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      -  ``none``
3966
3967      With ``sysvinit``, the init manager is set to
3968      :wikipedia:`SysVinit <Init#SysV-style>`, the traditional UNIX init
3969      system. This is the default choice in the Poky distribution, together with
3970      the Udev device manager (see the ":ref:`device-manager`" section).
3971
3972      With ``systemd``, the init manager becomes :wikipedia:`systemd <Systemd>`,
3973      which comes with the :wikipedia:`udev <Udev>` device manager.
3974
3975      With ``mdev-busybox``, the init manager becomes the much simpler BusyBox
3976      init, together with the BusyBox mdev device manager. This is the simplest
3977      and lightest solution, and probably the best choice for low-end systems
3978      with a rather slow CPU and a limited amount of RAM.
3979
3980      With ``none``, the init manager is also set to ``sysvinit``. This is the
3981      default setting in OpenEmbedded-Core. This option also selects the
3982      :wikipedia:`udev <Udev>` device manager.
3983
3984      More concretely, this is used to include
3985      ``conf/distro/include/init-manager-${INIT_MANAGER}.inc`` into the global
3986      configuration. You can have a look at the
3987      :yocto_git:`meta/conf/distro/include/init-manager-*.inc </poky/tree/meta/conf/distro/include>`
3988      files for more information, and also the ":ref:`init-manager`"
3989      section in the Yocto Project Development Tasks Manual.
3990
3991   :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
3992      Indicates the deploy directory used by :ref:`ref-tasks-bundle_initramfs`
3993      where the :term:`INITRAMFS_IMAGE` will be fetched from. This variable is
3994      set by default to ``${DEPLOY_DIR_IMAGE}`` in the
3995      :ref:`ref-classes-kernel` class and it's only meant to be changed when
3996      building an :term:`Initramfs` image from a separate multiconfig via
3997      :term:`INITRAMFS_MULTICONFIG`.
3998
3999   :term:`INITRAMFS_FSTYPES`
4000      Defines the format for the output image of an initial RAM filesystem
4001      (:term:`Initramfs`), which is used during boot. Supported formats are the
4002      same as those supported by the
4003      :term:`IMAGE_FSTYPES` variable.
4004
4005      The default value of this variable, which is set in the
4006      ``meta/conf/bitbake.conf`` configuration file in the
4007      :term:`Source Directory`, is "cpio.gz". The Linux kernel's
4008      :term:`Initramfs` mechanism, as opposed to the initial RAM filesystem
4009      :wikipedia:`initrd <Initrd>` mechanism, expects
4010      an optionally compressed cpio archive.
4011
4012   :term:`INITRAMFS_IMAGE`
4013      Specifies the :term:`PROVIDES` name of an image
4014      recipe that is used to build an initial RAM filesystem (:term:`Initramfs`)
4015      image. In other words, the :term:`INITRAMFS_IMAGE` variable causes an
4016      additional recipe to be built as a dependency to whatever root
4017      filesystem recipe you might be using (e.g. ``core-image-sato``). The
4018      :term:`Initramfs` image recipe you provide should set
4019      :term:`IMAGE_FSTYPES` to
4020      :term:`INITRAMFS_FSTYPES`.
4021
4022      An :term:`Initramfs` image provides a temporary root filesystem used for
4023      early system initialization (e.g. loading of modules needed to locate
4024      and mount the "real" root filesystem).
4025
4026      .. note::
4027
4028         See the ``meta/recipes-core/images/core-image-minimal-initramfs.bb``
4029         recipe in the :term:`Source Directory`
4030         for an example :term:`Initramfs` recipe. To select this sample recipe as
4031         the one built to provide the :term:`Initramfs` image, set :term:`INITRAMFS_IMAGE`
4032         to "core-image-minimal-initramfs".
4033
4034      You can also find more information by referencing the
4035      ``meta-poky/conf/templates/default/local.conf.sample.extended``
4036      configuration file in the Source Directory, the :ref:`ref-classes-image`
4037      class, and the :ref:`ref-classes-kernel` class to see how to use the
4038      :term:`INITRAMFS_IMAGE` variable.
4039
4040      If :term:`INITRAMFS_IMAGE` is empty, which is the default, then no
4041      :term:`Initramfs` image is built.
4042
4043      For more information, you can also see the
4044      :term:`INITRAMFS_IMAGE_BUNDLE`
4045      variable, which allows the generated image to be bundled inside the
4046      kernel image. Additionally, for information on creating an :term:`Initramfs`
4047      image, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
4048      in the Yocto Project Development Tasks Manual.
4049
4050   :term:`INITRAMFS_IMAGE_BUNDLE`
4051      Controls whether or not the image recipe specified by
4052      :term:`INITRAMFS_IMAGE` is run through an
4053      extra pass
4054      (:ref:`ref-tasks-bundle_initramfs`) during
4055      kernel compilation in order to build a single binary that contains
4056      both the kernel image and the initial RAM filesystem (:term:`Initramfs`)
4057      image. This makes use of the
4058      :term:`CONFIG_INITRAMFS_SOURCE` kernel
4059      feature.
4060
4061      .. note::
4062
4063         Bundling the :term:`Initramfs` with the kernel conflates the code in the
4064         :term:`Initramfs` with the GPLv2 licensed Linux kernel binary. Thus only GPLv2
4065         compatible software may be part of a bundled :term:`Initramfs`.
4066
4067      .. note::
4068
4069         Using an extra compilation pass to bundle the :term:`Initramfs` avoids a
4070         circular dependency between the kernel recipe and the :term:`Initramfs`
4071         recipe should the :term:`Initramfs` include kernel modules. Should that be
4072         the case, the :term:`Initramfs` recipe depends on the kernel for the
4073         kernel modules, and the kernel depends on the :term:`Initramfs` recipe
4074         since the :term:`Initramfs` is bundled inside the kernel image.
4075
4076      The combined binary is deposited into the ``tmp/deploy`` directory,
4077      which is part of the :term:`Build Directory`.
4078
4079      Setting the variable to "1" in a configuration file causes the
4080      OpenEmbedded build system to generate a kernel image with the
4081      :term:`Initramfs` specified in :term:`INITRAMFS_IMAGE` bundled within::
4082
4083         INITRAMFS_IMAGE_BUNDLE = "1"
4084
4085      By default, the :ref:`ref-classes-kernel` class sets this variable to a
4086      null string as follows::
4087
4088         INITRAMFS_IMAGE_BUNDLE ?= ""
4089
4090      .. note::
4091
4092         You must set the :term:`INITRAMFS_IMAGE_BUNDLE` variable in a
4093         configuration file. You cannot set the variable in a recipe file.
4094
4095      See the
4096      :yocto_git:`local.conf.sample.extended </poky/tree/meta-poky/conf/templates/default/local.conf.sample.extended>`
4097      file for additional information. Also, for information on creating an
4098      :term:`Initramfs`, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
4099      in the Yocto Project Development Tasks Manual.
4100
4101   :term:`INITRAMFS_IMAGE_NAME`
4102
4103      This value needs to stay in sync with :term:`IMAGE_LINK_NAME`, but with
4104      :term:`INITRAMFS_IMAGE` instead of :term:`IMAGE_BASENAME`. The default value
4105      is set as follows:
4106
4107         INITRAMFS_IMAGE_NAME ?= "${@['${INITRAMFS_IMAGE}${IMAGE_MACHINE_SUFFIX}', ''][d.getVar('INITRAMFS_IMAGE') == '']}"
4108
4109      That is, if :term:`INITRAMFS_IMAGE` is set, the value of
4110      :term:`INITRAMFS_IMAGE_NAME` will be set based upon
4111      :term:`INITRAMFS_IMAGE` and :term:`IMAGE_MACHINE_SUFFIX`.
4112
4113
4114   :term:`INITRAMFS_LINK_NAME`
4115      The link name of the initial RAM filesystem image. This variable is
4116      set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4117      follows::
4118
4119         INITRAMFS_LINK_NAME ?= "initramfs-${KERNEL_ARTIFACT_LINK_NAME}"
4120
4121      The value of the
4122      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4123      file, has the following value::
4124
4125         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4126
4127      See the :term:`MACHINE` variable for additional
4128      information.
4129
4130   :term:`INITRAMFS_MULTICONFIG`
4131      Defines the multiconfig to create a multiconfig dependency to be used by
4132      the :ref:`ref-classes-kernel` class.
4133
4134      This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
4135      a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
4136
4137      For more information on how to bundle an :term:`Initramfs` image from a separate
4138      multiconfig see the ":ref:`dev-manual/building:Bundling an Initramfs Image From a Separate Multiconfig`"
4139      section in the Yocto Project Development Tasks Manual.
4140
4141   :term:`INITRAMFS_NAME`
4142      The base name of the initial RAM filesystem image. This variable is
4143      set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4144      follows::
4145
4146         INITRAMFS_NAME ?= "initramfs-${KERNEL_ARTIFACT_NAME}"
4147
4148      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4149
4150   :term:`INITRD`
4151      Indicates list of filesystem images to concatenate and use as an
4152      initial RAM disk (``initrd``).
4153
4154      The :term:`INITRD` variable is an optional variable used with the
4155      :ref:`ref-classes-image-live` class.
4156
4157   :term:`INITRD_IMAGE`
4158      When building a "live" bootable image (i.e. when
4159      :term:`IMAGE_FSTYPES` contains "live"),
4160      :term:`INITRD_IMAGE` specifies the image recipe that should be built to
4161      provide the initial RAM disk image. The default value is
4162      "core-image-minimal-initramfs".
4163
4164      See the :ref:`ref-classes-image-live` class for more information.
4165
4166   :term:`INITSCRIPT_NAME`
4167      The filename of the initialization script as installed to
4168      ``${sysconfdir}/init.d``.
4169
4170      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
4171      The variable is mandatory.
4172
4173   :term:`INITSCRIPT_PACKAGES`
4174      A list of the packages that contain initscripts. If multiple packages
4175      are specified, you need to append the package name to the other
4176      ``INITSCRIPT_*`` as an override.
4177
4178      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
4179      The variable is optional and defaults to the :term:`PN`
4180      variable.
4181
4182   :term:`INITSCRIPT_PARAMS`
4183      Specifies the options to pass to ``update-rc.d``. Here is an example::
4184
4185         INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
4186
4187      In this example, the script has a runlevel of 99, starts the script
4188      in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
4189
4190      The variable's default value is "defaults", which is set in the
4191      :ref:`ref-classes-update-rc.d` class.
4192
4193      The value in :term:`INITSCRIPT_PARAMS` is passed through to the
4194      ``update-rc.d`` command. For more information on valid parameters,
4195      please see the ``update-rc.d`` manual page at
4196      https://manpages.debian.org/buster/init-system-helpers/update-rc.d.8.en.html
4197
4198   :term:`INSANE_SKIP`
4199      Specifies the QA checks to skip for a specific package within a
4200      recipe. For example, to skip the check for symbolic link ``.so``
4201      files in the main package of a recipe, add the following to the
4202      recipe. The package name override must be used, which in this example
4203      is ``${PN}``::
4204
4205         INSANE_SKIP:${PN} += "dev-so"
4206
4207      See the ":ref:`ref-classes-insane`" section for a
4208      list of the valid QA checks you can specify using this variable.
4209
4210   :term:`INSTALL_TIMEZONE_FILE`
4211      By default, the ``tzdata`` recipe packages an ``/etc/timezone`` file.
4212      Set the :term:`INSTALL_TIMEZONE_FILE` variable to "0" at the
4213      configuration level to disable this behavior.
4214
4215   :term:`IPK_FEED_URIS`
4216      When the IPK backend is in use and package management is enabled on
4217      the target, you can use this variable to set up ``opkg`` in the
4218      target image to point to package feeds on a nominated server. Once
4219      the feed is established, you can perform installations or upgrades
4220      using the package manager at runtime.
4221
4222   :term:`KARCH`
4223      Defines the kernel architecture used when assembling the
4224      configuration. Architectures supported for this release are:
4225
4226      - powerpc
4227      - i386
4228      - x86_64
4229      - arm
4230      - qemu
4231      - mips
4232
4233      You define the :term:`KARCH` variable in the :ref:`kernel-dev/advanced:bsp descriptions`.
4234
4235   :term:`KBRANCH`
4236      A regular expression used by the build process to explicitly identify
4237      the kernel branch that is validated, patched, and configured during a
4238      build. You must set this variable to ensure the exact kernel branch
4239      you want is being used by the build process.
4240
4241      Values for this variable are set in the kernel's recipe file and the
4242      kernel's append file. For example, if you are using the
4243      ``linux-yocto_4.12`` kernel, the kernel recipe file is the
4244      ``meta/recipes-kernel/linux/linux-yocto_4.12.bb`` file. :term:`KBRANCH`
4245      is set as follows in that kernel recipe file::
4246
4247         KBRANCH ?= "standard/base"
4248
4249      This variable is also used from the kernel's append file to identify
4250      the kernel branch specific to a particular machine or target
4251      hardware. Continuing with the previous kernel example, the kernel's
4252      append file (i.e. ``linux-yocto_4.12.bbappend``) is located in the
4253      BSP layer for a given machine. For example, the append file for the
4254      Beaglebone, EdgeRouter, and generic versions of both 32 and 64-bit IA
4255      machines (``meta-yocto-bsp``) is named
4256      ``meta-yocto-bsp/recipes-kernel/linux/linux-yocto_4.12.bbappend``.
4257      Here are the related statements from that append file::
4258
4259         KBRANCH:genericx86 = "standard/base"
4260         KBRANCH:genericx86-64 = "standard/base"
4261         KBRANCH:edgerouter = "standard/edgerouter"
4262         KBRANCH:beaglebone = "standard/beaglebone"
4263
4264      The :term:`KBRANCH` statements
4265      identify the kernel branch to use when building for each supported
4266      BSP.
4267
4268   :term:`KBUILD_DEFCONFIG`
4269      When used with the :ref:`ref-classes-kernel-yocto`
4270      class, specifies an "in-tree" kernel configuration file for use
4271      during a kernel build.
4272
4273      Typically, when using a ``defconfig`` to configure a kernel during a
4274      build, you place the file in your layer in the same manner as you
4275      would place patch files and configuration fragment files (i.e.
4276      "out-of-tree"). However, if you want to use a ``defconfig`` file that
4277      is part of the kernel tree (i.e. "in-tree"), you can use the
4278      :term:`KBUILD_DEFCONFIG` variable and append the
4279      :term:`KMACHINE` variable to point to the
4280      ``defconfig`` file.
4281
4282      To use the variable, set it in the append file for your kernel recipe
4283      using the following form::
4284
4285         KBUILD_DEFCONFIG:<machine> ?= "defconfig_file"
4286
4287      Here is an example from a "raspberrypi2" :term:`MACHINE` build that uses
4288      a ``defconfig`` file named "bcm2709_defconfig"::
4289
4290         KBUILD_DEFCONFIG:raspberrypi2 = "bcm2709_defconfig"
4291
4292      As an alternative, you can use the following within your append file::
4293
4294         KBUILD_DEFCONFIG:pn-linux-yocto ?= "defconfig_file"
4295
4296      For more
4297      information on how to use the :term:`KBUILD_DEFCONFIG` variable, see the
4298      ":ref:`kernel-dev/common:using an "in-tree" \`\`defconfig\`\` file`"
4299      section in the Yocto Project Linux Kernel Development Manual.
4300
4301   :term:`KCONFIG_MODE`
4302      When used with the :ref:`ref-classes-kernel-yocto`
4303      class, specifies the kernel configuration values to use for options
4304      not specified in the provided ``defconfig`` file. Valid options are::
4305
4306         KCONFIG_MODE = "alldefconfig"
4307         KCONFIG_MODE = "allnoconfig"
4308
4309      In ``alldefconfig`` mode the options not explicitly specified will be
4310      assigned their Kconfig default value. In ``allnoconfig`` mode the
4311      options not explicitly specified will be disabled in the kernel
4312      config.
4313
4314      In case :term:`KCONFIG_MODE` is not set the behaviour will depend on where
4315      the ``defconfig`` file is coming from. An "in-tree" ``defconfig`` file
4316      will be handled in ``alldefconfig`` mode, a ``defconfig`` file placed
4317      in ``${WORKDIR}`` through a meta-layer will be handled in
4318      ``allnoconfig`` mode.
4319
4320      An "in-tree" ``defconfig`` file can be selected via the
4321      :term:`KBUILD_DEFCONFIG` variable. :term:`KCONFIG_MODE` does not need to
4322      be explicitly set.
4323
4324      A ``defconfig`` file compatible with ``allnoconfig`` mode can be
4325      generated by copying the ``.config`` file from a working Linux kernel
4326      build, renaming it to ``defconfig`` and placing it into the Linux
4327      kernel ``${WORKDIR}`` through your meta-layer. :term:`KCONFIG_MODE` does
4328      not need to be explicitly set.
4329
4330      A ``defconfig`` file compatible with ``alldefconfig`` mode can be
4331      generated using the
4332      :ref:`ref-tasks-savedefconfig`
4333      task and placed into the Linux kernel ``${WORKDIR}`` through your
4334      meta-layer. Explicitely set :term:`KCONFIG_MODE`::
4335
4336         KCONFIG_MODE = "alldefconfig"
4337
4338   :term:`KERNEL_ALT_IMAGETYPE`
4339      Specifies an alternate kernel image type for creation in addition to
4340      the kernel image type specified using the :term:`KERNEL_IMAGETYPE` and
4341      :term:`KERNEL_IMAGETYPES` variables.
