`DL_DIR` variable in the
2212      ``conf/local.conf`` file. This directory is self-maintaining and you
2213      should not have to touch it. By default, the directory is
2214      ``downloads`` in the :term:`Build Directory`::
2215
2216         #DL_DIR ?= "${TOPDIR}/downloads"
2217
2218      To specify a different download directory,
2219      simply remove the comment from the line and provide your directory.
2220
2221      During a first build, the system downloads many different source code
2222      tarballs from various upstream projects. Downloading can take a
2223      while, particularly if your network connection is slow. Tarballs are
2224      all stored in the directory defined by :term:`DL_DIR` and the build
2225      system looks there first to find source tarballs.
2226
2227      .. note::
2228
2229         When wiping and rebuilding, you can preserve this directory to
2230         speed up this part of subsequent builds.
2231
2232      You can safely share this directory between multiple builds on the
2233      same development machine. For additional information on how the build
2234      process gets source files when working behind a firewall or proxy
2235      server, see this specific question in the ":doc:`faq`"
2236      chapter. You can also refer to the
2237      ":yocto_wiki:`Working Behind a Network Proxy </Working_Behind_a_Network_Proxy>`"
2238      Wiki page.
2239
2240   :term:`DOC_COMPRESS`
2241      When inheriting the :ref:`ref-classes-compress_doc`
2242      class, this variable sets the compression policy used when the
2243      OpenEmbedded build system compresses man pages and info pages. By
2244      default, the compression method used is gz (gzip). Other policies
2245      available are xz and bz2.
2246
2247      For information on policies and on how to use this variable, see the
2248      comments in the ``meta/classes-recipe/compress_doc.bbclass`` file.
2249
2250   :term:`EFI_PROVIDER`
2251      When building bootable images (i.e. where ``hddimg``, ``iso``, or
2252      ``wic.vmdk`` is in :term:`IMAGE_FSTYPES`), the
2253      :term:`EFI_PROVIDER` variable specifies the EFI bootloader to use. The
2254      default is "grub-efi", but "systemd-boot" can be used instead.
2255
2256      See the :ref:`ref-classes-systemd-boot` and :ref:`ref-classes-image-live`
2257      classes for more information.
2258
2259   :term:`ENABLE_BINARY_LOCALE_GENERATION`
2260      Variable that controls which locales for ``glibc`` are generated
2261      during the build (useful if the target device has 64Mbytes of RAM or
2262      less).
2263
2264   :term:`ERR_REPORT_DIR`
2265      When used with the :ref:`ref-classes-report-error` class, specifies the
2266      path used for storing the debug files created by the :ref:`error reporting
2267      tool <dev-manual/error-reporting-tool:using the error reporting tool>`,
2268      which allows you to submit build errors you encounter to a central
2269      database. By default, the value of this variable is
2270      ``${``\ :term:`LOG_DIR`\ ``}/error-report``.
2271
2272      You can set :term:`ERR_REPORT_DIR` to the path you want the error
2273      reporting tool to store the debug files as follows in your
2274      ``local.conf`` file::
2275
2276         ERR_REPORT_DIR = "path"
2277
2278   :term:`ERROR_QA`
2279      Specifies the quality assurance checks whose failures are reported as
2280      errors by the OpenEmbedded build system. You set this variable in
2281      your distribution configuration file. For a list of the checks you
2282      can control with this variable, see the
2283      ":ref:`ref-classes-insane`" section.
2284
2285   :term:`ESDK_CLASS_INHERIT_DISABLE`
2286      A list of classes to remove from the :term:`INHERIT`
2287      value globally within the extensible SDK configuration. The
2288      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class sets the
2289      default value::
2290
2291         ESDK_CLASS_INHERIT_DISABLE ?= "buildhistory icecc"
2292
2293      Some classes are not generally applicable within the extensible SDK
2294      context. You can use this variable to disable those classes.
2295
2296      For additional information on how to customize the extensible SDK's
2297      configuration, see the
2298      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2299      section in the Yocto Project Application Development and the
2300      Extensible Software Development Kit (eSDK) manual.
2301
2302   :term:`ESDK_LOCALCONF_ALLOW`
2303      A list of variables allowed through from the OpenEmbedded build
2304      system configuration into the extensible SDK configuration. By
2305      default, the list of variables is empty and is set in the
2306      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class.
2307
2308      This list overrides the variables specified using the
2309      :term:`ESDK_LOCALCONF_REMOVE` variable as well as
2310      other variables automatically added due to the "/" character
2311      being found at the start of the
2312      value, which is usually indicative of being a path and thus might not
2313      be valid on the system where the SDK is installed.
2314
2315      For additional information on how to customize the extensible SDK's
2316      configuration, see the
2317      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2318      section in the Yocto Project Application Development and the
2319      Extensible Software Development Kit (eSDK) manual.
2320
2321   :term:`ESDK_LOCALCONF_REMOVE`
2322      A list of variables not allowed through from the OpenEmbedded build
2323      system configuration into the extensible SDK configuration. Usually,
2324      these are variables that are specific to the machine on which the
2325      build system is running and thus would be potentially problematic
2326      within the extensible SDK.
2327
2328      By default, :term:`ESDK_LOCALCONF_REMOVE` is set in the
2329      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class and
2330      excludes the following variables:
2331
2332      - :term:`CONF_VERSION`
2333      - :term:`BB_NUMBER_THREADS`
2334      - :term:`BB_NUMBER_PARSE_THREADS`
2335      - :term:`PARALLEL_MAKE`
2336      - :term:`PRSERV_HOST`
2337      - :term:`SSTATE_MIRRORS` :term:`DL_DIR`
2338      - :term:`SSTATE_DIR` :term:`TMPDIR`
2339      - :term:`BB_SERVER_TIMEOUT`
2340
2341      For additional information on how to customize the extensible SDK's
2342      configuration, see the
2343      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2344      section in the Yocto Project Application Development and the
2345      Extensible Software Development Kit (eSDK) manual.
2346
2347   :term:`EXCLUDE_FROM_SHLIBS`
2348      Triggers the OpenEmbedded build system's shared libraries resolver to
2349      exclude an entire package when scanning for shared libraries.
2350
2351      .. note::
2352
2353         The shared libraries resolver's functionality results in part from
2354         the internal function ``package_do_shlibs``, which is part of the
2355         :ref:`ref-tasks-package` task. You should be aware that the shared
2356         libraries resolver might implicitly define some dependencies between
2357         packages.
2358
2359      The :term:`EXCLUDE_FROM_SHLIBS` variable is similar to the
2360      :term:`PRIVATE_LIBS` variable, which excludes a
2361      package's particular libraries only and not the whole package.
2362
2363      Use the :term:`EXCLUDE_FROM_SHLIBS` variable by setting it to "1" for a
2364      particular package::
2365
2366         EXCLUDE_FROM_SHLIBS = "1"
2367
2368   :term:`EXCLUDE_FROM_WORLD`
2369      Directs BitBake to exclude a recipe from world builds (i.e.
2370      ``bitbake world``). During world builds, BitBake locates, parses and
2371      builds all recipes found in every layer exposed in the
2372      ``bblayers.conf`` configuration file.
2373
2374      To exclude a recipe from a world build using this variable, set the
2375      variable to "1" in the recipe.
2376
2377      .. note::
2378
2379         Recipes added to :term:`EXCLUDE_FROM_WORLD` may still be built during a
2380         world build in order to satisfy dependencies of other recipes. Adding
2381         a recipe to :term:`EXCLUDE_FROM_WORLD` only ensures that the recipe is not
2382         explicitly added to the list of build targets in a world build.
2383
2384   :term:`EXTENDPE`
2385      Used with file and pathnames to create a prefix for a recipe's
2386      version based on the recipe's :term:`PE` value. If :term:`PE`
2387      is set and greater than zero for a recipe, :term:`EXTENDPE` becomes that
2388      value (e.g if :term:`PE` is equal to "1" then :term:`EXTENDPE` becomes "1").
2389      If a recipe's :term:`PE` is not set (the default) or is equal to zero,
2390      :term:`EXTENDPE` becomes "".
2391
2392      See the :term:`STAMP` variable for an example.
2393
2394   :term:`EXTENDPKGV`
2395      The full package version specification as it appears on the final
2396      packages produced by a recipe. The variable's value is normally used
2397      to fix a runtime dependency to the exact same version of another
2398      package in the same recipe::
2399
2400         RDEPENDS:${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
2401
2402      The dependency relationships are intended to force the package
2403      manager to upgrade these types of packages in lock-step.
2404
2405   :term:`EXTERNAL_KERNEL_TOOLS`
2406      When set, the :term:`EXTERNAL_KERNEL_TOOLS` variable indicates that these
2407      tools are not in the source tree.
2408
2409      When kernel tools are available in the tree, they are preferred over
2410      any externally installed tools. Setting the :term:`EXTERNAL_KERNEL_TOOLS`
2411      variable tells the OpenEmbedded build system to prefer the installed
2412      external tools. See the :ref:`ref-classes-kernel-yocto` class in
2413      ``meta/classes-recipe`` to see how the variable is used.
2414
2415   :term:`EXTERNAL_TOOLCHAIN`
2416      When you intend to use an
2417      :ref:`external toolchain <dev-manual/external-toolchain:optionally using an external toolchain>`,
2418      this variable allows to specify the directory where this toolchain was
2419      installed.
2420
2421   :term:`EXTERNALSRC`
2422      When inheriting the :ref:`ref-classes-externalsrc`
2423      class, this variable points to the source tree, which is outside of
2424      the OpenEmbedded build system. When set, this variable sets the
2425      :term:`S` variable, which is what the OpenEmbedded build
2426      system uses to locate unpacked recipe source code.
2427
2428      See the ":ref:`ref-classes-externalsrc`" section for details. You
2429      can also find information on how to use this variable in the
2430      ":ref:`dev-manual/building:building software from an external source`"
2431      section in the Yocto Project Development Tasks Manual.
2432
2433   :term:`EXTERNALSRC_BUILD`
2434      When inheriting the :ref:`ref-classes-externalsrc`
2435      class, this variable points to the directory in which the recipe's
2436      source code is built, which is outside of the OpenEmbedded build
2437      system. When set, this variable sets the :term:`B` variable,
2438      which is what the OpenEmbedded build system uses to locate the
2439      :term:`Build Directory`.
2440
2441      See the ":ref:`ref-classes-externalsrc`" section for details. You
2442      can also find information on how to use this variable in the
2443      ":ref:`dev-manual/building:building software from an external source`"
2444      section in the Yocto Project Development Tasks Manual.
2445
2446   :term:`EXTRA_AUTORECONF`
2447      For recipes inheriting the :ref:`ref-classes-autotools`
2448      class, you can use :term:`EXTRA_AUTORECONF` to specify extra options to
2449      pass to the ``autoreconf`` command that is executed during the
2450      :ref:`ref-tasks-configure` task.
2451
2452      The default value is "--exclude=autopoint".
2453
2454   :term:`EXTRA_IMAGE_FEATURES`
2455      A list of additional features to include in an image. When listing
2456      more than one feature, separate them with a space.
2457
2458      Typically, you configure this variable in your ``local.conf`` file,
2459      which is found in the :term:`Build Directory`. Although you can use this
2460      variable from within a recipe, best practices dictate that you do not.
2461
2462      .. note::
2463
2464         To enable primary features from within the image recipe, use the
2465         :term:`IMAGE_FEATURES` variable.
2466
2467      Here are some examples of features you can add:
2468
2469        - "dbg-pkgs" --- adds -dbg packages for all installed packages including
2470          symbol information for debugging and profiling.
2471
2472        - "debug-tweaks" --- makes an image suitable for debugging. For example, allows root logins without passwords and
2473          enables post-installation logging. See the 'allow-empty-password' and
2474          'post-install-logging' features in the ":ref:`ref-features-image`"
2475          section for more information.
2476        - "dev-pkgs" --- adds -dev packages for all installed packages. This is
2477          useful if you want to develop against the libraries in the image.
2478        - "read-only-rootfs" --- creates an image whose root filesystem is
2479          read-only. See the
2480          ":ref:`dev-manual/read-only-rootfs:creating a read-only root filesystem`"
2481          section in the Yocto Project Development Tasks Manual for more
2482          information
2483        - "tools-debug" --- adds debugging tools such as gdb and strace.
2484        - "tools-sdk" --- adds development tools such as gcc, make,
2485          pkgconfig and so forth.
2486        - "tools-testapps" --- adds useful testing tools
2487          such as ts_print, aplay, arecord and so forth.
2488
2489      For a complete list of image features that ships with the Yocto
2490      Project, see the ":ref:`ref-features-image`" section.
2491
2492      For an example that shows how to customize your image by using this
2493      variable, see the ":ref:`dev-manual/customizing-images:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
2494      section in the Yocto Project Development Tasks Manual.
2495
2496   :term:`EXTRA_IMAGECMD`
2497      Specifies additional options for the image creation command that has
2498      been specified in :term:`IMAGE_CMD`. When setting
2499      this variable, use an override for the associated image type. Here is
2500      an example::
2501
2502         EXTRA_IMAGECMD:ext3 ?= "-i 4096"
2503
2504   :term:`EXTRA_IMAGEDEPENDS`
2505      A list of recipes to build that do not provide packages for
2506      installing into the root filesystem.
2507
2508      Sometimes a recipe is required to build the final image but is not
2509      needed in the root filesystem. You can use the :term:`EXTRA_IMAGEDEPENDS`
2510      variable to list these recipes and thus specify the dependencies. A
2511      typical example is a required bootloader in a machine configuration.
2512
2513      .. note::
2514
2515         To add packages to the root filesystem, see the various
2516         :term:`RDEPENDS` and :term:`RRECOMMENDS` variables.
2517
2518   :term:`EXTRA_OECMAKE`
2519      Additional `CMake <https://cmake.org/overview/>`__ options. See the
2520      :ref:`ref-classes-cmake` class for additional information.
2521
2522   :term:`EXTRA_OECONF`
2523      Additional ``configure`` script options. See
2524      :term:`PACKAGECONFIG_CONFARGS` for
2525      additional information on passing configure script options.
2526
2527   :term:`EXTRA_OEMAKE`
2528      Additional GNU ``make`` options.
2529
2530      Because the :term:`EXTRA_OEMAKE` defaults to "", you need to set the
2531      variable to specify any required GNU options.
2532
2533      :term:`PARALLEL_MAKE` and
2534      :term:`PARALLEL_MAKEINST` also make use of
2535      :term:`EXTRA_OEMAKE` to pass the required flags.
2536
2537   :term:`EXTRA_OESCONS`
2538      When inheriting the :ref:`ref-classes-scons` class, this
2539      variable specifies additional configuration options you want to pass
2540      to the ``scons`` command line.
2541
2542   :term:`EXTRA_OEMESON`
2543      Additional `Meson <https://mesonbuild.com/>`__ options. See the
2544      :ref:`ref-classes-meson` class for additional information.
2545
2546      In addition to standard Meson options, such options correspond to
2547      `Meson build options <https://mesonbuild.com/Build-options.html>`__
2548      defined in the ``meson_options.txt`` file in the sources to build.
2549      Here is an example::
2550
2551         EXTRA_OEMESON = "-Dpython=disabled -Dvalgrind=disabled"
2552
2553      Note that any custom value for the Meson ``--buildtype`` option
2554      should be set through the :term:`MESON_BUILDTYPE` variable.
2555
2556   :term:`EXTRA_USERS_PARAMS`
2557      When inheriting the :ref:`ref-classes-extrausers`
2558      class, this variable provides image level user and group operations.
2559      This is a more global method of providing user and group
2560      configuration as compared to using the
2561      :ref:`ref-classes-useradd` class, which ties user and
2562      group configurations to a specific recipe.
2563
2564      The set list of commands you can configure using the
2565      :term:`EXTRA_USERS_PARAMS` is shown in the
2566      :ref:`ref-classes-extrausers` class. These commands map to the normal
2567      Unix commands of the same names::
2568
2569         # EXTRA_USERS_PARAMS = "\
2570         # useradd -p '' tester; \
2571         # groupadd developers; \
2572         # userdel nobody; \
2573         # groupdel -g video; \
2574         # groupmod -g 1020 developers; \
2575         # usermod -s /bin/sh tester; \
2576         # "
2577
2578      Hardcoded passwords are supported via the ``-p`` parameters for
2579      ``useradd`` or ``usermod``, but only hashed.
2580
2581      Here is an example that adds two users named "tester-jim" and "tester-sue" and assigns
2582      passwords. First on host, create the (escaped) password hash::
2583
2584         printf "%q" $(mkpasswd -m sha256crypt tester01)
2585
2586      The resulting hash is set to a variable and used in ``useradd`` command parameters::
2587
2588         inherit extrausers
2589         PASSWD = "\$X\$ABC123\$A-Long-Hash"
2590         EXTRA_USERS_PARAMS = "\
2591             useradd -p '${PASSWD}' tester-jim; \
2592             useradd -p '${PASSWD}' tester-sue; \
2593             "
2594
2595      Finally, here is an example that sets the root password::
2596
2597         inherit extrausers
2598         EXTRA_USERS_PARAMS = "\
2599             usermod -p '${PASSWD}' root; \
2600             "
2601
2602      .. note::
2603
2604         From a security perspective, hardcoding a default password is not
2605         generally a good idea or even legal in some jurisdictions. It is
2606         recommended that you do not do this if you are building a production
2607         image.
2608
2609      Additionally there is a special ``passwd-expire`` command that will
2610      cause the password for a user to be expired and thus force changing it
2611      on first login, for example::
2612
2613         EXTRA_USERS_PARAMS += " useradd myuser; passwd-expire myuser;"
2614
2615      .. note::
2616
2617         At present, ``passwd-expire`` may only work for remote logins when
2618         using OpenSSH and not dropbear as an SSH server.
2619
2620   :term:`EXTRANATIVEPATH`
2621      A list of subdirectories of
2622      ``${``\ :term:`STAGING_BINDIR_NATIVE`\ ``}``
2623      added to the beginning of the environment variable ``PATH``. As an
2624      example, the following prepends
2625      "${STAGING_BINDIR_NATIVE}/foo:${STAGING_BINDIR_NATIVE}/bar:" to
2626      ``PATH``::
2627
2628         EXTRANATIVEPATH = "foo bar"
2629
2630   :term:`FAKEROOT`
2631      See :term:`bitbake:FAKEROOT` in the BitBake manual.
2632
2633   :term:`FAKEROOTBASEENV`
2634      See :term:`bitbake:FAKEROOTBASEENV` in the BitBake manual.
2635
2636   :term:`FAKEROOTCMD`
2637      See :term:`bitbake:FAKEROOTCMD` in the BitBake manual.
2638
2639   :term:`FAKEROOTDIRS`
2640      See :term:`bitbake:FAKEROOTDIRS` in the BitBake manual.
2641
2642   :term:`FAKEROOTENV`
2643      See :term:`bitbake:FAKEROOTENV` in the BitBake manual.
2644
2645   :term:`FAKEROOTNOENV`
2646      See :term:`bitbake:FAKEROOTNOENV` in the BitBake manual.
2647
2648   :term:`FEATURE_PACKAGES`
2649      Defines one or more packages to include in an image when a specific
2650      item is included in :term:`IMAGE_FEATURES`.
2651      When setting the value, :term:`FEATURE_PACKAGES` should have the name of
2652      the feature item as an override. Here is an example::
2653
2654         FEATURE_PACKAGES_widget = "package1 package2"
2655
2656      In this example, if "widget" were added to :term:`IMAGE_FEATURES`,
2657      package1 and package2 would be included in the image.
2658
2659      .. note::
2660
2661         Packages installed by features defined through :term:`FEATURE_PACKAGES`
2662         are often package groups. While similarly named, you should not
2663         confuse the :term:`FEATURE_PACKAGES` variable with package groups, which
2664         are discussed elsewhere in the documentation.
2665
2666   :term:`FEED_DEPLOYDIR_BASE_URI`
2667      Points to the base URL of the server and location within the
2668      document-root that provides the metadata and packages required by
2669      OPKG to support runtime package management of IPK packages. You set
2670      this variable in your ``local.conf`` file.
2671
2672      Consider the following example::
2673
2674         FEED_DEPLOYDIR_BASE_URI = "http://192.168.7.1/BOARD-dir"
2675
2676      This example assumes you are serving
2677      your packages over HTTP and your databases are located in a directory
2678      named ``BOARD-dir``, which is underneath your HTTP server's
2679      document-root. In this case, the OpenEmbedded build system generates
2680      a set of configuration files for you in your target that work with
2681      the feed.
2682
2683   :term:`FETCHCMD`
2684      See :term:`bitbake:FETCHCMD` in the BitBake manual.
2685
2686   :term:`FILE`
2687      See :term:`bitbake:FILE` in the BitBake manual.
2688
2689   :term:`FILES`
2690      The list of files and directories that are placed in a package. The
2691      :term:`PACKAGES` variable lists the packages
2692      generated by a recipe.
2693
2694      To use the :term:`FILES` variable, provide a package name override that
2695      identifies the resulting package. Then, provide a space-separated
2696      list of files or paths that identify the files you want included as
2697      part of the resulting package. Here is an example::
2698
2699         FILES:${PN} += "${bindir}/mydir1 ${bindir}/mydir2/myfile"
2700
2701      .. note::
2702
2703         -  When specifying files or paths, you can pattern match using
2704            Python's
2705            `glob <https://docs.python.org/3/library/glob.html>`__
2706            syntax. For details on the syntax, see the documentation by
2707            following the previous link.
2708
2709         -  When specifying paths as part of the :term:`FILES` variable, it is
2710            good practice to use appropriate path variables. For example,
2711            use ``${sysconfdir}`` rather than ``/etc``, or ``${bindir}``
2712            rather than ``/usr/bin``. You can find a list of these
2713            variables at the top of the ``meta/conf/bitbake.conf`` file in
2714            the :term:`Source Directory`. You will also
2715            find the default values of the various ``FILES:*`` variables in
2716            this file.
2717
2718      If some of the files you provide with the :term:`FILES` variable are
2719      editable and you know they should not be overwritten during the
2720      package update process by the Package Management System (PMS), you
2721      can identify these files so that the PMS will not overwrite them. See
2722      the :term:`CONFFILES` variable for information on
2723      how to identify these files to the PMS.
2724
2725   :term:`FILES_SOLIBSDEV`
2726      Defines the file specification to match
2727      :term:`SOLIBSDEV`. In other words,
2728      :term:`FILES_SOLIBSDEV` defines the full path name of the development
2729      symbolic link (symlink) for shared libraries on the target platform.
2730
2731      The following statement from the ``bitbake.conf`` shows how it is
2732      set::
2733
2734         FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}"
2735
2736   :term:`FILESEXTRAPATHS`
2737      Extends the search path the OpenEmbedded build system uses when
2738      looking for files and patches as it processes recipes and append
2739      files. The default directories BitBake uses when it processes recipes
2740      are initially defined by the :term:`FILESPATH`
2741      variable. You can extend :term:`FILESPATH` variable by using
2742      :term:`FILESEXTRAPATHS`.
2743
2744      Best practices dictate that you accomplish this by using
2745      :term:`FILESEXTRAPATHS` from within a ``.bbappend`` file and that you
2746      prepend paths as follows::
2747
2748         FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
2749
2750      In the above example, the build system first
2751      looks for files in a directory that has the same name as the
2752      corresponding append file.
2753
2754      .. note::
2755
2756         When extending :term:`FILESEXTRAPATHS`, be sure to use the immediate
2757         expansion (``:=``) operator. Immediate expansion makes sure that
2758         BitBake evaluates :term:`THISDIR` at the time the
2759         directive is encountered rather than at some later time when
2760         expansion might result in a directory that does not contain the
2761         files you need.
2762
2763         Also, include the trailing separating colon character if you are
2764         prepending. The trailing colon character is necessary because you
2765         are directing BitBake to extend the path by prepending directories
2766         to the search path.
2767
2768      Here is another common use::
2769
2770         FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
2771
2772      In this example, the build system extends the
2773      :term:`FILESPATH` variable to include a directory named ``files`` that is
2774      in the same directory as the corresponding append file.
2775
2776      This next example specifically adds three paths::
2777
2778         FILESEXTRAPATHS:prepend := "path_1:path_2:path_3:"
2779
2780      A final example shows how you can extend the search path and include
2781      a :term:`MACHINE`-specific override, which is useful
2782      in a BSP layer::
2783
2784          FILESEXTRAPATHS:prepend:intel-x86-common := "${THISDIR}/${PN}:"
2785
2786      The previous statement appears in the
2787      ``linux-yocto-dev.bbappend`` file, which is found in the
2788      :ref:`overview-manual/development-environment:yocto project source repositories` in
2789      ``meta-intel/common/recipes-kernel/linux``. Here, the machine
2790      override is a special :term:`PACKAGE_ARCH`
2791      definition for multiple ``meta-intel`` machines.
2792
2793      .. note::
2794
2795         For a layer that supports a single BSP, the override could just be
2796         the value of :term:`MACHINE`.
2797
2798      By prepending paths in ``.bbappend`` files, you allow multiple append
2799      files that reside in different layers but are used for the same
2800      recipe to correctly extend the path.
2801
2802   :term:`FILESOVERRIDES`
2803      A subset of :term:`OVERRIDES` used by the OpenEmbedded build system for
2804      creating :term:`FILESPATH`. The :term:`FILESOVERRIDES` variable uses
2805      overrides to automatically extend the :term:`FILESPATH` variable. For an
2806      example of how that works, see the :term:`FILESPATH` variable
2807      description. Additionally, you find more information on how overrides
2808      are handled in the
2809      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
2810      section of the BitBake User Manual.
2811
2812      By default, the :term:`FILESOVERRIDES` variable is defined as::
2813
2814         FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
2815
2816      .. note::
2817
2818         Do not hand-edit the :term:`FILESOVERRIDES` variable. The values match up
2819         with expected overrides and are used in an expected manner by the
2820         build system.
2821
2822   :term:`FILESPATH`
2823      The default set of directories the OpenEmbedded build system uses
2824      when searching for patches and files.
2825
2826      During the build process, BitBake searches each directory in
2827      :term:`FILESPATH` in the specified order when looking for files and
2828      patches specified by each ``file://`` URI in a recipe's
2829      :term:`SRC_URI` statements.
2830
2831      The default value for the :term:`FILESPATH` variable is defined in the
2832      :ref:`ref-classes-base` class found in ``meta/classes-global`` in the
2833      :term:`Source Directory`::
2834
2835         FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
2836             "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
2837
2838      The
2839      :term:`FILESPATH` variable is automatically extended using the overrides
2840      from the :term:`FILESOVERRIDES` variable.
2841
2842      .. note::
2843
2844         -  Do not hand-edit the :term:`FILESPATH` variable. If you want the
2845            build system to look in directories other than the defaults,
2846            extend the :term:`FILESPATH` variable by using the
2847            :term:`FILESEXTRAPATHS` variable.
2848
2849         -  Be aware that the default :term:`FILESPATH` directories do not map
2850            to directories in custom layers where append files
2851            (``.bbappend``) are used. If you want the build system to find
2852            patches or files that reside with your append files, you need
2853            to extend the :term:`FILESPATH` variable by using the
2854            :term:`FILESEXTRAPATHS` variable.
2855
2856      You can take advantage of this searching behavior in useful ways. For
2857      example, consider a case where there is the following directory structure
2858      for general and machine-specific configurations::
2859
2860         files/defconfig
2861         files/MACHINEA/defconfig
2862         files/MACHINEB/defconfig
2863
2864      Also in the example, the :term:`SRC_URI` statement contains
2865      "file://defconfig". Given this scenario, you can set
2866      :term:`MACHINE` to "MACHINEA" and cause the build
2867      system to use files from ``files/MACHINEA``. Set :term:`MACHINE` to
2868      "MACHINEB" and the build system uses files from ``files/MACHINEB``.
2869      Finally, for any machine other than "MACHINEA" and "MACHINEB", the
2870      build system uses files from ``files/defconfig``.
2871
2872      You can find out more about the patching process in the
2873      ":ref:`overview-manual/concepts:patching`" section
2874      in the Yocto Project Overview and Concepts Manual and the
2875      ":ref:`dev-manual/new-recipe:patching code`" section in
2876      the Yocto Project Development Tasks Manual. See the
2877      :ref:`ref-tasks-patch` task as well.
2878
2879   :term:`FILESYSTEM_PERMS_TABLES`
2880      Allows you to define your own file permissions settings table as part
2881      of your configuration for the packaging process. For example, suppose
2882      you need a consistent set of custom permissions for a set of groups
2883      and users across an entire work project. It is best to do this in the
2884      packages themselves but this is not always possible.
2885
2886      By default, the OpenEmbedded build system uses the ``fs-perms.txt``,
2887      which is located in the ``meta/files`` folder in the :term:`Source Directory`.
2888      If you create your own file
2889      permissions setting table, you should place it in your layer or the
2890      distro's layer.
2891
2892      You define the :term:`FILESYSTEM_PERMS_TABLES` variable in the
2893      ``conf/local.conf`` file, which is found in the :term:`Build Directory`,
2894      to point to your custom ``fs-perms.txt``. You can specify more than a
2895      single file permissions setting table. The paths you specify to these
2896      files must be defined within the :term:`BBPATH` variable.
2897
2898      For guidance on how to create your own file permissions settings
2899      table file, examine the existing ``fs-perms.txt``.
2900
2901   :term:`FIT_CONF_DEFAULT_DTB`
2902      Specifies the default device tree binary (dtb) file for a fitImage when
2903      multiple are provided.
2904
2905   :term:`FIT_DESC`
2906      Specifies the description string encoded into a fitImage. The default
2907      value is set by the :ref:`ref-classes-kernel-fitimage`
2908      class as follows::
2909
2910         FIT_DESC ?= "U-Boot fitImage for ${DISTRO_NAME}/${PV}/${MACHINE}"
2911
2912   :term:`FIT_GENERATE_KEYS`
2913      Decides whether to generate the keys for signing fitImage if they
2914      don't already exist. The keys are created in :term:`UBOOT_SIGN_KEYDIR`.
2915      The default value is 0.
2916
2917   :term:`FIT_HASH_ALG`
2918      Specifies the hash algorithm used in creating the FIT Image. For e.g. sha256.
2919
2920   :term:`FIT_KERNEL_COMP_ALG`
2921      Compression algorithm to use for the kernel image inside the FIT Image.
2922      At present, the only supported values are "gzip" (default), "lzo" or "none".
2923      If you set this variable to anything other than "none" you may also need
2924      to set :term:`FIT_KERNEL_COMP_ALG_EXTENSION`.
2925
2926   :term:`FIT_KERNEL_COMP_ALG_EXTENSION`
2927      File extension corresponding to :term:`FIT_KERNEL_COMP_ALG`. The default
2928      value is ".gz". If you set :term:`FIT_KERNEL_COMP_ALG` to "lzo",
2929      you may want to set this variable to ".lzo".
2930
2931   :term:`FIT_KEY_GENRSA_ARGS`
2932      Arguments to openssl genrsa for generating RSA private key for signing
2933      fitImage. The default value is "-F4". i.e. the public exponent 65537 to
2934      use.
2935
2936   :term:`FIT_KEY_REQ_ARGS`
2937      Arguments to openssl req for generating certificate for signing fitImage.
2938      The default value is "-batch -new". batch for non interactive mode
2939      and new for generating new keys.
2940
2941   :term:`FIT_KEY_SIGN_PKCS`
2942      Format for public key certificate used in signing fitImage.
2943      The default value is "x509".
2944
2945   :term:`FIT_SIGN_ALG`
2946      Specifies the signature algorithm used in creating the FIT Image.
2947      For e.g. rsa2048.
2948
2949   :term:`FIT_PAD_ALG`
2950      Specifies the padding algorithm used in creating the FIT Image.
2951      The default value is "pkcs-1.5".
2952
2953   :term:`FIT_SIGN_INDIVIDUAL`
2954      If set to "1", then the :ref:`ref-classes-kernel-fitimage`
2955      class will sign the kernel, dtb and ramdisk images individually in addition
2956      to signing the fitImage itself. This could be useful if you are
2957      intending to verify signatures in another context than booting via
2958      U-Boot.
2959
2960   :term:`FIT_SIGN_NUMBITS`
2961      Size of private key in number of bits used in fitImage. The default
2962      value is "2048".
2963
2964   :term:`FONT_EXTRA_RDEPENDS`
2965      When inheriting the :ref:`ref-classes-fontcache` class,
2966      this variable specifies the runtime dependencies for font packages.
2967      By default, the :term:`FONT_EXTRA_RDEPENDS` is set to "fontconfig-utils".
2968
2969   :term:`FONT_PACKAGES`
2970      When inheriting the :ref:`ref-classes-fontcache` class, this variable
2971      identifies packages containing font files that need to be cached by
2972      Fontconfig. By default, the :ref:`ref-classes-fontcache` class assumes
2973      that fonts are in the recipe's main package (i.e.
2974      ``${``\ :term:`PN`\ ``}``). Use this variable if fonts you
2975      need are in a package other than that main package.
2976
2977   :term:`FORCE_RO_REMOVE`
2978      Forces the removal of the packages listed in ``ROOTFS_RO_UNNEEDED``
2979      during the generation of the root filesystem.
2980
2981      Set the variable to "1" to force the removal of these packages.
2982
2983   :term:`FULL_OPTIMIZATION`
2984      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
2985      compiling an optimized system. This variable defaults to "-O2 -pipe
2986      ${DEBUG_FLAGS}".
2987
2988   :term:`GCCPIE`
2989      Enables Position Independent Executables (PIE) within the GNU C
2990      Compiler (GCC). Enabling PIE in the GCC makes Return Oriented
2991      Programming (ROP) attacks much more difficult to execute.
2992
2993      By default the ``security_flags.inc`` file enables PIE by setting the
2994      variable as follows::
2995
2996         GCCPIE ?= "--enable-default-pie"
2997
2998   :term:`GCCVERSION`
2999      Specifies the default version of the GNU C Compiler (GCC) used for
3000      compilation. By default, :term:`GCCVERSION` is set to "8.x" in the
3001      ``meta/conf/distro/include/tcmode-default.inc`` include file::
3002
3003         GCCVERSION ?= "8.%"
3004
3005      You can override this value by setting it in a
3006      configuration file such as the ``local.conf``.
3007
3008   :term:`GDB`
3009      The minimal command and arguments to run the GNU Debugger.
3010
3011   :term:`GIR_EXTRA_LIBS_PATH`
3012      Allows to specify an extra search path for ``.so`` files
3013      in GLib related recipes using GObject introspection,
3014      and which do not compile without this setting.
3015      See the ":ref:`dev-manual/gobject-introspection:enabling gobject introspection support`"
3016      section for details.
3017
3018   :term:`GITDIR`
3019      The directory in which a local copy of a Git repository is stored
3020      when it is cloned.
3021
3022   :term:`GITHUB_BASE_URI`
3023      When inheriting the :ref:`ref-classes-github-releases`
3024      class, specifies the base URL for fetching releases for the github
3025      project you wish to fetch sources from. The default value is as follows::
3026
3027         GITHUB_BASE_URI ?= "https://github.com/${BPN}/${BPN}/releases/"
3028
3029   :term:`GLIBC_GENERATE_LOCALES`
3030      Specifies the list of GLIBC locales to generate should you not wish
3031      to generate all LIBC locals, which can be time consuming.
3032
3033      .. note::
3034
3035         If you specifically remove the locale ``en_US.UTF-8``, you must set
3036         :term:`IMAGE_LINGUAS` appropriately.
3037
3038      You can set :term:`GLIBC_GENERATE_LOCALES` in your ``local.conf`` file.
3039      By default, all locales are generated::
3040
3041         GLIBC_GENERATE_LOCALES = "en_GB.UTF-8 en_US.UTF-8"
3042
3043   :term:`GO_IMPORT`
3044      When inheriting the :ref:`ref-classes-go` class, this mandatory variable
3045      sets the import path for the Go package that will be created for the code
3046      to build. If you have a ``go.mod`` file in the source directory, this
3047      typically matches the path in the ``module`` line in this file.
3048
3049      Other Go programs importing this package will use this path.
3050
3051      Here is an example setting from the
3052      :yocto_git:`go-helloworld_0.1.bb </poky/tree/meta/recipes-extended/go-examples/go-helloworld_0.1.bb>`
3053      recipe::
3054
3055          GO_IMPORT = "golang.org/x/example"
3056
3057   :term:`GO_INSTALL`
3058      When inheriting the :ref:`ref-classes-go` class, this optional variable
3059      specifies which packages in the sources should be compiled and
3060      installed in the Go build space by the
3061      `go install <https://go.dev/ref/mod#go-install>`__ command.
3062
3063      Here is an example setting from the
3064      :oe_git:`crucible </meta-openembedded/tree/meta-oe/recipes-support/crucible/>`
3065      recipe::
3066
3067         GO_INSTALL = "\
3068             ${GO_IMPORT}/cmd/crucible \
3069             ${GO_IMPORT}/cmd/habtool \
3070         "
3071
3072      By default, :term:`GO_INSTALL` is defined as::
3073
3074         GO_INSTALL ?= "${GO_IMPORT}/..."
3075
3076      The ``...`` wildcard means that it will catch all
3077      packages found in the sources.
3078
3079      See the :term:`GO_INSTALL_FILTEROUT` variable for
3080      filtering out unwanted packages from the ones
3081      found from the :term:`GO_INSTALL` value.
3082
3083   :term:`GO_INSTALL_FILTEROUT`
3084      When using the Go "vendor" mechanism to bring in dependencies for a Go
3085      package, the default :term:`GO_INSTALL` setting, which uses the ``...``
3086      wildcard, will include the vendored packages in the build, which produces
3087      incorrect results.
3088
3089      There are also some Go packages that are structured poorly, so that the
3090      ``...`` wildcard results in building example or test code that should not
3091      be included in the build, or could fail to build.
3092
3093      This optional variable allows for filtering out a subset of the sources.
3094      It defaults to excluding everything under the ``vendor`` subdirectory
3095      under package's main directory. This is the normal location for vendored
3096      packages, but it can be overridden by a recipe to filter out other
3097      subdirectories if needed.
3098
3099   :term:`GO_WORKDIR`
3100      When using Go Modules, the current working directory must be the directory
3101      containing the ``go.mod`` file, or one of its subdirectories. When the
3102      ``go`` tool is used, it will automatically look for the ``go.mod`` file
3103      in the Go working directory or in any parent directory, but not in
3104      subdirectories.
3105
3106      When using the :ref:`ref-classes-go-mod` class to use Go modules,
3107      the optional :term:`GO_WORKDIR` variable, defaulting to the value
3108      of :term:`GO_IMPORT`, allows to specify a different Go working directory.
3109
3110   :term:`GROUPADD_PARAM`
3111      When inheriting the :ref:`ref-classes-useradd` class,
3112      this variable specifies for a package what parameters should be
3113      passed to the ``groupadd`` command if you wish to add a group to the
3114      system when the package is installed.
3115
3116      Here is an example from the ``dbus`` recipe::
3117
3118         GROUPADD_PARAM:${PN} = "-r netdev"
3119
3120      For information on the standard Linux shell command
3121      ``groupadd``, see https://linux.die.net/man/8/groupadd.
3122
3123   :term:`GROUPMEMS_PARAM`
3124      When inheriting the :ref:`ref-classes-useradd` class,
3125      this variable specifies for a package what parameters should be
3126      passed to the ``groupmems`` command if you wish to modify the members
3127      of a group when the package is installed.