4342
4343   :term:`KERNEL_ARTIFACT_NAME`
4344      Specifies the name of all of the build artifacts. You can change the
4345      name of the artifacts by changing the :term:`KERNEL_ARTIFACT_NAME`
4346      variable.
4347
4348      The value of :term:`KERNEL_ARTIFACT_NAME`, which is set in the
4349      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file, has the
4350      following default value::
4351
4352         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}${IMAGE_MACHINE_SUFFIX}${IMAGE_VERSION_SUFFIX}"
4353
4354      See the :term:`PKGE`, :term:`PKGV`, :term:`PKGR`, :term:`IMAGE_MACHINE_SUFFIX`
4355      and :term:`IMAGE_VERSION_SUFFIX` variables for additional information.
4356
4357   :term:`KERNEL_CLASSES`
4358      A list of classes defining kernel image types that the
4359      :ref:`ref-classes-kernel` class should inherit. You typically
4360      append this variable to enable extended image types. An example is
4361      ":ref:`ref-classes-kernel-fitimage`", which enables
4362      fitImage support and resides in ``meta/classes-recipe/kernel-fitimage.bbclass``.
4363      You can register custom kernel image types with the
4364      :ref:`ref-classes-kernel` class using this variable.
4365
4366   :term:`KERNEL_DANGLING_FEATURES_WARN_ONLY`
4367      When kernel configuration fragments are missing for some
4368      :term:`KERNEL_FEATURES` specified by layers or BSPs,
4369      building and configuring the kernel stops with an error.
4370
4371      You can turn these errors into warnings by setting the
4372      following in ``conf/local.conf``::
4373
4374         KERNEL_DANGLING_FEATURES_WARN_ONLY = "1"
4375
4376      You will still be warned that runtime issues may occur,
4377      but at least the kernel configuration and build process will
4378      be allowed to continue.
4379
4380   :term:`KERNEL_DEBUG_TIMESTAMPS`
4381      If set to "1", enables timestamping functionality during building
4382      the kernel. The default is "0" to disable this for reproducibility
4383      reasons.
4384
4385   :term:`KERNEL_DEPLOY_DEPEND`
4386      Provides a means of controlling the dependency of an image recipe
4387      on the kernel. The default value is "virtual/kernel:do_deploy",
4388      however for a small initramfs image or other images that do not
4389      need the kernel, this can be set to "" in the image recipe.
4390
4391   :term:`KERNEL_DEVICETREE`
4392      Specifies the name of the generated Linux kernel device tree (i.e.
4393      the ``.dtb``) file.
4394
4395      .. note::
4396
4397         There is legacy support for specifying the full path to the device
4398         tree. However, providing just the ``.dtb`` file is preferred.
4399
4400      In order to use this variable, the :ref:`ref-classes-kernel-devicetree`
4401      class must be inherited.
4402
4403   :term:`KERNEL_DTB_LINK_NAME`
4404      The link name of the kernel device tree binary (DTB). This variable
4405      is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4406      follows::
4407
4408         KERNEL_DTB_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4409
4410      The
4411      value of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in
4412      the same file, has the following value::
4413
4414         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4415
4416      See the :term:`MACHINE` variable for additional
4417      information.
4418
4419   :term:`KERNEL_DTB_NAME`
4420      The base name of the kernel device tree binary (DTB). This variable
4421      is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as
4422      follows::
4423
4424         KERNEL_DTB_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4425
4426      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4427
4428   :term:`KERNEL_DTC_FLAGS`
4429      Specifies the ``dtc`` flags that are passed to the Linux kernel build
4430      system when generating the device trees (via ``DTC_FLAGS`` environment
4431      variable).
4432
4433      In order to use this variable, the :ref:`ref-classes-kernel-devicetree`
4434      class must be inherited.
4435
4436   :term:`KERNEL_EXTRA_ARGS`
4437      Specifies additional ``make`` command-line arguments the OpenEmbedded
4438      build system passes on when compiling the kernel.
4439
4440   :term:`KERNEL_FEATURES`
4441      Includes additional kernel metadata. In the OpenEmbedded build
4442      system, the default Board Support Packages (BSPs)
4443      :term:`Metadata` is provided through the
4444      :term:`KMACHINE` and :term:`KBRANCH`
4445      variables. You can use the :term:`KERNEL_FEATURES` variable from within
4446      the kernel recipe or kernel append file to further add metadata for
4447      all BSPs or specific BSPs.
4448
4449      The metadata you add through this variable includes config fragments
4450      and features descriptions, which usually includes patches as well as
4451      config fragments. You typically override the :term:`KERNEL_FEATURES`
4452      variable for a specific machine. In this way, you can provide
4453      validated, but optional, sets of kernel configurations and features.
4454
4455      For example, the following example from the ``linux-yocto-rt_4.12``
4456      kernel recipe adds "netfilter" and "taskstats" features to all BSPs
4457      as well as "virtio" configurations to all QEMU machines. The last two
4458      statements add specific configurations to targeted machine types::
4459
4460         KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc features/taskstats/taskstats.scc"
4461         KERNEL_FEATURES:append = " ${KERNEL_EXTRA_FEATURES}"
4462         KERNEL_FEATURES:append:qemuall = " cfg/virtio.scc"
4463         KERNEL_FEATURES:append:qemux86 = "  cfg/sound.scc cfg/paravirt_kvm.scc"
4464         KERNEL_FEATURES:append:qemux86-64 = " cfg/sound.scc"
4465
4466   :term:`KERNEL_FIT_LINK_NAME`
4467      The link name of the kernel flattened image tree (FIT) image. This
4468      variable is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass``
4469      file as follows::
4470
4471         KERNEL_FIT_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4472
4473      The value of the
4474      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4475      file, has the following value::
4476
4477         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4478
4479      See the :term:`MACHINE` variable for additional
4480      information.
4481
4482   :term:`KERNEL_FIT_NAME`
4483      The base name of the kernel flattened image tree (FIT) image. This
4484      variable is set in the ``meta/classes-recipe/kernel-artifact-names.bbclass``
4485      file as follows::
4486
4487         KERNEL_FIT_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4488
4489      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4490
4491   :term:`KERNEL_IMAGE_LINK_NAME`
4492      The link name for the kernel image. This variable is set in the
4493      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
4494
4495         KERNEL_IMAGE_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4496
4497      The value of
4498      the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4499      file, has the following value::
4500
4501         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4502
4503      See the :term:`MACHINE` variable for additional
4504      information.
4505
4506   :term:`KERNEL_IMAGE_MAXSIZE`
4507      Specifies the maximum size of the kernel image file in kilobytes. If
4508      :term:`KERNEL_IMAGE_MAXSIZE` is set, the size of the kernel image file is
4509      checked against the set value during the
4510      :ref:`ref-tasks-sizecheck` task. The task fails if
4511      the kernel image file is larger than the setting.
4512
4513      :term:`KERNEL_IMAGE_MAXSIZE` is useful for target devices that have a
4514      limited amount of space in which the kernel image must be stored.
4515
4516      By default, this variable is not set, which means the size of the
4517      kernel image is not checked.
4518
4519   :term:`KERNEL_IMAGE_NAME`
4520      The base name of the kernel image. This variable is set in the
4521      ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
4522
4523         KERNEL_IMAGE_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4524
4525      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
4526
4527   :term:`KERNEL_IMAGETYPE`
4528      The type of kernel to build for a device, usually set by the machine
4529      configuration files and defaults to "zImage". This variable is used
4530      when building the kernel and is passed to ``make`` as the target to
4531      build.
4532
4533      To build additional kernel image types, use :term:`KERNEL_IMAGETYPES`.
4534
4535   :term:`KERNEL_IMAGETYPES`
4536      Lists additional types of kernel images to build for a device in addition
4537      to image type specified in :term:`KERNEL_IMAGETYPE`. Usually set by the
4538      machine configuration files.
4539
4540   :term:`KERNEL_MODULE_AUTOLOAD`
4541      Lists kernel modules that need to be auto-loaded during boot.
4542
4543      .. note::
4544
4545         This variable replaces the deprecated :term:`module_autoload`
4546         variable.
4547
4548      You can use the :term:`KERNEL_MODULE_AUTOLOAD` variable anywhere that it
4549      can be recognized by the kernel recipe or by an out-of-tree kernel
4550      module recipe (e.g. a machine configuration file, a distribution
4551      configuration file, an append file for the recipe, or the recipe
4552      itself).
4553
4554      Specify it as follows::
4555
4556         KERNEL_MODULE_AUTOLOAD += "module_name1 module_name2 module_name3"
4557
4558      Including :term:`KERNEL_MODULE_AUTOLOAD` causes the OpenEmbedded build
4559      system to populate the ``/etc/modules-load.d/modname.conf`` file with
4560      the list of modules to be auto-loaded on boot. The modules appear
4561      one-per-line in the file. Here is an example of the most common use
4562      case::
4563
4564         KERNEL_MODULE_AUTOLOAD += "module_name"
4565
4566      For information on how to populate the ``modname.conf`` file with
4567      ``modprobe.d`` syntax lines, see the :term:`KERNEL_MODULE_PROBECONF` variable.
4568
4569   :term:`KERNEL_MODULE_PROBECONF`
4570      Provides a list of modules for which the OpenEmbedded build system
4571      expects to find ``module_conf_``\ modname values that specify
4572      configuration for each of the modules. For information on how to
4573      provide those module configurations, see the
4574      :term:`module_conf_* <module_conf>` variable.
4575
4576   :term:`KERNEL_PATH`
4577      The location of the kernel sources. This variable is set to the value
4578      of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`
4579      class. For information on how this variable is used, see the
4580      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4581      section in the Yocto Project Linux Kernel Development Manual.
4582
4583      To help maximize compatibility with out-of-tree drivers used to build
4584      modules, the OpenEmbedded build system also recognizes and uses the
4585      :term:`KERNEL_SRC` variable, which is identical to
4586      the :term:`KERNEL_PATH` variable. Both variables are common variables
4587      used by external Makefiles to point to the kernel source directory.
4588
4589   :term:`KERNEL_SRC`
4590      The location of the kernel sources. This variable is set to the value
4591      of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`
4592      class. For information on how this variable is used, see the
4593      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4594      section in the Yocto Project Linux Kernel Development Manual.
4595
4596      To help maximize compatibility with out-of-tree drivers used to build
4597      modules, the OpenEmbedded build system also recognizes and uses the
4598      :term:`KERNEL_PATH` variable, which is identical
4599      to the :term:`KERNEL_SRC` variable. Both variables are common variables
4600      used by external Makefiles to point to the kernel source directory.
4601
4602   :term:`KERNEL_VERSION`
4603      Specifies the version of the kernel as extracted from ``version.h``
4604      or ``utsrelease.h`` within the kernel sources. Effects of setting
4605      this variable do not take effect until the kernel has been
4606      configured. Consequently, attempting to refer to this variable in
4607      contexts prior to configuration will not work.
4608
4609   :term:`KERNELDEPMODDEPEND`
4610      Specifies whether the data referenced through
4611      :term:`PKGDATA_DIR` is needed or not.
4612      :term:`KERNELDEPMODDEPEND` does not control whether or not that data
4613      exists, but simply whether or not it is used. If you do not need to
4614      use the data, set the :term:`KERNELDEPMODDEPEND` variable in your
4615      :term:`Initramfs` recipe. Setting the variable there when the data is not
4616      needed avoids a potential dependency loop.
4617
4618   :term:`KFEATURE_DESCRIPTION`
4619      Provides a short description of a configuration fragment. You use
4620      this variable in the ``.scc`` file that describes a configuration
4621      fragment file. Here is the variable used in a file named ``smp.scc``
4622      to describe SMP being enabled::
4623
4624          define KFEATURE_DESCRIPTION "Enable SMP"
4625
4626   :term:`KMACHINE`
4627      The machine as known by the kernel. Sometimes the machine name used
4628      by the kernel does not match the machine name used by the
4629      OpenEmbedded build system. For example, the machine name that the
4630      OpenEmbedded build system understands as ``core2-32-intel-common``
4631      goes by a different name in the Linux Yocto kernel. The kernel
4632      understands that machine as ``intel-core2-32``. For cases like these,
4633      the :term:`KMACHINE` variable maps the kernel machine name to the
4634      OpenEmbedded build system machine name.
4635
4636      These mappings between different names occur in the Yocto Linux
4637      Kernel's ``meta`` branch. As an example take a look in the
4638      ``common/recipes-kernel/linux/linux-yocto_3.19.bbappend`` file::
4639
4640         LINUX_VERSION:core2-32-intel-common = "3.19.0"
4641         COMPATIBLE_MACHINE:core2-32-intel-common = "${MACHINE}"
4642         SRCREV_meta:core2-32-intel-common = "8897ef68b30e7426bc1d39895e71fb155d694974"
4643         SRCREV_machine:core2-32-intel-common = "43b9eced9ba8a57add36af07736344dcc383f711"
4644         KMACHINE:core2-32-intel-common = "intel-core2-32"
4645         KBRANCH:core2-32-intel-common = "standard/base"
4646         KERNEL_FEATURES:append:core2-32-intel-common = " ${KERNEL_FEATURES_INTEL_COMMON}"
4647
4648      The :term:`KMACHINE` statement says
4649      that the kernel understands the machine name as "intel-core2-32".
4650      However, the OpenEmbedded build system understands the machine as
4651      "core2-32-intel-common".
4652
4653   :term:`KTYPE`
4654      Defines the kernel type to be used in assembling the configuration.
4655      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4656      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4657      section in the
4658      Yocto Project Linux Kernel Development Manual for more information on
4659      kernel types.
4660
4661      You define the :term:`KTYPE` variable in the
4662      :ref:`kernel-dev/advanced:bsp descriptions`. The
4663      value you use must match the value used for the
4664      :term:`LINUX_KERNEL_TYPE` value used by the
4665      kernel recipe.
4666
4667   :term:`LABELS`
4668      Provides a list of targets for automatic configuration.
4669
4670      See the :ref:`ref-classes-grub-efi` class for more
4671      information on how this variable is used.
4672
4673   :term:`LAYERDEPENDS`
4674      Lists the layers, separated by spaces, on which this recipe depends.
4675      Optionally, you can specify a specific layer version for a dependency
4676      by adding it to the end of the layer name. Here is an example::
4677
4678         LAYERDEPENDS_mylayer = "anotherlayer (=3)"
4679
4680      In this previous example,
4681      version 3 of "anotherlayer" is compared against
4682      :term:`LAYERVERSION`\ ``_anotherlayer``.
4683
4684      An error is produced if any dependency is missing or the version
4685      numbers (if specified) do not match exactly. This variable is used in
4686      the ``conf/layer.conf`` file and must be suffixed with the name of
4687      the specific layer (e.g. ``LAYERDEPENDS_mylayer``).
4688
4689   :term:`LAYERDIR`
4690      When used inside the ``layer.conf`` configuration file, this variable
4691      provides the path of the current layer. This variable is not
4692      available outside of ``layer.conf`` and references are expanded
4693      immediately when parsing of the file completes.
4694
4695   :term:`LAYERDIR_RE`
4696      See :term:`bitbake:LAYERDIR_RE` in the BitBake manual.
4697
4698   :term:`LAYERRECOMMENDS`
4699      Lists the layers, separated by spaces, recommended for use with this
4700      layer.
4701
4702      Optionally, you can specify a specific layer version for a
4703      recommendation by adding the version to the end of the layer name.
4704      Here is an example::
4705
4706         LAYERRECOMMENDS_mylayer = "anotherlayer (=3)"
4707
4708      In this previous example, version 3 of "anotherlayer" is compared
4709      against ``LAYERVERSION_anotherlayer``.
4710
4711      This variable is used in the ``conf/layer.conf`` file and must be
4712      suffixed with the name of the specific layer (e.g.
4713      ``LAYERRECOMMENDS_mylayer``).
4714
4715   :term:`LAYERSERIES_COMPAT`
4716      See :term:`bitbake:LAYERSERIES_COMPAT` in the BitBake manual.
4717
4718   :term:`LAYERVERSION`
4719      Optionally specifies the version of a layer as a single number. You
4720      can use this within :term:`LAYERDEPENDS` for
4721      another layer in order to depend on a specific version of the layer.
4722      This variable is used in the ``conf/layer.conf`` file and must be
4723      suffixed with the name of the specific layer (e.g.
4724      ``LAYERVERSION_mylayer``).
4725
4726   :term:`LD`
4727      The minimal command and arguments used to run the linker.
4728
4729   :term:`LDFLAGS`
4730      Specifies the flags to pass to the linker. This variable is exported
4731      to an environment variable and thus made visible to the software
4732      being built during the compilation step.
4733
4734      Default initialization for :term:`LDFLAGS` varies depending on what is
4735      being built:
4736
4737      -  :term:`TARGET_LDFLAGS` when building for the
4738         target
4739
4740      -  :term:`BUILD_LDFLAGS` when building for the
4741         build host (i.e. ``-native``)
4742
4743      -  :term:`BUILDSDK_LDFLAGS` when building for
4744         an SDK (i.e. ``nativesdk-``)
4745
4746   :term:`LEAD_SONAME`
4747      Specifies the lead (or primary) compiled library file (i.e. ``.so``)
4748      that the :ref:`ref-classes-debian` class applies its
4749      naming policy to given a recipe that packages multiple libraries.
4750
4751      This variable works in conjunction with the :ref:`ref-classes-debian`
4752      class.
4753
4754   :term:`LIC_FILES_CHKSUM`
4755      Checksums of the license text in the recipe source code.
4756
4757      This variable tracks changes in license text of the source code
4758      files. If the license text is changed, it will trigger a build
4759      failure, which gives the developer an opportunity to review any
4760      license change.
4761
4762      This variable must be defined for all recipes (unless
4763      :term:`LICENSE` is set to "CLOSED").
4764
4765      For more information, see the ":ref:`dev-manual/licenses:tracking license changes`"
4766      section in the Yocto Project Development Tasks Manual.
4767
4768   :term:`LICENSE`
4769      The list of source licenses for the recipe. Follow these rules:
4770
4771      -  Do not use spaces within individual license names.
4772
4773      -  Separate license names using \| (pipe) when there is a choice
4774         between licenses.
4775
4776      -  Separate license names using & (ampersand) when there are
4777         multiple licenses for different parts of the source.
4778
4779      -  You can use spaces between license names.
4780
4781      -  For standard licenses, use the names of the files in
4782         ``meta/files/common-licenses/`` or the
4783         :term:`SPDXLICENSEMAP` flag names defined in
4784         ``meta/conf/licenses.conf``.
4785
4786      Here are some examples::
4787
4788         LICENSE = "LGPL-2.1-only | GPL-3.0-only"
4789         LICENSE = "MPL-1.0 & LGPL-2.1-only"
4790         LICENSE = "GPL-2.0-or-later"
4791
4792      The first example is from the
4793      recipes for Qt, which the user may choose to distribute under either
4794      the LGPL version 2.1 or GPL version 3. The second example is from
4795      Cairo where two licenses cover different parts of the source code.
4796      The final example is from ``sysstat``, which presents a single
4797      license.
4798
4799      You can also specify licenses on a per-package basis to handle
4800      situations where components of the output have different licenses.
4801      For example, a piece of software whose code is licensed under GPLv2
4802      but has accompanying documentation licensed under the GNU Free
4803      Documentation License 1.2 could be specified as follows::
4804
4805         LICENSE = "GFDL-1.2 & GPL-2.0-only"
4806         LICENSE:${PN} = "GPL-2.0.only"
4807         LICENSE:${PN}-doc = "GFDL-1.2"
4808
4809   :term:`LICENSE_CREATE_PACKAGE`
4810      Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
4811      build system to create an extra package (i.e.
4812      ``${``\ :term:`PN`\ ``}-lic``) for each recipe and to add
4813      those packages to the
4814      :term:`RRECOMMENDS`\ ``:${PN}``.
4815
4816      The ``${PN}-lic`` package installs a directory in
4817      ``/usr/share/licenses`` named ``${PN}``, which is the recipe's base
4818      name, and installs files in that directory that contain license and
4819      copyright information (i.e. copies of the appropriate license files
4820      from ``meta/common-licenses`` that match the licenses specified in
4821      the :term:`LICENSE` variable of the recipe metadata
4822      and copies of files marked in
4823      :term:`LIC_FILES_CHKSUM` as containing
4824      license text).
4825
4826      For related information on providing license text, see the
4827      :term:`COPY_LIC_DIRS` variable, the
4828      :term:`COPY_LIC_MANIFEST` variable, and the
4829      ":ref:`dev-manual/licenses:providing license text`"
4830      section in the Yocto Project Development Tasks Manual.
4831
4832   :term:`LICENSE_FLAGS`
4833      Specifies additional flags for a recipe you must allow through
4834      :term:`LICENSE_FLAGS_ACCEPTED` in
4835      order for the recipe to be built. When providing multiple flags,
4836      separate them with spaces.
4837
4838      This value is independent of :term:`LICENSE` and is
4839      typically used to mark recipes that might require additional licenses
4840      in order to be used in a commercial product. For more information,
4841      see the
4842      ":ref:`dev-manual/licenses:enabling commercially licensed recipes`"
4843      section in the Yocto Project Development Tasks Manual.
4844
4845   :term:`LICENSE_FLAGS_ACCEPTED`
4846      Lists license flags that when specified in
4847      :term:`LICENSE_FLAGS` within a recipe should not
4848      prevent that recipe from being built.  For more information, see the
4849      ":ref:`dev-manual/licenses:enabling commercially licensed recipes`"
4850      section in the Yocto Project Development Tasks Manual.
4851
4852   :term:`LICENSE_PATH`
4853      Path to additional licenses used during the build. By default, the
4854      OpenEmbedded build system uses :term:`COMMON_LICENSE_DIR` to define the
4855      directory that holds common license text used during the build. The
4856      :term:`LICENSE_PATH` variable allows you to extend that location to other
4857      areas that have additional licenses::
4858
4859         LICENSE_PATH += "path-to-additional-common-licenses"
4860
4861   :term:`LINUX_KERNEL_TYPE`
4862      Defines the kernel type to be used in assembling the configuration.
4863      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4864      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4865      section in the
4866      Yocto Project Linux Kernel Development Manual for more information on
4867      kernel types.
4868
4869      If you do not specify a :term:`LINUX_KERNEL_TYPE`, it defaults to
4870      "standard". Together with :term:`KMACHINE`, the
4871      :term:`LINUX_KERNEL_TYPE` variable defines the search arguments used by
4872      the kernel tools to find the appropriate description within the
4873      kernel :term:`Metadata` with which to build out the sources
4874      and configuration.
4875
4876   :term:`LINUX_VERSION`
4877      The Linux version from ``kernel.org`` on which the Linux kernel image
4878      being built using the OpenEmbedded build system is based. You define
4879      this variable in the kernel recipe. For example, the
4880      ``linux-yocto-3.4.bb`` kernel recipe found in
4881      ``meta/recipes-kernel/linux`` defines the variables as follows::
4882
4883         LINUX_VERSION ?= "3.4.24"
4884
4885      The :term:`LINUX_VERSION` variable is used to define :term:`PV`
4886      for the recipe::
4887
4888         PV = "${LINUX_VERSION}+git${SRCPV}"
4889
4890   :term:`LINUX_VERSION_EXTENSION`
4891      A string extension compiled into the version string of the Linux
4892      kernel built with the OpenEmbedded build system. You define this
4893      variable in the kernel recipe. For example, the linux-yocto kernel
4894      recipes all define the variable as follows::
4895
4896         LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
4897
4898      Defining this variable essentially sets the Linux kernel
4899      configuration item ``CONFIG_LOCALVERSION``, which is visible through
4900      the ``uname`` command. Here is an example that shows the extension
4901      assuming it was set as previously shown::
4902
4903         $ uname -r
4904         3.7.0-rc8-custom
4905
4906   :term:`LOG_DIR`
4907      Specifies the directory to which the OpenEmbedded build system writes
4908      overall log files. The default directory is ``${TMPDIR}/log``.
4909
4910      For the directory containing logs specific to each task, see the
4911      :term:`T` variable.
4912
4913   :term:`MACHINE`
4914      Specifies the target device for which the image is built. You define
4915      :term:`MACHINE` in the ``local.conf`` file found in the
4916      :term:`Build Directory`. By default, :term:`MACHINE` is set to
4917      "qemux86", which is an x86-based architecture machine to be emulated
4918      using QEMU::
4919
4920         MACHINE ?= "qemux86"
4921
4922      The variable corresponds to a machine configuration file of the same
4923      name, through which machine-specific configurations are set. Thus,
4924      when :term:`MACHINE` is set to "qemux86", the corresponding
4925      ``qemux86.conf`` machine configuration file can be found in
4926      the :term:`Source Directory` in
4927      ``meta/conf/machine``.
4928
4929      The list of machines supported by the Yocto Project as shipped
4930      include the following::
4931
4932         MACHINE ?= "qemuarm"
4933         MACHINE ?= "qemuarm64"
4934         MACHINE ?= "qemumips"
4935         MACHINE ?= "qemumips64"
4936         MACHINE ?= "qemuppc"
4937         MACHINE ?= "qemux86"
4938         MACHINE ?= "qemux86-64"
4939         MACHINE ?= "genericx86"
4940         MACHINE ?= "genericx86-64"
4941         MACHINE ?= "beaglebone"
4942         MACHINE ?= "edgerouter"
4943
4944      The last five are Yocto Project reference hardware
4945      boards, which are provided in the ``meta-yocto-bsp`` layer.
4946
4947      .. note::
4948
4949         Adding additional Board Support Package (BSP) layers to your
4950         configuration adds new possible settings for :term:`MACHINE`.
4951
4952   :term:`MACHINE_ARCH`
4953      Specifies the name of the machine-specific architecture. This
4954      variable is set automatically from :term:`MACHINE` or
4955      :term:`TUNE_PKGARCH`. You should not hand-edit
4956      the :term:`MACHINE_ARCH` variable.
4957
4958   :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4959      A list of required machine-specific packages to install as part of
4960      the image being built. The build process depends on these packages
4961      being present. Furthermore, because this is a "machine-essential"
4962      variable, the list of packages are essential for the machine to boot.
4963      The impact of this variable affects images based on
4964      ``packagegroup-core-boot``, including the ``core-image-minimal``
4965      image.
4966
4967      This variable is similar to the
4968      :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` variable with the exception
4969      that the image being built has a build dependency on the variable's
4970      list of packages. In other words, the image will not build if a file
4971      in this list is not found.
4972
4973      As an example, suppose the machine for which you are building
4974      requires ``example-init`` to be run during boot to initialize the
4975      hardware. In this case, you would use the following in the machine's
4976      ``.conf`` configuration file::
4977
4978         MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
4979
4980   :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS`
4981      A list of recommended machine-specific packages to install as part of
4982      the image being built. The build process does not depend on these
4983      packages being present. However, because this is a
4984      "machine-essential" variable, the list of packages are essential for
4985      the machine to boot. The impact of this variable affects images based
4986      on ``packagegroup-core-boot``, including the ``core-image-minimal``
4987      image.
4988
4989      This variable is similar to the :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4990      variable with the exception that the image being built does not have
4991      a build dependency on the variable's list of packages. In other
4992      words, the image will still build if a package in this list is not
4993      found. Typically, this variable is used to handle essential kernel
4994      modules, whose functionality may be selected to be built into the
4995      kernel rather than as a module, in which case a package will not be
4996      produced.
4997
4998      Consider an example where you have a custom kernel where a specific
4999      touchscreen driver is required for the machine to be usable. However,
5000      the driver can be built as a module or into the kernel depending on
5001      the kernel configuration. If the driver is built as a module, you
5002      want it to be installed. But, when the driver is built into the
5003      kernel, you still want the build to succeed. This variable sets up a
5004      "recommends" relationship so that in the latter case, the build will
5005      not fail due to the missing package. To accomplish this, assuming the
5006      package for the module was called ``kernel-module-ab123``, you would
5007      use the following in the machine's ``.conf`` configuration file::
5008
5009         MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
5010
5011      .. note::
5012
5013         In this example, the ``kernel-module-ab123`` recipe needs to
5014         explicitly set its :term:`PACKAGES` variable to ensure that BitBake
5015         does not use the kernel recipe's :term:`PACKAGES_DYNAMIC` variable to
5016         satisfy the dependency.
5017
5018      Some examples of these machine essentials are flash, screen,
5019      keyboard, mouse, or touchscreen drivers (depending on the machine).
5020
5021   :term:`MACHINE_EXTRA_RDEPENDS`
5022      A list of machine-specific packages to install as part of the image
5023      being built that are not essential for the machine to boot. However,
5024      the build process for more fully-featured images depends on the
5025      packages being present.
5026
5027      This variable affects all images based on ``packagegroup-base``,
5028      which does not include the ``core-image-minimal`` or
5029      ``core-image-full-cmdline`` images.
5030
5031      The variable is similar to the :term:`MACHINE_EXTRA_RRECOMMENDS` variable
5032      with the exception that the image being built has a build dependency
5033      on the variable's list of packages. In other words, the image will
5034      not build if a file in this list is not found.
5035
5036      An example is a machine that has WiFi capability but is not essential
5037      for the machine to boot the image. However, if you are building a
5038      more fully-featured image, you want to enable the WiFi. The package
5039      containing the firmware for the WiFi hardware is always expected to
5040      exist, so it is acceptable for the build process to depend upon
5041      finding the package. In this case, assuming the package for the
5042      firmware was called ``wifidriver-firmware``, you would use the
5043      following in the ``.conf`` file for the machine::
5044
5045         MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
5046
5047   :term:`MACHINE_EXTRA_RRECOMMENDS`
5048      A list of machine-specific packages to install as part of the image
5049      being built that are not essential for booting the machine. The image
5050      being built has no build dependency on this list of packages.
5051
5052      This variable affects only images based on ``packagegroup-base``,
5053      which does not include the ``core-image-minimal`` or
5054      ``core-image-full-cmdline`` images.
5055
5056      This variable is similar to the :term:`MACHINE_EXTRA_RDEPENDS` variable
5057      with the exception that the image being built does not have a build
5058      dependency on the variable's list of packages. In other words, the
5059      image will build if a file in this list is not found.
5060
5061      An example is a machine that has WiFi capability but is not essential
5062      For the machine to boot the image. However, if you are building a
5063      more fully-featured image, you want to enable WiFi. In this case, the
5064      package containing the WiFi kernel module will not be produced if the
5065      WiFi driver is built into the kernel, in which case you still want
5066      the build to succeed instead of failing as a result of the package
5067      not being found. To accomplish this, assuming the package for the
5068      module was called ``kernel-module-examplewifi``, you would use the
5069      following in the ``.conf`` file for the machine::
5070
5071         MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
5072
5073   :term:`MACHINE_FEATURES`
5074      Specifies the list of hardware features the
5075      :term:`MACHINE` is capable of supporting. For related
5076      information on enabling features, see the
5077      :term:`DISTRO_FEATURES`,
5078      :term:`COMBINED_FEATURES`, and
5079      :term:`IMAGE_FEATURES` variables.
5080
5081      For a list of hardware features supported by the Yocto Project as
5082      shipped, see the ":ref:`ref-features-machine`" section.
5083
5084   :term:`MACHINE_FEATURES_BACKFILL`
5085      A list of space-separated features to be added to
5086      :term:`MACHINE_FEATURES` if not also present in
5087      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`.
5088
5089      This variable is set in the ``meta/conf/bitbake.conf`` file. It is not
5090      intended to be user-configurable. It is best to just reference the
5091      variable to see which machine features are being
5092      :ref:`backfilled <ref-features-backfill>` for all machine configurations.
5093
5094   :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`
5095      A list of space-separated features from :term:`MACHINE_FEATURES_BACKFILL`
5096      that should not be :ref:`backfilled <ref-features-backfill>` (i.e. added
5097      to :term:`MACHINE_FEATURES`) during the build.
5098
5099      This corresponds to an opt-out mechanism. When new default machine
5100      features are introduced, machine definition maintainers can review
5101      (`consider`) them and decide to exclude them from the
5102      :ref:`backfilled <ref-features-backfill>` features. Therefore, the
5103      combination of :term:`MACHINE_FEATURES_BACKFILL` and
5104      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED` makes it possible to
5105      add new default features without breaking existing machine definitions.
5106
5107   :term:`MACHINEOVERRIDES`
5108      A colon-separated list of overrides that apply to the current
5109      machine. By default, this list includes the value of
5110      :term:`MACHINE`.
5111
5112      You can extend :term:`MACHINEOVERRIDES` to add extra overrides that
5113      should apply to a machine. For example, all machines emulated in QEMU
5114      (e.g. ``qemuarm``, ``qemux86``, and so forth) include a file named
5115      ``meta/conf/machine/include/qemu.inc`` that prepends the following
5116      override to :term:`MACHINEOVERRIDES`::
5117
5118         MACHINEOVERRIDES =. "qemuall:"
5119
5120      This
5121      override allows variables to be overridden for all machines emulated
5122      in QEMU, like in the following example from the ``connman-conf``
5123      recipe::
5124
5125         SRC_URI:append:qemuall = " file://wired.config \
5126             file://wired-setup \
5127             "
5128
5129      The underlying mechanism behind
5130      :term:`MACHINEOVERRIDES` is simply that it is included in the default
5131      value of :term:`OVERRIDES`.
5132
5133   :term:`MAINTAINER`
5134      The email address of the distribution maintainer.
5135
5136   :term:`MESON_BUILDTYPE`
5137      Value of the Meson ``--buildtype`` argument used by the
5138      :ref:`ref-classes-meson` class. It defaults to ``debug`` if
5139      :term:`DEBUG_BUILD` is set to "1", and ``plain`` otherwise.
5140
5141      See `Meson build options <https://mesonbuild.com/Builtin-options.html>`__
5142      for the values you could set in a recipe. Values such as ``plain``,
5143      ``debug``, ``debugoptimized``, ``release`` and ``minsize`` allow
5144      you to specify the inclusion of debugging symbols and the compiler
5145      optimizations (none, performance or size).
5146
5147   :term:`METADATA_BRANCH`
5148      The branch currently checked out for the OpenEmbedded-Core layer (path
5149      determined by :term:`COREBASE`).
5150
5151   :term:`METADATA_REVISION`
5152      The revision currently checked out for the OpenEmbedded-Core layer (path
5153      determined by :term:`COREBASE`).