3128
3129      For information on the standard Linux shell command ``groupmems``,
3130      see https://linux.die.net/man/8/groupmems.
3131
3132   :term:`GRUB_GFXSERIAL`
3133      Configures the GNU GRand Unified Bootloader (GRUB) to have graphics
3134      and serial in the boot menu. Set this variable to "1" in your
3135      ``local.conf`` or distribution configuration file to enable graphics
3136      and serial in the menu.
3137
3138      See the :ref:`ref-classes-grub-efi` class for more
3139      information on how this variable is used.
3140
3141   :term:`GRUB_OPTS`
3142      Additional options to add to the GNU GRand Unified Bootloader (GRUB)
3143      configuration. Use a semi-colon character (``;``) to separate
3144      multiple options.
3145
3146      The :term:`GRUB_OPTS` variable is optional. See the
3147      :ref:`ref-classes-grub-efi` class for more information
3148      on how this variable is used.
3149
3150   :term:`GRUB_TIMEOUT`
3151      Specifies the timeout before executing the default ``LABEL`` in the
3152      GNU GRand Unified Bootloader (GRUB).
3153
3154      The :term:`GRUB_TIMEOUT` variable is optional. See the
3155      :ref:`ref-classes-grub-efi` class for more information
3156      on how this variable is used.
3157
3158   :term:`GTKIMMODULES_PACKAGES`
3159      When inheriting the :ref:`ref-classes-gtk-immodules-cache` class,
3160      this variable specifies the packages that contain the GTK+ input
3161      method modules being installed when the modules are in packages other
3162      than the main package.
3163
3164   :term:`HGDIR`
3165      See :term:`bitbake:HGDIR` in the BitBake manual.
3166
3167   :term:`HOMEPAGE`
3168      Website where more information about the software the recipe is
3169      building can be found.
3170
3171   :term:`HOST_ARCH`
3172      The name of the target architecture, which is normally the same as
3173      :term:`TARGET_ARCH`. The OpenEmbedded build system
3174      supports many architectures. Here is an example list of architectures
3175      supported. This list is by no means complete as the architecture is
3176      configurable:
3177
3178      - arm
3179      - i586
3180      - x86_64
3181      - powerpc
3182      - powerpc64
3183      - mips
3184      - mipsel
3185
3186   :term:`HOST_CC_ARCH`
3187      Specifies architecture-specific compiler flags that are passed to the
3188      C compiler.
3189
3190      Default initialization for :term:`HOST_CC_ARCH` varies depending on what
3191      is being built:
3192
3193      -  :term:`TARGET_CC_ARCH` when building for the
3194         target
3195
3196      -  :term:`BUILD_CC_ARCH` when building for the build host (i.e.
3197         ``-native``)
3198
3199      -  ``BUILDSDK_CC_ARCH`` when building for an SDK (i.e.
3200         ``nativesdk-``)
3201
3202   :term:`HOST_OS`
3203      Specifies the name of the target operating system, which is normally
3204      the same as the :term:`TARGET_OS`. The variable can
3205      be set to "linux" for ``glibc``-based systems and to "linux-musl" for
3206      ``musl``. For ARM/EABI targets, there are also "linux-gnueabi" and
3207      "linux-musleabi" values possible.
3208
3209   :term:`HOST_PREFIX`
3210      Specifies the prefix for the cross-compile toolchain. :term:`HOST_PREFIX`
3211      is normally the same as :term:`TARGET_PREFIX`.
3212
3213   :term:`HOST_SYS`
3214      Specifies the system, including the architecture and the operating
3215      system, for which the build is occurring in the context of the
3216      current recipe.
3217
3218      The OpenEmbedded build system automatically sets this variable based
3219      on :term:`HOST_ARCH`,
3220      :term:`HOST_VENDOR`, and
3221      :term:`HOST_OS` variables.
3222
3223      .. note::
3224
3225         You do not need to set the variable yourself.
3226
3227      Consider these two examples:
3228
3229      -  Given a native recipe on a 32-bit x86 machine running Linux, the
3230         value is "i686-linux".
3231
3232      -  Given a recipe being built for a little-endian MIPS target running
3233         Linux, the value might be "mipsel-linux".
3234
3235   :term:`HOST_VENDOR`
3236      Specifies the name of the vendor. :term:`HOST_VENDOR` is normally the
3237      same as :term:`TARGET_VENDOR`.
3238
3239   :term:`HOSTTOOLS`
3240      A space-separated list (filter) of tools on the build host that
3241      should be allowed to be called from within build tasks. Using this
3242      filter helps reduce the possibility of host contamination. If a tool
3243      specified in the value of :term:`HOSTTOOLS` is not found on the build
3244      host, the OpenEmbedded build system produces an error and the build
3245      is not started.
3246
3247      For additional information, see
3248      :term:`HOSTTOOLS_NONFATAL`.
3249
3250   :term:`HOSTTOOLS_NONFATAL`
3251      A space-separated list (filter) of tools on the build host that
3252      should be allowed to be called from within build tasks. Using this
3253      filter helps reduce the possibility of host contamination. Unlike
3254      :term:`HOSTTOOLS`, the OpenEmbedded build system
3255      does not produce an error if a tool specified in the value of
3256      :term:`HOSTTOOLS_NONFATAL` is not found on the build host. Thus, you can
3257      use :term:`HOSTTOOLS_NONFATAL` to filter optional host tools.
3258
3259   :term:`ICECC_CLASS_DISABLE`
3260      Identifies user classes that you do not want the Icecream distributed
3261      compile support to consider. This variable is used by the
3262      :ref:`ref-classes-icecc` class. You set this variable in
3263      your ``local.conf`` file.
3264
3265      When you list classes using this variable, the recipes inheriting
3266      those classes will not benefit from distributed compilation across
3267      remote hosts. Instead they will be built locally.
3268
3269   :term:`ICECC_DISABLED`
3270      Disables or enables the ``icecc`` (Icecream) function. For more
3271      information on this function and best practices for using this
3272      variable, see the ":ref:`ref-classes-icecc`"
3273      section.
3274
3275      Setting this variable to "1" in your ``local.conf`` disables the
3276      function::
3277
3278         ICECC_DISABLED ??= "1"
3279
3280      To enable the function, set the variable as follows::
3281
3282         ICECC_DISABLED = ""
3283
3284   :term:`ICECC_ENV_EXEC`
3285      Points to the ``icecc-create-env`` script that you provide. This
3286      variable is used by the :ref:`ref-classes-icecc` class. You
3287      set this variable in your ``local.conf`` file.
3288
3289      If you do not point to a script that you provide, the OpenEmbedded
3290      build system uses the default script provided by the
3291      :oe_git:`icecc-create-env_0.1.bb
3292      </openembedded-core/tree/meta/recipes-devtools/icecc-create-env/icecc-create-env_0.1.bb>`
3293      recipe, which is a modified version and not the one that comes with
3294      ``icecream``.
3295
3296   :term:`ICECC_PARALLEL_MAKE`
3297      Extra options passed to the ``make`` command during the
3298      :ref:`ref-tasks-compile` task that specify parallel
3299      compilation. This variable usually takes the form of "-j x", where x
3300      represents the maximum number of parallel threads ``make`` can run.
3301
3302      .. note::
3303
3304         The options passed affect builds on all enabled machines on the
3305         network, which are machines running the ``iceccd`` daemon.
3306
3307      If your enabled machines support multiple cores, coming up with the
3308      maximum number of parallel threads that gives you the best
3309      performance could take some experimentation since machine speed,
3310      network lag, available memory, and existing machine loads can all
3311      affect build time. Consequently, unlike the
3312      :term:`PARALLEL_MAKE` variable, there is no
3313      rule-of-thumb for setting :term:`ICECC_PARALLEL_MAKE` to achieve optimal
3314      performance.
3315
3316      If you do not set :term:`ICECC_PARALLEL_MAKE`, the build system does not
3317      use it (i.e. the system does not detect and assign the number of
3318      cores as is done with :term:`PARALLEL_MAKE`).
3319
3320   :term:`ICECC_PATH`
3321      The location of the ``icecc`` binary. You can set this variable in
3322      your ``local.conf`` file. If your ``local.conf`` file does not define
3323      this variable, the :ref:`ref-classes-icecc` class attempts
3324      to define it by locating ``icecc`` using ``which``.
3325
3326   :term:`ICECC_RECIPE_DISABLE`
3327      Identifies user recipes that you do not want the Icecream distributed
3328      compile support to consider. This variable is used by the
3329      :ref:`ref-classes-icecc` class. You set this variable in
3330      your ``local.conf`` file.
3331
3332      When you list recipes using this variable, you are excluding them
3333      from distributed compilation across remote hosts. Instead they will
3334      be built locally.
3335
3336   :term:`ICECC_RECIPE_ENABLE`
3337      Identifies user recipes that use an empty
3338      :term:`PARALLEL_MAKE` variable that you want to
3339      force remote distributed compilation on using the Icecream
3340      distributed compile support. This variable is used by the
3341      :ref:`ref-classes-icecc` class. You set this variable in
3342      your ``local.conf`` file.
3343
3344   :term:`IMAGE_BASENAME`
3345      The base name of image output files. This variable defaults to the
3346      recipe name (``${``\ :term:`PN`\ ``}``).
3347
3348   :term:`IMAGE_BOOT_FILES`
3349      A space-separated list of files installed into the boot partition
3350      when preparing an image using the Wic tool with the
3351      ``bootimg-partition`` source plugin. By default,
3352      the files are
3353      installed under the same name as the source files. To change the
3354      installed name, separate it from the original name with a semi-colon
3355      (;). Source files need to be located in
3356      :term:`DEPLOY_DIR_IMAGE`. Here are two
3357      examples::
3358
3359         IMAGE_BOOT_FILES = "u-boot.img uImage;kernel"
3360         IMAGE_BOOT_FILES = "u-boot.${UBOOT_SUFFIX} ${KERNEL_IMAGETYPE}"
3361
3362      Alternatively, source files can be picked up using a glob pattern. In
3363      this case, the destination file must have the same name as the base
3364      name of the source file path. To install files into a directory
3365      within the target location, pass its name after a semi-colon (;).
3366      Here are two examples::
3367
3368         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*"
3369         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*;boot/"
3370
3371      The first example
3372      installs all files from ``${DEPLOY_DIR_IMAGE}/bcm2835-bootfiles``
3373      into the root of the target partition. The second example installs
3374      the same files into a ``boot`` directory within the target partition.
3375
3376      You can find information on how to use the Wic tool in the
3377      ":ref:`dev-manual/wic:creating partitioned images using wic`"
3378      section of the Yocto Project Development Tasks Manual. Reference
3379      material for Wic is located in the
3380      ":doc:`/ref-manual/kickstart`" chapter.
3381
3382   :term:`IMAGE_BUILDINFO_FILE`
3383      When using the :ref:`ref-classes-image-buildinfo` class,
3384      specifies the file in the image to write the build information into. The
3385      default value is "``${sysconfdir}/buildinfo``".
3386
3387   :term:`IMAGE_BUILDINFO_VARS`
3388      When using the :ref:`ref-classes-image-buildinfo` class,
3389      specifies the list of variables to include in the `Build Configuration`
3390      section of the output file (as a space-separated list). Defaults to
3391      ":term:`DISTRO` :term:`DISTRO_VERSION`".
3392
3393   :term:`IMAGE_CLASSES`
3394      A list of classes that all images should inherit. This is typically used
3395      to enable functionality across all image recipes.
3396
3397      Classes specified in :term:`IMAGE_CLASSES` must be located in the
3398      ``classes-recipe/`` or ``classes/`` subdirectories.
3399
3400   :term:`IMAGE_CMD`
3401      Specifies the command to create the image file for a specific image
3402      type, which corresponds to the value set in
3403      :term:`IMAGE_FSTYPES`, (e.g. ``ext3``,
3404      ``btrfs``, and so forth). When setting this variable, you should use
3405      an override for the associated type. Here is an example::
3406
3407         IMAGE_CMD:jffs2 = "mkfs.jffs2 --root=${IMAGE_ROOTFS} --faketime \
3408             --output=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.jffs2 \
3409             ${EXTRA_IMAGECMD}"
3410
3411      You typically do not need to set this variable unless you are adding
3412      support for a new image type. For more examples on how to set this
3413      variable, see the :ref:`ref-classes-image_types`
3414      class file, which is ``meta/classes-recipe/image_types.bbclass``.
3415
3416   :term:`IMAGE_DEVICE_TABLES`
3417      Specifies one or more files that contain custom device tables that
3418      are passed to the ``makedevs`` command as part of creating an image.
3419      These files list basic device nodes that should be created under
3420      ``/dev`` within the image. If :term:`IMAGE_DEVICE_TABLES` is not set,
3421      ``files/device_table-minimal.txt`` is used, which is located by
3422      :term:`BBPATH`. For details on how you should write
3423      device table files, see ``meta/files/device_table-minimal.txt`` as an
3424      example.
3425
3426   :term:`IMAGE_EFI_BOOT_FILES`
3427      A space-separated list of files installed into the boot partition
3428      when preparing an image using the Wic tool with the
3429      ``bootimg-efi`` source plugin. By default,
3430      the files are
3431      installed under the same name as the source files. To change the
3432      installed name, separate it from the original name with a semi-colon
3433      (;). Source files need to be located in
3434      :term:`DEPLOY_DIR_IMAGE`. Here are two
3435      examples::
3436
3437         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE};bz2"
3438         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE} microcode.cpio"
3439
3440      Alternatively, source files can be picked up using a glob pattern. In
3441      this case, the destination file must have the same name as the base
3442      name of the source file path. To install files into a directory
3443      within the target location, pass its name after a semi-colon (;).
3444      Here are two examples::
3445
3446         IMAGE_EFI_BOOT_FILES = "boot/loader/*"
3447         IMAGE_EFI_BOOT_FILES = "boot/loader/*;boot/"
3448
3449      The first example
3450      installs all files from ``${DEPLOY_DIR_IMAGE}/boot/loader/``
3451      into the root of the target partition. The second example installs
3452      the same files into a ``boot`` directory within the target partition.
3453
3454      You can find information on how to use the Wic tool in the
3455      ":ref:`dev-manual/wic:creating partitioned images using wic`"
3456      section of the Yocto Project Development Tasks Manual. Reference
3457      material for Wic is located in the
3458      ":doc:`/ref-manual/kickstart`" chapter.
3459
3460   :term:`IMAGE_FEATURES`
3461      The primary list of features to include in an image. Typically, you
3462      configure this variable in an image recipe. Although you can use this
3463      variable from your ``local.conf`` file, which is found in the
3464      :term:`Build Directory`, best practices dictate that you do
3465      not.
3466
3467      .. note::
3468
3469         To enable extra features from outside the image recipe, use the
3470         :term:`EXTRA_IMAGE_FEATURES` variable.
3471
3472      For a list of image features that ships with the Yocto Project, see
3473      the ":ref:`ref-features-image`" section.
3474
3475      For an example that shows how to customize your image by using this
3476      variable, see the ":ref:`dev-manual/customizing-images:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
3477      section in the Yocto Project Development Tasks Manual.
3478
3479   :term:`IMAGE_FSTYPES`
3480      Specifies the formats the OpenEmbedded build system uses during the
3481      build when creating the root filesystem. For example, setting
3482      :term:`IMAGE_FSTYPES` as follows causes the build system to create root
3483      filesystems using two formats: ``.ext3`` and ``.tar.bz2``::
3484
3485         IMAGE_FSTYPES = "ext3 tar.bz2"
3486
3487      For the complete list of supported image formats from which you can
3488      choose, see :term:`IMAGE_TYPES`.
3489
3490      .. note::
3491
3492         -  If an image recipe uses the "inherit image" line and you are
3493            setting :term:`IMAGE_FSTYPES` inside the recipe, you must set
3494            :term:`IMAGE_FSTYPES` prior to using the "inherit image" line.
3495
3496         -  Due to the way the OpenEmbedded build system processes this
3497            variable, you cannot update its contents by using ``:append``
3498            or ``:prepend``. You must use the ``+=`` operator to add one or
3499            more options to the :term:`IMAGE_FSTYPES` variable.
3500
3501   :term:`IMAGE_INSTALL`
3502      Used by recipes to specify the packages to install into an image
3503      through the :ref:`ref-classes-image` class. Use the
3504      :term:`IMAGE_INSTALL` variable with care to avoid ordering issues.
3505
3506      Image recipes set :term:`IMAGE_INSTALL` to specify the packages to
3507      install into an image through :ref:`ref-classes-image`. Additionally,
3508      there are "helper" classes such as the :ref:`ref-classes-core-image`
3509      class which can take lists used with :term:`IMAGE_FEATURES` and turn
3510      them into auto-generated entries in :term:`IMAGE_INSTALL` in addition
3511      to its default contents.
3512
3513      When you use this variable, it is best to use it as follows::
3514
3515         IMAGE_INSTALL:append = " package-name"
3516
3517      Be sure to include the space
3518      between the quotation character and the start of the package name or
3519      names.
3520
3521      .. note::
3522
3523         -  When working with a
3524            :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
3525            image, do not use the :term:`IMAGE_INSTALL` variable to specify
3526            packages for installation. Instead, use the
3527            :term:`PACKAGE_INSTALL` variable, which
3528            allows the initial RAM filesystem (:term:`Initramfs`) recipe to use a
3529            fixed set of packages and not be affected by :term:`IMAGE_INSTALL`.
3530            For information on creating an :term:`Initramfs`, see the
3531            ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`"
3532            section in the Yocto Project Development Tasks Manual.
3533
3534         -  Using :term:`IMAGE_INSTALL` with the
3535            :ref:`+= <bitbake-user-manual/bitbake-user-manual-metadata:appending (+=) and prepending (=+) with spaces>`
3536            BitBake operator within the ``/conf/local.conf`` file or from
3537            within an image recipe is not recommended. Use of this operator in
3538            these ways can cause ordering issues. Since
3539            :ref:`ref-classes-core-image` sets :term:`IMAGE_INSTALL` to a
3540            default value using the
3541            :ref:`?= <bitbake-user-manual/bitbake-user-manual-metadata:setting a default value (?=)>`
3542            operator, using a ``+=`` operation against :term:`IMAGE_INSTALL`
3543            results in unexpected behavior when used within
3544            ``conf/local.conf``. Furthermore, the same operation from within an
3545            image recipe may or may not succeed depending on the specific
3546            situation. In both these cases, the behavior is contrary to how
3547            most users expect the ``+=`` operator to work.
3548
3549   :term:`IMAGE_LINGUAS`
3550      Specifies the list of locales to install into the image during the
3551      root filesystem construction process. The OpenEmbedded build system
3552      automatically splits locale files, which are used for localization,
3553      into separate packages. Setting the :term:`IMAGE_LINGUAS` variable
3554      ensures that any locale packages that correspond to packages already
3555      selected for installation into the image are also installed. Here is
3556      an example::
3557
3558         IMAGE_LINGUAS = "pt-br de-de"
3559
3560      In this example, the build system ensures any Brazilian Portuguese
3561      and German locale files that correspond to packages in the image are
3562      installed (i.e. ``*-locale-pt-br`` and ``*-locale-de-de`` as well as
3563      ``*-locale-pt`` and ``*-locale-de``, since some software packages
3564      only provide locale files by language and not by country-specific
3565      language).
3566
3567      See the :term:`GLIBC_GENERATE_LOCALES`
3568      variable for information on generating GLIBC locales.
3569
3570
3571   :term:`IMAGE_LINK_NAME`
3572      The name of the output image symlink (which does not include
3573      the version part as :term:`IMAGE_NAME` does). The default value
3574      is derived using the :term:`IMAGE_BASENAME` and
3575      :term:`IMAGE_MACHINE_SUFFIX` variables::
3576
3577         IMAGE_LINK_NAME ?= "${IMAGE_BASENAME}${IMAGE_MACHINE_SUFFIX}"
3578
3579      .. note::
3580
3581         It is possible to set this to "" to disable symlink creation,
3582         however, you also need to set :term:`IMAGE_NAME` to still have
3583         a reasonable value e.g.::
3584
3585            IMAGE_LINK_NAME = ""
3586            IMAGE_NAME = "${IMAGE_BASENAME}${IMAGE_MACHINE_SUFFIX}${IMAGE_VERSION_SUFFIX}"
3587
3588   :term:`IMAGE_MACHINE_SUFFIX`
3589      Specifies the by default machine-specific suffix for image file names
3590      (before the extension). The default value is set as follows::
3591
3592         IMAGE_MACHINE_SUFFIX ??= "-${MACHINE}"
3593
3594      The default :term:`DEPLOY_DIR_IMAGE` already has a :term:`MACHINE`
3595      subdirectory, so you may find it unnecessary to also include this suffix
3596      in the name of every image file. If you prefer to remove the suffix you
3597      can set this variable to an empty string::
3598
3599         IMAGE_MACHINE_SUFFIX = ""
3600
3601      (Not to be confused with :term:`IMAGE_NAME_SUFFIX`.)
3602
3603   :term:`IMAGE_MANIFEST`
3604      The manifest file for the image. This file lists all the installed
3605      packages that make up the image. The file contains package
3606      information on a line-per-package basis as follows::
3607
3608          packagename packagearch version
3609
3610      The :ref:`rootfs-postcommands <ref-classes-rootfs*>` class defines the manifest
3611      file as follows::
3612
3613         IMAGE_MANIFEST ="${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.manifest"
3614
3615      The location is
3616      derived using the :term:`IMGDEPLOYDIR`
3617      and :term:`IMAGE_NAME` variables. You can find
3618      information on how the image is created in the ":ref:`overview-manual/concepts:image generation`"
3619      section in the Yocto Project Overview and Concepts Manual.
3620
3621   :term:`IMAGE_NAME`
3622      The name of the output image files minus the extension. By default
3623      this variable is set using the :term:`IMAGE_LINK_NAME`, and
3624      :term:`IMAGE_VERSION_SUFFIX` variables::
3625
3626         IMAGE_NAME ?= "${IMAGE_LINK_NAME}${IMAGE_VERSION_SUFFIX}"
3627
3628   :term:`IMAGE_NAME_SUFFIX`
3629      Suffix used for the image output filename --- defaults to ``".rootfs"``
3630      to distinguish the image file from other files created during image
3631      building; however if this suffix is redundant or not desired you can
3632      clear the value of this variable (set the value to ""). For example,
3633      this is typically cleared in :term:`Initramfs` image recipes.
3634
3635   :term:`IMAGE_OVERHEAD_FACTOR`
3636      Defines a multiplier that the build system applies to the initial
3637      image size for cases when the multiplier times the returned disk
3638      usage value for the image is greater than the sum of
3639      :term:`IMAGE_ROOTFS_SIZE` and :term:`IMAGE_ROOTFS_EXTRA_SPACE`. The result of
3640      the multiplier applied to the initial image size creates free disk
3641      space in the image as overhead. By default, the build process uses a
3642      multiplier of 1.3 for this variable. This default value results in
3643      30% free disk space added to the image when this method is used to
3644      determine the final generated image size. You should be aware that
3645      post install scripts and the package management system uses disk
3646      space inside this overhead area. Consequently, the multiplier does
3647      not produce an image with all the theoretical free disk space. See
3648      :term:`IMAGE_ROOTFS_SIZE` for information on how the build system
3649      determines the overall image size.
3650
3651      The default 30% free disk space typically gives the image enough room
3652      to boot and allows for basic post installs while still leaving a
3653      small amount of free disk space. If 30% free space is inadequate, you
3654      can increase the default value. For example, the following setting
3655      gives you 50% free space added to the image::
3656
3657         IMAGE_OVERHEAD_FACTOR = "1.5"
3658
3659      Alternatively, you can ensure a specific amount of free disk space is
3660      added to the image by using the :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3661      variable.
3662
3663   :term:`IMAGE_PKGTYPE`
3664      Defines the package type (i.e. DEB, RPM, IPK, or TAR) used by the
3665      OpenEmbedded build system. The variable is defined appropriately by
3666      the :ref:`ref-classes-package_deb`, :ref:`ref-classes-package_rpm`,
3667      or :ref:`ref-classes-package_ipk` class.
3668
3669      The :ref:`ref-classes-populate-sdk-*` and :ref:`ref-classes-image`
3670      classes use the :term:`IMAGE_PKGTYPE` for packaging up images and SDKs.
3671
3672      You should not set the :term:`IMAGE_PKGTYPE` manually. Rather, the
3673      variable is set indirectly through the appropriate
3674      :ref:`package_* <ref-classes-package>` class using the
3675      :term:`PACKAGE_CLASSES` variable. The
3676      OpenEmbedded build system uses the first package type (e.g. DEB, RPM,
3677      or IPK) that appears with the variable
3678
3679      .. note::
3680
3681         Files using the ``.tar`` format are never used as a substitute
3682         packaging format for DEB, RPM, and IPK formatted files for your image
3683         or SDK.
3684
3685   :term:`IMAGE_POSTPROCESS_COMMAND`
3686      Specifies a list of functions to call once the OpenEmbedded build
3687      system creates the final image output files. You can specify
3688      functions separated by semicolons::
3689
3690         IMAGE_POSTPROCESS_COMMAND += "function; ... "
3691
3692      If you need to pass the root filesystem path to a command within the
3693      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3694      directory that becomes the root filesystem image. See the
3695      :term:`IMAGE_ROOTFS` variable for more
3696      information.
3697
3698   :term:`IMAGE_PREPROCESS_COMMAND`
3699      Specifies a list of functions to call before the OpenEmbedded build
3700      system creates the final image output files. You can specify
3701      functions separated by semicolons::
3702
3703         IMAGE_PREPROCESS_COMMAND += "function; ... "
3704
3705      If you need to pass the root filesystem path to a command within the
3706      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3707      directory that becomes the root filesystem image. See the
3708      :term:`IMAGE_ROOTFS` variable for more
3709      information.
3710
3711   :term:`IMAGE_ROOTFS`
3712      The location of the root filesystem while it is under construction
3713      (i.e. during the :ref:`ref-tasks-rootfs` task). This
3714      variable is not configurable. Do not change it.
3715
3716   :term:`IMAGE_ROOTFS_ALIGNMENT`
3717      Specifies the alignment for the output image file in Kbytes. If the
3718      size of the image is not a multiple of this value, then the size is
3719      rounded up to the nearest multiple of the value. The default value is
3720      "1". See :term:`IMAGE_ROOTFS_SIZE` for
3721      additional information.
3722
3723   :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3724      Defines additional free disk space created in the image in Kbytes. By
3725      default, this variable is set to "0". This free disk space is added
3726      to the image after the build system determines the image size as
3727      described in :term:`IMAGE_ROOTFS_SIZE`.
3728
3729      This variable is particularly useful when you want to ensure that a
3730      specific amount of free disk space is available on a device after an
3731      image is installed and running. For example, to be sure 5 Gbytes of
3732      free disk space is available, set the variable as follows::
3733
3734         IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
3735
3736      For example, the Yocto Project Build Appliance specifically requests
3737      40 Gbytes of extra space with the line::
3738
3739         IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
3740
3741   :term:`IMAGE_ROOTFS_SIZE`
3742      Defines the size in Kbytes for the generated image. The OpenEmbedded
3743      build system determines the final size for the generated image using
3744      an algorithm that takes into account the initial disk space used for
3745      the generated image, a requested size for the image, and requested
3746      additional free disk space to be added to the image. Programatically,
3747      the build system determines the final size of the generated image as
3748      follows::
3749
3750         if (image-du * overhead) < rootfs-size:
3751             internal-rootfs-size = rootfs-size + xspace
3752         else:
3753             internal-rootfs-size = (image-du * overhead) + xspace
3754         where:
3755             image-du = Returned value of the du command on the image.
3756             overhead = IMAGE_OVERHEAD_FACTOR
3757             rootfs-size = IMAGE_ROOTFS_SIZE
3758             internal-rootfs-size = Initial root filesystem size before any modifications.
3759             xspace = IMAGE_ROOTFS_EXTRA_SPACE
3760
3761      See the :term:`IMAGE_OVERHEAD_FACTOR`
3762      and :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3763      variables for related information.
3764
3765   :term:`IMAGE_TYPEDEP`
3766      Specifies a dependency from one image type on another. Here is an
3767      example from the :ref:`ref-classes-image-live` class::
3768
3769         IMAGE_TYPEDEP:live = "ext3"
3770
3771      In the previous example, the variable ensures that when "live" is
3772      listed with the :term:`IMAGE_FSTYPES` variable,
3773      the OpenEmbedded build system produces an ``ext3`` image first since
3774      one of the components of the live image is an ``ext3`` formatted
3775      partition containing the root filesystem.
3776
3777   :term:`IMAGE_TYPES`
3778      Specifies the complete list of supported image types by default:
3779
3780      - btrfs
3781      - container
3782      - cpio
3783      - cpio.gz
3784      - cpio.lz4
3785      - cpio.lzma
3786      - cpio.xz
3787      - cramfs
3788      - erofs
3789      - erofs-lz4
3790      - erofs-lz4hc
3791      - ext2
3792      - ext2.bz2
3793      - ext2.gz
3794      - ext2.lzma
3795      - ext3
3796      - ext3.gz
3797      - ext4
3798      - ext4.gz
3799      - f2fs
3800      - hddimg
3801      - iso
3802      - jffs2
3803      - jffs2.sum
3804      - multiubi
3805      - squashfs
3806      - squashfs-lz4
3807      - squashfs-lzo
3808      - squashfs-xz
3809      - tar
3810      - tar.bz2
3811      - tar.gz
3812      - tar.lz4
3813      - tar.xz
3814      - tar.zst
3815      - ubi
3816      - ubifs
3817      - wic
3818      - wic.bz2
3819      - wic.gz
3820      - wic.lzma
3821
3822      For more information about these types of images, see
3823      ``meta/classes-recipe/image_types*.bbclass`` in the :term:`Source Directory`.
3824
3825   :term:`IMAGE_VERSION_SUFFIX`
3826      Version suffix that is part of the default :term:`IMAGE_NAME` and
3827      :term:`KERNEL_ARTIFACT_NAME` values.
3828      Defaults to ``"-${DATETIME}"``, however you could set this to a
3829      version string that comes from your external build environment if
3830      desired, and this suffix would then be used consistently across
3831      the build artifacts.
3832
3833   :term:`IMGDEPLOYDIR`
3834      When inheriting the :ref:`ref-classes-image` class directly or
3835      through the :ref:`ref-classes-core-image` class, the
3836      :term:`IMGDEPLOYDIR` points to a temporary work area for deployed files
3837      that is set in the ``image`` class as follows::
3838
3839         IMGDEPLOYDIR = "${WORKDIR}/deploy-${PN}-image-complete"
3840
3841      Recipes inheriting the :ref:`ref-classes-image` class should copy
3842      files to be deployed into :term:`IMGDEPLOYDIR`, and the class will take
3843      care of copying them into :term:`DEPLOY_DIR_IMAGE` afterwards.
3844
3845   :term:`INCOMPATIBLE_LICENSE`
3846      Specifies a space-separated list of license names (as they would
3847      appear in :term:`LICENSE`) that should be excluded
3848      from the build. Recipes that provide no alternatives to listed
3849      incompatible licenses are not built. Packages that are individually
3850      licensed with the specified incompatible licenses will be deleted.
3851
3852      There is some support for wildcards in this variable's value,
3853      however it is restricted to specific licenses. Currently only
3854      these wildcards are allowed and expand as follows:
3855
3856      - ``AGPL-3.0*"``: ``AGPL-3.0-only``, ``AGPL-3.0-or-later``
3857      - ``GPL-3.0*``: ``GPL-3.0-only``, ``GPL-3.0-or-later``
3858      - ``LGPL-3.0*``: ``LGPL-3.0-only``, ``LGPL-3.0-or-later``
3859
3860      .. note::
3861
3862         This functionality is only regularly tested using the following
3863         setting::
3864
3865                 INCOMPATIBLE_LICENSE = "GPL-3.0* LGPL-3.0* AGPL-3.0*"
3866
3867
3868         Although you can use other settings, you might be required to
3869         remove dependencies on (or provide alternatives to) components that
3870         are required to produce a functional system image.
3871
3872   :term:`INCOMPATIBLE_LICENSE_EXCEPTIONS`
3873      Specifies a space-separated list of package and license pairs that
3874      are allowed to be used even if the license is specified in
3875      :term:`INCOMPATIBLE_LICENSE`. The package and license pairs are
3876      separated using a colon. Example::
3877
3878         INCOMPATIBLE_LICENSE_EXCEPTIONS = "gdbserver:GPL-3.0-only gdbserver:LGPL-3.0-only"
3879
3880   :term:`INHERIT`
3881      Causes the named class or classes to be inherited globally. Anonymous
3882      functions in the class or classes are not executed for the base
3883      configuration and in each individual recipe. The OpenEmbedded build
3884      system ignores changes to :term:`INHERIT` in individual recipes.
3885      Classes inherited using :term:`INHERIT` must be located in the
3886      ``classes-global/`` or ``classes/`` subdirectories.
3887
3888      For more information on :term:`INHERIT`, see the
3889      :ref:`bitbake-user-manual/bitbake-user-manual-metadata:\`\`inherit\`\` configuration directive`"
3890      section in the BitBake User Manual.
3891
3892   :term:`INHERIT_DISTRO`
3893      Lists classes that will be inherited at the distribution level. It is
3894      unlikely that you want to edit this variable.
3895
3896      Classes specified in :term:`INHERIT_DISTRO` must be located in the
3897      ``classes-global/`` or ``classes/`` subdirectories.
3898
3899      The default value of the variable is set as follows in the
3900      ``meta/conf/distro/defaultsetup.conf`` file::
3901
3902         INHERIT_DISTRO ?= "debian devshell sstate license"
3903
3904   :term:`INHIBIT_DEFAULT_DEPS`
3905      Prevents the default dependencies, namely the C compiler and standard
3906      C library (libc), from being added to :term:`DEPENDS`.
3907      This variable is usually used within recipes that do not require any
3908      compilation using the C compiler.
3909
3910      Set the variable to "1" to prevent the default dependencies from
3911      being added.
3912
3913   :term:`INHIBIT_PACKAGE_DEBUG_SPLIT`
3914      Prevents the OpenEmbedded build system from splitting out debug
3915      information during packaging. By default, the build system splits out
3916      debugging information during the
3917      :ref:`ref-tasks-package` task. For more information on
3918      how debug information is split out, see the
3919      :term:`PACKAGE_DEBUG_SPLIT_STYLE`
3920      variable.
3921
3922      To prevent the build system from splitting out debug information
3923      during packaging, set the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable as
3924      follows::
3925
3926         INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
3927
3928   :term:`INHIBIT_PACKAGE_STRIP`
3929      If set to "1", causes the build to not strip binaries in resulting
3930      packages and prevents the ``-dbg`` package from containing the source
3931      files.
3932
3933      By default, the OpenEmbedded build system strips binaries and puts
3934      the debugging symbols into ``${``\ :term:`PN`\ ``}-dbg``.
3935      Consequently, you should not set :term:`INHIBIT_PACKAGE_STRIP` when you
3936      plan to debug in general.
3937
3938   :term:`INHIBIT_SYSROOT_STRIP`
3939      If set to "1", causes the build to not strip binaries in the
3940      resulting sysroot.
3941
3942      By default, the OpenEmbedded build system strips binaries in the
3943      resulting sysroot. When you specifically set the
3944      :term:`INHIBIT_SYSROOT_STRIP` variable to "1" in your recipe, you inhibit
3945      this stripping.
3946
3947      If you want to use this variable, include the :ref:`ref-classes-staging`
3948      class. This class uses a ``sys_strip()`` function to test for the variable
3949      and acts accordingly.
3950
3951      .. note::
3952
3953         Use of the :term:`INHIBIT_SYSROOT_STRIP` variable occurs in rare and
3954         special circumstances. For example, suppose you are building
3955         bare-metal firmware by using an external GCC toolchain. Furthermore,
3956         even if the toolchain's binaries are strippable, there are other files
3957         needed for the build that are not strippable.
3958
3959   :term:`INIT_MANAGER`
3960      Specifies the system init manager to use. Available options are:
3961
3962      -  ``sysvinit``
3963      -  ``systemd``
3964      -  ``mdev-busybox``
3965
3966      With ``sysvinit``, the init manager is set to
3967      :wikipedia:`SysVinit <Init#SysV-style>`, the traditional UNIX init
3968      system. This is the default choice in the Poky distribution, together with
3969      the Udev device manager (see the ":ref:`device-manager`" section).
3970
3971      With ``systemd``, the init manager becomes :wikipedia:`systemd <Systemd>`,
3972      which comes with the :wikipedia:`udev <Udev>` device manager.
3973
3974      With ``mdev-busybox``, the init manager becomes the much simpler BusyBox
3975      init, together with the BusyBox mdev device manager. This is the simplest
3976      and lightest solution, and probably the best choice for low-end systems
3977      with a rather slow CPU and a limited amount of RAM.
3978
3979      More concretely, this is used to include
3980      ``conf/distro/include/init-manager-${INIT_MANAGER}.inc`` into the global
3981      configuration. You can have a look at the
3982      :yocto_git:`meta/conf/distro/include/init-manager-*.inc </poky/tree/meta/conf/distro/include>`
3983      files for more information, and also the ":ref:`init-manager`"
3984      section in the Yocto Project Development Tasks Manual.
3985
3986   :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
3987      Indicates the deploy directory used by :ref:`ref-tasks-bundle_initramfs`
3988      where the :term:`INITRAMFS_IMAGE` will be fetched from. This variable is
3989      set by default to ``${DEPLOY_DIR_IMAGE}`` in the
3990      :ref:`ref-classes-kernel` class and it's only meant to be changed when
3991      building an :term:`Initramfs` image from a separate multiconfig via
3992      :term:`INITRAMFS_MULTICONFIG`.
3993
3994   :term:`INITRAMFS_FSTYPES`
3995      Defines the format for the output image of an initial RAM filesystem
3996      (:term:`Initramfs`), which is used during boot. Supported formats are the
3997      same as those supported by the
3998      :term:`IMAGE_FSTYPES` variable.
3999
4000      The default value of this variable, which is set in the
4001      ``meta/conf/bitbake.conf`` configuration file in the
4002      :term:`Source Directory`, is "cpio.gz". The Linux kernel's
4003      :term:`Initramfs` mechanism, as opposed to the initial RAM filesystem
4004      :wikipedia:`initrd <Initrd>` mechanism, expects
4005      an optionally compressed cpio archive.
4006
4007   :term:`INITRAMFS_IMAGE`
4008      Specifies the :term:`PROVIDES` name of an image
4009      recipe that is used to build an initial RAM filesystem (:term:`Initramfs`)
4010      image. In other words, the :term:`INITRAMFS_IMAGE` variable causes an
4011      additional recipe to be built as a dependency to whatever root
4012      filesystem recipe you might be using (e.g. ``core-image-sato``). The
4013      :term:`Initramfs` image recipe you provide should set
4014      :term:`IMAGE_FSTYPES` to
4015      :term:`INITRAMFS_FSTYPES`.
4016
4017      An :term:`Initramfs` image provides a temporary root filesystem used for
4018      early system initialization (e.g. loading of modules needed to locate
4019      and mount the "real" root filesystem).