5154
5155   :term:`MIME_XDG_PACKAGES`
5156      The current implementation of the :ref:`ref-classes-mime-xdg`
5157      class cannot detect ``.desktop`` files installed through absolute
5158      symbolic links. Use this setting to make the class create post-install
5159      and post-remove scripts for these packages anyway, to invoke the
5160      ``update-destop-database`` command.
5161
5162   :term:`MIRRORS`
5163      Specifies additional paths from which the OpenEmbedded build system
5164      gets source code. When the build system searches for source code, it
5165      first tries the local download directory. If that location fails, the
5166      build system tries locations defined by
5167      :term:`PREMIRRORS`, the upstream source, and then
5168      locations specified by :term:`MIRRORS` in that order.
5169
5170      Assuming your distribution (:term:`DISTRO`) is "poky",
5171      the default value for :term:`MIRRORS` is defined in the
5172      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
5173
5174   :term:`MLPREFIX`
5175      Specifies a prefix has been added to :term:`PN` to create a
5176      special version of a recipe or package (i.e. a Multilib version). The
5177      variable is used in places where the prefix needs to be added to or
5178      removed from a name (e.g. the :term:`BPN` variable).
5179      :term:`MLPREFIX` gets set when a prefix has been added to :term:`PN`.
5180
5181      .. note::
5182
5183         The "ML" in :term:`MLPREFIX` stands for "MultiLib". This representation
5184         is historical and comes from a time when ":ref:`ref-classes-nativesdk`"
5185         was a suffix rather than a prefix on the recipe name. When
5186         ":ref:`ref-classes-nativesdk`" was turned into a prefix, it made sense
5187         to set :term:`MLPREFIX` for it as well.
5188
5189      To help understand when :term:`MLPREFIX` might be needed, consider when
5190      :term:`BBCLASSEXTEND` is used to provide a :ref:`ref-classes-nativesdk`
5191      version of a recipe in addition to the target version. If that recipe
5192      declares build-time dependencies on tasks in other recipes by using
5193      :term:`DEPENDS`, then a dependency on "foo" will automatically get
5194      rewritten to a dependency on "nativesdk-foo". However, dependencies like
5195      the following will not get rewritten automatically::
5196
5197         do_foo[depends] += "recipe:do_foo"
5198
5199      If you want such a dependency to also get transformed, you can do the
5200      following::
5201
5202         do_foo[depends] += "${MLPREFIX}recipe:do_foo"
5203
5204   :term:`module_autoload`
5205      This variable has been replaced by the :term:`KERNEL_MODULE_AUTOLOAD`
5206      variable. You should replace all occurrences of :term:`module_autoload`
5207      with additions to :term:`KERNEL_MODULE_AUTOLOAD`, for example::
5208
5209         module_autoload_rfcomm = "rfcomm"
5210
5211      should now be replaced with::
5212
5213         KERNEL_MODULE_AUTOLOAD += "rfcomm"
5214
5215      See the :term:`KERNEL_MODULE_AUTOLOAD` variable for more information.
5216
5217   :term:`module_conf`
5218      Specifies `modprobe.d <https://linux.die.net/man/5/modprobe.d>`__
5219      syntax lines for inclusion in the ``/etc/modprobe.d/modname.conf``
5220      file.
5221
5222      You can use this variable anywhere that it can be recognized by the
5223      kernel recipe or out-of-tree kernel module recipe (e.g. a machine
5224      configuration file, a distribution configuration file, an append file
5225      for the recipe, or the recipe itself). If you use this variable, you
5226      must also be sure to list the module name in the
5227      :term:`KERNEL_MODULE_PROBECONF`
5228      variable.
5229
5230      Here is the general syntax::
5231
5232         module_conf_module_name = "modprobe.d-syntax"
5233
5234      You must use the kernel module name override.
5235
5236      Run ``man modprobe.d`` in the shell to find out more information on
5237      the exact syntax you want to provide with :term:`module_conf`.
5238
5239      Including :term:`module_conf` causes the OpenEmbedded build system to
5240      populate the ``/etc/modprobe.d/modname.conf`` file with
5241      ``modprobe.d`` syntax lines. Here is an example that adds the options
5242      ``arg1`` and ``arg2`` to a module named ``mymodule``::
5243
5244         module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
5245
5246      For information on how to specify kernel modules to auto-load on
5247      boot, see the :term:`KERNEL_MODULE_AUTOLOAD` variable.
5248
5249   :term:`MODULE_TARBALL_DEPLOY`
5250      Controls creation of the ``modules-*.tgz`` file. Set this variable to
5251      "0" to disable creation of this file, which contains all of the
5252      kernel modules resulting from a kernel build.
5253
5254   :term:`MODULE_TARBALL_LINK_NAME`
5255      The link name of the kernel module tarball. This variable is set in
5256      the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
5257
5258         MODULE_TARBALL_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
5259
5260      The value
5261      of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the
5262      same file, has the following value::
5263
5264         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
5265
5266      See the :term:`MACHINE` variable for additional information.
5267
5268   :term:`MODULE_TARBALL_NAME`
5269      The base name of the kernel module tarball. This variable is set in
5270      the ``meta/classes-recipe/kernel-artifact-names.bbclass`` file as follows::
5271
5272         MODULE_TARBALL_NAME ?= "${KERNEL_ARTIFACT_NAME}"
5273
5274      See :term:`KERNEL_ARTIFACT_NAME` for additional information.
5275
5276   :term:`MOUNT_BASE`
5277      On non-systemd systems (where ``udev-extraconf`` is being used),
5278      specifies the base directory for auto-mounting filesystems. The
5279      default value is "/run/media".
5280
5281   :term:`MULTIMACH_TARGET_SYS`
5282      Uniquely identifies the type of the target system for which packages
5283      are being built. This variable allows output for different types of
5284      target systems to be put into different subdirectories of the same
5285      output directory.
5286
5287      The default value of this variable is::
5288
5289         ${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}
5290
5291      Some classes (e.g.  :ref:`ref-classes-cross-canadian`) modify the
5292      :term:`MULTIMACH_TARGET_SYS` value.
5293
5294      See the :term:`STAMP` variable for an example. See the
5295      :term:`STAGING_DIR_TARGET` variable for more information.
5296
5297   :term:`NATIVELSBSTRING`
5298      A string identifying the host distribution. Strings consist of the
5299      host distributor ID followed by the release, as reported by the
5300      ``lsb_release`` tool or as read from ``/etc/lsb-release``. For
5301      example, when running a build on Ubuntu 12.10, the value is
5302      "Ubuntu-12.10". If this information is unable to be determined, the
5303      value resolves to "Unknown".
5304
5305      This variable is used by default to isolate native shared state
5306      packages for different distributions (e.g. to avoid problems with
5307      ``glibc`` version incompatibilities). Additionally, the variable is
5308      checked against
5309      :term:`SANITY_TESTED_DISTROS` if that
5310      variable is set.
5311
5312   :term:`NM`
5313      The minimal command and arguments to run ``nm``.
5314
5315   :term:`NO_GENERIC_LICENSE`
5316      Avoids QA errors when you use a non-common, non-CLOSED license in a
5317      recipe. There are packages, such as the linux-firmware package, with many
5318      licenses that are not in any way common. Also, new licenses are added
5319      occasionally to avoid introducing a lot of common license files,
5320      which are only applicable to a specific package.
5321      :term:`NO_GENERIC_LICENSE` is used to allow copying a license that does
5322      not exist in common licenses.
5323
5324      The following example shows how to add :term:`NO_GENERIC_LICENSE` to a
5325      recipe::
5326
5327         NO_GENERIC_LICENSE[license_name] = "license_file_in_fetched_source"
5328
5329      Here is an example that
5330      uses the ``LICENSE.Abilis.txt`` file as the license from the fetched
5331      source::
5332
5333         NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt"
5334
5335   :term:`NO_RECOMMENDATIONS`
5336      Prevents installation of all "recommended-only" packages.
5337      Recommended-only packages are packages installed only through the
5338      :term:`RRECOMMENDS` variable). Setting the
5339      :term:`NO_RECOMMENDATIONS` variable to "1" turns this feature on::
5340
5341         NO_RECOMMENDATIONS = "1"
5342
5343      You can set this variable globally in your ``local.conf`` file or you
5344      can attach it to a specific image recipe by using the recipe name
5345      override::
5346
5347         NO_RECOMMENDATIONS:pn-target_image = "1"
5348
5349      It is important to realize that if you choose to not install packages
5350      using this variable and some other packages are dependent on them
5351      (i.e. listed in a recipe's :term:`RDEPENDS`
5352      variable), the OpenEmbedded build system ignores your request and
5353      will install the packages to avoid dependency errors.
5354
5355      .. note::
5356
5357         Some recommended packages might be required for certain system
5358         functionality, such as kernel modules. It is up to you to add
5359         packages with the :term:`IMAGE_INSTALL` variable.
5360
5361      This variable is only supported when using the IPK and RPM
5362      packaging backends. DEB is not supported.
5363
5364      See the :term:`BAD_RECOMMENDATIONS` and
5365      the :term:`PACKAGE_EXCLUDE` variables for
5366      related information.
5367
5368   :term:`NOAUTOPACKAGEDEBUG`
5369      Disables auto package from splitting ``.debug`` files. If a recipe
5370      requires ``FILES:${PN}-dbg`` to be set manually, the
5371      :term:`NOAUTOPACKAGEDEBUG` can be defined allowing you to define the
5372      content of the debug package. For example::
5373
5374         NOAUTOPACKAGEDEBUG = "1"
5375         FILES:${PN}-dev = "${includedir}/${QT_DIR_NAME}/Qt/*"
5376         FILES:${PN}-dbg = "/usr/src/debug/"
5377         FILES:${QT_BASE_NAME}-demos-doc = "${docdir}/${QT_DIR_NAME}/qch/qt.qch"
5378
5379   :term:`NON_MULTILIB_RECIPES`
5380      A list of recipes that should not be built for multilib. OE-Core's
5381      ``multilib.conf`` file defines a reasonable starting point for this
5382      list with::
5383
5384         NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot"
5385
5386   :term:`OBJCOPY`
5387      The minimal command and arguments to run ``objcopy``.
5388
5389   :term:`OBJDUMP`
5390      The minimal command and arguments to run ``objdump``.
5391
5392   :term:`OE_BINCONFIG_EXTRA_MANGLE`
5393      When inheriting the :ref:`ref-classes-binconfig` class,
5394      this variable specifies additional arguments passed to the "sed"
5395      command. The sed command alters any paths in configuration scripts
5396      that have been set up during compilation. Inheriting this class
5397      results in all paths in these scripts being changed to point into the
5398      ``sysroots/`` directory so that all builds that use the script will
5399      use the correct directories for the cross compiling layout.
5400
5401      See the ``meta/classes-recipe/binconfig.bbclass`` in the
5402      :term:`Source Directory` for details on how this class
5403      applies these additional sed command arguments.
5404
5405   :term:`OECMAKE_GENERATOR`
5406      A variable for the :ref:`ref-classes-cmake` class, allowing to choose
5407      which back-end will be generated by CMake to build an application.
5408
5409      By default, this variable is set to ``Ninja``, which is faster than GNU
5410      make, but if building is broken with Ninja, a recipe can use this
5411      variable to use GNU make instead::
5412
5413         OECMAKE_GENERATOR = "Unix Makefiles"
5414
5415   :term:`OE_IMPORTS`
5416      An internal variable used to tell the OpenEmbedded build system what
5417      Python modules to import for every Python function run by the system.
5418
5419      .. note::
5420
5421         Do not set this variable. It is for internal use only.
5422
5423   :term:`OE_INIT_ENV_SCRIPT`
5424      The name of the build environment setup script for the purposes of
5425      setting up the environment within the extensible SDK. The default
5426      value is "oe-init-build-env".
5427
5428      If you use a custom script to set up your build environment, set the
5429      :term:`OE_INIT_ENV_SCRIPT` variable to its name.
5430
5431   :term:`OE_TERMINAL`
5432      Controls how the OpenEmbedded build system spawns interactive
5433      terminals on the host development system (e.g. using the BitBake
5434      command with the ``-c devshell`` command-line option). For more
5435      information, see the ":ref:`dev-manual/development-shell:using a development shell`" section in
5436      the Yocto Project Development Tasks Manual.
5437
5438      You can use the following values for the :term:`OE_TERMINAL` variable:
5439
5440      - auto
5441      - gnome
5442      - xfce
5443      - rxvt
5444      - screen
5445      - konsole
5446      - none
5447
5448   :term:`OEROOT`
5449      The directory from which the top-level build environment setup script
5450      is sourced. The Yocto Project provides a top-level build environment
5451      setup script: :ref:`structure-core-script`. When you run this
5452      script, the :term:`OEROOT` variable resolves to the directory that
5453      contains the script.
5454
5455      For additional information on how this variable is used, see the
5456      initialization script.
5457
5458   :term:`OLDEST_KERNEL`
5459      Declares the oldest version of the Linux kernel that the produced
5460      binaries must support. This variable is passed into the build of the
5461      Embedded GNU C Library (``glibc``).
5462
5463      The default for this variable comes from the
5464      ``meta/conf/bitbake.conf`` configuration file. You can override this
5465      default by setting the variable in a custom distribution
5466      configuration file.
5467
5468   :term:`OVERLAYFS_ETC_DEVICE`
5469      When the :ref:`ref-classes-overlayfs-etc` class is
5470      inherited, specifies the device to be mounted for the read/write
5471      layer of ``/etc``. There is no default, so you must set this if you
5472      wish to enable :ref:`ref-classes-overlayfs-etc`, for
5473      example, assuming ``/dev/mmcblk0p2`` was the desired device::
5474
5475         OVERLAYFS_ETC_DEVICE = "/dev/mmcblk0p2"
5476
5477   :term:`OVERLAYFS_ETC_EXPOSE_LOWER`
5478      When the :ref:`ref-classes-overlayfs-etc` class is
5479      inherited, if set to "1" then a read-only access to the original
5480      ``/etc`` content will be provided as a ``lower/`` subdirectory of
5481      :term:`OVERLAYFS_ETC_MOUNT_POINT`. The default value is "0".
5482
5483   :term:`OVERLAYFS_ETC_FSTYPE`
5484      When the :ref:`ref-classes-overlayfs-etc` class is
5485      inherited, specifies the file system type for the read/write
5486      layer of ``/etc``. There is no default, so you must set this if you
5487      wish to enable :ref:`ref-classes-overlayfs-etc`,
5488      for example, assuming the file system is ext4::
5489
5490         OVERLAYFS_ETC_FSTYPE = "ext4"
5491
5492   :term:`OVERLAYFS_ETC_MOUNT_OPTIONS`
5493      When the :ref:`ref-classes-overlayfs-etc` class is
5494      inherited, specifies the mount options for the read-write layer.
5495      The default value is "defaults".
5496
5497   :term:`OVERLAYFS_ETC_MOUNT_POINT`
5498      When the :ref:`ref-classes-overlayfs-etc` class is
5499      inherited, specifies the parent mount path for the filesystem layers.
5500      There is no default, so you must set this if you wish to enable
5501      :ref:`ref-classes-overlayfs-etc`, for example if the desired path is
5502      "/data"::
5503
5504         OVERLAYFS_ETC_MOUNT_POINT = "/data"
5505
5506   :term:`OVERLAYFS_ETC_USE_ORIG_INIT_NAME`
5507      When the :ref:`ref-classes-overlayfs-etc` class is inherited, controls
5508      how the generated init will be named. For more information, see the
5509      :ref:`ref-classes-overlayfs-etc` class documentation. The default value
5510      is "1".
5511
5512   :term:`OVERLAYFS_MOUNT_POINT`
5513      When inheriting the :ref:`ref-classes-overlayfs` class,
5514      specifies mount point(s) to be used. For example::
5515
5516         OVERLAYFS_MOUNT_POINT[data] = "/data"
5517
5518      The assumes you have a ``data.mount`` systemd unit defined elsewhere in
5519      your BSP (e.g. in ``systemd-machine-units`` recipe) and it is installed
5520      into the image. For more information see :ref:`ref-classes-overlayfs`.
5521
5522      .. note::
5523
5524         Although the :ref:`ref-classes-overlayfs` class is
5525         inherited by individual recipes, :term:`OVERLAYFS_MOUNT_POINT`
5526         should be set in your machine configuration.
5527
5528   :term:`OVERLAYFS_QA_SKIP`
5529      When inheriting the :ref:`ref-classes-overlayfs` class,
5530      provides the ability to disable QA checks for particular overlayfs
5531      mounts. For example::
5532
5533         OVERLAYFS_QA_SKIP[data] = "mount-configured"
5534
5535      .. note::
5536
5537         Although the :ref:`ref-classes-overlayfs` class is
5538         inherited by individual recipes, :term:`OVERLAYFS_QA_SKIP`
5539         should be set in your machine configuration.
5540
5541   :term:`OVERLAYFS_WRITABLE_PATHS`
5542      When inheriting the :ref:`ref-classes-overlayfs` class,
5543      specifies writable paths used at runtime for the recipe. For
5544      example::
5545
5546         OVERLAYFS_WRITABLE_PATHS[data] = "/usr/share/my-custom-application"
5547
5548   :term:`OVERRIDES`
5549      A colon-separated list of overrides that currently apply. Overrides
5550      are a BitBake mechanism that allows variables to be selectively
5551      overridden at the end of parsing. The set of overrides in
5552      :term:`OVERRIDES` represents the "state" during building, which includes
5553      the current recipe being built, the machine for which it is being
5554      built, and so forth.