4020
4021      .. note::
4022
4023         See the ``meta/recipes-core/images/core-image-minimal-initramfs.bb``
4024         recipe in the :term:`Source Directory`
4025         for an example :term:`Initramfs` recipe. To select this sample recipe as
4026         the one built to provide the :term:`Initramfs` image, set :term:`INITRAMFS_IMAGE`
4027         to "core-image-minimal-initramfs".
4028
4029      You can also find more information by referencing the
4030      ``meta-poky/conf/templates/default/local.conf.sample.extended``
4031      configuration file in the Source Directory, the :ref:`ref-classes-image`
4032      class, and the :ref:`ref-classes-kernel` class to see how to use the
4033      :term:`INITRAMFS_IMAGE` variable.
4034
4035      If :term:`INITRAMFS_IMAGE` is empty, which is the default, then no
4036      :term:`Initramfs` image is built.
4037
4038      For more information, you can also see the
4039      :term:`INITRAMFS_IMAGE_BUNDLE`
4040      variable, which allows the generated image to be bundled inside the
4041      kernel image. Additionally, for information on creating an :term:`Initramfs`
4042      image, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
4043      in the Yocto Project Development Tasks Manual.
4044
4045   :term:`INITRAMFS_IMAGE_BUNDLE`
4046      Controls whether or not the image recipe specified by
4047      :term:`INITRAMFS_IMAGE` is run through an
4048      extra pass
4049      (:ref:`ref-tasks-bundle_initramfs`) during
4050      kernel compilation in order to build a single binary that contains
4051      both the kernel image and the initial RAM filesystem (:term:`Initramfs`)
4052      image. This makes use of the
4053      :term:`CONFIG_INITRAMFS_SOURCE` kernel
4054      feature.
4055
4056      .. note::
4057
4058         Bundling the :term:`Initramfs` with the kernel conflates the code in the
4059         :term:`Initramfs` with the GPLv2 licensed Linux kernel binary. Thus only GPLv2
4060         compatible software may be part of a bundled :term:`Initramfs`.
4061
4062      .. note::
4063
4064         Using an extra compilation pass to bundle the :term:`Initramfs` avoids a
4065         circular dependency between the kernel recipe and the :term:`Initramfs`
4066         recipe should the :term:`Initramfs` include kernel modules. Should that be
4067         the case, the :term:`Initramfs` recipe depends on the kernel for the
4068         kernel modules, and the kernel depends on the :term:`Initramfs` recipe
4069         since the :term:`Initramfs` is bundled inside the kernel image.
4070
4071      The combined binary is deposited into the ``tmp/deploy`` directory,
4072      which is part of the :term:`Build Directory`.
4073
4074      Setting the variable to "1" in a configuration file causes the
4075      OpenEmbedded build system to generate a kernel image with the
4076      :term:`Initramfs` specified in :term:`INITRAMFS_IMAGE` bundled within::
4077
4078         INITRAMFS_IMAGE_BUNDLE = "1"
4079
4080      By default, the :ref:`ref-classes-kernel` class sets this variable to a
4081      null string as follows::
4082
4083         INITRAMFS_IMAGE_BUNDLE ?= ""
4084
4085      .. note::
4086
4087         You must set the :term:`INITRAMFS_IMAGE_BUNDLE` variable in a
4088         configuration file. You cannot set the variable in a recipe file.
4089
4090      See the
4091      :yocto_git:`local.conf.sample.extended </poky/tree/meta-poky/conf/templates/default/local.conf.sample.extended>`
4092      file for additional information. Also, for information on creating an
4093      :term:`Initramfs`, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
4094      in the Yocto Project Development Tasks Manual.
4095
4096   :term:`INITRAMFS_IMAGE_NAME`
4097
4098      This value needs to stay in sync with :term:`IMAGE_LINK_NAME`, but with
4099      :term:`INITRAMFS_IMAGE` instead of :term:`IMAGE_BASENAME`. The default value
4100      is set as follows:
4101
4102         INITRAMFS_IMAGE_NAME ?= "${@['${INITRAMFS_IMAGE}${IMAGE_MACHINE_SUFFIX}', ''][d.getVar('INITRAMFS_IMAGE') == '']}"
4103
4104      That is, if :term:`INITRAMFS_IMAGE` is set, the value of
4105      :term:`INITRAMFS_IMAGE_NAME` will be set based upon
4106      :term:`INITRAMFS_IMAGE` and :term:`IMAGE_MACHINE_SUFFIX`.
4107
4108
4109   :term:`INITRAMFS_LINK_NAME`
4110      The link name of the initial RAM filesystem image. This variable is
4111      set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4112      follows::
4113
4114         INITRAMFS_LINK_NAME ?= "initramfs-${KERNEL_ARTIFACT_LINK_NAME}"
4115
4116      The value of the
4117      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4118      file, has the following value::
4119
4120         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4121
4122      See the :term:`MACHINE` variable for additional
4123      information.
4124
4125   :term:`INITRAMFS_MULTICONFIG`
4126      Defines the multiconfig to create a multiconfig dependency to be used by
4127      the :ref:`ref-classes-kernel` class.
4128
4129      This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
4130      a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
4131
4132      For more information on how to bundle an :term:`Initramfs` image from a separate
4133      multiconfig see the ":ref:`dev-manual/building:Bundling an Initramfs Image From a Separate Multiconfig`"
4134      section in the Yocto Project Development Tasks Manual.
4135
4136   :term:`INITRAMFS_NAME`
4137      The base name of the initial RAM filesystem image. This variable is
4138      set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4139      follows::
4140
4141         INITRAMFS_NAME ?= "initramfs-${KERNEL_ARTIFACT_NAME}"
4142
4143      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4144
4145   :term:`INITRD`
4146      Indicates list of filesystem images to concatenate and use as an
4147      initial RAM disk (``initrd``).
4148
4149      The :term:`INITRD` variable is an optional variable used with the
4150      :ref:`ref-classes-image-live` class.
4151
4152   :term:`INITRD_IMAGE`
4153      When building a "live" bootable image (i.e. when
4154      :term:`IMAGE_FSTYPES` contains "live"),
4155      :term:`INITRD_IMAGE` specifies the image recipe that should be built to
4156      provide the initial RAM disk image. The default value is
4157      "core-image-minimal-initramfs".
4158
4159      See the :ref:`ref-classes-image-live` class for more information.
4160
4161   :term:`INITSCRIPT_NAME`
4162      The filename of the initialization script as installed to
4163      ``${sysconfdir}/init.d``.
4164
4165      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
4166      The variable is mandatory.
4167
4168   :term:`INITSCRIPT_PACKAGES`
4169      A list of the packages that contain initscripts. If multiple packages
4170      are specified, you need to append the package name to the other
4171      ``INITSCRIPT_*`` as an override.
4172
4173      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
4174      The variable is optional and defaults to the :term:`PN`
4175      variable.
4176
4177   :term:`INITSCRIPT_PARAMS`
4178      Specifies the options to pass to ``update-rc.d``. Here is an example::
4179
4180         INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
4181
4182      In this example, the script has a runlevel of 99, starts the script
4183      in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
4184
4185      The variable's default value is "defaults", which is set in the
4186      :ref:`ref-classes-update-rc.d` class.
4187
4188      The value in :term:`INITSCRIPT_PARAMS` is passed through to the
4189      ``update-rc.d`` command. For more information on valid parameters,
4190      please see the ``update-rc.d`` manual page at
4191      https://manpages.debian.org/buster/init-system-helpers/update-rc.d.8.en.html
4192
4193   :term:`INSANE_SKIP`
4194      Specifies the QA checks to skip for a specific package within a
4195      recipe. For example, to skip the check for symbolic link ``.so``
4196      files in the main package of a recipe, add the following to the
4197      recipe. The package name override must be used, which in this example
4198      is ``${PN}``::
4199
4200         INSANE_SKIP:${PN} += "dev-so"
4201
4202      See the ":ref:`ref-classes-insane`" section for a
4203      list of the valid QA checks you can specify using this variable.
4204
4205   :term:`INSTALL_TIMEZONE_FILE`
4206      By default, the ``tzdata`` recipe packages an ``/etc/timezone`` file.
4207      Set the :term:`INSTALL_TIMEZONE_FILE` variable to "0" at the
4208      configuration level to disable this behavior.
4209
4210   :term:`IPK_FEED_URIS`
4211      When the IPK backend is in use and package management is enabled on
4212      the target, you can use this variable to set up ``opkg`` in the
4213      target image to point to package feeds on a nominated server. Once
4214      the feed is established, you can perform installations or upgrades
4215      using the package manager at runtime.
4216
4217   :term:`KARCH`
4218      Defines the kernel architecture used when assembling the
4219      configuration. Architectures supported for this release are:
4220
4221      - powerpc
4222      - i386
4223      - x86_64
4224      - arm
4225      - qemu
4226      - mips
4227
4228      You define the :term:`KARCH` variable in the :ref:`kernel-dev/advanced:bsp descriptions`.
4229
4230   :term:`KBRANCH`
4231      A regular expression used by the build process to explicitly identify
4232      the kernel branch that is validated, patched, and configured during a
4233      build. You must set this variable to ensure the exact kernel branch
4234      you want is being used by the build process.
4235
4236      Values for this variable are set in the kernel's recipe file and the
4237      kernel's append file. For example, if you are using the
4238      ``linux-yocto_4.12`` kernel, the kernel recipe file is the
4239      ``meta/recipes-kernel/linux/linux-yocto_4.12.bb`` file. :term:`KBRANCH`
4240      is set as follows in that kernel recipe file::
4241
4242         KBRANCH ?= "standard/base"
4243
4244      This variable is also used from the kernel's append file to identify
4245      the kernel branch specific to a particular machine or target
4246      hardware. Continuing with the previous kernel example, the kernel's
4247      append file (i.e. ``linux-yocto_4.12.bbappend``) is located in the
4248      BSP layer for a given machine. For example, the append file for the
4249      Beaglebone, EdgeRouter, and generic versions of both 32 and 64-bit IA
4250      machines (``meta-yocto-bsp``) is named
4251      ``meta-yocto-bsp/recipes-kernel/linux/linux-yocto_4.12.bbappend``.
4252      Here are the related statements from that append file::
4253
4254         KBRANCH:genericx86 = "standard/base"
4255         KBRANCH:genericx86-64 = "standard/base"
4256         KBRANCH:edgerouter = "standard/edgerouter"
4257         KBRANCH:beaglebone = "standard/beaglebone"
4258
4259      The :term:`KBRANCH` statements
4260      identify the kernel branch to use when building for each supported
4261      BSP.
4262
4263   :term:`KBUILD_DEFCONFIG`
4264      When used with the :ref:`ref-classes-kernel-yocto`
4265      class, specifies an "in-tree" kernel configuration file for use
4266      during a kernel build.
4267
4268      Typically, when using a ``defconfig`` to configure a kernel during a
4269      build, you place the file in your layer in the same manner as you
4270      would place patch files and configuration fragment files (i.e.
4271      "out-of-tree"). However, if you want to use a ``defconfig`` file that
4272      is part of the kernel tree (i.e. "in-tree"), you can use the
4273      :term:`KBUILD_DEFCONFIG` variable and append the
4274      :term:`KMACHINE` variable to point to the
4275      ``defconfig`` file.
4276
4277      To use the variable, set it in the append file for your kernel recipe
4278      using the following form::
4279
4280         KBUILD_DEFCONFIG:<machine> ?= "defconfig_file"
4281
4282      Here is an example from a "raspberrypi2" :term:`MACHINE` build that uses
4283      a ``defconfig`` file named "bcm2709_defconfig"::
4284
4285         KBUILD_DEFCONFIG:raspberrypi2 = "bcm2709_defconfig"
4286
4287      As an alternative, you can use the following within your append file::
4288
4289         KBUILD_DEFCONFIG:pn-linux-yocto ?= "defconfig_file"
4290
4291      For more
4292      information on how to use the :term:`KBUILD_DEFCONFIG` variable, see the
4293      ":ref:`kernel-dev/common:using an "in-tree" \`\`defconfig\`\` file`"
4294      section in the Yocto Project Linux Kernel Development Manual.
4295
4296   :term:`KCONFIG_MODE`
4297      When used with the :ref:`ref-classes-kernel-yocto`
4298      class, specifies the kernel configuration values to use for options
4299      not specified in the provided ``defconfig`` file. Valid options are::
4300
4301         KCONFIG_MODE = "alldefconfig"
4302         KCONFIG_MODE = "allnoconfig"
4303
4304      In ``alldefconfig`` mode the options not explicitly specified will be
4305      assigned their Kconfig default value. In ``allnoconfig`` mode the
4306      options not explicitly specified will be disabled in the kernel
4307      config.
4308
4309      In case :term:`KCONFIG_MODE` is not set the behaviour will depend on where
4310      the ``defconfig`` file is coming from. An "in-tree" ``defconfig`` file
4311      will be handled in ``alldefconfig`` mode, a ``defconfig`` file placed
4312      in ``${WORKDIR}`` through a meta-layer will be handled in
4313      ``allnoconfig`` mode.
4314
4315      An "in-tree" ``defconfig`` file can be selected via the
4316      :term:`KBUILD_DEFCONFIG` variable. :term:`KCONFIG_MODE` does not need to
4317      be explicitly set.
4318
4319      A ``defconfig`` file compatible with ``allnoconfig`` mode can be
4320      generated by copying the ``.config`` file from a working Linux kernel
4321      build, renaming it to ``defconfig`` and placing it into the Linux
4322      kernel ``${WORKDIR}`` through your meta-layer. :term:`KCONFIG_MODE` does
4323      not need to be explicitly set.
4324
4325      A ``defconfig`` file compatible with ``alldefconfig`` mode can be
4326      generated using the
4327      :ref:`ref-tasks-savedefconfig`
4328      task and placed into the Linux kernel ``${WORKDIR}`` through your
4329      meta-layer. Explicitely set :term:`KCONFIG_MODE`::
4330
4331         KCONFIG_MODE = "alldefconfig"
4332
4333   :term:`KERNEL_ALT_IMAGETYPE`
4334      Specifies an alternate kernel image type for creation in addition to
4335      the kernel image type specified using the :term:`KERNEL_IMAGETYPE` and
4336      :term:`KERNEL_IMAGETYPES` variables.
4337
4338   :term:`KERNEL_ARTIFACT_NAME`
4339      Specifies the name of all of the build artifacts. You can change the
4340      name of the artifacts by changing the :term:`KERNEL_ARTIFACT_NAME`
4341      variable.
4342
4343      The value of :term:`KERNEL_ARTIFACT_NAME`, which is set in the
4344      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file, has the
4345      following default value::
4346
4347         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}${IMAGE_MACHINE_SUFFIX}${IMAGE_VERSION_SUFFIX}"
4348
4349      See the :term:`PKGE`, :term:`PKGV`, :term:`PKGR`, :term:`IMAGE_MACHINE_SUFFIX`
4350      and :term:`IMAGE_VERSION_SUFFIX` variables for additional information.
4351
4352   :term:`KERNEL_CLASSES`
4353      A list of classes defining kernel image types that the
4354      :ref:`ref-classes-kernel` class should inherit. You typically
4355      append this variable to enable extended image types. An example is
4356      ":ref:`ref-classes-kernel-fitimage`", which enables
4357      fitImage support and resides in ``meta/classes-recipe/kernel-fitimage.bbclass``.
4358      You can register custom kernel image types with the
4359      :ref:`ref-classes-kernel` class using this variable.
4360
4361   :term:`KERNEL_DANGLING_FEATURES_WARN_ONLY`
4362      When kernel configuration fragments are missing for some
4363      :term:`KERNEL_FEATURES` specified by layers or BSPs,
4364      building and configuring the kernel stops with an error.
4365
4366      You can turn these errors into warnings by setting the
4367      following in ``conf/local.conf``::
4368
4369         KERNEL_DANGLING_FEATURES_WARN_ONLY = "1"
4370
4371      You will still be warned that runtime issues may occur,
4372      but at least the kernel configuration and build process will
4373      be allowed to continue.
4374
4375   :term:`KERNEL_DEBUG_TIMESTAMPS`
4376      If set to "1", enables timestamping functionality during building
4377      the kernel. The default is "0" to disable this for reproducibility
4378      reasons.
4379
4380   :term:`KERNEL_DEPLOY_DEPEND`
4381      Provides a means of controlling the dependency of an image recipe
4382      on the kernel. The default value is "virtual/kernel:do_deploy",
4383      however for a small initramfs image or other images that do not
4384      need the kernel, this can be set to "" in the image recipe.
4385
4386   :term:`KERNEL_DEVICETREE`
4387      Specifies the name of the generated Linux kernel device tree (i.e.
4388      the ``.dtb``) file.
4389
4390      .. note::
4391
4392         There is legacy support for specifying the full path to the device
4393         tree. However, providing just the ``.dtb`` file is preferred.
4394
4395      In order to use this variable, the :ref:`ref-classes-kernel-devicetree`
4396      class must be inherited.
4397
4398   :term:`KERNEL_DTB_LINK_NAME`
4399      The link name of the kernel device tree binary (DTB). This variable
4400      is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4401      follows::
4402
4403         KERNEL_DTB_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4404
4405      The
4406      value of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in
4407      the same file, has the following value::
4408
4409         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4410
4411      See the :term:`MACHINE` variable for additional
4412      information.
4413
4414   :term:`KERNEL_DTB_NAME`
4415      The base name of the kernel device tree binary (DTB). This variable
4416      is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4417      follows::
4418
4419         KERNEL_DTB_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4420
4421      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4422
4423   :term:`KERNEL_DTC_FLAGS`
4424      Specifies the ``dtc`` flags that are passed to the Linux kernel build
4425      system when generating the device trees (via ``DTC_FLAGS`` environment
4426      variable).
4427
4428      In order to use this variable, the :ref:`ref-classes-kernel-devicetree`
4429      class must be inherited.
4430
4431   :term:`KERNEL_EXTRA_ARGS`
4432      Specifies additional ``make`` command-line arguments the OpenEmbedded
4433      build system passes on when compiling the kernel.
4434
4435   :term:`KERNEL_FEATURES`
4436      Includes additional kernel metadata. In the OpenEmbedded build
4437      system, the default Board Support Packages (BSPs)
4438      :term:`Metadata` is provided through the
4439      :term:`KMACHINE` and :term:`KBRANCH`
4440      variables. You can use the :term:`KERNEL_FEATURES` variable from within
4441      the kernel recipe or kernel append file to further add metadata for
4442      all BSPs or specific BSPs.
4443
4444      The metadata you add through this variable includes config fragments
4445      and features descriptions, which usually includes patches as well as
4446      config fragments. You typically override the :term:`KERNEL_FEATURES`
4447      variable for a specific machine. In this way, you can provide
4448      validated, but optional, sets of kernel configurations and features.
4449
4450      For example, the following example from the ``linux-yocto-rt_4.12``
4451      kernel recipe adds "netfilter" and "taskstats" features to all BSPs
4452      as well as "virtio" configurations to all QEMU machines. The last two
4453      statements add specific configurations to targeted machine types::
4454
4455         KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc features/taskstats/taskstats.scc"
4456         KERNEL_FEATURES:append = " ${KERNEL_EXTRA_FEATURES}"
4457         KERNEL_FEATURES:append:qemuall = " cfg/virtio.scc"
4458         KERNEL_FEATURES:append:qemux86 = "  cfg/sound.scc cfg/paravirt_kvm.scc"
4459         KERNEL_FEATURES:append:qemux86-64 = " cfg/sound.scc"
4460
4461   :term:`KERNEL_FIT_LINK_NAME`
4462      The link name of the kernel flattened image tree (FIT) image. This
4463      variable is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass``
4464      file as follows::
4465
4466         KERNEL_FIT_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4467
4468      The value of the
4469      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4470      file, has the following value::
4471
4472         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4473
4474      See the :term:`MACHINE` variable for additional
4475      information.
4476
4477   :term:`KERNEL_FIT_NAME`
4478      The base name of the kernel flattened image tree (FIT) image. This
4479      variable is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass``
4480      file as follows::
4481
4482         KERNEL_FIT_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4483
4484      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4485
4486   :term:`KERNEL_IMAGE_LINK_NAME`
4487      The link name for the kernel image. This variable is set in the
4488      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
4489
4490         KERNEL_IMAGE_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4491
4492      The value of
4493      the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4494      file, has the following value::
4495
4496         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4497
4498      See the :term:`MACHINE` variable for additional
4499      information.
4500
4501   :term:`KERNEL_IMAGE_MAXSIZE`
4502      Specifies the maximum size of the kernel image file in kilobytes. If
4503      :term:`KERNEL_IMAGE_MAXSIZE` is set, the size of the kernel image file is
4504      checked against the set value during the
4505      :ref:`ref-tasks-sizecheck` task. The task fails if
4506      the kernel image file is larger than the setting.
4507
4508      :term:`KERNEL_IMAGE_MAXSIZE` is useful for target devices that have a
4509      limited amount of space in which the kernel image must be stored.
4510
4511      By default, this variable is not set, which means the size of the
4512      kernel image is not checked.
4513
4514   :term:`KERNEL_IMAGE_NAME`
4515      The base name of the kernel image. This variable is set in the
4516      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
4517
4518         KERNEL_IMAGE_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4519
4520      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4521
4522   :term:`KERNEL_IMAGETYPE`
4523      The type of kernel to build for a device, usually set by the machine
4524      configuration files and defaults to "zImage". This variable is used
4525      when building the kernel and is passed to ``make`` as the target to
4526      build.
4527
4528      To build additional kernel image types, use :term:`KERNEL_IMAGETYPES`.
4529
4530   :term:`KERNEL_IMAGETYPES`
4531      Lists additional types of kernel images to build for a device in addition
4532      to image type specified in :term:`KERNEL_IMAGETYPE`. Usually set by the
4533      machine configuration files.
4534
4535   :term:`KERNEL_MODULE_AUTOLOAD`
4536      Lists kernel modules that need to be auto-loaded during boot.
4537
4538      .. note::
4539
4540         This variable replaces the deprecated :term:`module_autoload`
4541         variable.
4542
4543      You can use the :term:`KERNEL_MODULE_AUTOLOAD` variable anywhere that it
4544      can be recognized by the kernel recipe or by an out-of-tree kernel
4545      module recipe (e.g. a machine configuration file, a distribution
4546      configuration file, an append file for the recipe, or the recipe
4547      itself).
4548
4549      Specify it as follows::
4550
4551         KERNEL_MODULE_AUTOLOAD += "module_name1 module_name2 module_name3"
4552
4553      Including :term:`KERNEL_MODULE_AUTOLOAD` causes the OpenEmbedded build
4554      system to populate the ``/etc/modules-load.d/modname.conf`` file with
4555      the list of modules to be auto-loaded on boot. The modules appear
4556      one-per-line in the file. Here is an example of the most common use
4557      case::
4558
4559         KERNEL_MODULE_AUTOLOAD += "module_name"
4560
4561      For information on how to populate the ``modname.conf`` file with
4562      ``modprobe.d`` syntax lines, see the :term:`KERNEL_MODULE_PROBECONF` variable.
4563
4564   :term:`KERNEL_MODULE_PROBECONF`
4565      Provides a list of modules for which the OpenEmbedded build system
4566      expects to find ``module_conf_``\ modname values that specify
4567      configuration for each of the modules. For information on how to
4568      provide those module configurations, see the
4569      :term:`module_conf_* <module_conf>` variable.
4570
4571   :term:`KERNEL_PATH`
4572      The location of the kernel sources. This variable is set to the value
4573      of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`
4574      class. For information on how this variable is used, see the
4575      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4576      section in the Yocto Project Linux Kernel Development Manual.
4577
4578      To help maximize compatibility with out-of-tree drivers used to build
4579      modules, the OpenEmbedded build system also recognizes and uses the
4580      :term:`KERNEL_SRC` variable, which is identical to
4581      the :term:`KERNEL_PATH` variable. Both variables are common variables
4582      used by external Makefiles to point to the kernel source directory.
4583
4584   :term:`KERNEL_SRC`
4585      The location of the kernel sources. This variable is set to the value
4586      of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`
4587      class. For information on how this variable is used, see the
4588      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4589      section in the Yocto Project Linux Kernel Development Manual.
4590
4591      To help maximize compatibility with out-of-tree drivers used to build
4592      modules, the OpenEmbedded build system also recognizes and uses the
4593      :term:`KERNEL_PATH` variable, which is identical
4594      to the :term:`KERNEL_SRC` variable. Both variables are common variables
4595      used by external Makefiles to point to the kernel source directory.
4596
4597   :term:`KERNEL_VERSION`
4598      Specifies the version of the kernel as extracted from ``version.h``
4599      or ``utsrelease.h`` within the kernel sources. Effects of setting
4600      this variable do not take effect until the kernel has been
4601      configured. Consequently, attempting to refer to this variable in
4602      contexts prior to configuration will not work.
4603
4604   :term:`KERNELDEPMODDEPEND`
4605      Specifies whether the data referenced through
4606      :term:`PKGDATA_DIR` is needed or not.
4607      :term:`KERNELDEPMODDEPEND` does not control whether or not that data
4608      exists, but simply whether or not it is used. If you do not need to
4609      use the data, set the :term:`KERNELDEPMODDEPEND` variable in your
4610      :term:`Initramfs` recipe. Setting the variable there when the data is not
4611      needed avoids a potential dependency loop.
4612
4613   :term:`KFEATURE_DESCRIPTION`
4614      Provides a short description of a configuration fragment. You use
4615      this variable in the ``.scc`` file that describes a configuration
4616      fragment file. Here is the variable used in a file named ``smp.scc``
4617      to describe SMP being enabled::
4618
4619          define KFEATURE_DESCRIPTION "Enable SMP"
4620
4621   :term:`KMACHINE`
4622      The machine as known by the kernel. Sometimes the machine name used
4623      by the kernel does not match the machine name used by the
4624      OpenEmbedded build system. For example, the machine name that the
4625      OpenEmbedded build system understands as ``core2-32-intel-common``
4626      goes by a different name in the Linux Yocto kernel. The kernel
4627      understands that machine as ``intel-core2-32``. For cases like these,
4628      the :term:`KMACHINE` variable maps the kernel machine name to the
4629      OpenEmbedded build system machine name.
4630
4631      These mappings between different names occur in the Yocto Linux
4632      Kernel's ``meta`` branch. As an example take a look in the
4633      ``common/recipes-kernel/linux/linux-yocto_3.19.bbappend`` file::
4634
4635         LINUX_VERSION:core2-32-intel-common = "3.19.0"
4636         COMPATIBLE_MACHINE:core2-32-intel-common = "${MACHINE}"
4637         SRCREV_meta:core2-32-intel-common = "8897ef68b30e7426bc1d39895e71fb155d694974"
4638         SRCREV_machine:core2-32-intel-common = "43b9eced9ba8a57add36af07736344dcc383f711"
4639         KMACHINE:core2-32-intel-common = "intel-core2-32"
4640         KBRANCH:core2-32-intel-common = "standard/base"
4641         KERNEL_FEATURES:append:core2-32-intel-common = " ${KERNEL_FEATURES_INTEL_COMMON}"
4642
4643      The :term:`KMACHINE` statement says
4644      that the kernel understands the machine name as "intel-core2-32".
4645      However, the OpenEmbedded build system understands the machine as
4646      "core2-32-intel-common".
4647
4648   :term:`KTYPE`
4649      Defines the kernel type to be used in assembling the configuration.
4650      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4651      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4652      section in the
4653      Yocto Project Linux Kernel Development Manual for more information on
4654      kernel types.
4655
4656      You define the :term:`KTYPE` variable in the
4657      :ref:`kernel-dev/advanced:bsp descriptions`. The
4658      value you use must match the value used for the
4659      :term:`LINUX_KERNEL_TYPE` value used by the
4660      kernel recipe.
4661
4662   :term:`LABELS`
4663      Provides a list of targets for automatic configuration.
4664
4665      See the :ref:`ref-classes-grub-efi` class for more
4666      information on how this variable is used.
4667
4668   :term:`LAYERDEPENDS`
4669      Lists the layers, separated by spaces, on which this recipe depends.
4670      Optionally, you can specify a specific layer version for a dependency
4671      by adding it to the end of the layer name. Here is an example::
4672
4673         LAYERDEPENDS_mylayer = "anotherlayer (=3)"
4674
4675      In this previous example,
4676      version 3 of "anotherlayer" is compared against
4677      :term:`LAYERVERSION`\ ``_anotherlayer``.
4678
4679      An error is produced if any dependency is missing or the version
4680      numbers (if specified) do not match exactly. This variable is used in
4681      the ``conf/layer.conf`` file and must be suffixed with the name of
4682      the specific layer (e.g. ``LAYERDEPENDS_mylayer``).
4683
4684   :term:`LAYERDIR`
4685      When used inside the ``layer.conf`` configuration file, this variable
4686      provides the path of the current layer. This variable is not
4687      available outside of ``layer.conf`` and references are expanded
4688      immediately when parsing of the file completes.
4689
4690   :term:`LAYERDIR_RE`
4691      See :term:`bitbake:LAYERDIR_RE` in the BitBake manual.
4692
4693   :term:`LAYERRECOMMENDS`
4694      Lists the layers, separated by spaces, recommended for use with this
4695      layer.
4696
4697      Optionally, you can specify a specific layer version for a
4698      recommendation by adding the version to the end of the layer name.
4699      Here is an example::
4700
4701         LAYERRECOMMENDS_mylayer = "anotherlayer (=3)"
4702
4703      In this previous example, version 3 of "anotherlayer" is compared
4704      against ``LAYERVERSION_anotherlayer``.
4705
4706      This variable is used in the ``conf/layer.conf`` file and must be
4707      suffixed with the name of the specific layer (e.g.
4708      ``LAYERRECOMMENDS_mylayer``).
4709
4710   :term:`LAYERSERIES_COMPAT`
4711      See :term:`bitbake:LAYERSERIES_COMPAT` in the BitBake manual.
4712
4713   :term:`LAYERVERSION`
4714      Optionally specifies the version of a layer as a single number. You
4715      can use this within :term:`LAYERDEPENDS` for
4716      another layer in order to depend on a specific version of the layer.
4717      This variable is used in the ``conf/layer.conf`` file and must be
4718      suffixed with the name of the specific layer (e.g.
4719      ``LAYERVERSION_mylayer``).
4720
4721   :term:`LD`
4722      The minimal command and arguments used to run the linker.
4723
4724   :term:`LDFLAGS`
4725      Specifies the flags to pass to the linker. This variable is exported
4726      to an environment variable and thus made visible to the software
4727      being built during the compilation step.
4728
4729      Default initialization for :term:`LDFLAGS` varies depending on what is
4730      being built:
4731
4732      -  :term:`TARGET_LDFLAGS` when building for the
4733         target
4734
4735      -  :term:`BUILD_LDFLAGS` when building for the
4736         build host (i.e. ``-native``)
4737
4738      -  :term:`BUILDSDK_LDFLAGS` when building for
4739         an SDK (i.e. ``nativesdk-``)
4740
4741   :term:`LEAD_SONAME`
4742      Specifies the lead (or primary) compiled library file (i.e. ``.so``)
4743      that the :ref:`ref-classes-debian` class applies its
4744      naming policy to given a recipe that packages multiple libraries.
4745
4746      This variable works in conjunction with the :ref:`ref-classes-debian`
4747      class.
4748
4749   :term:`LIC_FILES_CHKSUM`
4750      Checksums of the license text in the recipe source code.
4751
4752      This variable tracks changes in license text of the source code
4753      files. If the license text is changed, it will trigger a build
4754      failure, which gives the developer an opportunity to review any
4755      license change.
4756
4757      This variable must be defined for all recipes (unless
4758      :term:`LICENSE` is set to "CLOSED").
4759
4760      For more information, see the ":ref:`dev-manual/licenses:tracking license changes`"
4761      section in the Yocto Project Development Tasks Manual.
4762
4763   :term:`LICENSE`
4764      The list of source licenses for the recipe. Follow these rules:
4765
4766      -  Do not use spaces within individual license names.
4767
4768      -  Separate license names using \| (pipe) when there is a choice
4769         between licenses.
4770
4771      -  Separate license names using & (ampersand) when there are
4772         multiple licenses for different parts of the source.
4773
4774      -  You can use spaces between license names.
4775
4776      -  For standard licenses, use the names of the files in
4777         ``meta/files/common-licenses/`` or the
4778         :term:`SPDXLICENSEMAP` flag names defined in
4779         ``meta/conf/licenses.conf``.
4780
4781      Here are some examples::
4782
4783         LICENSE = "LGPL-2.1-only | GPL-3.0-only"
4784         LICENSE = "MPL-1.0 & LGPL-2.1-only"
4785         LICENSE = "GPL-2.0-or-later"
4786
4787      The first example is from the
4788      recipes for Qt, which the user may choose to distribute under either
4789      the LGPL version 2.1 or GPL version 3. The second example is from
4790      Cairo where two licenses cover different parts of the source code.
4791      The final example is from ``sysstat``, which presents a single
4792      license.
4793
4794      You can also specify licenses on a per-package basis to handle
4795      situations where components of the output have different licenses.
4796      For example, a piece of software whose code is licensed under GPLv2
4797      but has accompanying documentation licensed under the GNU Free
4798      Documentation License 1.2 could be specified as follows::
4799
4800         LICENSE = "GFDL-1.2 & GPL-2.0-only"
4801         LICENSE:${PN} = "GPL-2.0.only"
4802         LICENSE:${PN}-doc = "GFDL-1.2"
4803
4804   :term:`LICENSE_CREATE_PACKAGE`
4805      Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
4806      build system to create an extra package (i.e.
4807      ``${``\ :term:`PN`\ ``}-lic``) for each recipe and to add
4808      those packages to the
4809      :term:`RRECOMMENDS`\ ``:${PN}``.
4810
4811      The ``${PN}-lic`` package installs a directory in
4812      ``/usr/share/licenses`` named ``${PN}``, which is the recipe's base
4813      name, and installs files in that directory that contain license and
4814      copyright information (i.e. copies of the appropriate license files
4815      from ``meta/common-licenses`` that match the licenses specified in
4816      the :term:`LICENSE` variable of the recipe metadata
4817      and copies of files marked in
4818      :term:`LIC_FILES_CHKSUM` as containing
4819      license text).
4820
4821      For related information on providing license text, see the
4822      :term:`COPY_LIC_DIRS` variable, the
4823      :term:`COPY_LIC_MANIFEST` variable, and the
4824      ":ref:`dev-manual/licenses:providing license text`"
4825      section in the Yocto Project Development Tasks Manual.
4826
4827   :term:`LICENSE_FLAGS`
4828      Specifies additional flags for a recipe you must allow through
4829      :term:`LICENSE_FLAGS_ACCEPTED` in
4830      order for the recipe to be built. When providing multiple flags,
4831      separate them with spaces.
4832
4833      This value is independent of :term:`LICENSE` and is
4834      typically used to mark recipes that might require additional licenses
4835      in order to be used in a commercial product. For more information,
4836      see the
4837      ":ref:`dev-manual/licenses:enabling commercially licensed recipes`"
4838      section in the Yocto Project Development Tasks Manual.
4839
4840   :term:`LICENSE_FLAGS_ACCEPTED`
4841      Lists license flags that when specified in
4842      :term:`LICENSE_FLAGS` within a recipe should not
4843      prevent that recipe from being built.  For more information, see the
4844      ":ref:`dev-manual/licenses:enabling commercially licensed recipes`"
4845      section in the Yocto Project Development Tasks Manual.
4846
4847   :term:`LICENSE_PATH`
4848      Path to additional licenses used during the build. By default, the
4849      OpenEmbedded build system uses :term:`COMMON_LICENSE_DIR` to define the
4850      directory that holds common license text used during the build. The
4851      :term:`LICENSE_PATH` variable allows you to extend that location to other
4852      areas that have additional licenses::
4853
4854         LICENSE_PATH += "path-to-additional-common-licenses"
4855
4856   :term:`LINUX_KERNEL_TYPE`
4857      Defines the kernel type to be used in assembling the configuration.
4858      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4859      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4860      section in the
4861      Yocto Project Linux Kernel Development Manual for more information on
4862      kernel types.
4863
4864      If you do not specify a :term:`LINUX_KERNEL_TYPE`, it defaults to
4865      "standard". Together with :term:`KMACHINE`, the
4866      :term:`LINUX_KERNEL_TYPE` variable defines the search arguments used by
4867      the kernel tools to find the appropriate description within the
4868      kernel :term:`Metadata` with which to build out the sources
4869      and configuration.
4870
4871   :term:`LINUX_VERSION`
4872      The Linux version from ``kernel.org`` on which the Linux kernel image
4873      being built using the OpenEmbedded build system is based. You define
4874      this variable in the kernel recipe. For example, the
4875      ``linux-yocto-3.4.bb`` kernel recipe found in
4876      ``meta/recipes-kernel/linux`` defines the variables as follows::
4877
4878         LINUX_VERSION ?= "3.4.24"
4879
4880      The :term:`LINUX_VERSION` variable is used to define :term:`PV`
4881      for the recipe::
4882
4883         PV = "${LINUX_VERSION}+git${SRCPV}"
4884
4885   :term:`LINUX_VERSION_EXTENSION`
4886      A string extension compiled into the version string of the Linux
4887      kernel built with the OpenEmbedded build system. You define this
4888      variable in the kernel recipe. For example, the linux-yocto kernel
4889      recipes all define the variable as follows::
4890
4891         LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
4892
4893      Defining this variable essentially sets the Linux kernel
4894      configuration item ``CONFIG_LOCALVERSION``, which is visible through
4895      the ``uname`` command. Here is an example that shows the extension
4896      assuming it was set as previously shown::
4897
4898         $ uname -r
4899         3.7.0-rc8-custom
4900
4901   :term:`LOG_DIR`
4902      Specifies the directory to which the OpenEmbedded build system writes
4903      overall log files. The default directory is ``${TMPDIR}/log``.
4904
4905      For the directory containing logs specific to each task, see the
4906      :term:`T` variable.
4907
4908   :term:`MACHINE`
4909      Specifies the target device for which the image is built. You define
4910      :term:`MACHINE` in the ``local.conf`` file found in the
4911      :term:`Build Directory`. By default, :term:`MACHINE` is set to
4912      "qemux86", which is an x86-based architecture machine to be emulated
4913      using QEMU::
4914
4915         MACHINE ?= "qemux86"
4916
4917      The variable corresponds to a machine configuration file of the same
4918      name, through which machine-specific configurations are set. Thus,
4919      when :term:`MACHINE` is set to "qemux86", the corresponding
4920      ``qemux86.conf`` machine configuration file can be found in
4921      the :term:`Source Directory` in
4922      ``meta/conf/machine``.
4923
4924      The list of machines supported by the Yocto Project as shipped
4925      include the following::
4926
4927         MACHINE ?= "qemuarm"
4928         MACHINE ?= "qemuarm64"
4929         MACHINE ?= "qemumips"
4930         MACHINE ?= "qemumips64"
4931         MACHINE ?= "qemuppc"
4932         MACHINE ?= "qemux86"
4933         MACHINE ?= "qemux86-64"
4934         MACHINE ?= "genericx86"
4935         MACHINE ?= "genericx86-64"
4936         MACHINE ?= "beaglebone"
4937         MACHINE ?= "edgerouter"
4938
4939      The last five are Yocto Project reference hardware
4940      boards, which are provided in the ``meta-yocto-bsp`` layer.