5555
5556      As an example, if the string "an-override" appears as an element in
5557      the colon-separated list in :term:`OVERRIDES`, then the following
5558      assignment will override ``FOO`` with the value "overridden" at the
5559      end of parsing::
5560
5561         FOO:an-override = "overridden"
5562
5563      See the
5564      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
5565      section in the BitBake User Manual for more information on the
5566      overrides mechanism.
5567
5568      The default value of :term:`OVERRIDES` includes the values of the
5569      :term:`CLASSOVERRIDE`,
5570      :term:`MACHINEOVERRIDES`, and
5571      :term:`DISTROOVERRIDES` variables. Another
5572      important override included by default is ``pn-${PN}``. This override
5573      allows variables to be set for a single recipe within configuration
5574      (``.conf``) files. Here is an example::
5575
5576         FOO:pn-myrecipe = "myrecipe-specific value"
5577
5578      .. note::
5579
5580         An easy way to see what overrides apply is to search for :term:`OVERRIDES`
5581         in the output of the ``bitbake -e`` command. See the
5582         ":ref:`dev-manual/debugging:viewing variable values`" section in the Yocto
5583         Project Development Tasks Manual for more information.
5584
5585   :term:`P`
5586      The recipe name and version. :term:`P` is comprised of the following::
5587
5588         ${PN}-${PV}
5589
5590   :term:`P4DIR`
5591      See :term:`bitbake:P4DIR` in the BitBake manual.
5592
5593   :term:`PACKAGE_ADD_METADATA`
5594      This variable defines additional metadata to add to packages.
5595
5596      You may find you need to inject additional metadata into packages.
5597      This variable allows you to do that by setting the injected data as
5598      the value. Multiple fields can be added by splitting the content with
5599      the literal separator "\n".
5600
5601      The suffixes '_IPK', '_DEB', or '_RPM' can be applied to the variable
5602      to do package type specific settings. It can also be made package
5603      specific by using the package name as a suffix.
5604
5605      You can find out more about applying this variable in the
5606      ":ref:`dev-manual/packages:adding custom metadata to packages`"
5607      section in the Yocto Project Development Tasks Manual.
5608
5609   :term:`PACKAGE_ARCH`
5610      The architecture of the resulting package or packages.
5611
5612      By default, the value of this variable is set to
5613      :term:`TUNE_PKGARCH` when building for the
5614      target, :term:`BUILD_ARCH` when building for the
5615      build host, and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building for the
5616      SDK.
5617
5618      .. note::
5619
5620         See :term:`SDK_ARCH` for more information.
5621
5622      However, if your recipe's output packages are built specific to the
5623      target machine rather than generally for the architecture of the
5624      machine, you should set :term:`PACKAGE_ARCH` to the value of
5625      :term:`MACHINE_ARCH` in the recipe as follows::
5626
5627         PACKAGE_ARCH = "${MACHINE_ARCH}"
5628
5629   :term:`PACKAGE_ARCHS`
5630      Specifies a list of architectures compatible with the target machine.
5631      This variable is set automatically and should not normally be
5632      hand-edited. Entries are separated using spaces and listed in order
5633      of priority. The default value for :term:`PACKAGE_ARCHS` is "all any
5634      noarch ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
5635
5636   :term:`PACKAGE_BEFORE_PN`
5637      Enables easily adding packages to :term:`PACKAGES` before ``${PN}`` so
5638      that those added packages can pick up files that would normally be
5639      included in the default package.
5640
5641   :term:`PACKAGE_CLASSES`
5642      This variable, which is set in the ``local.conf`` configuration file
5643      found in the ``conf`` folder of the
5644      :term:`Build Directory`, specifies the package manager the
5645      OpenEmbedded build system uses when packaging data.
5646
5647      You can provide one or more of the following arguments for the
5648      variable::
5649
5650         PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
5651
5652      The build system uses only the first argument in the list as the
5653      package manager when creating your image or SDK. However, packages
5654      will be created using any additional packaging classes you specify.
5655      For example, if you use the following in your ``local.conf`` file::
5656
5657         PACKAGE_CLASSES ?= "package_ipk"
5658
5659      The OpenEmbedded build system uses
5660      the IPK package manager to create your image or SDK.
5661
5662      For information on packaging and build performance effects as a
5663      result of the package manager in use, see the
5664      ":ref:`ref-classes-package`" section.
5665
5666   :term:`PACKAGE_DEBUG_SPLIT_STYLE`
5667      Determines how to split up and package debug and source information
5668      when creating debugging packages to be used with the GNU Project
5669      Debugger (GDB). In general, based on the value of this variable,
5670      you can combine the source and debug info in a single package,
5671      you can break out the source into a separate package that can be
5672      installed independently, or you can choose to not have the source
5673      packaged at all.
5674
5675      The possible values of :term:`PACKAGE_DEBUG_SPLIT_STYLE` variable:
5676
5677      -  "``.debug``": All debugging and source info is placed in a single
5678         ``*-dbg`` package; debug symbol files are placed next to the
5679         binary in a ``.debug`` directory so that, if a binary is installed
5680         into ``/bin``, the corresponding debug symbol file is installed
5681         in ``/bin/.debug``. Source files are installed in the same ``*-dbg``
5682         package under ``/usr/src/debug``.
5683
5684      -  "``debug-file-directory``": As above, all debugging and source info
5685         is placed in a single ``*-dbg`` package; debug symbol files are
5686         placed entirely under the directory ``/usr/lib/debug`` and separated
5687         by the path from where the binary is installed, so that if a binary
5688         is installed in ``/bin``, the corresponding debug symbols are installed
5689         in ``/usr/lib/debug/bin``, and so on. As above, source is installed
5690         in the same package under ``/usr/src/debug``.
5691
5692      -  "``debug-with-srcpkg``": Debugging info is placed in the standard
5693         ``*-dbg`` package as with the ``.debug`` value, while source is
5694         placed in a separate ``*-src`` package, which can be installed
5695         independently.  This is the default setting for this variable,
5696         as defined in Poky's ``bitbake.conf`` file.
5697
5698      -  "``debug-without-src``": The same behavior as with the ``.debug``
5699         setting, but no source is packaged at all.
5700
5701      .. note::
5702
5703         Much of the above package splitting can be overridden via
5704         use of the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable.
5705
5706      You can find out more about debugging using GDB by reading the
5707      ":ref:`dev-manual/debugging:debugging with the gnu project debugger (gdb) remotely`" section
5708      in the Yocto Project Development Tasks Manual.
5709
5710   :term:`PACKAGE_EXCLUDE`
5711      Lists packages that should not be installed into an image. For
5712      example::
5713
5714         PACKAGE_EXCLUDE = "package_name package_name package_name ..."
5715
5716      You can set this variable globally in your ``local.conf`` file or you
5717      can attach it to a specific image recipe by using the recipe name
5718      override::
5719
5720         PACKAGE_EXCLUDE:pn-target_image = "package_name"
5721
5722      If you choose to not install a package using this variable and some
5723      other package is dependent on it (i.e. listed in a recipe's
5724      :term:`RDEPENDS` variable), the OpenEmbedded build
5725      system generates a fatal installation error. Because the build system
5726      halts the process with a fatal error, you can use the variable with
5727      an iterative development process to remove specific components from a
5728      system.
5729
5730      This variable is supported only when using the IPK and RPM
5731      packaging backends. DEB is not supported.
5732
5733      See the :term:`NO_RECOMMENDATIONS` and the
5734      :term:`BAD_RECOMMENDATIONS` variables for
5735      related information.
5736
5737   :term:`PACKAGE_EXCLUDE_COMPLEMENTARY`
5738      Prevents specific packages from being installed when you are
5739      installing complementary packages.
5740
5741      You might find that you want to prevent installing certain packages
5742      when you are installing complementary packages. For example, if you
5743      are using :term:`IMAGE_FEATURES` to install
5744      ``dev-pkgs``, you might not want to install all packages from a
5745      particular multilib. If you find yourself in this situation, you can
5746      use the :term:`PACKAGE_EXCLUDE_COMPLEMENTARY` variable to specify regular
5747      expressions to match the packages you want to exclude.
5748
5749   :term:`PACKAGE_EXTRA_ARCHS`
5750      Specifies the list of architectures compatible with the device CPU.
5751      This variable is useful when you build for several different devices
5752      that use miscellaneous processors such as XScale and ARM926-EJS.
5753
5754   :term:`PACKAGE_FEED_ARCHS`
5755      Optionally specifies the package architectures used as part of the
5756      package feed URIs during the build. When used, the
5757      :term:`PACKAGE_FEED_ARCHS` variable is appended to the final package feed
5758      URI, which is constructed using the
5759      :term:`PACKAGE_FEED_URIS` and
5760      :term:`PACKAGE_FEED_BASE_PATHS`
5761      variables.
5762
5763      .. note::
5764
5765         You can use the :term:`PACKAGE_FEED_ARCHS`
5766         variable to allow specific package architectures. If you do
5767         not need to allow specific architectures, which is a common
5768         case, you can omit this variable. Omitting the variable results in
5769         all available architectures for the current machine being included
5770         into remote package feeds.
5771
5772      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5773      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5774      defined in your ``local.conf`` file::
5775
5776         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5777                              https://example.com/packagerepos/updates"
5778         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5779         PACKAGE_FEED_ARCHS = "all core2-64"
5780
5781      Given these settings, the resulting package feeds are as follows:
5782
5783      .. code-block:: none
5784
5785         https://example.com/packagerepos/release/rpm/all
5786         https://example.com/packagerepos/release/rpm/core2-64
5787         https://example.com/packagerepos/release/rpm-dev/all
5788         https://example.com/packagerepos/release/rpm-dev/core2-64
5789         https://example.com/packagerepos/updates/rpm/all
5790         https://example.com/packagerepos/updates/rpm/core2-64
5791         https://example.com/packagerepos/updates/rpm-dev/all
5792         https://example.com/packagerepos/updates/rpm-dev/core2-64
5793
5794   :term:`PACKAGE_FEED_BASE_PATHS`
5795      Specifies the base path used when constructing package feed URIs. The
5796      :term:`PACKAGE_FEED_BASE_PATHS` variable makes up the middle portion of a
5797      package feed URI used by the OpenEmbedded build system. The base path
5798      lies between the :term:`PACKAGE_FEED_URIS`
5799      and :term:`PACKAGE_FEED_ARCHS` variables.
5800
5801      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5802      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5803      defined in your ``local.conf`` file::
5804
5805         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5806                              https://example.com/packagerepos/updates"
5807         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5808         PACKAGE_FEED_ARCHS = "all core2-64"
5809
5810      Given these settings, the resulting package feeds are as follows:
5811
5812      .. code-block:: none
5813
5814         https://example.com/packagerepos/release/rpm/all
5815         https://example.com/packagerepos/release/rpm/core2-64
5816         https://example.com/packagerepos/release/rpm-dev/all
5817         https://example.com/packagerepos/release/rpm-dev/core2-64
5818         https://example.com/packagerepos/updates/rpm/all
5819         https://example.com/packagerepos/updates/rpm/core2-64
5820         https://example.com/packagerepos/updates/rpm-dev/all
5821         https://example.com/packagerepos/updates/rpm-dev/core2-64
5822
5823   :term:`PACKAGE_FEED_URIS`
5824      Specifies the front portion of the package feed URI used by the
5825      OpenEmbedded build system. Each final package feed URI is comprised
5826      of :term:`PACKAGE_FEED_URIS`,
5827      :term:`PACKAGE_FEED_BASE_PATHS`, and
5828      :term:`PACKAGE_FEED_ARCHS` variables.
5829
5830      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5831      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5832      defined in your ``local.conf`` file::
5833
5834         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5835                              https://example.com/packagerepos/updates"
5836         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5837         PACKAGE_FEED_ARCHS = "all core2-64"
5838
5839      Given these settings, the resulting package feeds are as follows:
5840
5841      .. code-block:: none
5842
5843         https://example.com/packagerepos/release/rpm/all
5844         https://example.com/packagerepos/release/rpm/core2-64
5845         https://example.com/packagerepos/release/rpm-dev/all
5846         https://example.com/packagerepos/release/rpm-dev/core2-64
5847         https://example.com/packagerepos/updates/rpm/all
5848         https://example.com/packagerepos/updates/rpm/core2-64
5849         https://example.com/packagerepos/updates/rpm-dev/all
5850         https://example.com/packagerepos/updates/rpm-dev/core2-64
5851
5852   :term:`PACKAGE_INSTALL`
5853      The final list of packages passed to the package manager for
5854      installation into the image.
5855
5856      Because the package manager controls actual installation of all
5857      packages, the list of packages passed using :term:`PACKAGE_INSTALL` is
5858      not the final list of packages that are actually installed. This
5859      variable is internal to the image construction code. Consequently, in
5860      general, you should use the
5861      :term:`IMAGE_INSTALL` variable to specify
5862      packages for installation. The exception to this is when working with
5863      the :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
5864      image. When working with an initial RAM filesystem (:term:`Initramfs`) image,
5865      use the :term:`PACKAGE_INSTALL` variable. For information on creating an
5866      :term:`Initramfs`, see the ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" section
5867      in the Yocto Project Development Tasks Manual.
5868
5869   :term:`PACKAGE_INSTALL_ATTEMPTONLY`
5870      Specifies a list of packages the OpenEmbedded build system attempts
5871      to install when creating an image. If a listed package fails to
5872      install, the build system does not generate an error. This variable
5873      is generally not user-defined.
5874
5875   :term:`PACKAGE_PREPROCESS_FUNCS`
5876      Specifies a list of functions run to pre-process the
5877      :term:`PKGD` directory prior to splitting the files out
5878      to individual packages.
5879
5880   :term:`PACKAGE_WRITE_DEPS`
5881      Specifies a list of dependencies for post-installation and
5882      pre-installation scripts on native/cross tools. If your
5883      post-installation or pre-installation script can execute at root filesystem
5884      creation time rather than on the target but depends on a native tool
5885      in order to execute, you need to list the tools in
5886      :term:`PACKAGE_WRITE_DEPS`.
5887
5888      For information on running post-installation scripts, see the
5889      ":ref:`dev-manual/new-recipe:post-installation scripts`"
5890      section in the Yocto Project Development Tasks Manual.
5891
5892   :term:`PACKAGECONFIG`
5893      This variable provides a means of enabling or disabling features of a
5894      recipe on a per-recipe basis. :term:`PACKAGECONFIG` blocks are defined in
5895      recipes when you specify features and then arguments that define
5896      feature behaviors. Here is the basic block structure (broken over
5897      multiple lines for readability)::
5898
5899         PACKAGECONFIG ??= "f1 f2 f3 ..."
5900         PACKAGECONFIG[f1] = "\
5901             --with-f1, \
5902             --without-f1, \
5903             build-deps-for-f1, \
5904             runtime-deps-for-f1, \
5905             runtime-recommends-for-f1, \
5906             packageconfig-conflicts-for-f1"
5907         PACKAGECONFIG[f2] = "\
5908              ... and so on and so on ...
5909
5910      The :term:`PACKAGECONFIG` variable itself specifies a space-separated
5911      list of the features to enable. Following the features, you can
5912      determine the behavior of each feature by providing up to six
5913      order-dependent arguments, which are separated by commas. You can
5914      omit any argument you like but must retain the separating commas. The
5915      order is important and specifies the following:
5916
5917      #. Extra arguments that should be added to the configure script
5918         argument list (:term:`EXTRA_OECONF` or
5919         :term:`PACKAGECONFIG_CONFARGS`) if
5920         the feature is enabled.
5921
5922      #. Extra arguments that should be added to :term:`EXTRA_OECONF` or
5923         :term:`PACKAGECONFIG_CONFARGS` if the feature is disabled.
5924
5925      #. Additional build dependencies (:term:`DEPENDS`)
5926         that should be added if the feature is enabled.
5927
5928      #. Additional runtime dependencies (:term:`RDEPENDS`)
5929         that should be added if the feature is enabled.
5930
5931      #. Additional runtime recommendations
5932         (:term:`RRECOMMENDS`) that should be added if
5933         the feature is enabled.
5934
5935      #. Any conflicting (that is, mutually exclusive) :term:`PACKAGECONFIG`
5936         settings for this feature.
5937
5938      Consider the following :term:`PACKAGECONFIG` block taken from the
5939      ``librsvg`` recipe. In this example the feature is ``gtk``, which has
5940      three arguments that determine the feature's behavior::
5941
5942         PACKAGECONFIG[gtk] = "--with-gtk3,--without-gtk3,gtk+3"
5943
5944      The
5945      ``--with-gtk3`` and ``gtk+3`` arguments apply only if the feature is
5946      enabled. In this case, ``--with-gtk3`` is added to the configure
5947      script argument list and ``gtk+3`` is added to :term:`DEPENDS`. On the
5948      other hand, if the feature is disabled say through a ``.bbappend``
5949      file in another layer, then the second argument ``--without-gtk3`` is
5950      added to the configure script instead.
5951
5952      The basic :term:`PACKAGECONFIG` structure previously described holds true
5953      regardless of whether you are creating a block or changing a block.