4941
4942      .. note::
4943
4944         Adding additional Board Support Package (BSP) layers to your
4945         configuration adds new possible settings for :term:`MACHINE`.
4946
4947   :term:`MACHINE_ARCH`
4948      Specifies the name of the machine-specific architecture. This
4949      variable is set automatically from :term:`MACHINE` or
4950      :term:`TUNE_PKGARCH`. You should not hand-edit
4951      the :term:`MACHINE_ARCH` variable.
4952
4953   :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4954      A list of required machine-specific packages to install as part of
4955      the image being built. The build process depends on these packages
4956      being present. Furthermore, because this is a "machine-essential"
4957      variable, the list of packages are essential for the machine to boot.
4958      The impact of this variable affects images based on
4959      ``packagegroup-core-boot``, including the ``core-image-minimal``
4960      image.
4961
4962      This variable is similar to the
4963      :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` variable with the exception
4964      that the image being built has a build dependency on the variable's
4965      list of packages. In other words, the image will not build if a file
4966      in this list is not found.
4967
4968      As an example, suppose the machine for which you are building
4969      requires ``example-init`` to be run during boot to initialize the
4970      hardware. In this case, you would use the following in the machine's
4971      ``.conf`` configuration file::
4972
4973         MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
4974
4975   :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS`
4976      A list of recommended machine-specific packages to install as part of
4977      the image being built. The build process does not depend on these
4978      packages being present. However, because this is a
4979      "machine-essential" variable, the list of packages are essential for
4980      the machine to boot. The impact of this variable affects images based
4981      on ``packagegroup-core-boot``, including the ``core-image-minimal``
4982      image.
4983
4984      This variable is similar to the :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4985      variable with the exception that the image being built does not have
4986      a build dependency on the variable's list of packages. In other
4987      words, the image will still build if a package in this list is not
4988      found. Typically, this variable is used to handle essential kernel
4989      modules, whose functionality may be selected to be built into the
4990      kernel rather than as a module, in which case a package will not be
4991      produced.
4992
4993      Consider an example where you have a custom kernel where a specific
4994      touchscreen driver is required for the machine to be usable. However,
4995      the driver can be built as a module or into the kernel depending on
4996      the kernel configuration. If the driver is built as a module, you
4997      want it to be installed. But, when the driver is built into the
4998      kernel, you still want the build to succeed. This variable sets up a
4999      "recommends" relationship so that in the latter case, the build will
5000      not fail due to the missing package. To accomplish this, assuming the
5001      package for the module was called ``kernel-module-ab123``, you would
5002      use the following in the machine's ``.conf`` configuration file::
5003
5004         MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
5005
5006      .. note::
5007
5008         In this example, the ``kernel-module-ab123`` recipe needs to
5009         explicitly set its :term:`PACKAGES` variable to ensure that BitBake
5010         does not use the kernel recipe's :term:`PACKAGES_DYNAMIC` variable to
5011         satisfy the dependency.
5012
5013      Some examples of these machine essentials are flash, screen,
5014      keyboard, mouse, or touchscreen drivers (depending on the machine).
5015
5016   :term:`MACHINE_EXTRA_RDEPENDS`
5017      A list of machine-specific packages to install as part of the image
5018      being built that are not essential for the machine to boot. However,
5019      the build process for more fully-featured images depends on the
5020      packages being present.
5021
5022      This variable affects all images based on ``packagegroup-base``,
5023      which does not include the ``core-image-minimal`` or
5024      ``core-image-full-cmdline`` images.
5025
5026      The variable is similar to the :term:`MACHINE_EXTRA_RRECOMMENDS` variable
5027      with the exception that the image being built has a build dependency
5028      on the variable's list of packages. In other words, the image will
5029      not build if a file in this list is not found.
5030
5031      An example is a machine that has WiFi capability but is not essential
5032      for the machine to boot the image. However, if you are building a
5033      more fully-featured image, you want to enable the WiFi. The package
5034      containing the firmware for the WiFi hardware is always expected to
5035      exist, so it is acceptable for the build process to depend upon
5036      finding the package. In this case, assuming the package for the
5037      firmware was called ``wifidriver-firmware``, you would use the
5038      following in the ``.conf`` file for the machine::
5039
5040         MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
5041
5042   :term:`MACHINE_EXTRA_RRECOMMENDS`
5043      A list of machine-specific packages to install as part of the image
5044      being built that are not essential for booting the machine. The image
5045      being built has no build dependency on this list of packages.
5046
5047      This variable affects only images based on ``packagegroup-base``,
5048      which does not include the ``core-image-minimal`` or
5049      ``core-image-full-cmdline`` images.
5050
5051      This variable is similar to the :term:`MACHINE_EXTRA_RDEPENDS` variable
5052      with the exception that the image being built does not have a build
5053      dependency on the variable's list of packages. In other words, the
5054      image will build if a file in this list is not found.
5055
5056      An example is a machine that has WiFi capability but is not essential
5057      For the machine to boot the image. However, if you are building a
5058      more fully-featured image, you want to enable WiFi. In this case, the
5059      package containing the WiFi kernel module will not be produced if the
5060      WiFi driver is built into the kernel, in which case you still want
5061      the build to succeed instead of failing as a result of the package
5062      not being found. To accomplish this, assuming the package for the
5063      module was called ``kernel-module-examplewifi``, you would use the
5064      following in the ``.conf`` file for the machine::
5065
5066         MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
5067
5068   :term:`MACHINE_FEATURES`
5069      Specifies the list of hardware features the
5070      :term:`MACHINE` is capable of supporting. For related
5071      information on enabling features, see the
5072      :term:`DISTRO_FEATURES`,
5073      :term:`COMBINED_FEATURES`, and
5074      :term:`IMAGE_FEATURES` variables.
5075
5076      For a list of hardware features supported by the Yocto Project as
5077      shipped, see the ":ref:`ref-features-machine`" section.
5078
5079   :term:`MACHINE_FEATURES_BACKFILL`
5080      A list of space-separated features to be added to
5081      :term:`MACHINE_FEATURES` if not also present in
5082      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`.
5083
5084      This variable is set in the ``meta/conf/bitbake.conf`` file. It is not
5085      intended to be user-configurable. It is best to just reference the
5086      variable to see which machine features are being
5087      :ref:`backfilled <ref-features-backfill>` for all machine configurations.
5088
5089   :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`
5090      A list of space-separated features from :term:`MACHINE_FEATURES_BACKFILL`
5091      that should not be :ref:`backfilled <ref-features-backfill>` (i.e. added
5092      to :term:`MACHINE_FEATURES`) during the build.
5093
5094      This corresponds to an opt-out mechanism. When new default machine
5095      features are introduced, machine definition maintainers can review
5096      (`consider`) them and decide to exclude them from the
5097      :ref:`backfilled <ref-features-backfill>` features. Therefore, the
5098      combination of :term:`MACHINE_FEATURES_BACKFILL` and
5099      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED` makes it possible to
5100      add new default features without breaking existing machine definitions.
5101
5102   :term:`MACHINEOVERRIDES`
5103      A colon-separated list of overrides that apply to the current
5104      machine. By default, this list includes the value of
5105      :term:`MACHINE`.
5106
5107      You can extend :term:`MACHINEOVERRIDES` to add extra overrides that
5108      should apply to a machine. For example, all machines emulated in QEMU
5109      (e.g. ``qemuarm``, ``qemux86``, and so forth) include a file named
5110      ``meta/conf/machine/include/qemu.inc`` that prepends the following
5111      override to :term:`MACHINEOVERRIDES`::
5112
5113         MACHINEOVERRIDES =. "qemuall:"
5114
5115      This
5116      override allows variables to be overridden for all machines emulated
5117      in QEMU, like in the following example from the ``connman-conf``
5118      recipe::
5119
5120         SRC_URI:append:qemuall = " file://wired.config \
5121             file://wired-setup \
5122             "
5123
5124      The underlying mechanism behind
5125      :term:`MACHINEOVERRIDES` is simply that it is included in the default
5126      value of :term:`OVERRIDES`.
5127
5128   :term:`MAINTAINER`
5129      The email address of the distribution maintainer.
5130
5131   :term:`MESON_BUILDTYPE`
5132      Value of the Meson ``--buildtype`` argument used by the
5133      :ref:`ref-classes-meson` class. It defaults to ``debug`` if
5134      :term:`DEBUG_BUILD` is set to "1", and ``plain`` otherwise.
5135
5136      See `Meson build options <https://mesonbuild.com/Builtin-options.html>`__
5137      for the values you could set in a recipe. Values such as ``plain``,
5138      ``debug``, ``debugoptimized``, ``release`` and ``minsize`` allow
5139      you to specify the inclusion of debugging symbols and the compiler
5140      optimizations (none, performance or size).
5141
5142   :term:`METADATA_BRANCH`
5143      The branch currently checked out for the OpenEmbedded-Core layer (path
5144      determined by :term:`COREBASE`).
5145
5146   :term:`METADATA_REVISION`
5147      The revision currently checked out for the OpenEmbedded-Core layer (path
5148      determined by :term:`COREBASE`).
5149
5150   :term:`MIME_XDG_PACKAGES`
5151      The current implementation of the :ref:`ref-classes-mime-xdg`
5152      class cannot detect ``.desktop`` files installed through absolute
5153      symbolic links. Use this setting to make the class create post-install
5154      and post-remove scripts for these packages anyway, to invoke the
5155      ``update-destop-database`` command.
5156
5157   :term:`MIRRORS`
5158      Specifies additional paths from which the OpenEmbedded build system
5159      gets source code. When the build system searches for source code, it
5160      first tries the local download directory. If that location fails, the
5161      build system tries locations defined by
5162      :term:`PREMIRRORS`, the upstream source, and then
5163      locations specified by :term:`MIRRORS` in that order.
5164
5165      Assuming your distribution (:term:`DISTRO`) is "poky",
5166      the default value for :term:`MIRRORS` is defined in the
5167      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
5168
5169   :term:`MLPREFIX`
5170      Specifies a prefix has been added to :term:`PN` to create a
5171      special version of a recipe or package (i.e. a Multilib version). The
5172      variable is used in places where the prefix needs to be added to or
5173      removed from a name (e.g. the :term:`BPN` variable).
5174      :term:`MLPREFIX` gets set when a prefix has been added to :term:`PN`.
5175
5176      .. note::
5177
5178         The "ML" in :term:`MLPREFIX` stands for "MultiLib". This representation
5179         is historical and comes from a time when ":ref:`ref-classes-nativesdk`"
5180         was a suffix rather than a prefix on the recipe name. When
5181         ":ref:`ref-classes-nativesdk`" was turned into a prefix, it made sense
5182         to set :term:`MLPREFIX` for it as well.
5183
5184      To help understand when :term:`MLPREFIX` might be needed, consider when
5185      :term:`BBCLASSEXTEND` is used to provide a :ref:`ref-classes-nativesdk`
5186      version of a recipe in addition to the target version. If that recipe
5187      declares build-time dependencies on tasks in other recipes by using
5188      :term:`DEPENDS`, then a dependency on "foo" will automatically get
5189      rewritten to a dependency on "nativesdk-foo". However, dependencies like
5190      the following will not get rewritten automatically::
5191
5192         do_foo[depends] += "recipe:do_foo"
5193
5194      If you want such a dependency to also get transformed, you can do the
5195      following::
5196
5197         do_foo[depends] += "${MLPREFIX}recipe:do_foo"
5198
5199   :term:`module_autoload`
5200      This variable has been replaced by the :term:`KERNEL_MODULE_AUTOLOAD`
5201      variable. You should replace all occurrences of :term:`module_autoload`
5202      with additions to :term:`KERNEL_MODULE_AUTOLOAD`, for example::
5203
5204         module_autoload_rfcomm = "rfcomm"
5205
5206      should now be replaced with::
5207
5208         KERNEL_MODULE_AUTOLOAD += "rfcomm"
5209
5210      See the :term:`KERNEL_MODULE_AUTOLOAD` variable for more information.
5211
5212   :term:`module_conf`
5213      Specifies `modprobe.d <https://linux.die.net/man/5/modprobe.d>`__
5214      syntax lines for inclusion in the ``/etc/modprobe.d/modname.conf``
5215      file.
5216
5217      You can use this variable anywhere that it can be recognized by the
5218      kernel recipe or out-of-tree kernel module recipe (e.g. a machine
5219      configuration file, a distribution configuration file, an append file
5220      for the recipe, or the recipe itself). If you use this variable, you
5221      must also be sure to list the module name in the
5222      :term:`KERNEL_MODULE_PROBECONF`
5223      variable.
5224
5225      Here is the general syntax::
5226
5227         module_conf_module_name = "modprobe.d-syntax"
5228
5229      You must use the kernel module name override.
5230
5231      Run ``man modprobe.d`` in the shell to find out more information on
5232      the exact syntax you want to provide with :term:`module_conf`.
5233
5234      Including :term:`module_conf` causes the OpenEmbedded build system to
5235      populate the ``/etc/modprobe.d/modname.conf`` file with
5236      ``modprobe.d`` syntax lines. Here is an example that adds the options
5237      ``arg1`` and ``arg2`` to a module named ``mymodule``::
5238
5239         module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
5240
5241      For information on how to specify kernel modules to auto-load on
5242      boot, see the :term:`KERNEL_MODULE_AUTOLOAD` variable.
5243
5244   :term:`MODULE_TARBALL_DEPLOY`
5245      Controls creation of the ``modules-*.tgz`` file. Set this variable to
5246      "0" to disable creation of this file, which contains all of the
5247      kernel modules resulting from a kernel build.
5248
5249   :term:`MODULE_TARBALL_LINK_NAME`
5250      The link name of the kernel module tarball. This variable is set in
5251      the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
5252
5253         MODULE_TARBALL_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
5254
5255      The value
5256      of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the
5257      same file, has the following value::
5258
5259         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
5260
5261      See the :term:`MACHINE` variable for additional information.
5262
5263   :term:`MODULE_TARBALL_NAME`
5264      The base name of the kernel module tarball. This variable is set in
5265      the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
5266
5267         MODULE_TARBALL_NAME ?= "${KERNEL_ARTIFACT_NAME}"
5268
5269      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
5270
5271   :term:`MOUNT_BASE`
5272      On non-systemd systems (where ``udev-extraconf`` is being used),
5273      specifies the base directory for auto-mounting filesystems. The
5274      default value is "/run/media".
5275
5276   :term:`MULTIMACH_TARGET_SYS`
5277      Uniquely identifies the type of the target system for which packages
5278      are being built. This variable allows output for different types of
5279      target systems to be put into different subdirectories of the same
5280      output directory.
5281
5282      The default value of this variable is::
5283
5284         ${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}
5285
5286      Some classes (e.g.  :ref:`ref-classes-cross-canadian`) modify the
5287      :term:`MULTIMACH_TARGET_SYS` value.
5288
5289      See the :term:`STAMP` variable for an example. See the
5290      :term:`STAGING_DIR_TARGET` variable for more information.
5291
5292   :term:`NATIVELSBSTRING`
5293      A string identifying the host distribution. Strings consist of the
5294      host distributor ID followed by the release, as reported by the
5295      ``lsb_release`` tool or as read from ``/etc/lsb-release``. For
5296      example, when running a build on Ubuntu 12.10, the value is
5297      "Ubuntu-12.10". If this information is unable to be determined, the
5298      value resolves to "Unknown".
5299
5300      This variable is used by default to isolate native shared state
5301      packages for different distributions (e.g. to avoid problems with
5302      ``glibc`` version incompatibilities). Additionally, the variable is
5303      checked against
5304      :term:`SANITY_TESTED_DISTROS` if that
5305      variable is set.
5306
5307   :term:`NM`
5308      The minimal command and arguments to run ``nm``.
5309
5310   :term:`NO_GENERIC_LICENSE`
5311      Avoids QA errors when you use a non-common, non-CLOSED license in a
5312      recipe. There are packages, such as the linux-firmware package, with many
5313      licenses that are not in any way common. Also, new licenses are added
5314      occasionally to avoid introducing a lot of common license files,
5315      which are only applicable to a specific package.
5316      :term:`NO_GENERIC_LICENSE` is used to allow copying a license that does
5317      not exist in common licenses.
5318
5319      The following example shows how to add :term:`NO_GENERIC_LICENSE` to a
5320      recipe::
5321
5322         NO_GENERIC_LICENSE[license_name] = "license_file_in_fetched_source"
5323
5324      Here is an example that
5325      uses the ``LICENSE.Abilis.txt`` file as the license from the fetched
5326      source::
5327
5328         NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt"
5329
5330   :term:`NO_RECOMMENDATIONS`
5331      Prevents installation of all "recommended-only" packages.
5332      Recommended-only packages are packages installed only through the
5333      :term:`RRECOMMENDS` variable). Setting the
5334      :term:`NO_RECOMMENDATIONS` variable to "1" turns this feature on::
5335
5336         NO_RECOMMENDATIONS = "1"
5337
5338      You can set this variable globally in your ``local.conf`` file or you
5339      can attach it to a specific image recipe by using the recipe name
5340      override::
5341
5342         NO_RECOMMENDATIONS:pn-target_image = "1"
5343
5344      It is important to realize that if you choose to not install packages
5345      using this variable and some other packages are dependent on them
5346      (i.e. listed in a recipe's :term:`RDEPENDS`
5347      variable), the OpenEmbedded build system ignores your request and
5348      will install the packages to avoid dependency errors.
5349
5350      .. note::
5351
5352         Some recommended packages might be required for certain system
5353         functionality, such as kernel modules. It is up to you to add
5354         packages with the :term:`IMAGE_INSTALL` variable.
5355
5356      This variable is only supported when using the IPK and RPM
5357      packaging backends. DEB is not supported.
5358
5359      See the :term:`BAD_RECOMMENDATIONS` and
5360      the :term:`PACKAGE_EXCLUDE` variables for
5361      related information.
5362
5363   :term:`NOAUTOPACKAGEDEBUG`
5364      Disables auto package from splitting ``.debug`` files. If a recipe
5365      requires ``FILES:${PN}-dbg`` to be set manually, the
5366      :term:`NOAUTOPACKAGEDEBUG` can be defined allowing you to define the
5367      content of the debug package. For example::
5368
5369         NOAUTOPACKAGEDEBUG = "1"
5370         FILES:${PN}-dev = "${includedir}/${QT_DIR_NAME}/Qt/*"
5371         FILES:${PN}-dbg = "/usr/src/debug/"
5372         FILES:${QT_BASE_NAME}-demos-doc = "${docdir}/${QT_DIR_NAME}/qch/qt.qch"
5373
5374   :term:`NON_MULTILIB_RECIPES`
5375      A list of recipes that should not be built for multilib. OE-Core's
5376      ``multilib.conf`` file defines a reasonable starting point for this
5377      list with::
5378
5379         NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot"
5380
5381   :term:`OBJCOPY`
5382      The minimal command and arguments to run ``objcopy``.
5383
5384   :term:`OBJDUMP`
5385      The minimal command and arguments to run ``objdump``.
5386
5387   :term:`OE_BINCONFIG_EXTRA_MANGLE`
5388      When inheriting the :ref:`ref-classes-binconfig` class,
5389      this variable specifies additional arguments passed to the "sed"
5390      command. The sed command alters any paths in configuration scripts
5391      that have been set up during compilation. Inheriting this class
5392      results in all paths in these scripts being changed to point into the
5393      ``sysroots/`` directory so that all builds that use the script will
5394      use the correct directories for the cross compiling layout.
5395
5396      See the ``meta/classes-recipe/binconfig.bbclass`` in the
5397      :term:`Source Directory` for details on how this class
5398      applies these additional sed command arguments.
5399
5400   :term:`OECMAKE_GENERATOR`
5401      A variable for the :ref:`ref-classes-cmake` class, allowing to choose
5402      which back-end will be generated by CMake to build an application.
5403
5404      By default, this variable is set to ``Ninja``, which is faster than GNU
5405      make, but if building is broken with Ninja, a recipe can use this
5406      variable to use GNU make instead::
5407
5408         OECMAKE_GENERATOR = "Unix Makefiles"
5409
5410   :term:`OE_IMPORTS`
5411      An internal variable used to tell the OpenEmbedded build system what
5412      Python modules to import for every Python function run by the system.
5413
5414      .. note::
5415
5416         Do not set this variable. It is for internal use only.
5417
5418   :term:`OE_INIT_ENV_SCRIPT`
5419      The name of the build environment setup script for the purposes of
5420      setting up the environment within the extensible SDK. The default
5421      value is "oe-init-build-env".
5422
5423      If you use a custom script to set up your build environment, set the
5424      :term:`OE_INIT_ENV_SCRIPT` variable to its name.
5425
5426   :term:`OE_TERMINAL`
5427      Controls how the OpenEmbedded build system spawns interactive
5428      terminals on the host development system (e.g. using the BitBake
5429      command with the ``-c devshell`` command-line option). For more
5430      information, see the ":ref:`dev-manual/development-shell:using a development shell`" section in
5431      the Yocto Project Development Tasks Manual.
5432
5433      You can use the following values for the :term:`OE_TERMINAL` variable:
5434
5435      - auto
5436      - gnome
5437      - xfce
5438      - rxvt
5439      - screen
5440      - konsole
5441      - none
5442
5443   :term:`OEROOT`
5444      The directory from which the top-level build environment setup script
5445      is sourced. The Yocto Project provides a top-level build environment
5446      setup script: :ref:`structure-core-script`. When you run this
5447      script, the :term:`OEROOT` variable resolves to the directory that
5448      contains the script.
5449
5450      For additional information on how this variable is used, see the
5451      initialization script.
5452
5453   :term:`OLDEST_KERNEL`
5454      Declares the oldest version of the Linux kernel that the produced
5455      binaries must support. This variable is passed into the build of the
5456      Embedded GNU C Library (``glibc``).
5457
5458      The default for this variable comes from the
5459      ``meta/conf/bitbake.conf`` configuration file. You can override this
5460      default by setting the variable in a custom distribution
5461      configuration file.
5462
5463   :term:`OVERLAYFS_ETC_DEVICE`
5464      When the :ref:`ref-classes-overlayfs-etc` class is
5465      inherited, specifies the device to be mounted for the read/write
5466      layer of ``/etc``. There is no default, so you must set this if you
5467      wish to enable :ref:`ref-classes-overlayfs-etc`, for
5468      example, assuming ``/dev/mmcblk0p2`` was the desired device::
5469
5470         OVERLAYFS_ETC_DEVICE = "/dev/mmcblk0p2"
5471
5472   :term:`OVERLAYFS_ETC_EXPOSE_LOWER`
5473      When the :ref:`ref-classes-overlayfs-etc` class is
5474      inherited, if set to "1" then a read-only access to the original
5475      ``/etc`` content will be provided as a ``lower/`` subdirectory of
5476      :term:`OVERLAYFS_ETC_MOUNT_POINT`. The default value is "0".
5477
5478   :term:`OVERLAYFS_ETC_FSTYPE`
5479      When the :ref:`ref-classes-overlayfs-etc` class is
5480      inherited, specifies the file system type for the read/write
5481      layer of ``/etc``. There is no default, so you must set this if you
5482      wish to enable :ref:`ref-classes-overlayfs-etc`,
5483      for example, assuming the file system is ext4::
5484
5485         OVERLAYFS_ETC_FSTYPE = "ext4"
5486
5487   :term:`OVERLAYFS_ETC_MOUNT_OPTIONS`
5488      When the :ref:`ref-classes-overlayfs-etc` class is
5489      inherited, specifies the mount options for the read-write layer.
5490      The default value is "defaults".
5491
5492   :term:`OVERLAYFS_ETC_MOUNT_POINT`
5493      When the :ref:`ref-classes-overlayfs-etc` class is
5494      inherited, specifies the parent mount path for the filesystem layers.
5495      There is no default, so you must set this if you wish to enable
5496      :ref:`ref-classes-overlayfs-etc`, for example if the desired path is
5497      "/data"::
5498
5499         OVERLAYFS_ETC_MOUNT_POINT = "/data"
5500
5501   :term:`OVERLAYFS_ETC_USE_ORIG_INIT_NAME`
5502      When the :ref:`ref-classes-overlayfs-etc` class is inherited, controls
5503      how the generated init will be named. For more information, see the
5504      :ref:`ref-classes-overlayfs-etc` class documentation. The default value
5505      is "1".
5506
5507   :term:`OVERLAYFS_MOUNT_POINT`
5508      When inheriting the :ref:`ref-classes-overlayfs` class,
5509      specifies mount point(s) to be used. For example::
5510
5511         OVERLAYFS_MOUNT_POINT[data] = "/data"
5512
5513      The assumes you have a ``data.mount`` systemd unit defined elsewhere in
5514      your BSP (e.g. in ``systemd-machine-units`` recipe) and it is installed
5515      into the image. For more information see :ref:`ref-classes-overlayfs`.
5516
5517      .. note::
5518
5519         Although the :ref:`ref-classes-overlayfs` class is
5520         inherited by individual recipes, :term:`OVERLAYFS_MOUNT_POINT`
5521         should be set in your machine configuration.
5522
5523   :term:`OVERLAYFS_QA_SKIP`
5524      When inheriting the :ref:`ref-classes-overlayfs` class,
5525      provides the ability to disable QA checks for particular overlayfs
5526      mounts. For example::
5527
5528         OVERLAYFS_QA_SKIP[data] = "mount-configured"
5529
5530      .. note::
5531
5532         Although the :ref:`ref-classes-overlayfs` class is
5533         inherited by individual recipes, :term:`OVERLAYFS_QA_SKIP`
5534         should be set in your machine configuration.
5535
5536   :term:`OVERLAYFS_WRITABLE_PATHS`
5537      When inheriting the :ref:`ref-classes-overlayfs` class,
5538      specifies writable paths used at runtime for the recipe. For
5539      example::
5540
5541         OVERLAYFS_WRITABLE_PATHS[data] = "/usr/share/my-custom-application"
5542
5543   :term:`OVERRIDES`
5544      A colon-separated list of overrides that currently apply. Overrides
5545      are a BitBake mechanism that allows variables to be selectively
5546      overridden at the end of parsing. The set of overrides in
5547      :term:`OVERRIDES` represents the "state" during building, which includes
5548      the current recipe being built, the machine for which it is being
5549      built, and so forth.
5550
5551      As an example, if the string "an-override" appears as an element in
5552      the colon-separated list in :term:`OVERRIDES`, then the following
5553      assignment will override ``FOO`` with the value "overridden" at the
5554      end of parsing::
5555
5556         FOO:an-override = "overridden"
5557
5558      See the
5559      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
5560      section in the BitBake User Manual for more information on the
5561      overrides mechanism.
5562
5563      The default value of :term:`OVERRIDES` includes the values of the
5564      :term:`CLASSOVERRIDE`,
5565      :term:`MACHINEOVERRIDES`, and
5566      :term:`DISTROOVERRIDES` variables. Another
5567      important override included by default is ``pn-${PN}``. This override
5568      allows variables to be set for a single recipe within configuration
5569      (``.conf``) files. Here is an example::
5570
5571         FOO:pn-myrecipe = "myrecipe-specific value"
5572
5573      .. note::
5574
5575         An easy way to see what overrides apply is to search for :term:`OVERRIDES`
5576         in the output of the ``bitbake -e`` command. See the
5577         ":ref:`dev-manual/debugging:viewing variable values`" section in the Yocto
5578         Project Development Tasks Manual for more information.
5579
5580   :term:`P`
5581      The recipe name and version. :term:`P` is comprised of the following::
5582
5583         ${PN}-${PV}
5584
5585   :term:`P4DIR`
5586      See :term:`bitbake:P4DIR` in the BitBake manual.
5587
5588   :term:`PACKAGE_ADD_METADATA`
5589      This variable defines additional metadata to add to packages.
5590
5591      You may find you need to inject additional metadata into packages.
5592      This variable allows you to do that by setting the injected data as
5593      the value. Multiple fields can be added by splitting the content with
5594      the literal separator "\n".
5595
5596      The suffixes '_IPK', '_DEB', or '_RPM' can be applied to the variable
5597      to do package type specific settings. It can also be made package
5598      specific by using the package name as a suffix.
5599
5600      You can find out more about applying this variable in the
5601      ":ref:`dev-manual/packages:adding custom metadata to packages`"
5602      section in the Yocto Project Development Tasks Manual.
5603
5604   :term:`PACKAGE_ARCH`
5605      The architecture of the resulting package or packages.
5606
5607      By default, the value of this variable is set to
5608      :term:`TUNE_PKGARCH` when building for the
5609      target, :term:`BUILD_ARCH` when building for the
5610      build host, and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building for the
5611      SDK.
5612
5613      .. note::
5614
5615         See :term:`SDK_ARCH` for more information.
5616
5617      However, if your recipe's output packages are built specific to the
5618      target machine rather than generally for the architecture of the
5619      machine, you should set :term:`PACKAGE_ARCH` to the value of
5620      :term:`MACHINE_ARCH` in the recipe as follows::
5621
5622         PACKAGE_ARCH = "${MACHINE_ARCH}"
5623
5624   :term:`PACKAGE_ARCHS`
5625      Specifies a list of architectures compatible with the target machine.
5626      This variable is set automatically and should not normally be
5627      hand-edited. Entries are separated using spaces and listed in order
5628      of priority. The default value for :term:`PACKAGE_ARCHS` is "all any
5629      noarch ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
5630
5631   :term:`PACKAGE_BEFORE_PN`
5632      Enables easily adding packages to :term:`PACKAGES` before ``${PN}`` so
5633      that those added packages can pick up files that would normally be
5634      included in the default package.
5635
5636   :term:`PACKAGE_CLASSES`
5637      This variable, which is set in the ``local.conf`` configuration file
5638      found in the ``conf`` folder of the
5639      :term:`Build Directory`, specifies the package manager the
5640      OpenEmbedded build system uses when packaging data.
5641
5642      You can provide one or more of the following arguments for the
5643      variable::
5644
5645         PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
5646
5647      The build system uses only the first argument in the list as the
5648      package manager when creating your image or SDK. However, packages
5649      will be created using any additional packaging classes you specify.
5650      For example, if you use the following in your ``local.conf`` file::
5651
5652         PACKAGE_CLASSES ?= "package_ipk"
5653
5654      The OpenEmbedded build system uses
5655      the IPK package manager to create your image or SDK.
5656
5657      For information on packaging and build performance effects as a
5658      result of the package manager in use, see the
5659      ":ref:`ref-classes-package`" section.
5660
5661   :term:`PACKAGE_DEBUG_SPLIT_STYLE`
5662      Determines how to split up and package debug and source information
5663      when creating debugging packages to be used with the GNU Project
5664      Debugger (GDB). In general, based on the value of this variable,
5665      you can combine the source and debug info in a single package,
5666      you can break out the source into a separate package that can be
5667      installed independently, or you can choose to not have the source
5668      packaged at all.
5669
5670      The possible values of :term:`PACKAGE_DEBUG_SPLIT_STYLE` variable:
5671
5672      -  "``.debug``": All debugging and source info is placed in a single
5673         ``*-dbg`` package; debug symbol files are placed next to the
5674         binary in a ``.debug`` directory so that, if a binary is installed
5675         into ``/bin``, the corresponding debug symbol file is installed
5676         in ``/bin/.debug``. Source files are installed in the same ``*-dbg``
5677         package under ``/usr/src/debug``.
5678
5679      -  "``debug-file-directory``": As above, all debugging and source info
5680         is placed in a single ``*-dbg`` package; debug symbol files are
5681         placed entirely under the directory ``/usr/lib/debug`` and separated
5682         by the path from where the binary is installed, so that if a binary
5683         is installed in ``/bin``, the corresponding debug symbols are installed
5684         in ``/usr/lib/debug/bin``, and so on. As above, source is installed
5685         in the same package under ``/usr/src/debug``.
5686
5687      -  "``debug-with-srcpkg``": Debugging info is placed in the standard
5688         ``*-dbg`` package as with the ``.debug`` value, while source is
5689         placed in a separate ``*-src`` package, which can be installed
5690         independently.  This is the default setting for this variable,
5691         as defined in Poky's ``bitbake.conf`` file.
5692
5693      -  "``debug-without-src``": The same behavior as with the ``.debug``
5694         setting, but no source is packaged at all.
5695
5696      .. note::
5697
5698         Much of the above package splitting can be overridden via
5699         use of the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable.
5700
5701      You can find out more about debugging using GDB by reading the
5702      ":ref:`dev-manual/debugging:debugging with the gnu project debugger (gdb) remotely`" section
5703      in the Yocto Project Development Tasks Manual.
5704
5705   :term:`PACKAGE_EXCLUDE`
5706      Lists packages that should not be installed into an image. For
5707      example::
5708
5709         PACKAGE_EXCLUDE = "package_name package_name package_name ..."
5710
5711      You can set this variable globally in your ``local.conf`` file or you
5712      can attach it to a specific image recipe by using the recipe name
5713      override::
5714
5715         PACKAGE_EXCLUDE:pn-target_image = "package_name"
5716
5717      If you choose to not install a package using this variable and some
5718      other package is dependent on it (i.e. listed in a recipe's
5719      :term:`RDEPENDS` variable), the OpenEmbedded build
5720      system generates a fatal installation error. Because the build system
5721      halts the process with a fatal error, you can use the variable with
5722      an iterative development process to remove specific components from a
5723      system.
5724
5725      This variable is supported only when using the IPK and RPM
5726      packaging backends. DEB is not supported.
5727
5728      See the :term:`NO_RECOMMENDATIONS` and the
5729      :term:`BAD_RECOMMENDATIONS` variables for
5730      related information.
5731
5732   :term:`PACKAGE_EXCLUDE_COMPLEMENTARY`
5733      Prevents specific packages from being installed when you are
5734      installing complementary packages.
5735
5736      You might find that you want to prevent installing certain packages
5737      when you are installing complementary packages. For example, if you
5738      are using :term:`IMAGE_FEATURES` to install
5739      ``dev-pkgs``, you might not want to install all packages from a
5740      particular multilib. If you find yourself in this situation, you can
5741      use the :term:`PACKAGE_EXCLUDE_COMPLEMENTARY` variable to specify regular
5742      expressions to match the packages you want to exclude.
5743
5744   :term:`PACKAGE_EXTRA_ARCHS`
5745      Specifies the list of architectures compatible with the device CPU.
5746      This variable is useful when you build for several different devices
5747      that use miscellaneous processors such as XScale and ARM926-EJS.
5748
5749   :term:`PACKAGE_FEED_ARCHS`
5750      Optionally specifies the package architectures used as part of the
5751      package feed URIs during the build. When used, the
5752      :term:`PACKAGE_FEED_ARCHS` variable is appended to the final package feed
5753      URI, which is constructed using the
5754      :term:`PACKAGE_FEED_URIS` and
5755      :term:`PACKAGE_FEED_BASE_PATHS`
5756      variables.
5757
5758      .. note::
5759
5760         You can use the :term:`PACKAGE_FEED_ARCHS`
5761         variable to allow specific package architectures. If you do
5762         not need to allow specific architectures, which is a common
5763         case, you can omit this variable. Omitting the variable results in
5764         all available architectures for the current machine being included
5765         into remote package feeds.
5766
5767      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5768      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5769      defined in your ``local.conf`` file::
5770
5771         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5772                              https://example.com/packagerepos/updates"
5773         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5774         PACKAGE_FEED_ARCHS = "all core2-64"
5775
5776      Given these settings, the resulting package feeds are as follows:
5777
5778      .. code-block:: none
5779
5780         https://example.com/packagerepos/release/rpm/all
5781         https://example.com/packagerepos/release/rpm/core2-64
5782         https://example.com/packagerepos/release/rpm-dev/all
5783         https://example.com/packagerepos/release/rpm-dev/core2-64
5784         https://example.com/packagerepos/updates/rpm/all
5785         https://example.com/packagerepos/updates/rpm/core2-64
5786         https://example.com/packagerepos/updates/rpm-dev/all
5787         https://example.com/packagerepos/updates/rpm-dev/core2-64
5788
5789   :term:`PACKAGE_FEED_BASE_PATHS`
5790      Specifies the base path used when constructing package feed URIs. The
5791      :term:`PACKAGE_FEED_BASE_PATHS` variable makes up the middle portion of a
5792      package feed URI used by the OpenEmbedded build system. The base path
5793      lies between the :term:`PACKAGE_FEED_URIS`
5794      and :term:`PACKAGE_FEED_ARCHS` variables.
5795
5796      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5797      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5798      defined in your ``local.conf`` file::
5799
5800         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5801                              https://example.com/packagerepos/updates"
5802         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5803         PACKAGE_FEED_ARCHS = "all core2-64"
5804
5805      Given these settings, the resulting package feeds are as follows:
5806
5807      .. code-block:: none
5808
5809         https://example.com/packagerepos/release/rpm/all
5810         https://example.com/packagerepos/release/rpm/core2-64
5811         https://example.com/packagerepos/release/rpm-dev/all
5812         https://example.com/packagerepos/release/rpm-dev/core2-64
5813         https://example.com/packagerepos/updates/rpm/all
5814         https://example.com/packagerepos/updates/rpm/core2-64
5815         https://example.com/packagerepos/updates/rpm-dev/all
5816         https://example.com/packagerepos/updates/rpm-dev/core2-64
5817
5818   :term:`PACKAGE_FEED_URIS`
5819      Specifies the front portion of the package feed URI used by the
5820      OpenEmbedded build system. Each final package feed URI is comprised
5821      of :term:`PACKAGE_FEED_URIS`,
5822      :term:`PACKAGE_FEED_BASE_PATHS`, and
5823      :term:`PACKAGE_FEED_ARCHS` variables.
5824
5825      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5826      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5827      defined in your ``local.conf`` file::
5828
5829         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5830                              https://example.com/packagerepos/updates"
5831         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5832         PACKAGE_FEED_ARCHS = "all core2-64"
5833
5834      Given these settings, the resulting package feeds are as follows:
5835
5836      .. code-block:: none
5837
5838         https://example.com/packagerepos/release/rpm/all
5839         https://example.com/packagerepos/release/rpm/core2-64
5840         https://example.com/packagerepos/release/rpm-dev/all
5841         https://example.com/packagerepos/release/rpm-dev/core2-64
5842         https://example.com/packagerepos/updates/rpm/all
5843         https://example.com/packagerepos/updates/rpm/core2-64
5844         https://example.com/packagerepos/updates/rpm-dev/all
5845         https://example.com/packagerepos/updates/rpm-dev/core2-64
5846
5847   :term:`PACKAGE_INSTALL`
5848      The final list of packages passed to the package manager for
5849      installation into the image.
5850
5851      Because the package manager controls actual installation of all
5852      packages, the list of packages passed using :term:`PACKAGE_INSTALL` is
5853      not the final list of packages that are actually installed. This
5854      variable is internal to the image construction code. Consequently, in
5855      general, you should use the
5856      :term:`IMAGE_INSTALL` variable to specify
5857      packages for installation. The exception to this is when working with
5858      the :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
5859      image. When working with an initial RAM filesystem (:term:`Initramfs`) image,
5860      use the :term:`PACKAGE_INSTALL` variable. For information on creating an
5861      :term:`Initramfs`, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
5862      in the Yocto Project Development Tasks Manual.
5863
5864   :term:`PACKAGE_INSTALL_ATTEMPTONLY`
5865      Specifies a list of packages the OpenEmbedded build system attempts
5866      to install when creating an image. If a listed package fails to
5867      install, the build system does not generate an error. This variable
5868      is generally not user-defined.
5869
5870   :term:`PACKAGE_PREPROCESS_FUNCS`
5871      Specifies a list of functions run to pre-process the
5872      :term:`PKGD` directory prior to splitting the files out
5873      to individual packages.
5874
5875   :term:`PACKAGE_WRITE_DEPS`
5876      Specifies a list of dependencies for post-installation and
5877      pre-installation scripts on native/cross tools. If your
5878      post-installation or pre-installation script can execute at root filesystem
5879      creation time rather than on the target but depends on a native tool
5880      in order to execute, you need to list the tools in
5881      :term:`PACKAGE_WRITE_DEPS`.
5882
5883      For information on running post-installation scripts, see the
5884      ":ref:`dev-manual/new-recipe:post-installation scripts`"
5885      section in the Yocto Project Development Tasks Manual.
5886
5887   :term:`PACKAGECONFIG`
5888      This variable provides a means of enabling or disabling features of a
5889      recipe on a per-recipe basis. :term:`PACKAGECONFIG` blocks are defined in
5890      recipes when you specify features and then arguments that define
5891      feature behaviors. Here is the basic block structure (broken over
5892      multiple lines for readability)::
5893
5894         PACKAGECONFIG ??= "f1 f2 f3 ..."
5895         PACKAGECONFIG[f1] = "\
5896             --with-f1, \
5897             --without-f1, \
5898             build-deps-for-f1, \
5899             runtime-deps-for-f1, \
5900             runtime-recommends-for-f1, \
5901             packageconfig-conflicts-for-f1"
5902         PACKAGECONFIG[f2] = "\
5903              ... and so on and so on ...
5904
5905      The :term:`PACKAGECONFIG` variable itself specifies a space-separated
5906      list of the features to enable. Following the features, you can
5907      determine the behavior of each feature by providing up to six
5908      order-dependent arguments, which are separated by commas. You can
5909      omit any argument you like but must retain the separating commas. The
5910      order is important and specifies the following:
5911
5912      #. Extra arguments that should be added to the configure script
5913         argument list (:term:`EXTRA_OECONF` or
5914         :term:`PACKAGECONFIG_CONFARGS`) if
5915         the feature is enabled.
5916
5917      #. Extra arguments that should be added to :term:`EXTRA_OECONF` or
5918         :term:`PACKAGECONFIG_CONFARGS` if the feature is disabled.
5919
5920      #. Additional build dependencies (:term:`DEPENDS`)
5921         that should be added if the feature is enabled.
5922
5923      #. Additional runtime dependencies (:term:`RDEPENDS`)
5924         that should be added if the feature is enabled.
5925
5926      #. Additional runtime recommendations
5927         (:term:`RRECOMMENDS`) that should be added if
5928         the feature is enabled.
5929
5930      #. Any conflicting (that is, mutually exclusive) :term:`PACKAGECONFIG`
5931         settings for this feature.
5932
5933      Consider the following :term:`PACKAGECONFIG` block taken from the
5934      ``librsvg`` recipe. In this example the feature is ``gtk``, which has
5935      three arguments that determine the feature's behavior::
5936
5937         PACKAGECONFIG[gtk] = "--with-gtk3,--without-gtk3,gtk+3"
5938
5939      The
5940      ``--with-gtk3`` and ``gtk+3`` arguments apply only if the feature is
5941      enabled. In this case, ``--with-gtk3`` is added to the configure
5942      script argument list and ``gtk+3`` is added to :term:`DEPENDS`. On the
5943      other hand, if the feature is disabled say through a ``.bbappend``
5944      file in another layer, then the second argument ``--without-gtk3`` is
5945      added to the configure script instead.
5946
5947      The basic :term:`PACKAGECONFIG` structure previously described holds true
5948      regardless of whether you are creating a block or changing a block.
5949      When creating a block, use the structure inside your recipe.
5950
5951      If you want to change an existing :term:`PACKAGECONFIG` block, you can do
5952      so one of two ways:
5953
5954      -  *Append file:* Create an append file named
5955         ``recipename.bbappend`` in your layer and override the value of
5956         :term:`PACKAGECONFIG`. You can either completely override the
5957         variable::
5958
5959            PACKAGECONFIG = "f4 f5"
5960
5961         Or, you can just append the variable::
5962
5963            PACKAGECONFIG:append = " f4"
5964
5965      -  *Configuration file:* This method is identical to changing the
5966         block through an append file except you edit your ``local.conf``
5967         or ``mydistro.conf`` file. As with append files previously
5968         described, you can either completely override the variable::
5969
5970            PACKAGECONFIG:pn-recipename = "f4 f5"
5971
5972         Or, you can just amend the variable::
5973
5974            PACKAGECONFIG:append:pn-recipename = " f4"
5975
5976   :term:`PACKAGECONFIG_CONFARGS`
5977      A space-separated list of configuration options generated from the
5978      :term:`PACKAGECONFIG` setting.
5979
5980      Classes such as :ref:`ref-classes-autotools` and :ref:`ref-classes-cmake`
5981      use :term:`PACKAGECONFIG_CONFARGS` to pass :term:`PACKAGECONFIG` options
5982      to ``configure`` and ``cmake``, respectively. If you are using
5983      :term:`PACKAGECONFIG` but not a class that handles the
5984      :ref:`ref-tasks-configure` task, then you need to use
5985      :term:`PACKAGECONFIG_CONFARGS` appropriately.
5986
5987   :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY`
5988      For recipes inheriting the :ref:`ref-classes-packagegroup` class, setting
5989      :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY` to "1" specifies that the
5990      normal complementary packages (i.e. ``-dev``, ``-dbg``, and so forth)
5991      should not be automatically created by the ``packagegroup`` recipe,
5992      which is the default behavior.
5993
5994   :term:`PACKAGES`
5995      The list of packages the recipe creates. The default value is the
5996      following::
5997
5998         ${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
5999
6000      During packaging, the :ref:`ref-tasks-package` task
6001      goes through :term:`PACKAGES` and uses the :term:`FILES`
6002      variable corresponding to each package to assign files to the
6003      package. If a file matches the :term:`FILES` variable for more than one
6004      package in :term:`PACKAGES`, it will be assigned to the earliest
6005      (leftmost) package.
6006
6007      Packages in the variable's list that are empty (i.e. where none of
6008      the patterns in ``FILES:``\ pkg match any files installed by the
6009      :ref:`ref-tasks-install` task) are not generated,
6010      unless generation is forced through the
6011      :term:`ALLOW_EMPTY` variable.
6012
6013   :term:`PACKAGES_DYNAMIC`
6014      A promise that your recipe satisfies runtime dependencies for
6015      optional modules that are found in other recipes.
6016      :term:`PACKAGES_DYNAMIC` does not actually satisfy the dependencies, it
6017      only states that they should be satisfied. For example, if a hard,
6018      runtime dependency (:term:`RDEPENDS`) of another
6019      package is satisfied at build time through the :term:`PACKAGES_DYNAMIC`
6020      variable, but a package with the module name is never actually
6021      produced, then the other package will be broken. Thus, if you attempt
6022      to include that package in an image, you will get a dependency
6023      failure from the packaging system during the
6024      :ref:`ref-tasks-rootfs` task.
6025
6026      Typically, if there is a chance that such a situation can occur and
6027      the package that is not created is valid without the dependency being
6028      satisfied, then you should use :term:`RRECOMMENDS`
6029      (a soft runtime dependency) instead of :term:`RDEPENDS`.
6030
6031      For an example of how to use the :term:`PACKAGES_DYNAMIC` variable when
6032      you are splitting packages, see the
6033      ":ref:`dev-manual/packages:handling optional module packaging`"
6034      section in the Yocto Project Development Tasks Manual.
6035
6036   :term:`PACKAGESPLITFUNCS`
6037      Specifies a list of functions run to perform additional splitting of
6038      files into individual packages. Recipes can either prepend to this
6039      variable or prepend to the ``populate_packages`` function in order to
6040      perform additional package splitting. In either case, the function
6041      should set :term:`PACKAGES`,
6042      :term:`FILES`, :term:`RDEPENDS` and
6043      other packaging variables appropriately in order to perform the
6044      desired splitting.
6045
6046   :term:`PARALLEL_MAKE`
6047
6048      Extra options passed to the build tool command (``make``,
6049      ``ninja`` or more specific build engines, like the Go language one)
6050      during the :ref:`ref-tasks-compile` task, to specify parallel compilation
6051      on the local build host. This variable is usually in the form "-j x",
6052      where x represents the maximum number of parallel threads such engines
6053      can run.
6054
6055      .. note::
6056
6057         For software compiled by ``make``, in order for :term:`PARALLEL_MAKE`
6058         to be effective, ``make`` must be called with
6059         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
6060         way to ensure this is to use the ``oe_runmake`` function.
6061
6062      By default, the OpenEmbedded build system automatically sets this
6063      variable to be equal to the number of cores the build system uses.
6064
6065      .. note::
6066
6067         If the software being built experiences dependency issues during
6068         the :ref:`ref-tasks-compile` task that result in race conditions, you can clear
6069         the :term:`PARALLEL_MAKE` variable within the recipe as a workaround. For
6070         information on addressing race conditions, see the
6071         ":ref:`dev-manual/debugging:debugging parallel make races`"
6072         section in the Yocto Project Development Tasks Manual.
6073
6074      For single socket systems (i.e. one CPU), you should not have to
6075      override this variable to gain optimal parallelism during builds.
6076      However, if you have very large systems that employ multiple physical
6077      CPUs, you might want to make sure the :term:`PARALLEL_MAKE` variable is
6078      not set higher than "-j 20".
6079
6080      For more information on speeding up builds, see the
6081      ":ref:`dev-manual/speeding-up-build:speeding up a build`"
6082      section in the Yocto Project Development Tasks Manual.
6083
6084   :term:`PARALLEL_MAKEINST`
6085      Extra options passed to the build tool install command
6086      (``make install``, ``ninja install`` or more specific ones)
6087      during the :ref:`ref-tasks-install` task in order to specify
6088      parallel installation. This variable defaults to the value of
6089      :term:`PARALLEL_MAKE`.
6090
6091      .. note::
6092
6093         For software compiled by ``make``, in order for :term:`PARALLEL_MAKEINST`
6094         to be effective, ``make`` must be called with
6095         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
6096         way to ensure this is to use the ``oe_runmake`` function.
6097
6098         If the software being built experiences dependency issues during
6099         the :ref:`ref-tasks-install` task that result in race conditions, you can
6100         clear the :term:`PARALLEL_MAKEINST` variable within the recipe as a
6101         workaround. For information on addressing race conditions, see the
6102         ":ref:`dev-manual/debugging:debugging parallel make races`"
6103         section in the Yocto Project Development Tasks Manual.
6104
6105   :term:`PATCHRESOLVE`
6106      Determines the action to take when a patch fails. You can set this
6107      variable to one of two values: "noop" and "user".
6108
6109      The default value of "noop" causes the build to simply fail when the
6110      OpenEmbedded build system cannot successfully apply a patch. Setting
6111      the value to "user" causes the build system to launch a shell and
6112      places you in the right location so that you can manually resolve the
6113      conflicts.
6114
6115      Set this variable in your ``local.conf`` file.
6116
6117   :term:`PATCHTOOL`
6118      Specifies the utility used to apply patches for a recipe during the
6119      :ref:`ref-tasks-patch` task. You can specify one of
6120      three utilities: "patch", "quilt", or "git". The default utility used
6121      is "quilt" except for the quilt-native recipe itself. Because the
6122      quilt tool is not available at the time quilt-native is being
6123      patched, it uses "patch".
6124
6125      If you wish to use an alternative patching tool, set the variable in
6126      the recipe using one of the following::
6127
6128         PATCHTOOL = "patch"
6129         PATCHTOOL = "quilt"
6130         PATCHTOOL = "git"
6131
6132   :term:`PE`
6133      The epoch of the recipe. By default, this variable is unset. The
6134      variable is used to make upgrades possible when the versioning scheme
6135      changes in some backwards incompatible way.
6136
6137      :term:`PE` is the default value of the :term:`PKGE` variable.
6138
6139   :term:`PEP517_WHEEL_PATH`
6140      When used by recipes that inherit the :ref:`ref-classes-python_pep517`
6141      class, denotes the path to ``dist/`` (short for distribution) where the
6142      binary archive ``wheel`` is built.
6143
6144   :term:`PERSISTENT_DIR`
6145      See :term:`bitbake:PERSISTENT_DIR` in the BitBake manual.
6146
6147   :term:`PF`
6148      Specifies the recipe or package name and includes all version and
6149      revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
6150      ``bash-4.2-r1/``). This variable is comprised of the following:
6151      ${:term:`PN`}-${:term:`EXTENDPE`}${:term:`PV`}-${:term:`PR`}
6152
6153   :term:`PIXBUF_PACKAGES`
6154      When inheriting the :ref:`ref-classes-pixbufcache`
6155      class, this variable identifies packages that contain the pixbuf
6156      loaders used with ``gdk-pixbuf``. By default, the
6157      :ref:`ref-classes-pixbufcache` class assumes that
6158      the loaders are in the recipe's main package (i.e.
6159      ``${``\ :term:`PN`\ ``}``). Use this variable if the
6160      loaders you need are in a package other than that main package.
6161
6162   :term:`PKG`
6163      The name of the resulting package created by the OpenEmbedded build
6164      system.
6165
6166      .. note::
6167
6168         When using the :term:`PKG` variable, you must use a package name override.
6169
6170      For example, when the :ref:`ref-classes-debian` class renames the output
6171      package, it does so by setting ``PKG:packagename``.
6172
6173   :term:`PKG_CONFIG_PATH`
6174      The path to ``pkg-config`` files for the current build context.
6175      ``pkg-config`` reads this variable from the environment.
6176
6177   :term:`PKGD`
6178      Points to the destination directory for files to be packaged before
6179      they are split into individual packages. This directory defaults to
6180      the following::
6181
6182         ${WORKDIR}/package
6183
6184      Do not change this default.
6185
6186   :term:`PKGDATA_DIR`
6187      Points to a shared, global-state directory that holds data generated
6188      during the packaging process. During the packaging process, the
6189      :ref:`ref-tasks-packagedata` task packages data
6190      for each recipe and installs it into this temporary, shared area.
6191      This directory defaults to the following, which you should not
6192      change::
6193
6194         ${STAGING_DIR_HOST}/pkgdata
6195
6196      For examples of how this data is used, see the
6197      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6198      section in the Yocto Project Overview and Concepts Manual and the
6199      ":ref:`dev-manual/debugging:viewing package information with \`\`oe-pkgdata-util\`\``"
6200      section in the Yocto Project Development Tasks Manual. For more
6201      information on the shared, global-state directory, see
6202      :term:`STAGING_DIR_HOST`.
6203
6204   :term:`PKGDEST`
6205      Points to the parent directory for files to be packaged after they
6206      have been split into individual packages. This directory defaults to
6207      the following::
6208
6209         ${WORKDIR}/packages-split
6210
6211      Under this directory, the build system creates directories for each
6212      package specified in :term:`PACKAGES`. Do not change
6213      this default.
6214
6215   :term:`PKGDESTWORK`
6216      Points to a temporary work area where the
6217      :ref:`ref-tasks-package` task saves package metadata.
6218      The :term:`PKGDESTWORK` location defaults to the following::
6219
6220         ${WORKDIR}/pkgdata
6221
6222      Do not change this default.
6223
6224      The :ref:`ref-tasks-packagedata` task copies the
6225      package metadata from :term:`PKGDESTWORK` to
6226      :term:`PKGDATA_DIR` to make it available globally.
6227
6228   :term:`PKGE`
6229      The epoch of the package(s) built by the recipe. By default, :term:`PKGE`
6230      is set to :term:`PE`.
6231
6232   :term:`PKGR`
6233      The revision of the package(s) built by the recipe. By default,
6234      :term:`PKGR` is set to :term:`PR`.
6235
6236   :term:`PKGV`
6237      The version of the package(s) built by the recipe. By default,
6238      :term:`PKGV` is set to :term:`PV`.
6239
6240   :term:`PN`
6241      This variable can have two separate functions depending on the
6242      context: a recipe name or a resulting package name.
6243
6244      :term:`PN` refers to a recipe name in the context of a file used by the
6245      OpenEmbedded build system as input to create a package. The name is
6246      normally extracted from the recipe file name. For example, if the
6247      recipe is named ``expat_2.0.1.bb``, then the default value of :term:`PN`
6248      will be "expat".
6249
6250      The variable refers to a package name in the context of a file
6251      created or produced by the OpenEmbedded build system.
6252
6253      If applicable, the :term:`PN` variable also contains any special suffix
6254      or prefix. For example, using ``bash`` to build packages for the
6255      native machine, :term:`PN` is ``bash-native``. Using ``bash`` to build
6256      packages for the target and for Multilib, :term:`PN` would be ``bash``
6257      and ``lib64-bash``, respectively.
6258
6259   :term:`POPULATE_SDK_POST_HOST_COMMAND`
6260      Specifies a list of functions to call once the OpenEmbedded build
6261      system has created the host part of the SDK. You can specify
6262      functions separated by semicolons::
6263
6264          POPULATE_SDK_POST_HOST_COMMAND += "function; ... "
6265
6266      If you need to pass the SDK path to a command within a function, you
6267      can use ``${SDK_DIR}``, which points to the parent directory used by
6268      the OpenEmbedded build system when creating SDK output. See the
6269      :term:`SDK_DIR` variable for more information.
6270
6271   :term:`POPULATE_SDK_POST_TARGET_COMMAND`
6272      Specifies a list of functions to call once the OpenEmbedded build
6273      system has created the target part of the SDK. You can specify
6274      functions separated by semicolons::
6275
6276         POPULATE_SDK_POST_TARGET_COMMAND += "function; ... "
6277
6278      If you need to pass the SDK path to a command within a function, you
6279      can use ``${SDK_DIR}``, which points to the parent directory used by
6280      the OpenEmbedded build system when creating SDK output. See the
6281      :term:`SDK_DIR` variable for more information.
6282
6283   :term:`PR`
6284      The revision of the recipe. The default value for this variable is
6285      "r0". Subsequent revisions of the recipe conventionally have the
6286      values "r1", "r2", and so forth. When :term:`PV` increases,
6287      :term:`PR` is conventionally reset to "r0".
6288
6289      .. note::
6290
6291         The OpenEmbedded build system does not need the aid of :term:`PR`
6292         to know when to rebuild a recipe. The build system uses the task
6293         :ref:`input checksums <overview-manual/concepts:checksums (signatures)>` along with the
6294         :ref:`stamp <structure-build-tmp-stamps>` and
6295         :ref:`overview-manual/concepts:shared state cache`
6296         mechanisms.
6297
6298      The :term:`PR` variable primarily becomes significant when a package
6299      manager dynamically installs packages on an already built image. In
6300      this case, :term:`PR`, which is the default value of
6301      :term:`PKGR`, helps the package manager distinguish which
6302      package is the most recent one in cases where many packages have the
6303      same :term:`PV` (i.e. :term:`PKGV`). A component having many packages with
6304      the same :term:`PV` usually means that the packages all install the same
6305      upstream version, but with later (:term:`PR`) version packages including
6306      packaging fixes.
6307
6308      .. note::
6309
6310         :term:`PR` does not need to be increased for changes that do not change the
6311         package contents or metadata.
6312
6313      Because manually managing :term:`PR` can be cumbersome and error-prone,
6314      an automated solution exists. See the
6315      ":ref:`dev-manual/packages:working with a pr service`" section
6316      in the Yocto Project Development Tasks Manual for more information.
6317
6318   :term:`PREFERRED_PROVIDER`
6319      If multiple recipes provide the same item, this variable determines
6320      which recipe is preferred and thus provides the item (i.e. the
6321      preferred provider). You should always suffix this variable with the
6322      name of the provided item. And, you should define the variable using
6323      the preferred recipe's name (:term:`PN`). Here is a common
6324      example::
6325
6326         PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
6327
6328      In the previous example, multiple recipes are providing "virtual/kernel".
6329      The :term:`PREFERRED_PROVIDER` variable is set with the name (:term:`PN`) of
6330      the recipe you prefer to provide "virtual/kernel".
6331
6332      Following are more examples::
6333
6334         PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
6335         PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
6336
6337      For more
6338      information, see the ":ref:`dev-manual/new-recipe:using virtual providers`"
6339      section in the Yocto Project Development Tasks Manual.
6340
6341      .. note::
6342
6343         If you use a ``virtual/\*`` item with :term:`PREFERRED_PROVIDER`, then any
6344         recipe that :term:`PROVIDES` that item but is not selected (defined)
6345         by :term:`PREFERRED_PROVIDER` is prevented from building, which is usually
6346         desirable since this mechanism is designed to select between mutually
6347         exclusive alternative providers.
6348
6349   :term:`PREFERRED_PROVIDERS`
6350      See :term:`bitbake:PREFERRED_PROVIDERS` in the BitBake manual.
6351
6352   :term:`PREFERRED_VERSION`
6353      If there are multiple versions of a recipe available, this variable
6354      determines which version should be given preference. You must always
6355      suffix the variable with the :term:`PN` you want to select (`python` in
6356      the first example below), and you should specify the :term:`PV`
6357      accordingly (`3.4.0` in the example).
6358
6359      The :term:`PREFERRED_VERSION` variable supports limited wildcard use
6360      through the "``%``" character. You can use the character to match any
6361      number of characters, which can be useful when specifying versions
6362      that contain long revision numbers that potentially change. Here are
6363      two examples::
6364
6365         PREFERRED_VERSION_python = "3.4.0"
6366         PREFERRED_VERSION_linux-yocto = "5.0%"
6367
6368      .. note::
6369
6370         The use of the "%" character is limited in that it only works at the end of the
6371         string. You cannot use the wildcard character in any other
6372         location of the string.
6373
6374      The specified version is matched against :term:`PV`, which
6375      does not necessarily match the version part of the recipe's filename.
6376      For example, consider two recipes ``foo_1.2.bb`` and ``foo_git.bb``
6377      where ``foo_git.bb`` contains the following assignment::
6378
6379         PV = "1.1+git${SRCPV}"
6380
6381      In this case, the correct way to select
6382      ``foo_git.bb`` is by using an assignment such as the following::
6383
6384         PREFERRED_VERSION_foo = "1.1+git%"
6385
6386      Compare that previous example
6387      against the following incorrect example, which does not work::
6388
6389         PREFERRED_VERSION_foo = "git"
6390
6391      Sometimes the :term:`PREFERRED_VERSION` variable can be set by
6392      configuration files in a way that is hard to change. You can use
6393      :term:`OVERRIDES` to set a machine-specific
6394      override. Here is an example::
6395
6396         PREFERRED_VERSION_linux-yocto:qemux86 = "5.0%"
6397
6398      Although not recommended, worst case, you can also use the
6399      "forcevariable" override, which is the strongest override possible.
6400      Here is an example::
6401
6402         PREFERRED_VERSION_linux-yocto:forcevariable = "5.0%"
6403
6404      .. note::
6405
6406         The ``:forcevariable`` override is not handled specially. This override
6407         only works because the default value of :term:`OVERRIDES` includes "forcevariable".
6408
6409      If a recipe with the specified version is not available, a warning
6410      message will be shown. See :term:`REQUIRED_VERSION` if you want this
6411      to be an error instead.
6412
6413   :term:`PREMIRRORS`
6414      Specifies additional paths from which the OpenEmbedded build system
6415      gets source code. When the build system searches for source code, it
6416      first tries the local download directory. If that location fails, the
6417      build system tries locations defined by :term:`PREMIRRORS`, the upstream
6418      source, and then locations specified by
6419      :term:`MIRRORS` in that order.
6420
6421      Assuming your distribution (:term:`DISTRO`) is "poky",
6422      the default value for :term:`PREMIRRORS` is defined in the
6423      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
6424
6425      Typically, you could add a specific server for the build system to
6426      attempt before any others by adding something like the following to
6427      the ``local.conf`` configuration file in the
6428      :term:`Build Directory`::
6429
6430         PREMIRRORS:prepend = "\
6431             git://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6432             ftp://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6433             http://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6434             https://.*/.* &YOCTO_DL_URL;/mirror/sources/"
6435
6436      These changes cause the
6437      build system to intercept Git, FTP, HTTP, and HTTPS requests and
6438      direct them to the ``http://`` sources mirror. You can use
6439      ``file://`` URLs to point to local directories or network shares as
6440      well.
6441
6442   :term:`PRIORITY`
6443      Indicates the importance of a package.
6444
6445      :term:`PRIORITY` is considered to be part of the distribution policy
6446      because the importance of any given recipe depends on the purpose for
6447      which the distribution is being produced. Thus, :term:`PRIORITY` is not
6448      normally set within recipes.
6449
6450      You can set :term:`PRIORITY` to "required", "standard", "extra", and
6451      "optional", which is the default.
6452
6453   :term:`PRIVATE_LIBS`
6454      Specifies libraries installed within a recipe that should be ignored
6455      by the OpenEmbedded build system's shared library resolver. This
6456      variable is typically used when software being built by a recipe has
6457      its own private versions of a library normally provided by another
6458      recipe. In this case, you would not want the package containing the
6459      private libraries to be set as a dependency on other unrelated
6460      packages that should instead depend on the package providing the
6461      standard version of the library.
6462
6463      Libraries specified in this variable should be specified by their
6464      file name. For example, from the Firefox recipe in meta-browser::
6465
6466         PRIVATE_LIBS = "libmozjs.so \
6467                         libxpcom.so \
6468                         libnspr4.so \
6469                         libxul.so \
6470                         libmozalloc.so \
6471                         libplc4.so \
6472                         libplds4.so"
6473
6474      For more information, see the
6475      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6476      section in the Yocto Project Overview and Concepts Manual.
6477
6478   :term:`PROVIDES`
6479      A list of aliases by which a particular recipe can be known. By
6480      default, a recipe's own :term:`PN` is implicitly already in its
6481      :term:`PROVIDES` list and therefore does not need to mention that it
6482      provides itself. If a recipe uses :term:`PROVIDES`, the additional
6483      aliases are synonyms for the recipe and can be useful for satisfying
6484      dependencies of other recipes during the build as specified by
6485      :term:`DEPENDS`.
6486
6487      Consider the following example :term:`PROVIDES` statement from the recipe
6488      file ``eudev_3.2.9.bb``::
6489
6490         PROVIDES += "udev"
6491
6492      The :term:`PROVIDES` statement
6493      results in the "eudev" recipe also being available as simply "udev".
6494
6495      .. note::
6496
6497         A recipe's own recipe name (:term:`PN`) is always implicitly prepended
6498         to :term:`PROVIDES`, so while using "+=" in the above example may not be
6499         strictly necessary it is recommended to avoid confusion.
6500
6501      In addition to providing recipes under alternate names, the
6502      :term:`PROVIDES` mechanism is also used to implement virtual targets. A
6503      virtual target is a name that corresponds to some particular
6504      functionality (e.g. a Linux kernel). Recipes that provide the
6505      functionality in question list the virtual target in :term:`PROVIDES`.
6506      Recipes that depend on the functionality in question can include the
6507      virtual target in :term:`DEPENDS` to leave the choice of provider open.
6508
6509      Conventionally, virtual targets have names on the form
6510      "virtual/function" (e.g. "virtual/kernel"). The slash is simply part
6511      of the name and has no syntactical significance.
6512
6513      The :term:`PREFERRED_PROVIDER` variable is
6514      used to select which particular recipe provides a virtual target.
6515
6516      .. note::
6517
6518         A corresponding mechanism for virtual runtime dependencies
6519         (packages) exists. However, the mechanism does not depend on any
6520         special functionality beyond ordinary variable assignments. For
6521         example, ``VIRTUAL-RUNTIME_dev_manager`` refers to the package of
6522         the component that manages the ``/dev`` directory.
6523
6524         Setting the "preferred provider" for runtime dependencies is as
6525         simple as using the following assignment in a configuration file::
6526
6527                 VIRTUAL-RUNTIME_dev_manager = "udev"
6528
6529
6530   :term:`PRSERV_HOST`
6531      The network based :term:`PR` service host and port.
6532
6533      The ``conf/templates/default/local.conf.sample.extended`` configuration
6534      file in the :term:`Source Directory` shows how the :term:`PRSERV_HOST`
6535      variable is set::
6536
6537         PRSERV_HOST = "localhost:0"
6538
6539      You must
6540      set the variable if you want to automatically start a local :ref:`PR
6541      service <dev-manual/packages:working with a pr service>`. You can
6542      set :term:`PRSERV_HOST` to other values to use a remote PR service.
6543
6544
6545   :term:`PSEUDO_IGNORE_PATHS`
6546      A comma-separated (without spaces) list of path prefixes that should be ignored
6547      by pseudo when monitoring and recording file operations, in order to avoid
6548      problems with files being written to outside of the pseudo context and
6549      reduce pseudo's overhead. A path is ignored if it matches any prefix in the list
6550      and can include partial directory (or file) names.
6551
6552
6553   :term:`PTEST_ENABLED`
6554      Specifies whether or not :ref:`Package
6555      Test <dev-manual/packages:testing packages with ptest>` (ptest)
6556      functionality is enabled when building a recipe. You should not set
6557      this variable directly. Enabling and disabling building Package Tests
6558      at build time should be done by adding "ptest" to (or removing it
6559      from) :term:`DISTRO_FEATURES`.
6560
6561   :term:`PV`
6562      The version of the recipe. The version is normally extracted from the
6563      recipe filename. For example, if the recipe is named
6564      ``expat_2.0.1.bb``, then the default value of :term:`PV` will be "2.0.1".
6565      :term:`PV` is generally not overridden within a recipe unless it is
6566      building an unstable (i.e. development) version from a source code
6567      repository (e.g. Git or Subversion).
6568
6569      :term:`PV` is the default value of the :term:`PKGV` variable.
6570
6571   :term:`PYPI_PACKAGE`
6572      When inheriting the :ref:`ref-classes-pypi` class, specifies the
6573      `PyPI <https://pypi.org/>`__ package name to be built. The default value
6574      is set based upon :term:`BPN` (stripping any "python-" or "python3-"
6575      prefix off if present), however for some packages it will need to be set
6576      explicitly if that will not match the package name (e.g. where the
6577      package name has a prefix, underscores, uppercase letters etc.)
6578
6579   :term:`PYTHON_ABI`
6580      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
6581      class, denotes the Application Binary Interface (ABI) currently in use
6582      for Python. By default, the ABI is "m". You do not have to set this
6583      variable as the OpenEmbedded build system sets it for you.
6584
6585      The OpenEmbedded build system uses the ABI to construct directory
6586      names used when installing the Python headers and libraries in
6587      sysroot (e.g. ``.../python3.3m/...``).
6588
6589   :term:`PYTHON_PN`
6590      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
6591      class, specifies the major Python version being built. For Python 3.x,
6592      :term:`PYTHON_PN` would be "python3". You do not have to set this
6593      variable as the OpenEmbedded build system automatically sets it for you.
6594
6595      The variable allows recipes to use common infrastructure such as the
6596      following::
6597
6598         DEPENDS += "${PYTHON_PN}-native"
6599
6600      In the previous example,
6601      the version of the dependency is :term:`PYTHON_PN`.
6602
6603   :term:`QA_EMPTY_DIRS`
6604      Specifies a list of directories that are expected to be empty when
6605      packaging; if ``empty-dirs`` appears in :term:`ERROR_QA` or
6606      :term:`WARN_QA` these will be checked and an error or warning
6607      (respectively) will be produced.
6608
6609      The default :term:`QA_EMPTY_DIRS` value is set in
6610      :ref:`insane.bbclass <ref-classes-insane>`.
6611
6612   :term:`QA_EMPTY_DIRS_RECOMMENDATION`
6613      Specifies a recommendation for why a directory must be empty,
6614      which will be included in the error message if a specific directory
6615      is found to contain files. Must be overridden with the directory
6616      path to match on.
6617
6618      If no recommendation is specified for a directory, then the default
6619      "but it is expected to be empty" will be used.
6620
6621      An example message shows if files were present in '/dev'::
6622
6623         QA_EMPTY_DIRS_RECOMMENDATION:/dev = "but all devices must be created at runtime"
6624
6625   :term:`RANLIB`
6626      The minimal command and arguments to run ``ranlib``.
6627
6628   :term:`RCONFLICTS`
6629      The list of packages that conflict with packages. Note that packages
6630      will not be installed if conflicting packages are not first removed.
6631
6632      Like all package-controlling variables, you must always use them in
6633      conjunction with a package name override. Here is an example::
6634
6635         RCONFLICTS:${PN} = "another_conflicting_package_name"
6636
6637      BitBake, which the OpenEmbedded build system uses, supports
6638      specifying versioned dependencies. Although the syntax varies
6639      depending on the packaging format, BitBake hides these differences
6640      from you. Here is the general syntax to specify versions with the
6641      :term:`RCONFLICTS` variable::
6642
6643         RCONFLICTS:${PN} = "package (operator version)"
6644
6645      For ``operator``, you can specify the following:
6646
6647      - =
6648      - <
6649      - >
6650      - <=
6651      - >=
6652
6653      For example, the following sets up a dependency on version 1.2 or
6654      greater of the package ``foo``::
6655
6656         RCONFLICTS:${PN} = "foo (>= 1.2)"
6657
6658   :term:`RDEPENDS`
6659      Lists runtime dependencies of a package. These dependencies are other
6660      packages that must be installed in order for the package to function
6661      correctly. As an example, the following assignment declares that the
6662      package ``foo`` needs the packages ``bar`` and ``baz`` to be
6663      installed::
6664
6665         RDEPENDS:foo = "bar baz"
6666
6667      The most common types of package
6668      runtime dependencies are automatically detected and added. Therefore,
6669      most recipes do not need to set :term:`RDEPENDS`. For more information,
6670      see the
6671      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6672      section in the Yocto Project Overview and Concepts Manual.
6673
6674      The practical effect of the above :term:`RDEPENDS` assignment is that
6675      ``bar`` and ``baz`` will be declared as dependencies inside the
6676      package ``foo`` when it is written out by one of the
6677      :ref:`do_package_write_* <ref-tasks-package_write_deb>` tasks.
6678      Exactly how this is done depends on which package format is used,
6679      which is determined by
6680      :term:`PACKAGE_CLASSES`. When the
6681      corresponding package manager installs the package, it will know to
6682      also install the packages on which it depends.
6683
6684      To ensure that the packages ``bar`` and ``baz`` get built, the
6685      previous :term:`RDEPENDS` assignment also causes a task dependency to be
6686      added. This dependency is from the recipe's
6687      :ref:`ref-tasks-build` (not to be confused with
6688      :ref:`ref-tasks-compile`) task to the
6689      :ref:`do_package_write_* <ref-tasks-package_write_deb>` task of the recipes that build ``bar`` and
6690      ``baz``.
6691
6692      The names of the packages you list within :term:`RDEPENDS` must be the
6693      names of other packages --- they cannot be recipe names. Although
6694      package names and recipe names usually match, the important point
6695      here is that you are providing package names within the :term:`RDEPENDS`
6696      variable. For an example of the default list of packages created from
6697      a recipe, see the :term:`PACKAGES` variable.
6698
6699      Because the :term:`RDEPENDS` variable applies to packages being built,
6700      you should always use the variable in a form with an attached package
6701      name (remember that a single recipe can build multiple packages). For
6702      example, suppose you are building a development package that depends
6703      on the ``perl`` package. In this case, you would use the following
6704      :term:`RDEPENDS` statement::
6705
6706         RDEPENDS:${PN}-dev += "perl"
6707
6708      In the example,
6709      the development package depends on the ``perl`` package. Thus, the
6710      :term:`RDEPENDS` variable has the ``${PN}-dev`` package name as part of
6711      the variable.
6712
6713      .. note::
6714
6715         ``RDEPENDS:${PN}-dev`` includes ``${``\ :term:`PN`\ ``}``
6716         by default. This default is set in the BitBake configuration file
6717         (``meta/conf/bitbake.conf``). Be careful not to accidentally remove
6718         ``${PN}`` when modifying ``RDEPENDS:${PN}-dev``. Use the "+=" operator
6719         rather than the "=" operator.
6720
6721      The package names you use with :term:`RDEPENDS` must appear as they would
6722      in the :term:`PACKAGES` variable. The :term:`PKG` variable
6723      allows a different name to be used for the final package (e.g. the
6724      :ref:`ref-classes-debian` class uses this to rename
6725      packages), but this final package name cannot be used with
6726      :term:`RDEPENDS`, which makes sense as :term:`RDEPENDS` is meant to be
6727      independent of the package format used.
6728
6729      BitBake, which the OpenEmbedded build system uses, supports
6730      specifying versioned dependencies. Although the syntax varies
6731      depending on the packaging format, BitBake hides these differences
6732      from you. Here is the general syntax to specify versions with the
6733      :term:`RDEPENDS` variable::
6734
6735         RDEPENDS:${PN} = "package (operator version)"
6736
6737      For ``operator``, you can specify the following:
6738
6739      - =
6740      - <
6741      - >
6742      - <=
6743      - >=
6744
6745      For version, provide the version number.
6746
6747      .. note::
6748
6749         You can use :term:`EXTENDPKGV` to provide a full package version
6750         specification.
6751
6752      For example, the following sets up a dependency on version 1.2 or
6753      greater of the package ``foo``::
6754
6755         RDEPENDS:${PN} = "foo (>= 1.2)"
6756
6757      For information on build-time dependencies, see the :term:`DEPENDS`
6758      variable. You can also see the
6759      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
6760      ":ref:`bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
6761      BitBake User Manual for additional information on tasks and dependencies.
6762
6763   :term:`RECIPE_NO_UPDATE_REASON`
6764      If a recipe should not be replaced by a more recent upstream version,
6765      putting the reason why in this variable in a recipe allows
6766      ``devtool check-upgrade-status`` command to display it, as explained
6767      in the ":ref:`ref-manual/devtool-reference:checking on the upgrade status of a recipe`"
6768      section.
6769
6770   :term:`REPODIR`
6771      See :term:`bitbake:REPODIR` in the BitBake manual.
6772
6773   :term:`REQUIRED_DISTRO_FEATURES`
6774      When inheriting the :ref:`ref-classes-features_check`
6775      class, this variable identifies distribution features that must exist
6776      in the current configuration in order for the OpenEmbedded build
6777      system to build the recipe. In other words, if the
6778      :term:`REQUIRED_DISTRO_FEATURES` variable lists a feature that does not
6779      appear in :term:`DISTRO_FEATURES` within the current configuration, then
6780      the recipe will be skipped, and if the build system attempts to build
6781      the recipe then an error will be triggered.
6782
6783   :term:`REQUIRED_VERSION`
6784      If there are multiple versions of a recipe available, this variable
6785      determines which version should be given preference.
6786      :term:`REQUIRED_VERSION` works in exactly the same manner as
6787      :term:`PREFERRED_VERSION`, except that if the specified version is not
6788      available then an error message is shown and the build fails
6789      immediately.
6790
6791      If both :term:`REQUIRED_VERSION` and :term:`PREFERRED_VERSION` are set
6792      for the same recipe, the :term:`REQUIRED_VERSION` value applies.
6793
6794   :term:`RM_WORK_EXCLUDE`
6795      With :ref:`ref-classes-rm-work` enabled, this variable
6796      specifies a list of recipes whose work directories should not be removed.