5954      When creating a block, use the structure inside your recipe.
5955
5956      If you want to change an existing :term:`PACKAGECONFIG` block, you can do
5957      so one of two ways:
5958
5959      -  *Append file:* Create an append file named
5960         ``recipename.bbappend`` in your layer and override the value of
5961         :term:`PACKAGECONFIG`. You can either completely override the
5962         variable::
5963
5964            PACKAGECONFIG = "f4 f5"
5965
5966         Or, you can just append the variable::
5967
5968            PACKAGECONFIG:append = " f4"
5969
5970      -  *Configuration file:* This method is identical to changing the
5971         block through an append file except you edit your ``local.conf``
5972         or ``mydistro.conf`` file. As with append files previously
5973         described, you can either completely override the variable::
5974
5975            PACKAGECONFIG:pn-recipename = "f4 f5"
5976
5977         Or, you can just amend the variable::
5978
5979            PACKAGECONFIG:append:pn-recipename = " f4"
5980
5981   :term:`PACKAGECONFIG_CONFARGS`
5982      A space-separated list of configuration options generated from the
5983      :term:`PACKAGECONFIG` setting.
5984
5985      Classes such as :ref:`ref-classes-autotools` and :ref:`ref-classes-cmake`
5986      use :term:`PACKAGECONFIG_CONFARGS` to pass :term:`PACKAGECONFIG` options
5987      to ``configure`` and ``cmake``, respectively. If you are using
5988      :term:`PACKAGECONFIG` but not a class that handles the
5989      :ref:`ref-tasks-configure` task, then you need to use
5990      :term:`PACKAGECONFIG_CONFARGS` appropriately.
5991
5992   :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY`
5993      For recipes inheriting the :ref:`ref-classes-packagegroup` class, setting
5994      :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY` to "1" specifies that the
5995      normal complementary packages (i.e. ``-dev``, ``-dbg``, and so forth)
5996      should not be automatically created by the ``packagegroup`` recipe,
5997      which is the default behavior.
5998
5999   :term:`PACKAGES`
6000      The list of packages the recipe creates. The default value is the
6001      following::
6002
6003         ${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
6004
6005      During packaging, the :ref:`ref-tasks-package` task
6006      goes through :term:`PACKAGES` and uses the :term:`FILES`
6007      variable corresponding to each package to assign files to the
6008      package. If a file matches the :term:`FILES` variable for more than one
6009      package in :term:`PACKAGES`, it will be assigned to the earliest
6010      (leftmost) package.
6011
6012      Packages in the variable's list that are empty (i.e. where none of
6013      the patterns in ``FILES:``\ pkg match any files installed by the
6014      :ref:`ref-tasks-install` task) are not generated,
6015      unless generation is forced through the
6016      :term:`ALLOW_EMPTY` variable.
6017
6018   :term:`PACKAGES_DYNAMIC`
6019      A promise that your recipe satisfies runtime dependencies for
6020      optional modules that are found in other recipes.
6021      :term:`PACKAGES_DYNAMIC` does not actually satisfy the dependencies, it
6022      only states that they should be satisfied. For example, if a hard,
6023      runtime dependency (:term:`RDEPENDS`) of another
6024      package is satisfied at build time through the :term:`PACKAGES_DYNAMIC`
6025      variable, but a package with the module name is never actually
6026      produced, then the other package will be broken. Thus, if you attempt
6027      to include that package in an image, you will get a dependency
6028      failure from the packaging system during the
6029      :ref:`ref-tasks-rootfs` task.
6030
6031      Typically, if there is a chance that such a situation can occur and
6032      the package that is not created is valid without the dependency being
6033      satisfied, then you should use :term:`RRECOMMENDS`
6034      (a soft runtime dependency) instead of :term:`RDEPENDS`.
6035
6036      For an example of how to use the :term:`PACKAGES_DYNAMIC` variable when
6037      you are splitting packages, see the
6038      ":ref:`dev-manual/packages:handling optional module packaging`"
6039      section in the Yocto Project Development Tasks Manual.
6040
6041   :term:`PACKAGESPLITFUNCS`
6042      Specifies a list of functions run to perform additional splitting of
6043      files into individual packages. Recipes can either prepend to this
6044      variable or prepend to the ``populate_packages`` function in order to
6045      perform additional package splitting. In either case, the function
6046      should set :term:`PACKAGES`,
6047      :term:`FILES`, :term:`RDEPENDS` and
6048      other packaging variables appropriately in order to perform the
6049      desired splitting.
6050
6051   :term:`PARALLEL_MAKE`
6052
6053      Extra options passed to the build tool command (``make``,
6054      ``ninja`` or more specific build engines, like the Go language one)
6055      during the :ref:`ref-tasks-compile` task, to specify parallel compilation
6056      on the local build host. This variable is usually in the form "-j x",
6057      where x represents the maximum number of parallel threads such engines
6058      can run.
6059
6060      .. note::
6061
6062         For software compiled by ``make``, in order for :term:`PARALLEL_MAKE`
6063         to be effective, ``make`` must be called with
6064         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
6065         way to ensure this is to use the ``oe_runmake`` function.
6066
6067      By default, the OpenEmbedded build system automatically sets this
6068      variable to be equal to the number of cores the build system uses.
6069
6070      .. note::
6071
6072         If the software being built experiences dependency issues during
6073         the :ref:`ref-tasks-compile` task that result in race conditions, you can clear
6074         the :term:`PARALLEL_MAKE` variable within the recipe as a workaround. For
6075         information on addressing race conditions, see the
6076         ":ref:`dev-manual/debugging:debugging parallel make races`"
6077         section in the Yocto Project Development Tasks Manual.
6078
6079      For single socket systems (i.e. one CPU), you should not have to
6080      override this variable to gain optimal parallelism during builds.
6081      However, if you have very large systems that employ multiple physical
6082      CPUs, you might want to make sure the :term:`PARALLEL_MAKE` variable is
6083      not set higher than "-j 20".
6084
6085      For more information on speeding up builds, see the
6086      ":ref:`dev-manual/speeding-up-build:speeding up a build`"
6087      section in the Yocto Project Development Tasks Manual.
6088
6089   :term:`PARALLEL_MAKEINST`
6090      Extra options passed to the build tool install command
6091      (``make install``, ``ninja install`` or more specific ones)
6092      during the :ref:`ref-tasks-install` task in order to specify
6093      parallel installation. This variable defaults to the value of
6094      :term:`PARALLEL_MAKE`.
6095
6096      .. note::
6097
6098         For software compiled by ``make``, in order for :term:`PARALLEL_MAKEINST`
6099         to be effective, ``make`` must be called with
6100         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
6101         way to ensure this is to use the ``oe_runmake`` function.
6102
6103         If the software being built experiences dependency issues during
6104         the :ref:`ref-tasks-install` task that result in race conditions, you can
6105         clear the :term:`PARALLEL_MAKEINST` variable within the recipe as a
6106         workaround. For information on addressing race conditions, see the
6107         ":ref:`dev-manual/debugging:debugging parallel make races`"
6108         section in the Yocto Project Development Tasks Manual.
6109
6110   :term:`PATCHRESOLVE`
6111      Determines the action to take when a patch fails. You can set this
6112      variable to one of two values: "noop" and "user".
6113
6114      The default value of "noop" causes the build to simply fail when the
6115      OpenEmbedded build system cannot successfully apply a patch. Setting
6116      the value to "user" causes the build system to launch a shell and
6117      places you in the right location so that you can manually resolve the
6118      conflicts.
6119
6120      Set this variable in your ``local.conf`` file.
6121
6122   :term:`PATCHTOOL`
6123      Specifies the utility used to apply patches for a recipe during the
6124      :ref:`ref-tasks-patch` task. You can specify one of
6125      three utilities: "patch", "quilt", or "git". The default utility used
6126      is "quilt" except for the quilt-native recipe itself. Because the
6127      quilt tool is not available at the time quilt-native is being
6128      patched, it uses "patch".
6129
6130      If you wish to use an alternative patching tool, set the variable in
6131      the recipe using one of the following::
6132
6133         PATCHTOOL = "patch"
6134         PATCHTOOL = "quilt"
6135         PATCHTOOL = "git"
6136
6137   :term:`PE`
6138      The epoch of the recipe. By default, this variable is unset. The
6139      variable is used to make upgrades possible when the versioning scheme
6140      changes in some backwards incompatible way.
6141
6142      :term:`PE` is the default value of the :term:`PKGE` variable.
6143
6144   :term:`PEP517_WHEEL_PATH`
6145      When used by recipes that inherit the :ref:`ref-classes-python_pep517`
6146      class, denotes the path to ``dist/`` (short for distribution) where the
6147      binary archive ``wheel`` is built.
6148
6149   :term:`PERSISTENT_DIR`
6150      See :term:`bitbake:PERSISTENT_DIR` in the BitBake manual.
6151
6152   :term:`PF`
6153      Specifies the recipe or package name and includes all version and
6154      revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
6155      ``bash-4.2-r1/``). This variable is comprised of the following:
6156      ${:term:`PN`}-${:term:`EXTENDPE`}${:term:`PV`}-${:term:`PR`}
6157
6158   :term:`PIXBUF_PACKAGES`
6159      When inheriting the :ref:`ref-classes-pixbufcache`
6160      class, this variable identifies packages that contain the pixbuf
6161      loaders used with ``gdk-pixbuf``. By default, the
6162      :ref:`ref-classes-pixbufcache` class assumes that
6163      the loaders are in the recipe's main package (i.e.
6164      ``${``\ :term:`PN`\ ``}``). Use this variable if the
6165      loaders you need are in a package other than that main package.
6166
6167   :term:`PKG`
6168      The name of the resulting package created by the OpenEmbedded build
6169      system.
6170
6171      .. note::
6172
6173         When using the :term:`PKG` variable, you must use a package name override.
6174
6175      For example, when the :ref:`ref-classes-debian` class renames the output
6176      package, it does so by setting ``PKG:packagename``.
6177
6178   :term:`PKG_CONFIG_PATH`
6179      The path to ``pkg-config`` files for the current build context.
6180      ``pkg-config`` reads this variable from the environment.
6181
6182   :term:`PKGD`
6183      Points to the destination directory for files to be packaged before
6184      they are split into individual packages. This directory defaults to
6185      the following::
6186
6187         ${WORKDIR}/package
6188
6189      Do not change this default.
6190
6191   :term:`PKGDATA_DIR`
6192      Points to a shared, global-state directory that holds data generated
6193      during the packaging process. During the packaging process, the
6194      :ref:`ref-tasks-packagedata` task packages data
6195      for each recipe and installs it into this temporary, shared area.
6196      This directory defaults to the following, which you should not
6197      change::
6198
6199         ${STAGING_DIR_HOST}/pkgdata
6200
6201      For examples of how this data is used, see the
6202      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6203      section in the Yocto Project Overview and Concepts Manual and the
6204      ":ref:`dev-manual/debugging:viewing package information with \`\`oe-pkgdata-util\`\``"
6205      section in the Yocto Project Development Tasks Manual. For more
6206      information on the shared, global-state directory, see
6207      :term:`STAGING_DIR_HOST`.
6208
6209   :term:`PKGDEST`
6210      Points to the parent directory for files to be packaged after they
6211      have been split into individual packages. This directory defaults to
6212      the following::
6213
6214         ${WORKDIR}/packages-split
6215
6216      Under this directory, the build system creates directories for each
6217      package specified in :term:`PACKAGES`. Do not change
6218      this default.
6219
6220   :term:`PKGDESTWORK`
6221      Points to a temporary work area where the
6222      :ref:`ref-tasks-package` task saves package metadata.
6223      The :term:`PKGDESTWORK` location defaults to the following::
6224
6225         ${WORKDIR}/pkgdata
6226
6227      Do not change this default.
6228
6229      The :ref:`ref-tasks-packagedata` task copies the
6230      package metadata from :term:`PKGDESTWORK` to
6231      :term:`PKGDATA_DIR` to make it available globally.
6232
6233   :term:`PKGE`
6234      The epoch of the package(s) built by the recipe. By default, :term:`PKGE`
6235      is set to :term:`PE`.
6236
6237   :term:`PKGR`
6238      The revision of the package(s) built by the recipe. By default,
6239      :term:`PKGR` is set to :term:`PR`.
6240
6241   :term:`PKGV`
6242      The version of the package(s) built by the recipe. By default,
6243      :term:`PKGV` is set to :term:`PV`.
6244
6245   :term:`PN`
6246      This variable can have two separate functions depending on the
6247      context: a recipe name or a resulting package name.
6248
6249      :term:`PN` refers to a recipe name in the context of a file used by the
6250      OpenEmbedded build system as input to create a package. The name is
6251      normally extracted from the recipe file name. For example, if the
6252      recipe is named ``expat_2.0.1.bb``, then the default value of :term:`PN`
6253      will be "expat".
6254
6255      The variable refers to a package name in the context of a file
6256      created or produced by the OpenEmbedded build system.
6257
6258      If applicable, the :term:`PN` variable also contains any special suffix
6259      or prefix. For example, using ``bash`` to build packages for the
6260      native machine, :term:`PN` is ``bash-native``. Using ``bash`` to build
6261      packages for the target and for Multilib, :term:`PN` would be ``bash``
6262      and ``lib64-bash``, respectively.
6263
6264   :term:`POPULATE_SDK_POST_HOST_COMMAND`
6265      Specifies a list of functions to call once the OpenEmbedded build
6266      system has created the host part of the SDK. You can specify
6267      functions separated by semicolons::
6268
6269          POPULATE_SDK_POST_HOST_COMMAND += "function; ... "
6270
6271      If you need to pass the SDK path to a command within a function, you
6272      can use ``${SDK_DIR}``, which points to the parent directory used by
6273      the OpenEmbedded build system when creating SDK output. See the
6274      :term:`SDK_DIR` variable for more information.
6275
6276   :term:`POPULATE_SDK_POST_TARGET_COMMAND`
6277      Specifies a list of functions to call once the OpenEmbedded build
6278      system has created the target part of the SDK. You can specify
6279      functions separated by semicolons::
6280
6281         POPULATE_SDK_POST_TARGET_COMMAND += "function; ... "
6282
6283      If you need to pass the SDK path to a command within a function, you
6284      can use ``${SDK_DIR}``, which points to the parent directory used by
6285      the OpenEmbedded build system when creating SDK output. See the
6286      :term:`SDK_DIR` variable for more information.
6287
6288   :term:`PR`
6289      The revision of the recipe. The default value for this variable is
6290      "r0". Subsequent revisions of the recipe conventionally have the
6291      values "r1", "r2", and so forth. When :term:`PV` increases,
6292      :term:`PR` is conventionally reset to "r0".
6293
6294      .. note::
6295
6296         The OpenEmbedded build system does not need the aid of :term:`PR`
6297         to know when to rebuild a recipe. The build system uses the task
6298         :ref:`input checksums <overview-manual/concepts:checksums (signatures)>` along with the
6299         :ref:`stamp <structure-build-tmp-stamps>` and
6300         :ref:`overview-manual/concepts:shared state cache`
6301         mechanisms.
6302
6303      The :term:`PR` variable primarily becomes significant when a package
6304      manager dynamically installs packages on an already built image. In
6305      this case, :term:`PR`, which is the default value of
6306      :term:`PKGR`, helps the package manager distinguish which
6307      package is the most recent one in cases where many packages have the
6308      same :term:`PV` (i.e. :term:`PKGV`). A component having many packages with
6309      the same :term:`PV` usually means that the packages all install the same
6310      upstream version, but with later (:term:`PR`) version packages including
6311      packaging fixes.
6312
6313      .. note::
6314
6315         :term:`PR` does not need to be increased for changes that do not change the
6316         package contents or metadata.
6317
6318      Because manually managing :term:`PR` can be cumbersome and error-prone,
6319      an automated solution exists. See the
6320      ":ref:`dev-manual/packages:working with a pr service`" section
6321      in the Yocto Project Development Tasks Manual for more information.
6322
6323   :term:`PREFERRED_PROVIDER`
6324      If multiple recipes provide the same item, this variable determines
6325      which recipe is preferred and thus provides the item (i.e. the
6326      preferred provider). You should always suffix this variable with the
6327      name of the provided item. And, you should define the variable using
6328      the preferred recipe's name (:term:`PN`). Here is a common
6329      example::
6330
6331         PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
6332
6333      In the previous example, multiple recipes are providing "virtual/kernel".
6334      The :term:`PREFERRED_PROVIDER` variable is set with the name (:term:`PN`) of
6335      the recipe you prefer to provide "virtual/kernel".
6336
6337      Following are more examples::
6338
6339         PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
6340         PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
6341
6342      For more
6343      information, see the ":ref:`dev-manual/new-recipe:using virtual providers`"
6344      section in the Yocto Project Development Tasks Manual.
6345
6346      .. note::
6347
6348         If you use a ``virtual/\*`` item with :term:`PREFERRED_PROVIDER`, then any
6349         recipe that :term:`PROVIDES` that item but is not selected (defined)
6350         by :term:`PREFERRED_PROVIDER` is prevented from building, which is usually
6351         desirable since this mechanism is designed to select between mutually
6352         exclusive alternative providers.
6353
6354   :term:`PREFERRED_PROVIDERS`
6355      See :term:`bitbake:PREFERRED_PROVIDERS` in the BitBake manual.
6356
6357   :term:`PREFERRED_VERSION`
6358      If there are multiple versions of a recipe available, this variable
6359      determines which version should be given preference. You must always
6360      suffix the variable with the :term:`PN` you want to select (`python` in
6361      the first example below), and you should specify the :term:`PV`
6362      accordingly (`3.4.0` in the example).