6797      See the ":ref:`ref-classes-rm-work`" section for more details.
6798
6799   :term:`ROOT_HOME`
6800      Defines the root home directory. By default, this directory is set as
6801      follows in the BitBake configuration file::
6802
6803         ROOT_HOME ??= "/home/root"
6804
6805      .. note::
6806
6807         This default value is likely used because some embedded solutions
6808         prefer to have a read-only root filesystem and prefer to keep
6809         writeable data in one place.
6810
6811      You can override the default by setting the variable in any layer or
6812      in the ``local.conf`` file. Because the default is set using a "weak"
6813      assignment (i.e. "??="), you can use either of the following forms to
6814      define your override::
6815
6816         ROOT_HOME = "/root"
6817         ROOT_HOME ?= "/root"
6818
6819      These
6820      override examples use ``/root``, which is probably the most commonly
6821      used override.
6822
6823   :term:`ROOTFS`
6824      Indicates a filesystem image to include as the root filesystem.
6825
6826      The :term:`ROOTFS` variable is an optional variable used with the
6827      :ref:`ref-classes-image-live` class.
6828
6829   :term:`ROOTFS_POSTINSTALL_COMMAND`
6830      Specifies a list of functions to call after the OpenEmbedded build
6831      system has installed packages. You can specify functions separated by
6832      semicolons::
6833
6834         ROOTFS_POSTINSTALL_COMMAND += "function; ... "
6835
6836      If you need to pass the root filesystem path to a command within a
6837      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6838      directory that becomes the root filesystem image. See the
6839      :term:`IMAGE_ROOTFS` variable for more
6840      information.
6841
6842   :term:`ROOTFS_POSTPROCESS_COMMAND`
6843      Specifies a list of functions to call once the OpenEmbedded build
6844      system has created the root filesystem. You can specify functions
6845      separated by semicolons::
6846
6847         ROOTFS_POSTPROCESS_COMMAND += "function; ... "
6848
6849      If you need to pass the root filesystem path to a command within a
6850      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6851      directory that becomes the root filesystem image. See the
6852      :term:`IMAGE_ROOTFS` variable for more
6853      information.
6854
6855   :term:`ROOTFS_POSTUNINSTALL_COMMAND`
6856      Specifies a list of functions to call after the OpenEmbedded build
6857      system has removed unnecessary packages. When runtime package
6858      management is disabled in the image, several packages are removed
6859      including ``base-passwd``, ``shadow``, and ``update-alternatives``.
6860      You can specify functions separated by semicolons::
6861
6862         ROOTFS_POSTUNINSTALL_COMMAND += "function; ... "
6863
6864      If you need to pass the root filesystem path to a command within a
6865      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6866      directory that becomes the root filesystem image. See the
6867      :term:`IMAGE_ROOTFS` variable for more
6868      information.
6869
6870   :term:`ROOTFS_PREPROCESS_COMMAND`
6871      Specifies a list of functions to call before the OpenEmbedded build
6872      system has created the root filesystem. You can specify functions
6873      separated by semicolons::
6874
6875         ROOTFS_PREPROCESS_COMMAND += "function; ... "
6876
6877      If you need to pass the root filesystem path to a command within a
6878      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6879      directory that becomes the root filesystem image. See the
6880      :term:`IMAGE_ROOTFS` variable for more
6881      information.
6882
6883   :term:`RPROVIDES`
6884      A list of package name aliases that a package also provides. These
6885      aliases are useful for satisfying runtime dependencies of other
6886      packages both during the build and on the target (as specified by
6887      :term:`RDEPENDS`).
6888
6889      .. note::
6890
6891         A package's own name is implicitly already in its :term:`RPROVIDES` list.
6892
6893      As with all package-controlling variables, you must always use the
6894      variable in conjunction with a package name override. Here is an
6895      example::
6896
6897         RPROVIDES:${PN} = "widget-abi-2"
6898
6899   :term:`RRECOMMENDS`
6900      A list of packages that extends the usability of a package being
6901      built. The package being built does not depend on this list of
6902      packages in order to successfully build, but rather uses them for
6903      extended usability. To specify runtime dependencies for packages, see
6904      the :term:`RDEPENDS` variable.
6905
6906      The package manager will automatically install the :term:`RRECOMMENDS`
6907      list of packages when installing the built package. However, you can
6908      prevent listed packages from being installed by using the
6909      :term:`BAD_RECOMMENDATIONS`,
6910      :term:`NO_RECOMMENDATIONS`, and
6911      :term:`PACKAGE_EXCLUDE` variables.
6912
6913      Packages specified in :term:`RRECOMMENDS` need not actually be produced.
6914      However, there must be a recipe providing each package, either
6915      through the :term:`PACKAGES` or
6916      :term:`PACKAGES_DYNAMIC` variables or the
6917      :term:`RPROVIDES` variable, or an error will occur
6918      during the build. If such a recipe does exist and the package is not
6919      produced, the build continues without error.
6920
6921      Because the :term:`RRECOMMENDS` variable applies to packages being built,
6922      you should always attach an override to the variable to specify the
6923      particular package whose usability is being extended. For example,
6924      suppose you are building a development package that is extended to
6925      support wireless functionality. In this case, you would use the
6926      following::
6927
6928         RRECOMMENDS:${PN}-dev += "wireless_package_name"
6929
6930      In the
6931      example, the package name (``${PN}-dev``) must appear as it would in
6932      the :term:`PACKAGES` namespace before any renaming of the output package
6933      by classes such as :ref:`ref-classes-debian`.
6934
6935      BitBake, which the OpenEmbedded build system uses, supports
6936      specifying versioned recommends. Although the syntax varies depending
6937      on the packaging format, BitBake hides these differences from you.
6938      Here is the general syntax to specify versions with the
6939      :term:`RRECOMMENDS` variable::
6940
6941         RRECOMMENDS:${PN} = "package (operator version)"
6942
6943      For ``operator``, you can specify the following:
6944
6945      - =
6946      - <
6947      - >
6948      - <=
6949      - >=
6950
6951      For example, the following sets up a recommend on version 1.2 or
6952      greater of the package ``foo``::
6953
6954         RRECOMMENDS:${PN} = "foo (>= 1.2)"
6955
6956   :term:`RREPLACES`
6957      A list of packages replaced by a package. The package manager uses
6958      this variable to determine which package should be installed to
6959      replace other package(s) during an upgrade. In order to also have the
6960      other package(s) removed at the same time, you must add the name of
6961      the other package to the :term:`RCONFLICTS` variable.
6962
6963      As with all package-controlling variables, you must use this variable
6964      in conjunction with a package name override. Here is an example::
6965
6966         RREPLACES:${PN} = "other_package_being_replaced"
6967
6968      BitBake, which the OpenEmbedded build system uses, supports
6969      specifying versioned replacements. Although the syntax varies
6970      depending on the packaging format, BitBake hides these differences
6971      from you. Here is the general syntax to specify versions with the
6972      :term:`RREPLACES` variable::
6973
6974         RREPLACES:${PN} = "package (operator version)"
6975
6976      For ``operator``, you can specify the following:
6977
6978      - =
6979      - <
6980      - >
6981      - <=
6982      - >=
6983
6984      For example, the following sets up a replacement using version 1.2
6985      or greater of the package ``foo``::
6986
6987          RREPLACES:${PN} = "foo (>= 1.2)"
6988
6989   :term:`RSUGGESTS`
6990      A list of additional packages that you can suggest for installation
6991      by the package manager at the time a package is installed. Not all
6992      package managers support this functionality.
6993
6994      As with all package-controlling variables, you must always use this
6995      variable in conjunction with a package name override. Here is an
6996      example::
6997
6998         RSUGGESTS:${PN} = "useful_package another_package"
6999
7000   :term:`RUST_CHANNEL`
7001      Specifies which version of Rust to build - "stable", "beta" or "nightly".
7002      The default value is "stable". Set this at your own risk, as values other
7003      than "stable" are not guaranteed to work at a given time.
7004
7005   :term:`S`
7006      The location in the :term:`Build Directory` where
7007      unpacked recipe source code resides. By default, this directory is
7008      ``${``\ :term:`WORKDIR`\ ``}/${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
7009      where ``${BPN}`` is the base recipe name and ``${PV}`` is the recipe
7010      version. If the source tarball extracts the code to a directory named
7011      anything other than ``${BPN}-${PV}``, or if the source code is
7012      fetched from an SCM such as Git or Subversion, then you must set
7013      :term:`S` in the recipe so that the OpenEmbedded build system knows where
7014      to find the unpacked source.
7015
7016      As an example, assume a :term:`Source Directory`
7017      top-level folder named ``poky`` and a default :term:`Build Directory` at
7018      ``poky/build``. In this case, the work directory the build system
7019      uses to keep the unpacked recipe for ``db`` is the following::
7020
7021         poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
7022
7023      The unpacked source code resides in the ``db-5.1.19`` folder.
7024
7025      This next example assumes a Git repository. By default, Git
7026      repositories are cloned to ``${WORKDIR}/git`` during
7027      :ref:`ref-tasks-fetch`. Since this path is different
7028      from the default value of :term:`S`, you must set it specifically so the
7029      source can be located::
7030
7031         SRC_URI = "git://path/to/repo.git;branch=main"
7032         S = "${WORKDIR}/git"
7033
7034   :term:`SANITY_REQUIRED_UTILITIES`
7035      Specifies a list of command-line utilities that should be checked for
7036      during the initial sanity checking process when running BitBake. If
7037      any of the utilities are not installed on the build host, then
7038      BitBake immediately exits with an error.
7039
7040   :term:`SANITY_TESTED_DISTROS`
7041      A list of the host distribution identifiers that the build system has
7042      been tested against. Identifiers consist of the host distributor ID
7043      followed by the release, as reported by the ``lsb_release`` tool or
7044      as read from ``/etc/lsb-release``. Separate the list items with
7045      explicit newline characters (``\n``). If :term:`SANITY_TESTED_DISTROS` is
7046      not empty and the current value of
7047      :term:`NATIVELSBSTRING` does not appear in the
7048      list, then the build system reports a warning that indicates the
7049      current host distribution has not been tested as a build host.
7050
7051   :term:`SDK_ARCH`
7052      The target architecture for the SDK. Typically, you do not directly
7053      set this variable. Instead, use :term:`SDKMACHINE`.
7054
7055   :term:`SDK_ARCHIVE_TYPE`
7056      Specifies the type of archive to create for the SDK. Valid values:
7057
7058      - ``tar.xz`` (default)
7059      - ``zip``
7060
7061      Only one archive type can be specified.
7062
7063   :term:`SDK_BUILDINFO_FILE`
7064      When using the :ref:`ref-classes-image-buildinfo` class,
7065      specifies the file in the SDK to write the build information into. The
7066      default value is "``/buildinfo``".
7067
7068   :term:`SDK_CUSTOM_TEMPLATECONF`
7069      When building the extensible SDK, if :term:`SDK_CUSTOM_TEMPLATECONF` is set to
7070      "1" and a ``conf/templateconf.cfg`` file exists in the :term:`Build Directory`
7071      (:term:`TOPDIR`) then this will be copied into the SDK.
7072
7073   :term:`SDK_DEPLOY`
7074      The directory set up and used by the
7075      :ref:`populate_sdk_base <ref-classes-populate-sdk>` class to which the
7076      SDK is deployed. The :ref:`populate_sdk_base <ref-classes-populate-sdk>`
7077      class defines :term:`SDK_DEPLOY` as follows::
7078
7079         SDK_DEPLOY = "${TMPDIR}/deploy/sdk"
7080
7081   :term:`SDK_DIR`
7082      The parent directory used by the OpenEmbedded build system when
7083      creating SDK output. The
7084      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class defines
7085      the variable as follows::
7086
7087         SDK_DIR = "${WORKDIR}/sdk"
7088
7089      .. note::
7090
7091         The :term:`SDK_DIR` directory is a temporary directory as it is part of
7092         :term:`WORKDIR`. The final output directory is :term:`SDK_DEPLOY`.
7093
7094   :term:`SDK_EXT_TYPE`
7095      Controls whether or not shared state artifacts are copied into the
7096      extensible SDK. The default value of "full" copies all of the
7097      required shared state artifacts into the extensible SDK. The value
7098      "minimal" leaves these artifacts out of the SDK.
7099
7100      .. note::
7101
7102         If you set the variable to "minimal", you need to ensure
7103         :term:`SSTATE_MIRRORS` is set in the SDK's configuration to enable the
7104         artifacts to be fetched as needed.
7105
7106   :term:`SDK_HOST_MANIFEST`
7107      The manifest file for the host part of the SDK. This file lists all
7108      the installed packages that make up the host part of the SDK. The
7109      file contains package information on a line-per-package basis as
7110      follows::
7111
7112         packagename packagearch version
7113
7114      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
7115      defines the manifest file as follows::
7116
7117         SDK_HOST_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.host.manifest"
7118
7119      The location is derived using the :term:`SDK_DEPLOY` and
7120      :term:`TOOLCHAIN_OUTPUTNAME` variables.
7121
7122   :term:`SDK_INCLUDE_PKGDATA`
7123      When set to "1", specifies to include the packagedata for all recipes
7124      in the "world" target in the extensible SDK. Including this data
7125      allows the ``devtool search`` command to find these recipes in search
7126      results, as well as allows the ``devtool add`` command to map
7127      dependencies more effectively.
7128
7129      .. note::
7130
7131         Enabling the :term:`SDK_INCLUDE_PKGDATA`
7132         variable significantly increases build time because all of world
7133         needs to be built. Enabling the variable also slightly increases
7134         the size of the extensible SDK.
7135
7136   :term:`SDK_INCLUDE_TOOLCHAIN`
7137      When set to "1", specifies to include the toolchain in the extensible
7138      SDK. Including the toolchain is useful particularly when
7139      :term:`SDK_EXT_TYPE` is set to "minimal" to keep
7140      the SDK reasonably small but you still want to provide a usable
7141      toolchain. For example, suppose you want to use the toolchain from an
7142      IDE or from other tools and you do not want to perform additional
7143      steps to install the toolchain.
7144
7145      The :term:`SDK_INCLUDE_TOOLCHAIN` variable defaults to "0" if
7146      :term:`SDK_EXT_TYPE` is set to "minimal", and defaults to "1" if
7147      :term:`SDK_EXT_TYPE` is set to "full".
7148
7149   :term:`SDK_NAME`
7150      The base name for SDK output files. The name is derived from the
7151      :term:`DISTRO`, :term:`TCLIBC`,
7152      :term:`SDK_ARCH`,
7153      :term:`IMAGE_BASENAME`, and
7154      :term:`TUNE_PKGARCH` variables::
7155
7156         SDK_NAME = "${DISTRO}-${TCLIBC}-${SDK_ARCH}-${IMAGE_BASENAME}-${TUNE_PKGARCH}"
7157
7158   :term:`SDK_OS`
7159      Specifies the operating system for which the SDK will be built. The
7160      default value is the value of :term:`BUILD_OS`.
7161
7162   :term:`SDK_OUTPUT`
7163      The location used by the OpenEmbedded build system when creating SDK
7164      output. The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>`
7165      class defines the variable as follows::
7166
7167         SDK_DIR = "${WORKDIR}/sdk"
7168         SDK_OUTPUT = "${SDK_DIR}/image"
7169         SDK_DEPLOY = "${DEPLOY_DIR}/sdk"
7170
7171      .. note::
7172
7173         The :term:`SDK_OUTPUT` directory is a temporary directory as it is part of
7174         :term:`WORKDIR` by way of :term:`SDK_DIR`. The final output directory is
7175         :term:`SDK_DEPLOY`.
7176
7177   :term:`SDK_PACKAGE_ARCHS`
7178      Specifies a list of architectures compatible with the SDK machine.
7179      This variable is set automatically and should not normally be
7180      hand-edited. Entries are separated using spaces and listed in order
7181      of priority. The default value for :term:`SDK_PACKAGE_ARCHS` is "all any
7182      noarch ${SDK_ARCH}-${SDKPKGSUFFIX}".
7183
7184   :term:`SDK_POSTPROCESS_COMMAND`
7185      Specifies a list of functions to call once the OpenEmbedded build
7186      system creates the SDK. You can specify functions separated by
7187      semicolons: SDK_POSTPROCESS_COMMAND += "function; ... "
7188
7189      If you need to pass an SDK path to a command within a function, you
7190      can use ``${SDK_DIR}``, which points to the parent directory used by
7191      the OpenEmbedded build system when creating SDK output. See the
7192      :term:`SDK_DIR` variable for more information.
7193
7194   :term:`SDK_PREFIX`
7195      The toolchain binary prefix used for
7196      :ref:`ref-classes-nativesdk` recipes. The
7197      OpenEmbedded build system uses the :term:`SDK_PREFIX` value to set the
7198      :term:`TARGET_PREFIX` when building
7199      ``nativesdk`` recipes. The default value is "${SDK_SYS}-".
7200
7201   :term:`SDK_RECRDEP_TASKS`
7202      A list of shared state tasks added to the extensible SDK. By default,
7203      the following tasks are added:
7204
7205      - :ref:`ref-tasks-populate_lic`
7206      - :ref:`ref-tasks-package_qa`
7207      - :ref:`ref-tasks-populate_sysroot`
7208      - :ref:`ref-tasks-deploy`
7209
7210      Despite the default value of "" for the
7211      :term:`SDK_RECRDEP_TASKS` variable, the above four tasks are always added
7212      to the SDK. To specify tasks beyond these four, you need to use the
7213      :term:`SDK_RECRDEP_TASKS` variable (e.g. you are defining additional
7214      tasks that are needed in order to build
7215      :term:`SDK_TARGETS`).
7216
7217   :term:`SDK_SYS`
7218      Specifies the system, including the architecture and the operating
7219      system, for which the SDK will be built.
7220
7221      The OpenEmbedded build system automatically sets this variable based
7222      on :term:`SDK_ARCH`,
7223      :term:`SDK_VENDOR`, and
7224      :term:`SDK_OS`. You do not need to set the :term:`SDK_SYS`
7225      variable yourself.
7226
7227   :term:`SDK_TARGET_MANIFEST`
7228      The manifest file for the target part of the SDK. This file lists all
7229      the installed packages that make up the target part of the SDK. The
7230      file contains package information on a line-per-package basis as
7231      follows::
7232
7233         packagename packagearch version
7234
7235      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
7236      defines the manifest file as follows::
7237
7238         SDK_TARGET_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.target.manifest"
7239
7240      The location is derived using the :term:`SDK_DEPLOY` and
7241      :term:`TOOLCHAIN_OUTPUTNAME` variables.
7242
7243   :term:`SDK_TARGETS`
7244      A list of targets to install from shared state as part of the
7245      standard or extensible SDK installation. The default value is "${PN}"
7246      (i.e. the image from which the SDK is built).
7247
7248      The :term:`SDK_TARGETS` variable is an internal variable and typically
7249      would not be changed.
7250
7251   :term:`SDK_TITLE`
7252      The title to be printed when running the SDK installer. By default,
7253      this title is based on the :term:`DISTRO_NAME` or
7254      :term:`DISTRO` variable and is set in the
7255      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
7256      follows::
7257
7258         SDK_TITLE ??= "${@d.getVar('DISTRO_NAME') or d.getVar('DISTRO')} SDK"
7259
7260      For the default distribution "poky",
7261      :term:`SDK_TITLE` is set to "Poky (Yocto Project Reference Distro)".
7262
7263      For information on how to change this default title, see the
7264      ":ref:`sdk-manual/appendix-customizing:changing the extensible sdk installer title`"
7265      section in the Yocto Project Application Development and the
7266      Extensible Software Development Kit (eSDK) manual.
7267
7268   :term:`SDK_TOOLCHAIN_LANGS`
7269      Specifies programming languages to support in the SDK, as a
7270      space-separated list. Currently supported items are ``rust`` and ``go``.
7271
7272   :term:`SDK_UPDATE_URL`
7273      An optional URL for an update server for the extensible SDK. If set,
7274      the value is used as the default update server when running
7275      ``devtool sdk-update`` within the extensible SDK.
7276
7277   :term:`SDK_VENDOR`
7278      Specifies the name of the SDK vendor.
7279
7280   :term:`SDK_VERSION`
7281      Specifies the version of the SDK. The Poky distribution configuration file
7282      (``/meta-poky/conf/distro/poky.conf``) sets the default
7283      :term:`SDK_VERSION` as follows::
7284
7285         SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"
7286
7287      For additional information, see the
7288      :term:`DISTRO_VERSION` and
7289      :term:`METADATA_REVISION` variables.
7290
7291   :term:`SDK_ZIP_OPTIONS`
7292      Specifies extra options to pass to the ``zip`` command when zipping the SDK
7293      (i.e. when :term:`SDK_ARCHIVE_TYPE` is set to "zip"). The default value is
7294      "-y".
7295
7296   :term:`SDKEXTPATH`
7297      The default installation directory for the Extensible SDK. By
7298      default, this directory is based on the :term:`DISTRO`
7299      variable and is set in the
7300      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
7301      follows::
7302
7303         SDKEXTPATH ??= "~/${@d.getVar('DISTRO')}_sdk"
7304
7305      For the
7306      default distribution "poky", the :term:`SDKEXTPATH` is set to "poky_sdk".
7307
7308      For information on how to change this default directory, see the
7309      ":ref:`sdk-manual/appendix-customizing:changing the default sdk installation directory`"
7310      section in the Yocto Project Application Development and the
7311      Extensible Software Development Kit (eSDK) manual.
7312
7313   :term:`SDKIMAGE_FEATURES`
7314      Equivalent to :term:`IMAGE_FEATURES`. However, this variable applies to
7315      the SDK generated from an image using the following command::
7316
7317         $ bitbake -c populate_sdk imagename
7318
7319   :term:`SDKMACHINE`
7320      The machine for which the SDK is built. In other words, the SDK is built
7321      such that it runs on the target you specify with the :term:`SDKMACHINE`
7322      value. The value points to a corresponding ``.conf`` file under
7323      ``conf/machine-sdk/`` in the enabled layers, for example ``aarch64``,
7324      ``i586``, ``i686``, ``ppc64``, ``ppc64le``, and ``x86_64`` are
7325      :oe_git:`available in OpenEmbedded-Core </openembedded-core/tree/meta/conf/machine-sdk>`.
7326
7327      The variable defaults to :term:`BUILD_ARCH` so that SDKs are built for the
7328      architecture of the build machine.
7329
7330      .. note::
7331
7332         You cannot set the :term:`SDKMACHINE`
7333         variable in your distribution configuration file. If you do, the
7334         configuration will not take effect.
7335
7336   :term:`SDKPATH`
7337      Defines the path offered to the user for installation of the SDK that
7338      is generated by the OpenEmbedded build system. The path appears as
7339      the default location for installing the SDK when you run the SDK's
7340      installation script. You can override the offered path when you run
7341      the script.
7342
7343   :term:`SDKTARGETSYSROOT`
7344      The full path to the sysroot used for cross-compilation within an SDK
7345      as it will be when installed into the default
7346      :term:`SDKPATH`.
7347
7348   :term:`SECTION`
7349      The section in which packages should be categorized. Package
7350      management utilities can make use of this variable.
7351
7352   :term:`SELECTED_OPTIMIZATION`
7353      Specifies the optimization flags passed to the C compiler when
7354      building for the target. The flags are passed through the default
7355      value of the :term:`TARGET_CFLAGS` variable.
7356
7357      The :term:`SELECTED_OPTIMIZATION` variable takes the value of
7358      :term:`FULL_OPTIMIZATION` unless :term:`DEBUG_BUILD` = "1", in which
7359      case the value of :term:`DEBUG_OPTIMIZATION` is used.
7360
7361   :term:`SERIAL_CONSOLES`
7362      Defines a serial console (TTY) to enable using
7363      :wikipedia:`getty <Getty_(Unix)>`. Provide a value that specifies the
7364      baud rate followed by the TTY device name separated by a semicolon.
7365      Use spaces to separate multiple devices::
7366
7367         SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
7368
7369   :term:`SERIAL_CONSOLES_CHECK`
7370      Specifies serial consoles, which must be listed in
7371      :term:`SERIAL_CONSOLES`, to check against
7372      ``/proc/console`` before enabling them using getty. This variable
7373      allows aliasing in the format: <device>:<alias>. If a device was
7374      listed as "sclp_line0" in ``/dev/`` and "ttyS0" was listed in
7375      ``/proc/console``, you would do the following::
7376
7377         SERIAL_CONSOLES_CHECK = "slcp_line0:ttyS0"
7378
7379      This variable is currently only supported with SysVinit (i.e. not
7380      with systemd). Note that :term:`SERIAL_CONSOLES_CHECK` also requires
7381      ``/etc/inittab`` to be writable when used with SysVinit. This makes it
7382      incompatible with customizations such as the following::
7383
7384         EXTRA_IMAGE_FEATURES += "read-only-rootfs"
7385
7386   :term:`SETUPTOOLS_BUILD_ARGS`
7387      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7388      class, this variable can be used to specify additional arguments to be
7389      passed to ``setup.py build`` in the ``setuptools3_do_compile()`` task.
7390
7391   :term:`SETUPTOOLS_INSTALL_ARGS`
7392      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7393      class, this variable can be used to specify additional arguments to be
7394      passed to ``setup.py install`` in the ``setuptools3_do_install()`` task.
7395
7396   :term:`SETUPTOOLS_SETUP_PATH`
7397      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7398      class, this variable should be used to specify the directory in which
7399      the ``setup.py`` file is located if it is not at the root of the source
7400      tree (as specified by :term:`S`). For example, in a recipe where the
7401      sources are fetched from a Git repository and ``setup.py`` is in a
7402      ``python/pythonmodule`` subdirectory, you would have this::
7403
7404         S = "${WORKDIR}/git"
7405         SETUPTOOLS_SETUP_PATH = "${S}/python/pythonmodule"
7406
7407   :term:`SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS`
7408      A list of recipe dependencies that should not be used to determine
7409      signatures of tasks from one recipe when they depend on tasks from
7410      another recipe. For example::
7411
7412         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
7413
7414      In the previous example, ``intone`` depends on ``mplayer2``.
7415
7416      You can use the special token ``"*"`` on the left-hand side of the
7417      dependency to match all recipes except the one on the right-hand
7418      side. Here is an example::
7419
7420         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "*->quilt-native"
7421
7422      In the previous example, all recipes except ``quilt-native`` ignore
7423      task signatures from the ``quilt-native`` recipe when determining
7424      their task signatures.
7425
7426      Use of this variable is one mechanism to remove dependencies that
7427      affect task signatures and thus force rebuilds when a recipe changes.
7428
7429      .. note::
7430
7431         If you add an inappropriate dependency for a recipe relationship,
7432         the software might break during runtime if the interface of the
7433         second recipe was changed after the first recipe had been built.
7434
7435   :term:`SIGGEN_EXCLUDERECIPES_ABISAFE`
7436      A list of recipes that are completely stable and will never change.
7437      The ABI for the recipes in the list are presented by output from the
7438      tasks run to build the recipe. Use of this variable is one way to
7439      remove dependencies from one recipe on another that affect task
7440      signatures and thus force rebuilds when the recipe changes.
7441
7442      .. note::
7443
7444         If you add an inappropriate variable to this list, the software
7445         might break at runtime if the interface of the recipe was changed
7446         after the other had been built.
7447
7448   :term:`SITEINFO_BITS`
7449      Specifies the number of bits for the target system CPU. The value
7450      should be either "32" or "64".
7451
7452   :term:`SITEINFO_ENDIANNESS`
7453      Specifies the endian byte order of the target system. The value
7454      should be either "le" for little-endian or "be" for big-endian.
7455
7456   :term:`SKIP_FILEDEPS`
7457      Enables removal of all files from the "Provides" section of an RPM
7458      package. Removal of these files is required for packages containing
7459      prebuilt binaries and libraries such as ``libstdc++`` and ``glibc``.
7460
7461      To enable file removal, set the variable to "1" in your
7462      ``conf/local.conf`` configuration file in your:
7463      :term:`Build Directory`::
7464
7465         SKIP_FILEDEPS = "1"
7466
7467   :term:`SKIP_RECIPE`
7468      Used to prevent the OpenEmbedded build system from building a given
7469      recipe. Specify the :term:`PN` value as a variable flag (``varflag``)
7470      and provide a reason, which will be reported when attempting to
7471      build the recipe.
7472
7473      To prevent a recipe from being built, use the :term:`SKIP_RECIPE`
7474      variable in your ``local.conf`` file or distribution configuration.
7475      Here is an example which prevents ``myrecipe`` from being built::
7476
7477         SKIP_RECIPE[myrecipe] = "Not supported by our organization."
7478
7479   :term:`SOC_FAMILY`
7480      Groups together machines based upon the same family of SOC (System On
7481      Chip). You typically set this variable in a common ``.inc`` file that
7482      you include in the configuration files of all the machines.
7483
7484      .. note::
7485
7486         You must include ``conf/machine/include/soc-family.inc`` for this
7487         variable to appear in :term:`MACHINEOVERRIDES`.
7488
7489   :term:`SOLIBS`
7490      Defines the suffix for shared libraries used on the target platform.
7491      By default, this suffix is ".so.*" for all Linux-based systems and is
7492      defined in the ``meta/conf/bitbake.conf`` configuration file.
7493
7494      You will see this variable referenced in the default values of
7495      ``FILES:${PN}``.
7496
7497   :term:`SOLIBSDEV`
7498      Defines the suffix for the development symbolic link (symlink) for
7499      shared libraries on the target platform. By default, this suffix is
7500      ".so" for Linux-based systems and is defined in the
7501      ``meta/conf/bitbake.conf`` configuration file.
7502
7503      You will see this variable referenced in the default values of
7504      ``FILES:${PN}-dev``.
7505
7506   :term:`SOURCE_DATE_EPOCH`
7507      This defines a date expressed in number of seconds since
7508      the UNIX EPOCH (01 Jan 1970 00:00:00 UTC), which is used by
7509      multiple build systems to force a timestamp in built binaries.
7510      Many upstream projects already support this variable.
7511
7512      You will find more details in the `official specifications
7513      <https://reproducible-builds.org/specs/source-date-epoch/>`__.
7514
7515      A value for each recipe is computed from the sources by
7516      :oe_git:`meta/lib/oe/reproducible.py </openembedded-core/tree/meta/lib/oe/reproducible.py>`.
7517
7518      If a recipe wishes to override the default behavior, it should set its
7519      own :term:`SOURCE_DATE_EPOCH` value::
7520
7521          SOURCE_DATE_EPOCH = "1613559011"
7522
7523   :term:`SOURCE_MIRROR_FETCH`
7524      When you are fetching files to create a mirror of sources (i.e.
7525      creating a source mirror), setting :term:`SOURCE_MIRROR_FETCH` to "1" in
7526      your ``local.conf`` configuration file ensures the source for all
7527      recipes are fetched regardless of whether or not a recipe is
7528      compatible with the configuration. A recipe is considered
7529      incompatible with the currently configured machine when either or
7530      both the :term:`COMPATIBLE_MACHINE`
7531      variable and :term:`COMPATIBLE_HOST` variables
7532      specify compatibility with a machine other than that of the current
7533      machine or host.
7534
7535      .. note::
7536
7537         Do not set the :term:`SOURCE_MIRROR_FETCH`
7538         variable unless you are creating a source mirror. In other words,
7539         do not set the variable during a normal build.
7540
7541   :term:`SOURCE_MIRROR_URL`
7542      Defines your own :term:`PREMIRRORS` from which to
7543      first fetch source before attempting to fetch from the upstream
7544      specified in :term:`SRC_URI`.
7545
7546      To use this variable, you must globally inherit the
7547      :ref:`ref-classes-own-mirrors` class and then provide
7548      the URL to your mirrors. Here is the general syntax::
7549
7550         INHERIT += "own-mirrors"
7551         SOURCE_MIRROR_URL = "http://example.com/my_source_mirror"
7552
7553      .. note::
7554
7555         You can specify only a single URL in :term:`SOURCE_MIRROR_URL`.
7556
7557   :term:`SPDX_ARCHIVE_PACKAGED`
7558      This option allows to add to :term:`SPDX` output compressed archives
7559      of the files in the generated target packages.
7560
7561      Such archives are available in
7562      ``tmp/deploy/spdx/MACHINE/packages/packagename.tar.zst``
7563      under the :term:`Build Directory`.
7564
7565      Enable this option as follows::
7566
7567         SPDX_ARCHIVE_PACKAGED = "1"
7568
7569      According to our tests on release 4.1 "langdale", building
7570      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling this
7571      option multiplied the size of the ``tmp/deploy/spdx`` directory by a
7572      factor of 13 (+1.6 GiB for this image), compared to just using the
7573      :ref:`ref-classes-create-spdx` class with no option.
7574
7575      Note that this option doesn't increase the size of :term:`SPDX`
7576      files in ``tmp/deploy/images/MACHINE``.
7577
7578   :term:`SPDX_ARCHIVE_SOURCES`
7579      This option allows to add to :term:`SPDX` output compressed archives
7580      of the sources for packages installed on the target. It currently
7581      only works when :term:`SPDX_INCLUDE_SOURCES` is set.
7582
7583      This is one way of fulfilling "source code access" license
7584      requirements.
7585
7586      Such source archives are available in
7587      ``tmp/deploy/spdx/MACHINE/recipes/recipe-packagename.tar.zst``
7588      under the :term:`Build Directory`.
7589
7590      Enable this option as follows::
7591
7592         SPDX_INCLUDE_SOURCES = "1"
7593         SPDX_ARCHIVE_SOURCES = "1"
7594
7595      According to our tests on release 4.1 "langdale", building
7596      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling
7597      these options multiplied the size of the ``tmp/deploy/spdx``
7598      directory by a factor of 11 (+1.4 GiB for this image),
7599      compared to just using the :ref:`ref-classes-create-spdx`
7600      class with no option.
7601
7602      Note that using this option only marginally increases the size
7603      of the :term:`SPDX` output in ``tmp/deploy/images/MACHINE/``
7604      (+ 0.07\% with the tested image), compared to just enabling
7605      :term:`SPDX_INCLUDE_SOURCES`.
7606
7607   :term:`SPDX_CUSTOM_ANNOTATION_VARS`
7608      This option allows to associate `SPDX annotations
7609      <https://spdx.github.io/spdx-spec/v2.3/annotations/>`__ to a recipe,
7610      using the values of variables in the recipe::
7611
7612         ANNOTATION1 = "First annotation for recipe"
7613         ANNOTATION2 = "Second annotation for recipe"
7614         SPDX_CUSTOM_ANNOTATION_VARS = "ANNOTATION1 ANNOTATION2"
7615
7616      This will add a new block to the recipe ``.sdpx.json`` output::
7617
7618         "annotations": [
7619           {
7620             "annotationDate": "2023-04-18T08:32:12Z",
7621             "annotationType": "OTHER",
7622             "annotator": "Tool: oe-spdx-creator - 1.0",
7623             "comment": "ANNOTATION1=First annotation for recipe"
7624           },
7625           {
7626             "annotationDate": "2023-04-18T08:32:12Z",
7627             "annotationType": "OTHER",
7628             "annotator": "Tool: oe-spdx-creator - 1.0",
7629             "comment": "ANNOTATION2=Second annotation for recipe"
7630           }
7631         ],
7632
7633   :term:`SPDX_INCLUDE_SOURCES`
7634      This option allows to add a description of the source files used to build
7635      the host tools and the target packages, to the ``spdx.json`` files in
7636      ``tmp/deploy/spdx/MACHINE/recipes/`` under the :term:`Build Directory`.
7637      As a consequence, the ``spdx.json`` files under the ``by-namespace`` and
7638      ``packages`` subdirectories in ``tmp/deploy/spdx/MACHINE`` are also
7639      modified to include references to such source file descriptions.
7640
7641      Enable this option as follows::
7642
7643         SPDX_INCLUDE_SOURCES = "1"
7644
7645      According to our tests on release 4.1 "langdale", building
7646      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling
7647      this option multiplied the total size of the ``tmp/deploy/spdx``
7648      directory by a factor of 3  (+291 MiB for this image),
7649      and the size of the ``IMAGE-MACHINE.spdx.tar.zst`` in
7650      ``tmp/deploy/images/MACHINE`` by a factor of 130 (+15 MiB for this
7651      image), compared to just using the :ref:`ref-classes-create-spdx` class
7652      with no option.
7653
7654   :term:`SPDX_PRETTY`
7655      This option makes the SPDX output more human-readable, using
7656      identation and newlines, instead of the default output in a
7657      single line::
7658
7659         SPDX_PRETTY = "1"
7660
7661      The generated SPDX files are approximately 20% bigger, but
7662      this option is recommended if you want to inspect the SPDX
7663      output files with a text editor.
7664
7665   :term:`SPDXLICENSEMAP`
7666      Maps commonly used license names to their SPDX counterparts found in
7667      ``meta/files/common-licenses/``. For the default :term:`SPDXLICENSEMAP`
7668      mappings, see the ``meta/conf/licenses.conf`` file.
7669
7670      For additional information, see the :term:`LICENSE`
7671      variable.
7672
7673   :term:`SPECIAL_PKGSUFFIX`
7674      A list of prefixes for :term:`PN` used by the OpenEmbedded
7675      build system to create variants of recipes or packages. The list
7676      specifies the prefixes to strip off during certain circumstances such
7677      as the generation of the :term:`BPN` variable.
7678
7679   :term:`SPL_BINARY`
7680      The file type for the Secondary Program Loader (SPL). Some devices
7681      use an SPL from which to boot (e.g. the BeagleBone development
7682      board). For such cases, you can declare the file type of the SPL
7683      binary in the ``u-boot.inc`` include file, which is used in the
7684      U-Boot recipe.
7685
7686      The SPL file type is set to "null" by default in the ``u-boot.inc``
7687      file as follows::
7688
7689         # Some versions of u-boot build an SPL (Second Program Loader) image that
7690         # should be packaged along with the u-boot binary as well as placed in the
7691         # deploy directory. For those versions they can set the following variables
7692         # to allow packaging the SPL.
7693         SPL_BINARY ?= ""
7694         SPL_BINARYNAME ?= "${@os.path.basename(d.getVar("SPL_BINARY"))}"
7695         SPL_IMAGE ?= "${SPL_BINARYNAME}-${MACHINE}-${PV}-${PR}"
7696         SPL_SYMLINK ?= "${SPL_BINARYNAME}-${MACHINE}"
7697
7698      The :term:`SPL_BINARY` variable helps form
7699      various ``SPL_*`` variables used by the OpenEmbedded build system.
7700
7701      See the BeagleBone machine configuration example in the
7702      ":ref:`dev-manual/layers:adding a layer using the \`\`bitbake-layers\`\` script`"
7703      section in the Yocto Project Board Support Package Developer's Guide
7704      for additional information.
7705
7706   :term:`SRCREV_FORMAT`
7707      See :term:`bitbake:SRCREV_FORMAT` in the BitBake manual.
7708
7709   :term:`SRC_URI`
7710
7711      See the BitBake manual for the initial description for this variable:
7712      :term:`bitbake:SRC_URI`.
7713
7714      The following features are added by OpenEmbedded and the Yocto Project.
7715
7716      There are standard and recipe-specific options. Here are standard ones:
7717
7718      -  ``apply`` --- whether to apply the patch or not. The default
7719         action is to apply the patch.
7720
7721      -  ``striplevel`` --- which striplevel to use when applying the
7722         patch. The default level is 1.