6363
6364      The :term:`PREFERRED_VERSION` variable supports limited wildcard use
6365      through the "``%``" character. You can use the character to match any
6366      number of characters, which can be useful when specifying versions
6367      that contain long revision numbers that potentially change. Here are
6368      two examples::
6369
6370         PREFERRED_VERSION_python = "3.4.0"
6371         PREFERRED_VERSION_linux-yocto = "5.0%"
6372
6373      .. note::
6374
6375         The use of the "%" character is limited in that it only works at the end of the
6376         string. You cannot use the wildcard character in any other
6377         location of the string.
6378
6379      The specified version is matched against :term:`PV`, which
6380      does not necessarily match the version part of the recipe's filename.
6381      For example, consider two recipes ``foo_1.2.bb`` and ``foo_git.bb``
6382      where ``foo_git.bb`` contains the following assignment::
6383
6384         PV = "1.1+git${SRCPV}"
6385
6386      In this case, the correct way to select
6387      ``foo_git.bb`` is by using an assignment such as the following::
6388
6389         PREFERRED_VERSION_foo = "1.1+git%"
6390
6391      Compare that previous example
6392      against the following incorrect example, which does not work::
6393
6394         PREFERRED_VERSION_foo = "git"
6395
6396      Sometimes the :term:`PREFERRED_VERSION` variable can be set by
6397      configuration files in a way that is hard to change. You can use
6398      :term:`OVERRIDES` to set a machine-specific
6399      override. Here is an example::
6400
6401         PREFERRED_VERSION_linux-yocto:qemux86 = "5.0%"
6402
6403      Although not recommended, worst case, you can also use the
6404      "forcevariable" override, which is the strongest override possible.
6405      Here is an example::
6406
6407         PREFERRED_VERSION_linux-yocto:forcevariable = "5.0%"
6408
6409      .. note::
6410
6411         The ``:forcevariable`` override is not handled specially. This override
6412         only works because the default value of :term:`OVERRIDES` includes "forcevariable".
6413
6414      If a recipe with the specified version is not available, a warning
6415      message will be shown. See :term:`REQUIRED_VERSION` if you want this
6416      to be an error instead.
6417
6418   :term:`PREMIRRORS`
6419      Specifies additional paths from which the OpenEmbedded build system
6420      gets source code. When the build system searches for source code, it
6421      first tries the local download directory. If that location fails, the
6422      build system tries locations defined by :term:`PREMIRRORS`, the upstream
6423      source, and then locations specified by
6424      :term:`MIRRORS` in that order.
6425
6426      Assuming your distribution (:term:`DISTRO`) is "poky",
6427      the default value for :term:`PREMIRRORS` is defined in the
6428      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
6429
6430      Typically, you could add a specific server for the build system to
6431      attempt before any others by adding something like the following to
6432      the ``local.conf`` configuration file in the
6433      :term:`Build Directory`::
6434
6435         PREMIRRORS:prepend = "\
6436             git://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6437             ftp://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6438             http://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
6439             https://.*/.* &YOCTO_DL_URL;/mirror/sources/"
6440
6441      These changes cause the
6442      build system to intercept Git, FTP, HTTP, and HTTPS requests and
6443      direct them to the ``http://`` sources mirror. You can use
6444      ``file://`` URLs to point to local directories or network shares as
6445      well.
6446
6447   :term:`PRIORITY`
6448      Indicates the importance of a package.
6449
6450      :term:`PRIORITY` is considered to be part of the distribution policy
6451      because the importance of any given recipe depends on the purpose for
6452      which the distribution is being produced. Thus, :term:`PRIORITY` is not
6453      normally set within recipes.
6454
6455      You can set :term:`PRIORITY` to "required", "standard", "extra", and
6456      "optional", which is the default.
6457
6458   :term:`PRIVATE_LIBS`
6459      Specifies libraries installed within a recipe that should be ignored
6460      by the OpenEmbedded build system's shared library resolver. This
6461      variable is typically used when software being built by a recipe has
6462      its own private versions of a library normally provided by another
6463      recipe. In this case, you would not want the package containing the
6464      private libraries to be set as a dependency on other unrelated
6465      packages that should instead depend on the package providing the
6466      standard version of the library.
6467
6468      Libraries specified in this variable should be specified by their
6469      file name. For example, from the Firefox recipe in meta-browser::
6470
6471         PRIVATE_LIBS = "libmozjs.so \
6472                         libxpcom.so \
6473                         libnspr4.so \
6474                         libxul.so \
6475                         libmozalloc.so \
6476                         libplc4.so \
6477                         libplds4.so"
6478
6479      For more information, see the
6480      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6481      section in the Yocto Project Overview and Concepts Manual.
6482
6483   :term:`PROVIDES`
6484      A list of aliases by which a particular recipe can be known. By
6485      default, a recipe's own :term:`PN` is implicitly already in its
6486      :term:`PROVIDES` list and therefore does not need to mention that it
6487      provides itself. If a recipe uses :term:`PROVIDES`, the additional
6488      aliases are synonyms for the recipe and can be useful for satisfying
6489      dependencies of other recipes during the build as specified by
6490      :term:`DEPENDS`.
6491
6492      Consider the following example :term:`PROVIDES` statement from the recipe
6493      file ``eudev_3.2.9.bb``::
6494
6495         PROVIDES += "udev"
6496
6497      The :term:`PROVIDES` statement
6498      results in the "eudev" recipe also being available as simply "udev".
6499
6500      .. note::
6501
6502         A recipe's own recipe name (:term:`PN`) is always implicitly prepended
6503         to :term:`PROVIDES`, so while using "+=" in the above example may not be
6504         strictly necessary it is recommended to avoid confusion.
6505
6506      In addition to providing recipes under alternate names, the
6507      :term:`PROVIDES` mechanism is also used to implement virtual targets. A
6508      virtual target is a name that corresponds to some particular
6509      functionality (e.g. a Linux kernel). Recipes that provide the
6510      functionality in question list the virtual target in :term:`PROVIDES`.
6511      Recipes that depend on the functionality in question can include the
6512      virtual target in :term:`DEPENDS` to leave the choice of provider open.
6513
6514      Conventionally, virtual targets have names on the form
6515      "virtual/function" (e.g. "virtual/kernel"). The slash is simply part
6516      of the name and has no syntactical significance.
6517
6518      The :term:`PREFERRED_PROVIDER` variable is
6519      used to select which particular recipe provides a virtual target.
6520
6521      .. note::
6522
6523         A corresponding mechanism for virtual runtime dependencies
6524         (packages) exists. However, the mechanism does not depend on any
6525         special functionality beyond ordinary variable assignments. For
6526         example, ``VIRTUAL-RUNTIME_dev_manager`` refers to the package of
6527         the component that manages the ``/dev`` directory.
6528
6529         Setting the "preferred provider" for runtime dependencies is as
6530         simple as using the following assignment in a configuration file::
6531
6532                 VIRTUAL-RUNTIME_dev_manager = "udev"
6533
6534
6535   :term:`PRSERV_HOST`
6536      The network based :term:`PR` service host and port.
6537
6538      The ``conf/templates/default/local.conf.sample.extended`` configuration
6539      file in the :term:`Source Directory` shows how the :term:`PRSERV_HOST`
6540      variable is set::
6541
6542         PRSERV_HOST = "localhost:0"
6543
6544      You must
6545      set the variable if you want to automatically start a local :ref:`PR
6546      service <dev-manual/packages:working with a pr service>`. You can
6547      set :term:`PRSERV_HOST` to other values to use a remote PR service.
6548
6549
6550   :term:`PSEUDO_IGNORE_PATHS`
6551      A comma-separated (without spaces) list of path prefixes that should be ignored
6552      by pseudo when monitoring and recording file operations, in order to avoid
6553      problems with files being written to outside of the pseudo context and
6554      reduce pseudo's overhead. A path is ignored if it matches any prefix in the list
6555      and can include partial directory (or file) names.
6556
6557
6558   :term:`PTEST_ENABLED`
6559      Specifies whether or not :ref:`Package
6560      Test <dev-manual/packages:testing packages with ptest>` (ptest)
6561      functionality is enabled when building a recipe. You should not set
6562      this variable directly. Enabling and disabling building Package Tests
6563      at build time should be done by adding "ptest" to (or removing it
6564      from) :term:`DISTRO_FEATURES`.
6565
6566   :term:`PV`
6567      The version of the recipe. The version is normally extracted from the
6568      recipe filename. For example, if the recipe is named
6569      ``expat_2.0.1.bb``, then the default value of :term:`PV` will be "2.0.1".
6570      :term:`PV` is generally not overridden within a recipe unless it is
6571      building an unstable (i.e. development) version from a source code
6572      repository (e.g. Git or Subversion).
6573
6574      :term:`PV` is the default value of the :term:`PKGV` variable.
6575
6576   :term:`PYPI_PACKAGE`
6577      When inheriting the :ref:`ref-classes-pypi` class, specifies the
6578      `PyPI <https://pypi.org/>`__ package name to be built. The default value
6579      is set based upon :term:`BPN` (stripping any "python-" or "python3-"
6580      prefix off if present), however for some packages it will need to be set
6581      explicitly if that will not match the package name (e.g. where the
6582      package name has a prefix, underscores, uppercase letters etc.)
6583
6584   :term:`PYTHON_ABI`
6585      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
6586      class, denotes the Application Binary Interface (ABI) currently in use
6587      for Python. By default, the ABI is "m". You do not have to set this
6588      variable as the OpenEmbedded build system sets it for you.
6589
6590      The OpenEmbedded build system uses the ABI to construct directory
6591      names used when installing the Python headers and libraries in
6592      sysroot (e.g. ``.../python3.3m/...``).
6593
6594   :term:`PYTHON_PN`
6595      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
6596      class, specifies the major Python version being built. For Python 3.x,
6597      :term:`PYTHON_PN` would be "python3". You do not have to set this
6598      variable as the OpenEmbedded build system automatically sets it for you.
6599
6600      The variable allows recipes to use common infrastructure such as the
6601      following::
6602
6603         DEPENDS += "${PYTHON_PN}-native"
6604
6605      In the previous example,
6606      the version of the dependency is :term:`PYTHON_PN`.
6607
6608   :term:`QA_EMPTY_DIRS`
6609      Specifies a list of directories that are expected to be empty when
6610      packaging; if ``empty-dirs`` appears in :term:`ERROR_QA` or
6611      :term:`WARN_QA` these will be checked and an error or warning
6612      (respectively) will be produced.
6613
6614      The default :term:`QA_EMPTY_DIRS` value is set in
6615      :ref:`insane.bbclass <ref-classes-insane>`.
6616
6617   :term:`QA_EMPTY_DIRS_RECOMMENDATION`
6618      Specifies a recommendation for why a directory must be empty,
6619      which will be included in the error message if a specific directory
6620      is found to contain files. Must be overridden with the directory
6621      path to match on.
6622
6623      If no recommendation is specified for a directory, then the default
6624      "but it is expected to be empty" will be used.
6625
6626      An example message shows if files were present in '/dev'::
6627
6628         QA_EMPTY_DIRS_RECOMMENDATION:/dev = "but all devices must be created at runtime"
6629
6630   :term:`RANLIB`
6631      The minimal command and arguments to run ``ranlib``.
6632
6633   :term:`RCONFLICTS`
6634      The list of packages that conflict with packages. Note that packages
6635      will not be installed if conflicting packages are not first removed.
6636
6637      Like all package-controlling variables, you must always use them in
6638      conjunction with a package name override. Here is an example::
6639
6640         RCONFLICTS:${PN} = "another_conflicting_package_name"
6641
6642      BitBake, which the OpenEmbedded build system uses, supports
6643      specifying versioned dependencies. Although the syntax varies
6644      depending on the packaging format, BitBake hides these differences
6645      from you. Here is the general syntax to specify versions with the
6646      :term:`RCONFLICTS` variable::
6647
6648         RCONFLICTS:${PN} = "package (operator version)"
6649
6650      For ``operator``, you can specify the following:
6651
6652      - =
6653      - <
6654      - >
6655      - <=
6656      - >=
6657
6658      For example, the following sets up a dependency on version 1.2 or
6659      greater of the package ``foo``::
6660
6661         RCONFLICTS:${PN} = "foo (>= 1.2)"
6662
6663   :term:`RDEPENDS`
6664      Lists runtime dependencies of a package. These dependencies are other
6665      packages that must be installed in order for the package to function
6666      correctly. As an example, the following assignment declares that the
6667      package ``foo`` needs the packages ``bar`` and ``baz`` to be
6668      installed::
6669
6670         RDEPENDS:foo = "bar baz"
6671
6672      The most common types of package
6673      runtime dependencies are automatically detected and added. Therefore,
6674      most recipes do not need to set :term:`RDEPENDS`. For more information,
6675      see the
6676      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6677      section in the Yocto Project Overview and Concepts Manual.
6678
6679      The practical effect of the above :term:`RDEPENDS` assignment is that
6680      ``bar`` and ``baz`` will be declared as dependencies inside the
6681      package ``foo`` when it is written out by one of the
6682      :ref:`do_package_write_* <ref-tasks-package_write_deb>` tasks.
6683      Exactly how this is done depends on which package format is used,
6684      which is determined by
6685      :term:`PACKAGE_CLASSES`. When the
6686      corresponding package manager installs the package, it will know to
6687      also install the packages on which it depends.
6688
6689      To ensure that the packages ``bar`` and ``baz`` get built, the
6690      previous :term:`RDEPENDS` assignment also causes a task dependency to be
6691      added. This dependency is from the recipe's
6692      :ref:`ref-tasks-build` (not to be confused with
6693      :ref:`ref-tasks-compile`) task to the
6694      :ref:`do_package_write_* <ref-tasks-package_write_deb>` task of the recipes that build ``bar`` and
6695      ``baz``.
6696
6697      The names of the packages you list within :term:`RDEPENDS` must be the
6698      names of other packages --- they cannot be recipe names. Although
6699      package names and recipe names usually match, the important point
6700      here is that you are providing package names within the :term:`RDEPENDS`
6701      variable. For an example of the default list of packages created from
6702      a recipe, see the :term:`PACKAGES` variable.
6703
6704      Because the :term:`RDEPENDS` variable applies to packages being built,
6705      you should always use the variable in a form with an attached package
6706      name (remember that a single recipe can build multiple packages). For
6707      example, suppose you are building a development package that depends
6708      on the ``perl`` package. In this case, you would use the following
6709      :term:`RDEPENDS` statement::
6710
6711         RDEPENDS:${PN}-dev += "perl"
6712
6713      In the example,
6714      the development package depends on the ``perl`` package. Thus, the
6715      :term:`RDEPENDS` variable has the ``${PN}-dev`` package name as part of
6716      the variable.
6717
6718      .. note::
6719
6720         ``RDEPENDS:${PN}-dev`` includes ``${``\ :term:`PN`\ ``}``
6721         by default. This default is set in the BitBake configuration file
6722         (``meta/conf/bitbake.conf``). Be careful not to accidentally remove
6723         ``${PN}`` when modifying ``RDEPENDS:${PN}-dev``. Use the "+=" operator
6724         rather than the "=" operator.
6725
6726      The package names you use with :term:`RDEPENDS` must appear as they would
6727      in the :term:`PACKAGES` variable. The :term:`PKG` variable
6728      allows a different name to be used for the final package (e.g. the
6729      :ref:`ref-classes-debian` class uses this to rename
6730      packages), but this final package name cannot be used with
6731      :term:`RDEPENDS`, which makes sense as :term:`RDEPENDS` is meant to be
6732      independent of the package format used.
6733
6734      BitBake, which the OpenEmbedded build system uses, supports
6735      specifying versioned dependencies. Although the syntax varies
6736      depending on the packaging format, BitBake hides these differences
6737      from you. Here is the general syntax to specify versions with the
6738      :term:`RDEPENDS` variable::
6739
6740         RDEPENDS:${PN} = "package (operator version)"
6741
6742      For ``operator``, you can specify the following:
6743
6744      - =
6745      - <
6746      - >
6747      - <=
6748      - >=
6749
6750      For version, provide the version number.
6751
6752      .. note::
6753
6754         You can use :term:`EXTENDPKGV` to provide a full package version
6755         specification.
6756
6757      For example, the following sets up a dependency on version 1.2 or
6758      greater of the package ``foo``::
6759
6760         RDEPENDS:${PN} = "foo (>= 1.2)"
6761
6762      For information on build-time dependencies, see the :term:`DEPENDS`
6763      variable. You can also see the
6764      ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
6765      ":ref:`bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
6766      BitBake User Manual for additional information on tasks and dependencies.
6767
6768   :term:`RECIPE_NO_UPDATE_REASON`
6769      If a recipe should not be replaced by a more recent upstream version,
6770      putting the reason why in this variable in a recipe allows
6771      ``devtool check-upgrade-status`` command to display it, as explained
6772      in the ":ref:`ref-manual/devtool-reference:checking on the upgrade status of a recipe`"
6773      section.