7723
7724      -  ``patchdir`` --- specifies the directory in which the patch should
7725         be applied. The default is ``${``\ :term:`S`\ ``}``.
7726
7727      Here are options specific to recipes building code from a revision
7728      control system:
7729
7730      -  ``mindate`` --- apply the patch only if
7731         :term:`SRCDATE` is equal to or greater than
7732         ``mindate``.
7733
7734      -  ``maxdate`` --- apply the patch only if :term:`SRCDATE` is not later
7735         than ``maxdate``.
7736
7737      -  ``minrev`` --- apply the patch only if :term:`SRCREV` is equal to or
7738         greater than ``minrev``.
7739
7740      -  ``maxrev`` --- apply the patch only if :term:`SRCREV` is not later
7741         than ``maxrev``.
7742
7743      -  ``rev`` --- apply the patch only if :term:`SRCREV` is equal to
7744         ``rev``.
7745
7746      -  ``notrev`` --- apply the patch only if :term:`SRCREV` is not equal to
7747         ``rev``.
7748
7749      .. note::
7750
7751         If you want the build system to pick up files specified through
7752         a :term:`SRC_URI` statement from your append file, you need to be
7753         sure to extend the :term:`FILESPATH` variable by also using the
7754         :term:`FILESEXTRAPATHS` variable from within your append file.
7755
7756   :term:`SRC_URI_OVERRIDES_PACKAGE_ARCH`
7757      By default, the OpenEmbedded build system automatically detects
7758      whether :term:`SRC_URI` contains files that are machine-specific. If so,
7759      the build system automatically changes :term:`PACKAGE_ARCH`. Setting this
7760      variable to "0" disables this behavior.
7761
7762   :term:`SRCDATE`
7763      The date of the source code used to build the package. This variable
7764      applies only if the source was fetched from a Source Code Manager
7765      (SCM).
7766
7767   :term:`SRCPV`
7768      Returns the version string of the current package. This string is
7769      used to help define the value of :term:`PV`.
7770
7771      The :term:`SRCPV` variable is defined in the ``meta/conf/bitbake.conf``
7772      configuration file in the :term:`Source Directory` as
7773      follows::
7774
7775         SRCPV = "${@bb.fetch2.get_srcrev(d)}"
7776
7777      Recipes that need to define :term:`PV` do so with the help of the
7778      :term:`SRCPV`. For example, the ``ofono`` recipe (``ofono_git.bb``)
7779      located in ``meta/recipes-connectivity`` in the Source Directory
7780      defines :term:`PV` as follows::
7781
7782         PV = "0.12-git${SRCPV}"
7783
7784   :term:`SRCREV`
7785      The revision of the source code used to build the package. This
7786      variable applies to Subversion, Git, Mercurial, and Bazaar only. Note
7787      that if you want to build a fixed revision and you want to avoid
7788      performing a query on the remote repository every time BitBake parses
7789      your recipe, you should specify a :term:`SRCREV` that is a full revision
7790      identifier and not just a tag.
7791
7792      .. note::
7793
7794         For information on limitations when inheriting the latest revision
7795         of software using :term:`SRCREV`, see the :term:`AUTOREV` variable
7796         description and the
7797         ":ref:`dev-manual/packages:automatically incrementing a package version number`"
7798         section, which is in the Yocto Project Development Tasks Manual.
7799
7800   :term:`SRCTREECOVEREDTASKS`
7801      A list of tasks that are typically not relevant (and therefore skipped)
7802      when building using the :ref:`ref-classes-externalsrc`
7803      class. The default value as set in that class file is the set of tasks
7804      that are rarely needed when using external source::
7805
7806         SRCTREECOVEREDTASKS ?= "do_patch do_unpack do_fetch"
7807
7808      The notable exception is when processing external kernel source as
7809      defined in the :ref:`ref-classes-kernel-yocto` class file (formatted for
7810      aesthetics)::
7811
7812         SRCTREECOVEREDTASKS += "\
7813           do_validate_branches \
7814           do_kernel_configcheck \
7815           do_kernel_checkout \
7816           do_fetch \
7817           do_unpack \
7818           do_patch \
7819         "
7820
7821      See the associated :term:`EXTERNALSRC` and :term:`EXTERNALSRC_BUILD`
7822      variables for more information.
7823
7824   :term:`SSTATE_DIR`
7825      The directory for the shared state cache.
7826
7827   :term:`SSTATE_EXCLUDEDEPS_SYSROOT`
7828      This variable allows to specify indirect dependencies to exclude
7829      from sysroots, for example to avoid the situations when a dependency on
7830      any ``-native`` recipe will pull in all dependencies of that recipe
7831      in the recipe sysroot. This behaviour might not always be wanted,
7832      for example when that ``-native`` recipe depends on build tools
7833      that are not relevant for the current recipe.
7834
7835      This way, irrelevant dependencies are ignored, which could have
7836      prevented the reuse of prebuilt artifacts stored in the Shared
7837      State Cache.
7838
7839      :term:`SSTATE_EXCLUDEDEPS_SYSROOT` is evaluated as two regular
7840      expressions of recipe and dependency to ignore. An example
7841      is the rule in :oe_git:`meta/conf/layer.conf </openembedded-core/tree/meta/conf/layer.conf>`::
7842
7843         # Nothing needs to depend on libc-initial
7844         # base-passwd/shadow-sysroot don't need their dependencies
7845         SSTATE_EXCLUDEDEPS_SYSROOT += "\
7846             .*->.*-initial.* \
7847             .*(base-passwd|shadow-sysroot)->.* \
7848         "
7849
7850      The ``->`` substring represents the dependency between
7851      the two regular expressions.
7852
7853   :term:`SSTATE_MIRROR_ALLOW_NETWORK`
7854      If set to "1", allows fetches from mirrors that are specified in
7855      :term:`SSTATE_MIRRORS` to work even when
7856      fetching from the network is disabled by setting :term:`BB_NO_NETWORK` to
7857      "1". Using the :term:`SSTATE_MIRROR_ALLOW_NETWORK` variable is useful if
7858      you have set :term:`SSTATE_MIRRORS` to point to an internal server for
7859      your shared state cache, but you want to disable any other fetching
7860      from the network.
7861
7862   :term:`SSTATE_MIRRORS`
7863      Configures the OpenEmbedded build system to search other mirror
7864      locations for prebuilt cache data objects before building out the
7865      data. This variable works like fetcher :term:`MIRRORS`
7866      and :term:`PREMIRRORS` and points to the cache
7867      locations to check for the shared state (sstate) objects.
7868
7869      You can specify a filesystem directory or a remote URL such as HTTP
7870      or FTP. The locations you specify need to contain the shared state
7871      cache (sstate-cache) results from previous builds. The sstate-cache
7872      you point to can also be from builds on other machines.
7873
7874      When pointing to sstate build artifacts on another machine that uses
7875      a different GCC version for native builds, you must configure
7876      :term:`SSTATE_MIRRORS` with a regular expression that maps local search
7877      paths to server paths. The paths need to take into account
7878      :term:`NATIVELSBSTRING` set by the :ref:`ref-classes-uninative` class.
7879      For example, the following maps the local search path ``universal-4.9``
7880      to the server-provided path server_url_sstate_path::
7881
7882         SSTATE_MIRRORS ?= "file://universal-4.9/(.*) https://server_url_sstate_path/universal-4.8/\1"
7883
7884      If a mirror uses the same structure as
7885      :term:`SSTATE_DIR`, you need to add "PATH" at the
7886      end as shown in the examples below. The build system substitutes the
7887      correct path within the directory structure::
7888
7889         SSTATE_MIRRORS ?= "\
7890             file://.* https://someserver.tld/share/sstate/PATH;downloadfilename=PATH \
7891             file://.* file:///some-local-dir/sstate/PATH"
7892
7893   :term:`SSTATE_SCAN_FILES`
7894      Controls the list of files the OpenEmbedded build system scans for
7895      hardcoded installation paths. The variable uses a space-separated
7896      list of filenames (not paths) with standard wildcard characters
7897      allowed.
7898
7899      During a build, the OpenEmbedded build system creates a shared state
7900      (sstate) object during the first stage of preparing the sysroots.
7901      That object is scanned for hardcoded paths for original installation
7902      locations. The list of files that are scanned for paths is controlled
7903      by the :term:`SSTATE_SCAN_FILES` variable. Typically, recipes add files
7904      they want to be scanned to the value of :term:`SSTATE_SCAN_FILES` rather
7905      than the variable being comprehensively set. The
7906      :ref:`ref-classes-sstate` class specifies the default list of files.
7907
7908      For details on the process, see the :ref:`ref-classes-staging` class.
7909
7910   :term:`STAGING_BASE_LIBDIR_NATIVE`
7911      Specifies the path to the ``/lib`` subdirectory of the sysroot
7912      directory for the build host.
7913
7914   :term:`STAGING_BASELIBDIR`
7915      Specifies the path to the ``/lib`` subdirectory of the sysroot
7916      directory for the target for which the current recipe is being built
7917      (:term:`STAGING_DIR_HOST`).
7918
7919   :term:`STAGING_BINDIR`
7920      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7921      directory for the target for which the current recipe is being built
7922      (:term:`STAGING_DIR_HOST`).
7923
7924   :term:`STAGING_BINDIR_CROSS`
7925      Specifies the path to the directory containing binary configuration
7926      scripts. These scripts provide configuration information for other
7927      software that wants to make use of libraries or include files
7928      provided by the software associated with the script.
7929
7930      .. note::
7931
7932         This style of build configuration has been largely replaced by
7933         ``pkg-config``. Consequently, if ``pkg-config`` is supported by the
7934         library to which you are linking, it is recommended you use
7935         ``pkg-config`` instead of a provided configuration script.
7936
7937   :term:`STAGING_BINDIR_NATIVE`
7938      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7939      directory for the build host.
7940
7941   :term:`STAGING_DATADIR`
7942      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7943      directory for the target for which the current recipe is being built
7944      (:term:`STAGING_DIR_HOST`).
7945
7946   :term:`STAGING_DATADIR_NATIVE`
7947      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7948      directory for the build host.
7949
7950   :term:`STAGING_DIR`
7951      Helps construct the ``recipe-sysroots`` directory, which is used
7952      during packaging.
7953
7954      For information on how staging for recipe-specific sysroots occurs,
7955      see the :ref:`ref-tasks-populate_sysroot`
7956      task, the ":ref:`sdk-manual/extensible:sharing files between recipes`"
7957      section in the Yocto Project Development Tasks Manual, the
7958      ":ref:`overview-manual/concepts:configuration, compilation, and staging`"
7959      section in the Yocto Project Overview and Concepts Manual, and the
7960      :term:`SYSROOT_DIRS` variable.
7961
7962      .. note::
7963
7964         Recipes should never write files directly under the :term:`STAGING_DIR`
7965         directory because the OpenEmbedded build system manages the
7966         directory automatically. Instead, files should be installed to
7967         ``${``\ :term:`D`\ ``}`` within your recipe's :ref:`ref-tasks-install`
7968         task and then the OpenEmbedded build system will stage a subset of
7969         those files into the sysroot.
7970
7971   :term:`STAGING_DIR_HOST`
7972      Specifies the path to the sysroot directory for the system on which
7973      the component is built to run (the system that hosts the component).
7974      For most recipes, this sysroot is the one in which that recipe's
7975      :ref:`ref-tasks-populate_sysroot` task copies
7976      files. Exceptions include ``-native`` recipes, where the
7977      :ref:`ref-tasks-populate_sysroot` task instead uses
7978      :term:`STAGING_DIR_NATIVE`. Depending on
7979      the type of recipe and the build target, :term:`STAGING_DIR_HOST` can
7980      have the following values:
7981
7982      -  For recipes building for the target machine, the value is
7983         "${:term:`STAGING_DIR`}/${:term:`MACHINE`}".
7984
7985      -  For native recipes building for the build host, the value is empty
7986         given the assumption that when building for the build host, the
7987         build host's own directories should be used.
7988
7989         .. note::
7990
7991            ``-native`` recipes are not installed into host paths like such
7992            as ``/usr``. Rather, these recipes are installed into
7993            :term:`STAGING_DIR_NATIVE`. When compiling ``-native`` recipes,
7994            standard build environment variables such as
7995            :term:`CPPFLAGS` and
7996            :term:`CFLAGS` are set up so that both host paths
7997            and :term:`STAGING_DIR_NATIVE` are searched for libraries and
7998            headers using, for example, GCC's ``-isystem`` option.
7999
8000            Thus, the emphasis is that the ``STAGING_DIR*`` variables
8001            should be viewed as input variables by tasks such as
8002            :ref:`ref-tasks-configure`,
8003            :ref:`ref-tasks-compile`, and
8004            :ref:`ref-tasks-install`. Having the real system
8005            root correspond to :term:`STAGING_DIR_HOST` makes conceptual sense
8006            for ``-native`` recipes, as they make use of host headers and
8007            libraries.
8008
8009   :term:`STAGING_DIR_NATIVE`
8010      Specifies the path to the sysroot directory used when building
8011      components that run on the build host itself.
8012
8013   :term:`STAGING_DIR_TARGET`
8014      Specifies the path to the sysroot used for the system for which the
8015      component generates code. For components that do not generate code,
8016      which is the majority, :term:`STAGING_DIR_TARGET` is set to match
8017      :term:`STAGING_DIR_HOST`.
8018
8019      Some recipes build binaries that can run on the target system but those
8020      binaries in turn generate code for another different system (e.g.
8021      :ref:`ref-classes-cross-canadian` recipes). Using terminology from GNU,
8022      the primary system is referred to as the "HOST" and the secondary, or
8023      different, system is referred to as the "TARGET". Thus, the binaries
8024      run on the "HOST" system and generate binaries for the "TARGET"
8025      system. The :term:`STAGING_DIR_HOST` variable points to the sysroot used
8026      for the "HOST" system, while :term:`STAGING_DIR_TARGET` points to the
8027      sysroot used for the "TARGET" system.
8028
8029   :term:`STAGING_ETCDIR_NATIVE`
8030      Specifies the path to the ``/etc`` subdirectory of the sysroot
8031      directory for the build host.
8032
8033   :term:`STAGING_EXECPREFIXDIR`
8034      Specifies the path to the ``/usr`` subdirectory of the sysroot
8035      directory for the target for which the current recipe is being built
8036      (:term:`STAGING_DIR_HOST`).
8037
8038   :term:`STAGING_INCDIR`
8039      Specifies the path to the ``/usr/include`` subdirectory of the
8040      sysroot directory for the target for which the current recipe being
8041      built (:term:`STAGING_DIR_HOST`).
8042
8043   :term:`STAGING_INCDIR_NATIVE`
8044      Specifies the path to the ``/usr/include`` subdirectory of the
8045      sysroot directory for the build host.
8046
8047   :term:`STAGING_KERNEL_BUILDDIR`
8048      Points to the directory containing the kernel build artifacts.
8049      Recipes building software that needs to access kernel build artifacts
8050      (e.g. ``systemtap-uprobes``) can look in the directory specified with
8051      the :term:`STAGING_KERNEL_BUILDDIR` variable to find these artifacts
8052      after the kernel has been built.
8053
8054   :term:`STAGING_KERNEL_DIR`
8055      The directory with kernel headers that are required to build
8056      out-of-tree modules.
8057
8058   :term:`STAGING_LIBDIR`
8059      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
8060      directory for the target for which the current recipe is being built
8061      (:term:`STAGING_DIR_HOST`).
8062
8063   :term:`STAGING_LIBDIR_NATIVE`
8064      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
8065      directory for the build host.
8066
8067   :term:`STAMP`
8068      Specifies the base path used to create recipe stamp files. The path
8069      to an actual stamp file is constructed by evaluating this string and
8070      then appending additional information. Currently, the default
8071      assignment for :term:`STAMP` as set in the ``meta/conf/bitbake.conf``
8072      file is::
8073
8074         STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
8075
8076      For information on how BitBake uses stamp files to determine if a
8077      task should be rerun, see the
8078      ":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`"
8079      section in the Yocto Project Overview and Concepts Manual.
8080
8081      See :term:`STAMPS_DIR`,
8082      :term:`MULTIMACH_TARGET_SYS`,
8083      :term:`PN`, :term:`EXTENDPE`,
8084      :term:`PV`, and :term:`PR` for related variable
8085      information.
8086
8087   :term:`STAMPCLEAN`
8088      See :term:`bitbake:STAMPCLEAN` in the BitBake manual.
8089
8090   :term:`STAMPS_DIR`
8091      Specifies the base directory in which the OpenEmbedded build system
8092      places stamps. The default directory is ``${TMPDIR}/stamps``.
8093
8094   :term:`STRIP`
8095      The minimal command and arguments to run ``strip``, which is used to
8096      strip symbols.
8097
8098   :term:`SUMMARY`
8099      The short (72 characters or less) summary of the binary package for
8100      packaging systems such as ``opkg``, ``rpm``, or ``dpkg``. By default,
8101      :term:`SUMMARY` is used to define the
8102      :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
8103      not set in the recipe.
8104
8105   :term:`SVNDIR`
8106      The directory in which files checked out of a Subversion system are
8107      stored.
8108
8109   :term:`SYSLINUX_DEFAULT_CONSOLE`
8110      Specifies the kernel boot default console. If you want to use a
8111      console other than the default, set this variable in your recipe as
8112      follows where "X" is the console number you want to use::
8113
8114         SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
8115
8116      The :ref:`ref-classes-syslinux` class initially sets
8117      this variable to null but then checks for a value later.
8118
8119   :term:`SYSLINUX_OPTS`
8120      Lists additional options to add to the syslinux file. You need to set
8121      this variable in your recipe. If you want to list multiple options,
8122      separate the options with a semicolon character (``;``).
8123
8124      The :ref:`ref-classes-syslinux` class uses this variable
8125      to create a set of options.
8126
8127   :term:`SYSLINUX_SERIAL`
8128      Specifies the alternate serial port or turns it off. To turn off
8129      serial, set this variable to an empty string in your recipe. The
8130      variable's default value is set in the
8131      :ref:`ref-classes-syslinux` class as follows::
8132
8133         SYSLINUX_SERIAL ?= "0 115200"
8134
8135      The class checks for and uses the variable as needed.
8136
8137   :term:`SYSLINUX_SERIAL_TTY`
8138      Specifies the alternate console=tty... kernel boot argument. The
8139      variable's default value is set in the :ref:`ref-classes-syslinux`
8140      class as follows::
8141
8142         SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
8143
8144      The class checks for and uses the variable as needed.
8145
8146   :term:`SYSLINUX_SPLASH`
8147      An ``.LSS`` file used as the background for the VGA boot menu when
8148      you use the boot menu. You need to set this variable in your recipe.
8149
8150      The :ref:`ref-classes-syslinux` class checks for this
8151      variable and if found, the OpenEmbedded build system installs the
8152      splash screen.
8153
8154   :term:`SYSROOT_DESTDIR`
8155      Points to the temporary directory under the work directory (default
8156      "``${``\ :term:`WORKDIR`\ ``}/sysroot-destdir``")
8157      where the files populated into the sysroot are assembled during the
8158      :ref:`ref-tasks-populate_sysroot` task.
8159
8160   :term:`SYSROOT_DIRS`
8161      Directories that are staged into the sysroot by the
8162      :ref:`ref-tasks-populate_sysroot` task. By
8163      default, the following directories are staged::
8164
8165         SYSROOT_DIRS = " \
8166             ${includedir} \
8167             ${libdir} \
8168             ${base_libdir} \
8169             ${nonarch_base_libdir} \
8170             ${datadir} \
8171             /sysroot-only \
8172             "
8173
8174   :term:`SYSROOT_DIRS_IGNORE`
8175      Directories that are not staged into the sysroot by the
8176      :ref:`ref-tasks-populate_sysroot` task. You
8177      can use this variable to exclude certain subdirectories of
8178      directories listed in :term:`SYSROOT_DIRS` from
8179      staging. By default, the following directories are not staged::
8180
8181         SYSROOT_DIRS_IGNORE = " \
8182             ${mandir} \
8183             ${docdir} \
8184             ${infodir} \
8185             ${datadir}/X11/locale \
8186             ${datadir}/applications \
8187             ${datadir}/bash-completion \
8188             ${datadir}/fonts \
8189             ${datadir}/gtk-doc/html \
8190             ${datadir}/installed-tests \
8191             ${datadir}/locale \
8192             ${datadir}/pixmaps \
8193             ${datadir}/terminfo \
8194             ${libdir}/${BPN}/ptest \
8195             "
8196
8197   :term:`SYSROOT_DIRS_NATIVE`
8198      Extra directories staged into the sysroot by the
8199      :ref:`ref-tasks-populate_sysroot` task for
8200      ``-native`` recipes, in addition to those specified in
8201      :term:`SYSROOT_DIRS`. By default, the following
8202      extra directories are staged::
8203
8204         SYSROOT_DIRS_NATIVE = " \
8205             ${bindir} \
8206             ${sbindir} \
8207             ${base_bindir} \
8208             ${base_sbindir} \
8209             ${libexecdir} \
8210             ${sysconfdir} \
8211             ${localstatedir} \
8212             "
8213
8214      .. note::
8215
8216         Programs built by ``-native`` recipes run directly from the sysroot
8217         (:term:`STAGING_DIR_NATIVE`), which is why additional directories
8218         containing program executables and supporting files need to be staged.
8219
8220   :term:`SYSROOT_PREPROCESS_FUNCS`
8221      A list of functions to execute after files are staged into the
8222      sysroot. These functions are usually used to apply additional
8223      processing on the staged files, or to stage additional files.
8224
8225   :term:`SYSTEMD_AUTO_ENABLE`
8226      When inheriting the :ref:`ref-classes-systemd` class,
8227      this variable specifies whether the specified service in
8228      :term:`SYSTEMD_SERVICE` should start
8229      automatically or not. By default, the service is enabled to
8230      automatically start at boot time. The default setting is in the
8231      :ref:`ref-classes-systemd` class as follows::
8232
8233         SYSTEMD_AUTO_ENABLE ??= "enable"
8234
8235      You can disable the service by setting the variable to "disable".
8236
8237   :term:`SYSTEMD_BOOT_CFG`
8238      When :term:`EFI_PROVIDER` is set to
8239      "systemd-boot", the :term:`SYSTEMD_BOOT_CFG` variable specifies the
8240      configuration file that should be used. By default, the
8241      :ref:`ref-classes-systemd-boot` class sets the
8242      :term:`SYSTEMD_BOOT_CFG` as follows::
8243
8244         SYSTEMD_BOOT_CFG ?= "${S}/loader.conf"
8245
8246      For information on Systemd-boot, see the `Systemd-boot
8247      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8248
8249   :term:`SYSTEMD_BOOT_ENTRIES`
8250      When :term:`EFI_PROVIDER` is set to
8251      "systemd-boot", the :term:`SYSTEMD_BOOT_ENTRIES` variable specifies a
8252      list of entry files (``*.conf``) to install that contain one boot
8253      entry per file. By default, the :ref:`ref-classes-systemd-boot` class
8254      sets the :term:`SYSTEMD_BOOT_ENTRIES` as follows::
8255
8256          SYSTEMD_BOOT_ENTRIES ?= ""
8257
8258      For information on Systemd-boot, see the `Systemd-boot
8259      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8260
8261   :term:`SYSTEMD_BOOT_TIMEOUT`
8262      When :term:`EFI_PROVIDER` is set to
8263      "systemd-boot", the :term:`SYSTEMD_BOOT_TIMEOUT` variable specifies the
8264      boot menu timeout in seconds. By default, the
8265      :ref:`ref-classes-systemd-boot` class sets the
8266      :term:`SYSTEMD_BOOT_TIMEOUT` as follows::
8267
8268         SYSTEMD_BOOT_TIMEOUT ?= "10"
8269
8270      For information on Systemd-boot, see the `Systemd-boot
8271      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8272
8273   :term:`SYSTEMD_DEFAULT_TARGET`
8274
8275      This variable allows to set the default unit that systemd starts at bootup.
8276      Usually, this is either ``multi-user.target`` or ``graphical.target``.
8277      This works by creating a ``default.target`` symbolic link to the chosen systemd
8278      target file.
8279
8280      See `systemd's documentation
8281      <https://www.freedesktop.org/software/systemd/man/systemd.special.html>`__
8282      for details.
8283
8284      For example, this variable is used in the :oe_git:`core-image-minimal-xfce.bb
8285      </meta-openembedded/tree/meta-xfce/recipes-core/images/core-image-minimal-xfce.bb>`
8286      recipe::
8287
8288          SYSTEMD_DEFAULT_TARGET = "graphical.target"
8289
8290   :term:`SYSTEMD_PACKAGES`
8291      When inheriting the :ref:`ref-classes-systemd` class,
8292      this variable locates the systemd unit files when they are not found
8293      in the main recipe's package. By default, the :term:`SYSTEMD_PACKAGES`
8294      variable is set such that the systemd unit files are assumed to
8295      reside in the recipes main package::
8296
8297         SYSTEMD_PACKAGES ?= "${PN}"
8298
8299      If these unit files are not in this recipe's main package, you need
8300      to use :term:`SYSTEMD_PACKAGES` to list the package or packages in which
8301      the build system can find the systemd unit files.
8302
8303   :term:`SYSTEMD_SERVICE`
8304      When inheriting the :ref:`ref-classes-systemd` class,
8305      this variable specifies the systemd service name for a package.
8306
8307      Multiple services can be specified, each one separated by a space.
8308
8309      When you specify this file in your recipe, use a package name
8310      override to indicate the package to which the value applies. Here is
8311      an example from the connman recipe::
8312
8313         SYSTEMD_SERVICE:${PN} = "connman.service"
8314
8315      The package overrides that can be specified are directly related to the value of
8316      :term:`SYSTEMD_PACKAGES`. Overrides not included in :term:`SYSTEMD_PACKAGES`
8317      will be silently ignored.
8318
8319   :term:`SYSVINIT_ENABLED_GETTYS`
8320      When using :ref:`SysVinit <dev-manual/new-recipe:enabling system services>`,
8321      specifies a space-separated list of the virtual terminals that should
8322      run a :wikipedia:`getty <Getty_(Unix)>` (allowing login), assuming
8323      :term:`USE_VT` is not set to "0".
8324
8325      The default value for :term:`SYSVINIT_ENABLED_GETTYS` is "1" (i.e. only
8326      run a getty on the first virtual terminal).
8327
8328   :term:`T`
8329      This variable points to a directory were BitBake places temporary
8330      files, which consist mostly of task logs and scripts, when building a
8331      particular recipe. The variable is typically set as follows::
8332
8333         T = "${WORKDIR}/temp"
8334
8335      The :term:`WORKDIR` is the directory into which
8336      BitBake unpacks and builds the recipe. The default ``bitbake.conf``
8337      file sets this variable.
8338
8339      The :term:`T` variable is not to be confused with the
8340      :term:`TMPDIR` variable, which points to the root of
8341      the directory tree where BitBake places the output of an entire
8342      build.
8343
8344   :term:`TARGET_ARCH`
8345      The target machine's architecture. The OpenEmbedded build system
8346      supports many architectures. Here is an example list of architectures
8347      supported. This list is by no means complete as the architecture is
8348      configurable:
8349
8350      - arm
8351      - i586
8352      - x86_64
8353      - powerpc
8354      - powerpc64
8355      - mips
8356      - mipsel
8357
8358      For additional information on machine architectures, see the
8359      :term:`TUNE_ARCH` variable.
8360
8361   :term:`TARGET_AS_ARCH`
8362      Specifies architecture-specific assembler flags for the target
8363      system. :term:`TARGET_AS_ARCH` is initialized from
8364      :term:`TUNE_ASARGS` by default in the BitBake
8365      configuration file (``meta/conf/bitbake.conf``)::
8366
8367         TARGET_AS_ARCH = "${TUNE_ASARGS}"
8368
8369   :term:`TARGET_CC_ARCH`
8370      Specifies architecture-specific C compiler flags for the target
8371      system. :term:`TARGET_CC_ARCH` is initialized from
8372      :term:`TUNE_CCARGS` by default.
8373
8374      .. note::
8375
8376         It is a common workaround to append :term:`LDFLAGS` to
8377         :term:`TARGET_CC_ARCH` in recipes that build software for the target that
8378         would not otherwise respect the exported :term:`LDFLAGS` variable.
8379
8380   :term:`TARGET_CC_KERNEL_ARCH`
8381      This is a specific kernel compiler flag for a CPU or Application
8382      Binary Interface (ABI) tune. The flag is used rarely and only for
8383      cases where a userspace :term:`TUNE_CCARGS` is not
8384      compatible with the kernel compilation. The :term:`TARGET_CC_KERNEL_ARCH`
8385      variable allows the kernel (and associated modules) to use a
8386      different configuration. See the
8387      ``meta/conf/machine/include/arm/feature-arm-thumb.inc`` file in the
8388      :term:`Source Directory` for an example.
8389
8390   :term:`TARGET_CFLAGS`
8391      Specifies the flags to pass to the C compiler when building for the
8392      target. When building in the target context,
8393      :term:`CFLAGS` is set to the value of this variable by
8394      default.
8395
8396      Additionally, the SDK's environment setup script sets the :term:`CFLAGS`
8397      variable in the environment to the :term:`TARGET_CFLAGS` value so that
8398      executables built using the SDK also have the flags applied.
8399
8400   :term:`TARGET_CPPFLAGS`
8401      Specifies the flags to pass to the C pre-processor (i.e. to both the
8402      C and the C++ compilers) when building for the target. When building
8403      in the target context, :term:`CPPFLAGS` is set to the
8404      value of this variable by default.
8405
8406      Additionally, the SDK's environment setup script sets the
8407      :term:`CPPFLAGS` variable in the environment to the :term:`TARGET_CPPFLAGS`
8408      value so that executables built using the SDK also have the flags
8409      applied.
8410
8411   :term:`TARGET_CXXFLAGS`
8412      Specifies the flags to pass to the C++ compiler when building for the
8413      target. When building in the target context,
8414      :term:`CXXFLAGS` is set to the value of this variable
8415      by default.
8416
8417      Additionally, the SDK's environment setup script sets the
8418      :term:`CXXFLAGS` variable in the environment to the :term:`TARGET_CXXFLAGS`
8419      value so that executables built using the SDK also have the flags
8420      applied.
8421
8422   :term:`TARGET_FPU`
8423      Specifies the method for handling FPU code. For FPU-less targets,
8424      which include most ARM CPUs, the variable must be set to "soft". If
8425      not, the kernel emulation gets used, which results in a performance
8426      penalty.
8427
8428   :term:`TARGET_LD_ARCH`
8429      Specifies architecture-specific linker flags for the target system.
8430      :term:`TARGET_LD_ARCH` is initialized from
8431      :term:`TUNE_LDARGS` by default in the BitBake
8432      configuration file (``meta/conf/bitbake.conf``)::
8433
8434         TARGET_LD_ARCH = "${TUNE_LDARGS}"
8435
8436   :term:`TARGET_LDFLAGS`
8437      Specifies the flags to pass to the linker when building for the
8438      target. When building in the target context,
8439      :term:`LDFLAGS` is set to the value of this variable
8440      by default.
8441
8442      Additionally, the SDK's environment setup script sets the
8443      :term:`LDFLAGS` variable in the environment to the
8444      :term:`TARGET_LDFLAGS` value so that executables built using the SDK also
8445      have the flags applied.
8446
8447   :term:`TARGET_OS`
8448      Specifies the target's operating system. The variable can be set to
8449      "linux" for glibc-based systems (GNU C Library) and to "linux-musl"
8450      for musl libc. For ARM/EABI targets, the possible values are
8451      "linux-gnueabi" and "linux-musleabi".
8452
8453   :term:`TARGET_PREFIX`
8454      Specifies the prefix used for the toolchain binary target tools.
8455
8456      Depending on the type of recipe and the build target,
8457      :term:`TARGET_PREFIX` is set as follows:
8458
8459      -  For recipes building for the target machine, the value is
8460         "${:term:`TARGET_SYS`}-".
8461
8462      -  For native recipes, the build system sets the variable to the
8463         value of :term:`BUILD_PREFIX`.
8464
8465      -  For native SDK recipes (:ref:`ref-classes-nativesdk`),
8466         the build system sets the variable to the value of :term:`SDK_PREFIX`.
8467
8468   :term:`TARGET_SYS`
8469      Specifies the system, including the architecture and the operating
8470      system, for which the build is occurring in the context of the
8471      current recipe.
8472
8473      The OpenEmbedded build system automatically sets this variable based
8474      on :term:`TARGET_ARCH`,
8475      :term:`TARGET_VENDOR`, and
8476      :term:`TARGET_OS` variables.
8477
8478      .. note::
8479
8480         You do not need to set the :term:`TARGET_SYS` variable yourself.
8481
8482      Consider these two examples:
8483
8484      -  Given a native recipe on a 32-bit, x86 machine running Linux, the
8485         value is "i686-linux".
8486
8487      -  Given a recipe being built for a little-endian, MIPS target
8488         running Linux, the value might be "mipsel-linux".
8489
8490   :term:`TARGET_VENDOR`
8491      Specifies the name of the target vendor.
8492
8493   :term:`TCLIBC`
8494      Specifies the GNU standard C library (``libc``) variant to use during
8495      the build process.
8496
8497      You can select "glibc", "musl", "newlib", or "baremetal".
8498
8499   :term:`TCLIBCAPPEND`
8500      Specifies a suffix to be appended onto the :term:`TMPDIR` value. The
8501      suffix identifies the ``libc`` variant for building. When you are
8502      building for multiple variants with the same :term:`Build Directory`,
8503      this mechanism ensures that output for different ``libc`` variants is
8504      kept separate to avoid potential conflicts.
8505
8506      In the ``defaultsetup.conf`` file, the default value of
8507      :term:`TCLIBCAPPEND` is "-${TCLIBC}". However, distros such as poky,
8508      which normally only support one ``libc`` variant, set
8509      :term:`TCLIBCAPPEND` to "" in their distro configuration file resulting
8510      in no suffix being applied.
8511
8512   :term:`TCMODE`
8513      Specifies the toolchain selector. :term:`TCMODE` controls the
8514      characteristics of the generated packages and images by telling the
8515      OpenEmbedded build system which toolchain profile to use. By default,
8516      the OpenEmbedded build system builds its own internal toolchain. The
8517      variable's default value is "default", which uses that internal
8518      toolchain.
8519
8520      .. note::
8521
8522         If :term:`TCMODE` is set to a value other than "default", then it is your
8523         responsibility to ensure that the toolchain is compatible with the
8524         default toolchain. Using older or newer versions of these
8525         components might cause build problems. See
8526         :doc:`Release Information </migration-guides/index>` for your
8527         version of the Yocto Project, to find the specific components with
8528         which the toolchain must be compatible.
8529
8530      The :term:`TCMODE` variable is similar to :term:`TCLIBC`,
8531      which controls the variant of the GNU standard C library (``libc``)
8532      used during the build process: ``glibc`` or ``musl``.
8533
8534      With additional layers, it is possible to use a pre-compiled external
8535      toolchain. One example is the Sourcery G++ Toolchain. The support for
8536      this toolchain resides in the separate Mentor Graphics
8537      ``meta-sourcery`` layer at
8538      https://github.com/MentorEmbedded/meta-sourcery/.
8539
8540      The layer's ``README`` file contains information on how to use the
8541      Sourcery G++ Toolchain as an external toolchain. You will have to
8542      add the layer to your ``bblayers.conf`` file and then set the
8543      :term:`EXTERNAL_TOOLCHAIN` variable in your ``local.conf`` file to
8544      the location of the toolchain.
8545
8546      The fundamentals used for this example apply to any external
8547      toolchain. You can use ``meta-sourcery`` as a template for adding
8548      support for other external toolchains.
8549
8550      In addition to toolchain configuration, you will also need a
8551      corresponding toolchain recipe file. This recipe file needs to package
8552      up any pre-built objects in the toolchain such as ``libgcc``,
8553      ``libstdcc++``, any locales, and ``libc``.
8554
8555   :term:`TC_CXX_RUNTIME`
8556      Specifies the C/C++ STL and runtime variant to use during
8557      the build process. Default value is 'gnu'
8558
8559      You can select "gnu", "llvm", or "android".
8560
8561   :term:`TEMPLATECONF`
8562      Specifies the directory used by the build system to find templates
8563      from which to build the ``bblayers.conf`` and ``local.conf`` files.
8564      Use this variable if you wish to customize such files, and the default
8565      BitBake targets shown when sourcing the ``oe-init-build-env`` script.
8566
8567      For details, see the
8568      :ref:`dev-manual/custom-template-configuration-directory:creating a custom template configuration directory`
8569      section in the Yocto Project Development Tasks manual.
8570
8571      .. note::
8572
8573         You must set this variable in the external environment in order
8574         for it to work.
8575
8576   :term:`TEST_EXPORT_DIR`
8577      The location the OpenEmbedded build system uses to export tests when
8578      the :term:`TEST_EXPORT_ONLY` variable is set
8579      to "1".
8580
8581      The :term:`TEST_EXPORT_DIR` variable defaults to
8582      ``"${TMPDIR}/testimage/${PN}"``.
8583
8584   :term:`TEST_EXPORT_ONLY`
8585      Specifies to export the tests only. Set this variable to "1" if you
8586      do not want to run the tests but you want them to be exported in a
8587      manner that you to run them outside of the build system.
8588
8589   :term:`TEST_LOG_DIR`
8590      Holds the SSH log and the boot log for QEMU machines. The
8591      :term:`TEST_LOG_DIR` variable defaults to ``"${WORKDIR}/testimage"``.
8592
8593      .. note::
8594
8595         Actual test results reside in the task log (``log.do_testimage``),
8596         which is in the ``${WORKDIR}/temp/`` directory.
8597
8598   :term:`TEST_POWERCONTROL_CMD`
8599      For automated hardware testing, specifies the command to use to
8600      control the power of the target machine under test. Typically, this
8601      command would point to a script that performs the appropriate action
8602      (e.g. interacting with a web-enabled power strip). The specified
8603      command should expect to receive as the last argument "off", "on" or
8604      "cycle" specifying to power off, on, or cycle (power off and then
8605      power on) the device, respectively.
8606
8607   :term:`TEST_POWERCONTROL_EXTRA_ARGS`
8608      For automated hardware testing, specifies additional arguments to
8609      pass through to the command specified in
8610      :term:`TEST_POWERCONTROL_CMD`. Setting
8611      :term:`TEST_POWERCONTROL_EXTRA_ARGS` is optional. You can use it if you
8612      wish, for example, to separate the machine-specific and
8613      non-machine-specific parts of the arguments.
8614
8615   :term:`TEST_QEMUBOOT_TIMEOUT`
8616      The time in seconds allowed for an image to boot before automated
8617      runtime tests begin to run against an image. The default timeout
8618      period to allow the boot process to reach the login prompt is 500
8619      seconds. You can specify a different value in the ``local.conf``
8620      file.
8621
8622      For more information on testing images, see the
8623      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8624      section in the Yocto Project Development Tasks Manual.
8625
8626   :term:`TEST_SERIALCONTROL_CMD`
8627      For automated hardware testing, specifies the command to use to
8628      connect to the serial console of the target machine under test. This
8629      command simply needs to connect to the serial console and forward
8630      that connection to standard input and output as any normal terminal
8631      program does.
8632
8633      For example, to use the Picocom terminal program on serial device
8634      ``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows::
8635
8636         TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
8637
8638   :term:`TEST_SERIALCONTROL_EXTRA_ARGS`
8639      For automated hardware testing, specifies additional arguments to
8640      pass through to the command specified in
8641      :term:`TEST_SERIALCONTROL_CMD`. Setting
8642      :term:`TEST_SERIALCONTROL_EXTRA_ARGS` is optional. You can use it if you
8643      wish, for example, to separate the machine-specific and
8644      non-machine-specific parts of the command.
8645
8646   :term:`TEST_SERVER_IP`
8647      The IP address of the build machine (host machine). This IP address
8648      is usually automatically detected. However, if detection fails, this
8649      variable needs to be set to the IP address of the build machine (i.e.
8650      where the build is taking place).
8651
8652      .. note::
8653
8654         The :term:`TEST_SERVER_IP` variable is only used for a small number of
8655         tests such as the "dnf" test suite, which needs to download packages
8656         from ``WORKDIR/oe-rootfs-repo``.
8657
8658   :term:`TEST_SUITES`
8659      An ordered list of tests (modules) to run against an image when
8660      performing automated runtime testing.
8661
8662      The OpenEmbedded build system provides a core set of tests that can
8663      be used against images.
8664
8665      .. note::
8666
8667         Currently, there is only support for running these tests under
8668         QEMU.
8669
8670      Tests include ``ping``, ``ssh``, ``df`` among others. You can add
8671      your own tests to the list of tests by appending :term:`TEST_SUITES` as
8672      follows::
8673
8674         TEST_SUITES:append = " mytest"
8675
8676      Alternatively, you can
8677      provide the "auto" option to have all applicable tests run against
8678      the image::
8679
8680         TEST_SUITES:append = " auto"
8681
8682      Using this option causes the
8683      build system to automatically run tests that are applicable to the
8684      image. Tests that are not applicable are skipped.
8685
8686      The order in which tests are run is important. Tests that depend on
8687      another test must appear later in the list than the test on which
8688      they depend. For example, if you append the list of tests with two
8689      tests (``test_A`` and ``test_B``) where ``test_B`` is dependent on
8690      ``test_A``, then you must order the tests as follows::
8691
8692         TEST_SUITES = "test_A test_B"
8693
8694      For more information on testing images, see the
8695      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8696      section in the Yocto Project Development Tasks Manual.
8697
8698   :term:`TEST_TARGET`
8699      Specifies the target controller to use when running tests against a
8700      test image. The default controller to use is "qemu"::
8701
8702         TEST_TARGET = "qemu"
8703
8704      A target controller is a class that defines how an image gets
8705      deployed on a target and how a target is started. A layer can extend
8706      the controllers by adding a module in the layer's
8707      ``/lib/oeqa/controllers`` directory and by inheriting the
8708      ``BaseTarget`` class, which is an abstract class that cannot be used
8709      as a value of :term:`TEST_TARGET`.
8710
8711      You can provide the following arguments with :term:`TEST_TARGET`:
8712
8713      -  *"qemu":* Boots a QEMU image and runs the tests. See the
8714         ":ref:`dev-manual/runtime-testing:enabling runtime tests on qemu`" section
8715         in the Yocto Project Development Tasks Manual for more
8716         information.
8717
8718      -  *"simpleremote":* Runs the tests on target hardware that is
8719         already up and running. The hardware can be on the network or it
8720         can be a device running an image on QEMU. You must also set
8721         :term:`TEST_TARGET_IP` when you use
8722         "simpleremote".
8723
8724         .. note::
8725
8726            This argument is defined in
8727            ``meta/lib/oeqa/controllers/simpleremote.py``.
8728
8729      For information on running tests on hardware, see the
8730      ":ref:`dev-manual/runtime-testing:enabling runtime tests on hardware`"
8731      section in the Yocto Project Development Tasks Manual.
8732
8733   :term:`TEST_TARGET_IP`
8734      The IP address of your hardware under test. The :term:`TEST_TARGET_IP`
8735      variable has no effect when :term:`TEST_TARGET` is
8736      set to "qemu".
8737
8738      When you specify the IP address, you can also include a port. Here is
8739      an example::
8740
8741         TEST_TARGET_IP = "192.168.1.4:2201"
8742
8743      Specifying a port is
8744      useful when SSH is started on a non-standard port or in cases when
8745      your hardware under test is behind a firewall or network that is not
8746      directly accessible from your host and you need to do port address
8747      translation.
8748
8749   :term:`TESTIMAGE_AUTO`
8750      Automatically runs the series of automated tests for images when an
8751      image is successfully built. Setting :term:`TESTIMAGE_AUTO` to "1" causes
8752      any image that successfully builds to automatically boot under QEMU.
8753      Using the variable also adds in dependencies so that any SDK for
8754      which testing is requested is automatically built first.
8755
8756      These tests are written in Python making use of the ``unittest``
8757      module, and the majority of them run commands on the target system
8758      over ``ssh``. You can set this variable to "1" in your ``local.conf``
8759      file in the :term:`Build Directory` to have the
8760      OpenEmbedded build system automatically run these tests after an
8761      image successfully builds:
8762
8763         TESTIMAGE_AUTO = "1"
8764
8765      For more information
8766      on enabling, running, and writing these tests, see the
8767      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8768      section in the Yocto Project Development Tasks Manual and the
8769      ":ref:`ref-classes-testimage`" section.
8770
8771   :term:`THISDIR`
8772      The directory in which the file BitBake is currently parsing is
8773      located. Do not manually set this variable.
8774
8775   :term:`TIME`
8776      The time the build was started. Times appear using the hour, minute,
8777      and second (HMS) format (e.g. "140159" for one minute and fifty-nine
8778      seconds past 1400 hours).
8779
8780   :term:`TMPDIR`
8781      This variable is the base directory the OpenEmbedded build system
8782      uses for all build output and intermediate files (other than the
8783      shared state cache). By default, the :term:`TMPDIR` variable points to
8784      ``tmp`` within the :term:`Build Directory`.
8785
8786      If you want to establish this directory in a location other than the
8787      default, you can uncomment and edit the following statement in the
8788      ``conf/local.conf`` file in the :term:`Source Directory`::
8789
8790         #TMPDIR = "${TOPDIR}/tmp"
8791
8792      An example use for this scenario is to set :term:`TMPDIR` to a local disk,
8793      which does not use NFS, while having the :term:`Build Directory` use NFS.
8794
8795      The filesystem used by :term:`TMPDIR` must have standard filesystem
8796      semantics (i.e. mixed-case files are unique, POSIX file locking, and
8797      persistent inodes). Due to various issues with NFS and bugs in some
8798      implementations, NFS does not meet this minimum requirement.
8799      Consequently, :term:`TMPDIR` cannot be on NFS.
8800
8801   :term:`TOOLCHAIN_HOST_TASK`
8802      This variable lists packages the OpenEmbedded build system uses when
8803      building an SDK, which contains a cross-development environment. The
8804      packages specified by this variable are part of the toolchain set
8805      that runs on the :term:`SDKMACHINE`, and each
8806      package should usually have the prefix ``nativesdk-``. For example,
8807      consider the following command when building an SDK::
8808
8809         $ bitbake -c populate_sdk imagename
8810
8811      In this case, a default list of packages is
8812      set in this variable, but you can add additional packages to the
8813      list. See the
8814      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8815      in the Yocto Project Application Development and the Extensible
8816      Software Development Kit (eSDK) manual for more information.
8817
8818      For background information on cross-development toolchains in the
8819      Yocto Project development environment, see the
8820      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8821      section in the Yocto Project Overview and Concepts Manual. For
8822      information on setting up a cross-development environment, see the
8823      :doc:`/sdk-manual/index` manual.
8824
8825      Note that this variable applies to building an SDK, not an eSDK,
8826      in which case the :term:`TOOLCHAIN_HOST_TASK_ESDK` setting should be
8827      used instead.
8828
8829   :term:`TOOLCHAIN_HOST_TASK_ESDK`
8830      This variable allows to extend what is installed in the host
8831      portion of an eSDK. This is similar to :term:`TOOLCHAIN_HOST_TASK`
8832      applying to SDKs.
8833
8834   :term:`TOOLCHAIN_OUTPUTNAME`
8835      This variable defines the name used for the toolchain output. The
8836      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class sets
8837      the :term:`TOOLCHAIN_OUTPUTNAME` variable as follows::
8838
8839         TOOLCHAIN_OUTPUTNAME ?= "${SDK_NAME}-toolchain-${SDK_VERSION}"
8840
8841      See
8842      the :term:`SDK_NAME` and
8843      :term:`SDK_VERSION` variables for additional
8844      information.
8845
8846   :term:`TOOLCHAIN_TARGET_TASK`
8847      This variable lists packages the OpenEmbedded build system uses when
8848      it creates the target part of an SDK (i.e. the part built for the
8849      target hardware), which includes libraries and headers. Use this
8850      variable to add individual packages to the part of the SDK that runs
8851      on the target. See the
8852      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8853      in the Yocto Project Application Development and the Extensible
8854      Software Development Kit (eSDK) manual for more information.
8855
8856      For background information on cross-development toolchains in the
8857      Yocto Project development environment, see the
8858      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8859      section in the Yocto Project Overview and Concepts Manual. For
8860      information on setting up a cross-development environment, see the
8861      :doc:`/sdk-manual/index` manual.
8862
8863   :term:`TOPDIR`
8864      See :term:`bitbake:TOPDIR` in the BitBake manual.
8865
8866   :term:`TRANSLATED_TARGET_ARCH`
8867      A sanitized version of :term:`TARGET_ARCH`. This
8868      variable is used where the architecture is needed in a value where
8869      underscores are not allowed, for example within package filenames. In
8870      this case, dash characters replace any underscore characters used in
8871      :term:`TARGET_ARCH`.
8872
8873      Do not edit this variable.
8874
8875   :term:`TUNE_ARCH`
8876      The GNU canonical architecture for a specific architecture (i.e.
8877      ``arm``, ``armeb``, ``mips``, ``mips64``, and so forth). BitBake uses
8878      this value to setup configuration.
8879
8880      :term:`TUNE_ARCH` definitions are specific to a given architecture. The
8881      definitions can be a single static definition, or can be dynamically
8882      adjusted. You can see details for a given CPU family by looking at
8883      the architecture's ``README`` file. For example, the
8884      ``meta/conf/machine/include/mips/README`` file in the
8885      :term:`Source Directory` provides information for
8886      :term:`TUNE_ARCH` specific to the ``mips`` architecture.
8887
8888      :term:`TUNE_ARCH` is tied closely to
8889      :term:`TARGET_ARCH`, which defines the target
8890      machine's architecture. The BitBake configuration file
8891      (``meta/conf/bitbake.conf``) sets :term:`TARGET_ARCH` as follows::
8892
8893         TARGET_ARCH = "${TUNE_ARCH}"
8894
8895      The following list, which is by no means complete since architectures
8896      are configurable, shows supported machine architectures:
8897
8898      - arm
8899      - i586
8900      - x86_64
8901      - powerpc
8902      - powerpc64
8903      - mips
8904      - mipsel
8905
8906   :term:`TUNE_ASARGS`
8907      Specifies architecture-specific assembler flags for the target
8908      system. The set of flags is based on the selected tune features.
8909      :term:`TUNE_ASARGS` is set using the tune include files, which are
8910      typically under ``meta/conf/machine/include/`` and are influenced
8911      through :term:`TUNE_FEATURES`. For example, the
8912      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8913      for the x86 architecture as follows::
8914
8915         TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
8916
8917      .. note::
8918
8919         Board Support Packages (BSPs) select the tune. The selected tune,
8920         in turn, affects the tune variables themselves (i.e. the tune can
8921         supply its own set of flags).
8922
8923   :term:`TUNE_CCARGS`
8924      Specifies architecture-specific C compiler flags for the target
8925      system. The set of flags is based on the selected tune features.
8926      :term:`TUNE_CCARGS` is set using the tune include files, which are
8927      typically under ``meta/conf/machine/include/`` and are influenced
8928      through :term:`TUNE_FEATURES`.
8929
8930      .. note::
8931
8932         Board Support Packages (BSPs) select the tune. The selected tune,
8933         in turn, affects the tune variables themselves (i.e. the tune can
8934         supply its own set of flags).
8935
8936   :term:`TUNE_FEATURES`
8937      Features used to "tune" a compiler for optimal use given a specific
8938      processor. The features are defined within the tune files and allow
8939      arguments (i.e. ``TUNE_*ARGS``) to be dynamically generated based on
8940      the features.
8941
8942      The OpenEmbedded build system verifies the features to be sure they
8943      are not conflicting and that they are supported.
8944
8945      The BitBake configuration file (``meta/conf/bitbake.conf``) defines
8946      :term:`TUNE_FEATURES` as follows::
8947
8948         TUNE_FEATURES ??= "${TUNE_FEATURES:tune-${DEFAULTTUNE}}"
8949
8950      See the :term:`DEFAULTTUNE` variable for more information.
8951
8952   :term:`TUNE_LDARGS`
8953      Specifies architecture-specific linker flags for the target system.
8954      The set of flags is based on the selected tune features.
8955      :term:`TUNE_LDARGS` is set using the tune include files, which are
8956      typically under ``meta/conf/machine/include/`` and are influenced
8957      through :term:`TUNE_FEATURES`. For example, the
8958      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8959      for the x86 architecture as follows::
8960
8961         TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
8962
8963      .. note::
8964
8965         Board Support Packages (BSPs) select the tune. The selected tune,
8966         in turn, affects the tune variables themselves (i.e. the tune can
8967         supply its own set of flags).
8968
8969   :term:`TUNE_PKGARCH`
8970      The package architecture understood by the packaging system to define
8971      the architecture, ABI, and tuning of output packages. The specific
8972      tune is defined using the "_tune" override as follows::
8973
8974         TUNE_PKGARCH:tune-tune = "tune"
8975
8976      These tune-specific package architectures are defined in the machine
8977      include files. Here is an example of the "core2-32" tuning as used in
8978      the ``meta/conf/machine/include/x86/tune-core2.inc`` file::
8979
8980         TUNE_PKGARCH:tune-core2-32 = "core2-32"
8981
8982   :term:`TUNECONFLICTS[feature]`
8983      Specifies CPU or Application Binary Interface (ABI) tuning features
8984      that conflict with feature.
8985
8986      Known tuning conflicts are specified in the machine include files in
8987      the :term:`Source Directory`. Here is an example from
8988      the ``meta/conf/machine/include/mips/arch-mips.inc`` include file
8989      that lists the "o32" and "n64" features as conflicting with the "n32"
8990      feature::
8991
8992         TUNECONFLICTS[n32] = "o32 n64"
8993
8994   :term:`TUNEVALID[feature]`
8995      Specifies a valid CPU or Application Binary Interface (ABI) tuning
8996      feature. The specified feature is stored as a flag. Valid features
8997      are specified in the machine include files (e.g.
8998      ``meta/conf/machine/include/arm/arch-arm.inc``). Here is an example
8999      from that file::
9000
9001         TUNEVALID[bigendian] = "Enable big-endian mode."
9002
9003      See the machine include files in the :term:`Source Directory`
9004      for these features.
9005
9006   :term:`UBOOT_CONFIG`
9007      Configures the :term:`UBOOT_MACHINE` and can
9008      also define :term:`IMAGE_FSTYPES` for individual
9009      cases.
9010
9011      Following is an example from the ``meta-fsl-arm`` layer. ::
9012
9013         UBOOT_CONFIG ??= "sd"
9014         UBOOT_CONFIG[sd] = "mx6qsabreauto_config,sdcard"
9015         UBOOT_CONFIG[eimnor] = "mx6qsabreauto_eimnor_config"
9016         UBOOT_CONFIG[nand] = "mx6qsabreauto_nand_config,ubifs"
9017         UBOOT_CONFIG[spinor] = "mx6qsabreauto_spinor_config"
9018
9019      In this example, "sd" is selected as the configuration of the possible four for the
9020      :term:`UBOOT_MACHINE`. The "sd" configuration defines
9021      "mx6qsabreauto_config" as the value for :term:`UBOOT_MACHINE`, while the
9022      "sdcard" specifies the :term:`IMAGE_FSTYPES` to use for the U-Boot image.
9023
9024      For more information on how the :term:`UBOOT_CONFIG` is handled, see the
9025      :ref:`ref-classes-uboot-config` class.
9026
9027   :term:`UBOOT_DTB_LOADADDRESS`
9028      Specifies the load address for the dtb image used by U-Boot. During FIT
9029      image creation, the :term:`UBOOT_DTB_LOADADDRESS` variable is used in
9030      :ref:`ref-classes-kernel-fitimage` class to specify the load address to be
9031      used in creating the dtb sections of Image Tree Source for the FIT image.
9032
9033   :term:`UBOOT_DTBO_LOADADDRESS`
9034      Specifies the load address for the dtbo image used by U-Boot.  During FIT
9035      image creation, the :term:`UBOOT_DTBO_LOADADDRESS` variable is used in
9036      :ref:`ref-classes-kernel-fitimage` class to specify the load address to be
9037      used in creating the dtbo sections of Image Tree Source for the FIT image.
9038
9039   :term:`UBOOT_ENTRYPOINT`
9040      Specifies the entry point for the U-Boot image. During U-Boot image
9041      creation, the :term:`UBOOT_ENTRYPOINT` variable is passed as a
9042      command-line parameter to the ``uboot-mkimage`` utility.
9043
9044   :term:`UBOOT_LOADADDRESS`
9045      Specifies the load address for the U-Boot image. During U-Boot image
9046      creation, the :term:`UBOOT_LOADADDRESS` variable is passed as a
9047      command-line parameter to the ``uboot-mkimage`` utility.
9048
9049   :term:`UBOOT_LOCALVERSION`
9050      Appends a string to the name of the local version of the U-Boot
9051      image. For example, assuming the version of the U-Boot image built
9052      was "2013.10", the full version string reported by U-Boot would be
9053      "2013.10-yocto" given the following statement::
9054
9055         UBOOT_LOCALVERSION = "-yocto"
9056
9057   :term:`UBOOT_MACHINE`
9058      Specifies the value passed on the ``make`` command line when building
9059      a U-Boot image. The value indicates the target platform
9060      configuration. You typically set this variable from the machine
9061      configuration file (i.e. ``conf/machine/machine_name.conf``).
9062
9063      Please see the "Selection of Processor Architecture and Board Type"
9064      section in the U-Boot README for valid values for this variable.
9065
9066   :term:`UBOOT_MAKE_TARGET`
9067      Specifies the target called in the ``Makefile``. The default target
9068      is "all".
9069
9070   :term:`UBOOT_MKIMAGE`
9071      Specifies the name of the mkimage command as used by the
9072      :ref:`ref-classes-kernel-fitimage` class to assemble
9073      the FIT image. This can be used to substitute an alternative command, wrapper
9074      script or function if desired. The default is "uboot-mkimage".
9075
9076   :term:`UBOOT_MKIMAGE_DTCOPTS`
9077      Options for the device tree compiler passed to mkimage '-D' feature while
9078      creating FIT image in :ref:`ref-classes-kernel-fitimage` class. If
9079      :term:`UBOOT_MKIMAGE_DTCOPTS` is not set then
9080      :ref:`ref-classes-kernel-fitimage` will not pass the ``-D`` option to
9081      mkimage.
9082
9083   :term:`UBOOT_MKIMAGE_KERNEL_TYPE`
9084      Specifies the type argument for the kernel as passed to ``uboot-mkimage``.
9085      The default value is "kernel".
9086
9087   :term:`UBOOT_MKIMAGE_SIGN`
9088      Specifies the name of the mkimage command as used by the
9089      :ref:`ref-classes-kernel-fitimage` class to sign
9090      the FIT image after it has been assembled (if enabled). This can be used
9091      to substitute an alternative command, wrapper script or function if
9092      desired. The default is "${:term:`UBOOT_MKIMAGE`}".
9093
9094   :term:`UBOOT_MKIMAGE_SIGN_ARGS`
9095      Optionally specifies additional arguments for the
9096      :ref:`ref-classes-kernel-fitimage` class to pass to the
9097      mkimage command when signing the FIT image.
9098
9099   :term:`UBOOT_RD_ENTRYPOINT`
9100      Specifies the entrypoint for the RAM disk image. During FIT image
9101      creation, the :term:`UBOOT_RD_ENTRYPOINT` variable is used in
9102      :ref:`ref-classes-kernel-fitimage` class to specify the entrypoint to be
9103      used in creating the Image Tree Source for the FIT image.
9104
9105   :term:`UBOOT_RD_LOADADDRESS`
9106      Specifies the load address for the RAM disk image. During FIT image
9107      creation, the :term:`UBOOT_RD_LOADADDRESS` variable is used in
9108      :ref:`ref-classes-kernel-fitimage` class to specify the load address to
9109      be used in creating the Image Tree Source for the FIT image.
9110
9111   :term:`UBOOT_SIGN_ENABLE`
9112      Enable signing of FIT image. The default value is "0".
9113
9114   :term:`UBOOT_SIGN_KEYDIR`
9115      Location of the directory containing the RSA key and
9116      certificate used for signing FIT image.
9117
9118   :term:`UBOOT_SIGN_KEYNAME`
9119      The name of keys used for signing U-Boot FIT image stored in
9120      :term:`UBOOT_SIGN_KEYDIR` directory. For e.g. dev.key key and dev.crt
9121      certificate stored in :term:`UBOOT_SIGN_KEYDIR` directory will have
9122      :term:`UBOOT_SIGN_KEYNAME` set to "dev".
9123
9124   :term:`UBOOT_SUFFIX`
9125      Points to the generated U-Boot extension. For example, ``u-boot.sb``
9126      has a ``.sb`` extension.
9127
9128      The default U-Boot extension is ``.bin``
9129
9130   :term:`UBOOT_TARGET`
9131      Specifies the target used for building U-Boot. The target is passed
9132      directly as part of the "make" command (e.g. SPL and AIS). If you do
9133      not specifically set this variable, the OpenEmbedded build process
9134      passes and uses "all" for the target during the U-Boot building
9135      process.
9136
9137   :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`
9138      Specifies a list of options that, if reported by the configure script
9139      as being invalid, should not generate a warning during the
9140      :ref:`ref-tasks-configure` task. Normally, invalid
9141      configure options are simply not passed to the configure script (e.g.
9142      should be removed from :term:`EXTRA_OECONF` or
9143      :term:`PACKAGECONFIG_CONFARGS`).
9144      However, there are common options that are passed to all
9145      configure scripts at a class level, but might not be valid for some
9146      configure scripts. Therefore warnings about these options are useless.
9147      For these cases, the options are added to :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`.
9148
9149      The configure arguments check that uses
9150      :term:`UNKNOWN_CONFIGURE_OPT_IGNORE` is part of the
9151      :ref:`ref-classes-insane` class and is only enabled if the
9152      recipe inherits the :ref:`ref-classes-autotools` class.
9153
9154   :term:`UPDATERCPN`
9155      For recipes inheriting the
9156      :ref:`ref-classes-update-rc.d` class, :term:`UPDATERCPN`
9157      specifies the package that contains the initscript that is enabled.
9158
9159      The default value is "${PN}". Given that almost all recipes that
9160      install initscripts package them in the main package for the recipe,
9161      you rarely need to set this variable in individual recipes.
9162
9163   :term:`UPSTREAM_CHECK_COMMITS`
9164      You can perform a per-recipe check for what the latest upstream
9165      source code version is by calling ``devtool latest-version recipe``. If
9166      the recipe source code is provided from Git repositories, but
9167      releases are not identified by Git tags, set :term:`UPSTREAM_CHECK_COMMITS`
9168      to ``1`` in the recipe, and the OpenEmbedded build system
9169      will compare the latest commit with the one currently specified
9170      by the recipe (:term:`SRCREV`)::
9171
9172         UPSTREAM_CHECK_COMMITS = "1"
9173
9174   :term:`UPSTREAM_CHECK_GITTAGREGEX`
9175      You can perform a per-recipe check for what the latest upstream
9176      source code version is by calling ``devtool latest-version recipe``. If
9177      the recipe source code is provided from Git repositories, the
9178      OpenEmbedded build system determines the latest upstream version by
9179      picking the latest tag from the list of all repository tags.
9180
9181      You can use the :term:`UPSTREAM_CHECK_GITTAGREGEX` variable to provide a
9182      regular expression to filter only the relevant tags should the
9183      default filter not work correctly::
9184
9185         UPSTREAM_CHECK_GITTAGREGEX = "git_tag_regex"
9186
9187   :term:`UPSTREAM_CHECK_REGEX`
9188      Use the :term:`UPSTREAM_CHECK_REGEX` variable to specify a different
9189      regular expression instead of the default one when the package
9190      checking system is parsing the page found using
9191      :term:`UPSTREAM_CHECK_URI`::
9192
9193         UPSTREAM_CHECK_REGEX = "package_regex"
9194
9195   :term:`UPSTREAM_CHECK_URI`
9196      You can perform a per-recipe check for what the latest upstream
9197      source code version is by calling ``devtool latest-version recipe``. If
9198      the source code is provided from tarballs, the latest version is
9199      determined by fetching the directory listing where the tarball is and
9200      attempting to find a later tarball. When this approach does not work,
9201      you can use :term:`UPSTREAM_CHECK_URI` to provide a different URI that
9202      contains the link to the latest tarball::
9203
9204         UPSTREAM_CHECK_URI = "recipe_url"
9205
9206   :term:`UPSTREAM_VERSION_UNKNOWN`
9207      You can perform a per-recipe check for what the latest upstream
9208      source code version is by calling ``devtool latest-version recipe``.
9209      If no combination of the :term:`UPSTREAM_CHECK_URI`, :term:`UPSTREAM_CHECK_REGEX`,
9210      :term:`UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
9211      the recipe allows to determine what the latest upstream version is,
9212      you can set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1`` in the recipe
9213      to acknowledge that the check cannot be performed::
9214
9215         UPSTREAM_VERSION_UNKNOWN = "1"
9216
9217   :term:`USE_DEVFS`
9218      Determines if ``devtmpfs`` is used for ``/dev`` population. The
9219      default value used for :term:`USE_DEVFS` is "1" when no value is
9220      specifically set. Typically, you would set :term:`USE_DEVFS` to "0" for a
9221      statically populated ``/dev`` directory.
9222
9223      See the ":ref:`dev-manual/device-manager:selecting a device manager`" section in
9224      the Yocto Project Development Tasks Manual for information on how to
9225      use this variable.
9226
9227   :term:`USE_VT`
9228      When using
9229      :ref:`SysVinit <dev-manual/new-recipe:enabling system services>`,
9230      determines whether or not to run a :wikipedia:`getty <Getty_(Unix)>`
9231      on any virtual terminals in order to enable logging in through those
9232      terminals.
9233
9234      The default value used for :term:`USE_VT` is "1" when no default value is
9235      specifically set. Typically, you would set :term:`USE_VT` to "0" in the
9236      machine configuration file for machines that do not have a graphical
9237      display attached and therefore do not need virtual terminal
9238      functionality.
9239
9240   :term:`USER_CLASSES`
9241      A list of classes to globally inherit. These classes are used by the
9242      OpenEmbedded build system to enable extra features.
9243
9244      Classes inherited using :term:`USER_CLASSES` must be located in the
9245      ``classes-global/`` or ``classes/`` subdirectories.
9246
9247      The default list is set in your ``local.conf`` file::
9248
9249         USER_CLASSES ?= "buildstats"
9250
9251      For more information, see
9252      ``meta-poky/conf/templates/default/local.conf.sample`` in the
9253      :term:`Source Directory`.
9254
9255   :term:`USERADD_ERROR_DYNAMIC`
9256      If set to ``error``, forces the OpenEmbedded build system to produce
9257      an error if the user identification (``uid``) and group
9258      identification (``gid``) values are not defined in any of the files
9259      listed in :term:`USERADD_UID_TABLES` and
9260      :term:`USERADD_GID_TABLES`. If set to
9261      ``warn``, a warning will be issued instead.
9262
9263      The default behavior for the build system is to dynamically apply
9264      ``uid`` and ``gid`` values. Consequently, the
9265      :term:`USERADD_ERROR_DYNAMIC` variable is by default not set. If you plan
9266      on using statically assigned ``gid`` and ``uid`` values, you should
9267      set the :term:`USERADD_ERROR_DYNAMIC` variable in your ``local.conf``
9268      file as follows::
9269
9270         USERADD_ERROR_DYNAMIC = "error"
9271
9272      Overriding the
9273      default behavior implies you are going to also take steps to set
9274      static ``uid`` and ``gid`` values through use of the
9275      :term:`USERADDEXTENSION`,
9276      :term:`USERADD_UID_TABLES`, and
9277      :term:`USERADD_GID_TABLES` variables.
9278
9279      .. note::
9280
9281         There is a difference in behavior between setting
9282         :term:`USERADD_ERROR_DYNAMIC` to ``error`` and setting it to ``warn``.
9283         When it is set to ``warn``, the build system will report a warning for
9284         every undefined ``uid`` and ``gid`` in any recipe. But when it is set
9285         to ``error``, it will only report errors for recipes that are actually
9286         built.
9287         This saves you from having to add static IDs for recipes that you
9288         know will never be built.
9289
9290   :term:`USERADD_GID_TABLES`
9291      Specifies a password file to use for obtaining static group
9292      identification (``gid``) values when the OpenEmbedded build system
9293      adds a group to the system during package installation.
9294
9295      When applying static group identification (``gid``) values, the
9296      OpenEmbedded build system looks in :term:`BBPATH` for a
9297      ``files/group`` file and then applies those ``uid`` values. Set the
9298      variable as follows in your ``local.conf`` file::
9299
9300
9301         USERADD_GID_TABLES = "files/group"
9302
9303      .. note::
9304
9305         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
9306         causes the build system to use static ``gid`` values.
9307
9308   :term:`USERADD_PACKAGES`
9309      When inheriting the :ref:`ref-classes-useradd` class,
9310      this variable specifies the individual packages within the recipe
9311      that require users and/or groups to be added.
9312
9313      You must set this variable if the recipe inherits the class. For
9314      example, the following enables adding a user for the main package in
9315      a recipe::
9316
9317         USERADD_PACKAGES = "${PN}"
9318
9319      .. note::
9320
9321         It follows that if you are going to use the :term:`USERADD_PACKAGES`
9322         variable, you need to set one or more of the :term:`USERADD_PARAM`,
9323         :term:`GROUPADD_PARAM`, or :term:`GROUPMEMS_PARAM` variables.
9324
9325   :term:`USERADD_PARAM`
9326      When inheriting the :ref:`ref-classes-useradd` class,
9327      this variable specifies for a package what parameters should pass to
9328      the ``useradd`` command if you add a user to the system when the
9329      package is installed.
9330
9331      Here is an example from the ``dbus`` recipe::
9332
9333         USERADD_PARAM:${PN} = "--system --home ${localstatedir}/lib/dbus \
9334                                --no-create-home --shell /bin/false \
9335                                --user-group messagebus"
9336
9337      For information on the
9338      standard Linux shell command ``useradd``, see
9339      https://linux.die.net/man/8/useradd.
9340
9341   :term:`USERADD_UID_TABLES`
9342      Specifies a password file to use for obtaining static user
9343      identification (``uid``) values when the OpenEmbedded build system
9344      adds a user to the system during package installation.
9345
9346      When applying static user identification (``uid``) values, the
9347      OpenEmbedded build system looks in :term:`BBPATH` for a
9348      ``files/passwd`` file and then applies those ``uid`` values. Set the
9349      variable as follows in your ``local.conf`` file::
9350
9351         USERADD_UID_TABLES = "files/passwd"
9352
9353      .. note::
9354
9355         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
9356         causes the build system to use static ``uid`` values.
9357
9358   :term:`USERADDEXTENSION`
9359      When set to "useradd-staticids", causes the OpenEmbedded build system
9360      to base all user and group additions on a static ``passwd`` and
9361      ``group`` files found in :term:`BBPATH`.
9362
9363      To use static user identification (``uid``) and group identification
9364      (``gid``) values, set the variable as follows in your ``local.conf``
9365      file: USERADDEXTENSION = "useradd-staticids"
9366
9367      .. note::
9368
9369         Setting this variable to use static ``uid`` and ``gid``
9370         values causes the OpenEmbedded build system to employ the
9371         :ref:`ref-classes-useradd` class.
9372
9373      If you use static ``uid`` and ``gid`` information, you must also
9374      specify the ``files/passwd`` and ``files/group`` files by setting the
9375      :term:`USERADD_UID_TABLES` and
9376      :term:`USERADD_GID_TABLES` variables.
9377      Additionally, you should also set the
9378      :term:`USERADD_ERROR_DYNAMIC` variable.
9379
9380   :term:`VOLATILE_LOG_DIR`
9381      Specifies the persistence of the target's ``/var/log`` directory,
9382      which is used to house postinstall target log files.
9383
9384      By default, :term:`VOLATILE_LOG_DIR` is set to "yes", which means the
9385      file is not persistent. You can override this setting by setting the
9386      variable to "no" to make the log directory persistent.
9387
9388   :term:`VOLATILE_TMP_DIR`
9389      Specifies the persistence of the target's ``/tmp`` directory.
9390
9391      By default, :term:`VOLATILE_TMP_DIR` is set to "yes", in which case
9392      ``/tmp`` links to a directory which resides in RAM in a ``tmpfs``
9393      filesystem.
9394
9395      If instead, you want the ``/tmp`` directory to be persistent, set the
9396      variable to "no" to make it a regular directory in the root filesystem.
9397
9398      This supports both sysvinit and systemd based systems.
9399
9400   :term:`WARN_QA`
9401      Specifies the quality assurance checks whose failures are reported as
9402      warnings by the OpenEmbedded build system. You set this variable in
9403      your distribution configuration file. For a list of the checks you
9404      can control with this variable, see the
9405      ":ref:`ref-classes-insane`" section.
9406
9407   :term:`WATCHDOG_TIMEOUT`
9408      Specifies the timeout in seconds used by the ``watchdog`` recipe and
9409      also by ``systemd`` during reboot. The default is 60 seconds.
9410
9411   :term:`WIRELESS_DAEMON`
9412      For ``connman`` and ``packagegroup-base``, specifies the wireless
9413      daemon to use. The default is "wpa-supplicant" (note that the value
9414      uses a dash and not an underscore).
9415
9416   :term:`WKS_FILE`
9417      Specifies the location of the Wic kickstart file that is used by the
9418      OpenEmbedded build system to create a partitioned image
9419      (``image.wic``). For information on how to create a partitioned
9420      image, see the
9421      ":ref:`dev-manual/wic:creating partitioned images using wic`"
9422      section in the Yocto Project Development Tasks Manual. For details on
9423      the kickstart file format, see the ":doc:`/ref-manual/kickstart`" Chapter.
9424
9425   :term:`WKS_FILE_DEPENDS`
9426      When placed in the recipe that builds your image, this variable lists
9427      build-time dependencies. The :term:`WKS_FILE_DEPENDS` variable is only
9428      applicable when Wic images are active (i.e. when
9429      :term:`IMAGE_FSTYPES` contains entries related
9430      to Wic). If your recipe does not create Wic images, the variable has
9431      no effect.
9432
9433      The :term:`WKS_FILE_DEPENDS` variable is similar to the
9434      :term:`DEPENDS` variable. When you use the variable in
9435      your recipe that builds the Wic image, dependencies you list in the
9436      :term:`WKS_FILE_DEPENDS` variable are added to the :term:`DEPENDS` variable.
9437
9438      With the :term:`WKS_FILE_DEPENDS` variable, you have the possibility to
9439      specify a list of additional dependencies (e.g. native tools,
9440      bootloaders, and so forth), that are required to build Wic images.
9441      Following is an example::
9442
9443         WKS_FILE_DEPENDS = "some-native-tool"
9444
9445      In the
9446      previous example, some-native-tool would be replaced with an actual
9447      native tool on which the build would depend.
9448
9449   :term:`WKS_FILES`
9450      Specifies a list of candidate Wic kickstart files to be used by the
9451      OpenEmbedded build system to create a partitioned image. Only the
9452      first one that is found, from left to right, will be used.
9453
9454      This is only useful when there are multiple ``.wks`` files that can be
9455      used to produce an image. A typical case is when multiple layers are
9456      used for different hardware platforms, each supplying a different
9457      ``.wks`` file. In this case, you specify all possible ones through
9458      :term:`WKS_FILES`.
9459
9460      If only one ``.wks`` file is used, set :term:`WKS_FILE` instead.
9461
9462   :term:`WORKDIR`
9463      The pathname of the work directory in which the OpenEmbedded build
9464      system builds a recipe. This directory is located within the
9465      :term:`TMPDIR` directory structure and is specific to
9466      the recipe being built and the system for which it is being built.
9467
9468      The :term:`WORKDIR` directory is defined as follows::
9469
9470         ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
9471
9472      The actual directory depends on several things:
9473
9474      -  :term:`TMPDIR`: The top-level build output directory
9475      -  :term:`MULTIMACH_TARGET_SYS`: The target system identifier
9476      -  :term:`PN`: The recipe name
9477      -  :term:`EXTENDPE`: The epoch --- if :term:`PE` is not specified, which
9478         is usually the case for most recipes, then :term:`EXTENDPE` is blank.
9479      -  :term:`PV`: The recipe version
9480      -  :term:`PR`: The recipe revision
9481
9482      As an example, assume a Source Directory top-level folder name
9483      ``poky``, a default :term:`Build Directory` at ``poky/build``, and a
9484      ``qemux86-poky-linux`` machine target system. Furthermore, suppose
9485      your recipe is named ``foo_1.3.0-r0.bb``. In this case, the work
9486      directory the build system uses to build the package would be as
9487      follows::
9488
9489         poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
9490
9491   :term:`XSERVER`
9492      Specifies the packages that should be installed to provide an X
9493      server and drivers for the current machine, assuming your image
9494      directly includes ``packagegroup-core-x11-xserver`` or, perhaps
9495      indirectly, includes "x11-base" in
9496      :term:`IMAGE_FEATURES`.
9497
9498      The default value of :term:`XSERVER`, if not specified in the machine
9499      configuration, is "xserver-xorg xf86-video-fbdev xf86-input-evdev".
9500
9501   :term:`XZ_THREADS`
9502      Specifies the number of parallel threads that should be used when
9503      using xz compression.
9504
9505      By default this scales with core count, but is never set less than 2
9506      to ensure that multi-threaded mode is always used so that the output
9507      file contents are deterministic. Builds will work with a value of 1
9508      but the output will differ compared to the output from the compression
9509      generated when more than one thread is used.
9510
9511      On systems where many tasks run in parallel, setting a limit to this
9512      can be helpful in controlling system resource usage.
9513
9514   :term:`XZ_MEMLIMIT`
9515      Specifies the maximum memory the xz compression should use as a percentage
9516      of system memory. If unconstrained the xz compressor can use large amounts of
9517      memory and become problematic with parallelism elsewhere in the build.
9518      "50%" has been found to be a good value.
9519
9520   :term:`ZSTD_THREADS`
9521      Specifies the number of parallel threads that should be used when
9522      using ZStandard compression.
9523
9524      By default this scales with core count, but is never set less than 2
9525      to ensure that multi-threaded mode is always used so that the output
9526      file contents are deterministic. Builds will work with a value of 1
9527      but the output will differ compared to the output from the compression
9528      generated when more than one thread is used.
9529
9530      On systems where many tasks run in parallel, setting a limit to this
9531      can be helpful in controlling system resource usage.
9532