6774
6775   :term:`REPODIR`
6776      See :term:`bitbake:REPODIR` in the BitBake manual.
6777
6778   :term:`REQUIRED_DISTRO_FEATURES`
6779      When inheriting the :ref:`ref-classes-features_check`
6780      class, this variable identifies distribution features that must exist
6781      in the current configuration in order for the OpenEmbedded build
6782      system to build the recipe. In other words, if the
6783      :term:`REQUIRED_DISTRO_FEATURES` variable lists a feature that does not
6784      appear in :term:`DISTRO_FEATURES` within the current configuration, then
6785      the recipe will be skipped, and if the build system attempts to build
6786      the recipe then an error will be triggered.
6787
6788   :term:`REQUIRED_VERSION`
6789      If there are multiple versions of a recipe available, this variable
6790      determines which version should be given preference.
6791      :term:`REQUIRED_VERSION` works in exactly the same manner as
6792      :term:`PREFERRED_VERSION`, except that if the specified version is not
6793      available then an error message is shown and the build fails
6794      immediately.
6795
6796      If both :term:`REQUIRED_VERSION` and :term:`PREFERRED_VERSION` are set
6797      for the same recipe, the :term:`REQUIRED_VERSION` value applies.
6798
6799   :term:`RM_WORK_EXCLUDE`
6800      With :ref:`ref-classes-rm-work` enabled, this variable
6801      specifies a list of recipes whose work directories should not be removed.
6802      See the ":ref:`ref-classes-rm-work`" section for more details.
6803
6804   :term:`ROOT_HOME`
6805      Defines the root home directory. By default, this directory is set as
6806      follows in the BitBake configuration file::
6807
6808         ROOT_HOME ??= "/home/root"
6809
6810      .. note::
6811
6812         This default value is likely used because some embedded solutions
6813         prefer to have a read-only root filesystem and prefer to keep
6814         writeable data in one place.
6815
6816      You can override the default by setting the variable in any layer or
6817      in the ``local.conf`` file. Because the default is set using a "weak"
6818      assignment (i.e. "??="), you can use either of the following forms to
6819      define your override::
6820
6821         ROOT_HOME = "/root"
6822         ROOT_HOME ?= "/root"
6823
6824      These
6825      override examples use ``/root``, which is probably the most commonly
6826      used override.
6827
6828   :term:`ROOTFS`
6829      Indicates a filesystem image to include as the root filesystem.
6830
6831      The :term:`ROOTFS` variable is an optional variable used with the
6832      :ref:`ref-classes-image-live` class.
6833
6834   :term:`ROOTFS_POSTINSTALL_COMMAND`
6835      Specifies a list of functions to call after the OpenEmbedded build
6836      system has installed packages. You can specify functions separated by
6837      semicolons::
6838
6839         ROOTFS_POSTINSTALL_COMMAND += "function; ... "
6840
6841      If you need to pass the root filesystem path to a command within a
6842      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6843      directory that becomes the root filesystem image. See the
6844      :term:`IMAGE_ROOTFS` variable for more
6845      information.
6846
6847   :term:`ROOTFS_POSTPROCESS_COMMAND`
6848      Specifies a list of functions to call once the OpenEmbedded build
6849      system has created the root filesystem. You can specify functions
6850      separated by semicolons::
6851
6852         ROOTFS_POSTPROCESS_COMMAND += "function; ... "
6853
6854      If you need to pass the root filesystem path to a command within a
6855      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6856      directory that becomes the root filesystem image. See the
6857      :term:`IMAGE_ROOTFS` variable for more
6858      information.
6859
6860   :term:`ROOTFS_POSTUNINSTALL_COMMAND`
6861      Specifies a list of functions to call after the OpenEmbedded build
6862      system has removed unnecessary packages. When runtime package
6863      management is disabled in the image, several packages are removed
6864      including ``base-passwd``, ``shadow``, and ``update-alternatives``.
6865      You can specify functions separated by semicolons::
6866
6867         ROOTFS_POSTUNINSTALL_COMMAND += "function; ... "
6868
6869      If you need to pass the root filesystem path to a command within a
6870      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6871      directory that becomes the root filesystem image. See the
6872      :term:`IMAGE_ROOTFS` variable for more
6873      information.
6874
6875   :term:`ROOTFS_PREPROCESS_COMMAND`
6876      Specifies a list of functions to call before the OpenEmbedded build
6877      system has created the root filesystem. You can specify functions
6878      separated by semicolons::
6879
6880         ROOTFS_PREPROCESS_COMMAND += "function; ... "
6881
6882      If you need to pass the root filesystem path to a command within a
6883      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6884      directory that becomes the root filesystem image. See the
6885      :term:`IMAGE_ROOTFS` variable for more
6886      information.
6887
6888   :term:`RPROVIDES`
6889      A list of package name aliases that a package also provides. These
6890      aliases are useful for satisfying runtime dependencies of other
6891      packages both during the build and on the target (as specified by
6892      :term:`RDEPENDS`).
6893
6894      .. note::
6895
6896         A package's own name is implicitly already in its :term:`RPROVIDES` list.
6897
6898      As with all package-controlling variables, you must always use the
6899      variable in conjunction with a package name override. Here is an
6900      example::
6901
6902         RPROVIDES:${PN} = "widget-abi-2"
6903
6904   :term:`RRECOMMENDS`
6905      A list of packages that extends the usability of a package being
6906      built. The package being built does not depend on this list of
6907      packages in order to successfully build, but rather uses them for
6908      extended usability. To specify runtime dependencies for packages, see
6909      the :term:`RDEPENDS` variable.
6910
6911      The package manager will automatically install the :term:`RRECOMMENDS`
6912      list of packages when installing the built package. However, you can
6913      prevent listed packages from being installed by using the
6914      :term:`BAD_RECOMMENDATIONS`,
6915      :term:`NO_RECOMMENDATIONS`, and
6916      :term:`PACKAGE_EXCLUDE` variables.
6917
6918      Packages specified in :term:`RRECOMMENDS` need not actually be produced.
6919      However, there must be a recipe providing each package, either
6920      through the :term:`PACKAGES` or
6921      :term:`PACKAGES_DYNAMIC` variables or the
6922      :term:`RPROVIDES` variable, or an error will occur
6923      during the build. If such a recipe does exist and the package is not
6924      produced, the build continues without error.
6925
6926      Because the :term:`RRECOMMENDS` variable applies to packages being built,
6927      you should always attach an override to the variable to specify the
6928      particular package whose usability is being extended. For example,
6929      suppose you are building a development package that is extended to
6930      support wireless functionality. In this case, you would use the
6931      following::
6932
6933         RRECOMMENDS:${PN}-dev += "wireless_package_name"
6934
6935      In the
6936      example, the package name (``${PN}-dev``) must appear as it would in
6937      the :term:`PACKAGES` namespace before any renaming of the output package
6938      by classes such as :ref:`ref-classes-debian`.
6939
6940      BitBake, which the OpenEmbedded build system uses, supports
6941      specifying versioned recommends. Although the syntax varies depending
6942      on the packaging format, BitBake hides these differences from you.
6943      Here is the general syntax to specify versions with the
6944      :term:`RRECOMMENDS` variable::
6945
6946         RRECOMMENDS:${PN} = "package (operator version)"
6947
6948      For ``operator``, you can specify the following:
6949
6950      - =
6951      - <
6952      - >
6953      - <=
6954      - >=
6955
6956      For example, the following sets up a recommend on version 1.2 or
6957      greater of the package ``foo``::
6958
6959         RRECOMMENDS:${PN} = "foo (>= 1.2)"
6960
6961   :term:`RREPLACES`
6962      A list of packages replaced by a package. The package manager uses
6963      this variable to determine which package should be installed to
6964      replace other package(s) during an upgrade. In order to also have the
6965      other package(s) removed at the same time, you must add the name of
6966      the other package to the :term:`RCONFLICTS` variable.
6967
6968      As with all package-controlling variables, you must use this variable
6969      in conjunction with a package name override. Here is an example::
6970
6971         RREPLACES:${PN} = "other_package_being_replaced"
6972
6973      BitBake, which the OpenEmbedded build system uses, supports
6974      specifying versioned replacements. Although the syntax varies
6975      depending on the packaging format, BitBake hides these differences
6976      from you. Here is the general syntax to specify versions with the
6977      :term:`RREPLACES` variable::
6978
6979         RREPLACES:${PN} = "package (operator version)"
6980
6981      For ``operator``, you can specify the following:
6982
6983      - =
6984      - <
6985      - >
6986      - <=
6987      - >=
6988
6989      For example, the following sets up a replacement using version 1.2
6990      or greater of the package ``foo``::
6991
6992          RREPLACES:${PN} = "foo (>= 1.2)"
6993
6994   :term:`RSUGGESTS`
6995      A list of additional packages that you can suggest for installation
6996      by the package manager at the time a package is installed. Not all
6997      package managers support this functionality.
6998
6999      As with all package-controlling variables, you must always use this
7000      variable in conjunction with a package name override. Here is an
7001      example::
7002
7003         RSUGGESTS:${PN} = "useful_package another_package"
7004
7005   :term:`RUST_CHANNEL`
7006      Specifies which version of Rust to build - "stable", "beta" or "nightly".
7007      The default value is "stable". Set this at your own risk, as values other
7008      than "stable" are not guaranteed to work at a given time.
7009
7010   :term:`S`
7011      The location in the :term:`Build Directory` where
7012      unpacked recipe source code resides. By default, this directory is
7013      ``${``\ :term:`WORKDIR`\ ``}/${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
7014      where ``${BPN}`` is the base recipe name and ``${PV}`` is the recipe
7015      version. If the source tarball extracts the code to a directory named
7016      anything other than ``${BPN}-${PV}``, or if the source code is
7017      fetched from an SCM such as Git or Subversion, then you must set
7018      :term:`S` in the recipe so that the OpenEmbedded build system knows where
7019      to find the unpacked source.
7020
7021      As an example, assume a :term:`Source Directory`
7022      top-level folder named ``poky`` and a default :term:`Build Directory` at
7023      ``poky/build``. In this case, the work directory the build system
7024      uses to keep the unpacked recipe for ``db`` is the following::
7025
7026         poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
7027
7028      The unpacked source code resides in the ``db-5.1.19`` folder.
7029
7030      This next example assumes a Git repository. By default, Git
7031      repositories are cloned to ``${WORKDIR}/git`` during
7032      :ref:`ref-tasks-fetch`. Since this path is different
7033      from the default value of :term:`S`, you must set it specifically so the
7034      source can be located::
7035
7036         SRC_URI = "git://path/to/repo.git;branch=main"
7037         S = "${WORKDIR}/git"
7038
7039   :term:`SANITY_REQUIRED_UTILITIES`
7040      Specifies a list of command-line utilities that should be checked for
7041      during the initial sanity checking process when running BitBake. If
7042      any of the utilities are not installed on the build host, then
7043      BitBake immediately exits with an error.
7044
7045   :term:`SANITY_TESTED_DISTROS`
7046      A list of the host distribution identifiers that the build system has
7047      been tested against. Identifiers consist of the host distributor ID
7048      followed by the release, as reported by the ``lsb_release`` tool or
7049      as read from ``/etc/lsb-release``. Separate the list items with
7050      explicit newline characters (``\n``). If :term:`SANITY_TESTED_DISTROS` is
7051      not empty and the current value of
7052      :term:`NATIVELSBSTRING` does not appear in the
7053      list, then the build system reports a warning that indicates the
7054      current host distribution has not been tested as a build host.
7055
7056   :term:`SDK_ARCH`
7057      The target architecture for the SDK. Typically, you do not directly
7058      set this variable. Instead, use :term:`SDKMACHINE`.
7059
7060   :term:`SDK_ARCHIVE_TYPE`
7061      Specifies the type of archive to create for the SDK. Valid values:
7062
7063      - ``tar.xz`` (default)
7064      - ``zip``
7065
7066      Only one archive type can be specified.
7067
7068   :term:`SDK_BUILDINFO_FILE`
7069      When using the :ref:`ref-classes-image-buildinfo` class,
7070      specifies the file in the SDK to write the build information into. The
7071      default value is "``/buildinfo``".
7072
7073   :term:`SDK_CUSTOM_TEMPLATECONF`
7074      When building the extensible SDK, if :term:`SDK_CUSTOM_TEMPLATECONF` is set to
7075      "1" and a ``conf/templateconf.cfg`` file exists in the :term:`Build Directory`
7076      (:term:`TOPDIR`) then this will be copied into the SDK.
7077
7078   :term:`SDK_DEPLOY`
7079      The directory set up and used by the
7080      :ref:`populate_sdk_base <ref-classes-populate-sdk>` class to which the
7081      SDK is deployed. The :ref:`populate_sdk_base <ref-classes-populate-sdk>`
7082      class defines :term:`SDK_DEPLOY` as follows::
7083
7084         SDK_DEPLOY = "${TMPDIR}/deploy/sdk"
7085
7086   :term:`SDK_DIR`
7087      The parent directory used by the OpenEmbedded build system when
7088      creating SDK output. The
7089      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class defines
7090      the variable as follows::
7091
7092         SDK_DIR = "${WORKDIR}/sdk"
7093
7094      .. note::
7095
7096         The :term:`SDK_DIR` directory is a temporary directory as it is part of
7097         :term:`WORKDIR`. The final output directory is :term:`SDK_DEPLOY`.
7098
7099   :term:`SDK_EXT_TYPE`
7100      Controls whether or not shared state artifacts are copied into the
7101      extensible SDK. The default value of "full" copies all of the
7102      required shared state artifacts into the extensible SDK. The value
7103      "minimal" leaves these artifacts out of the SDK.
7104
7105      .. note::
7106
7107         If you set the variable to "minimal", you need to ensure
7108         :term:`SSTATE_MIRRORS` is set in the SDK's configuration to enable the
7109         artifacts to be fetched as needed.
7110
7111   :term:`SDK_HOST_MANIFEST`
7112      The manifest file for the host part of the SDK. This file lists all
7113      the installed packages that make up the host part of the SDK. The
7114      file contains package information on a line-per-package basis as
7115      follows::
7116
7117         packagename packagearch version
7118
7119      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
7120      defines the manifest file as follows::
7121
7122         SDK_HOST_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.host.manifest"
7123
7124      The location is derived using the :term:`SDK_DEPLOY` and
7125      :term:`TOOLCHAIN_OUTPUTNAME` variables.
7126
7127   :term:`SDK_INCLUDE_PKGDATA`
7128      When set to "1", specifies to include the packagedata for all recipes
7129      in the "world" target in the extensible SDK. Including this data
7130      allows the ``devtool search`` command to find these recipes in search
7131      results, as well as allows the ``devtool add`` command to map
7132      dependencies more effectively.
7133
7134      .. note::
7135
7136         Enabling the :term:`SDK_INCLUDE_PKGDATA`
7137         variable significantly increases build time because all of world
7138         needs to be built. Enabling the variable also slightly increases
7139         the size of the extensible SDK.
7140
7141   :term:`SDK_INCLUDE_TOOLCHAIN`
7142      When set to "1", specifies to include the toolchain in the extensible
7143      SDK. Including the toolchain is useful particularly when
7144      :term:`SDK_EXT_TYPE` is set to "minimal" to keep
7145      the SDK reasonably small but you still want to provide a usable
7146      toolchain. For example, suppose you want to use the toolchain from an
7147      IDE or from other tools and you do not want to perform additional
7148      steps to install the toolchain.
7149
7150      The :term:`SDK_INCLUDE_TOOLCHAIN` variable defaults to "0" if
7151      :term:`SDK_EXT_TYPE` is set to "minimal", and defaults to "1" if
7152      :term:`SDK_EXT_TYPE` is set to "full".
7153
7154   :term:`SDK_NAME`
7155      The base name for SDK output files. The name is derived from the
7156      :term:`DISTRO`, :term:`TCLIBC`,
7157      :term:`SDK_ARCH`,
7158      :term:`IMAGE_BASENAME`, and
7159      :term:`TUNE_PKGARCH` variables::
7160
7161         SDK_NAME = "${DISTRO}-${TCLIBC}-${SDK_ARCH}-${IMAGE_BASENAME}-${TUNE_PKGARCH}"
7162
7163   :term:`SDK_OS`
7164      Specifies the operating system for which the SDK will be built. The
7165      default value is the value of :term:`BUILD_OS`.
7166
7167   :term:`SDK_OUTPUT`
7168      The location used by the OpenEmbedded build system when creating SDK
7169      output. The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>`
7170      class defines the variable as follows::
7171
7172         SDK_DIR = "${WORKDIR}/sdk"
7173         SDK_OUTPUT = "${SDK_DIR}/image"
7174         SDK_DEPLOY = "${DEPLOY_DIR}/sdk"
7175
7176      .. note::
7177
7178         The :term:`SDK_OUTPUT` directory is a temporary directory as it is part of
7179         :term:`WORKDIR` by way of :term:`SDK_DIR`. The final output directory is
7180         :term:`SDK_DEPLOY`.
7181
7182   :term:`SDK_PACKAGE_ARCHS`
7183      Specifies a list of architectures compatible with the SDK machine.
7184      This variable is set automatically and should not normally be
7185      hand-edited. Entries are separated using spaces and listed in order
7186      of priority. The default value for :term:`SDK_PACKAGE_ARCHS` is "all any
7187      noarch ${SDK_ARCH}-${SDKPKGSUFFIX}".
7188
7189   :term:`SDK_POSTPROCESS_COMMAND`
7190      Specifies a list of functions to call once the OpenEmbedded build
7191      system creates the SDK. You can specify functions separated by
7192      semicolons: SDK_POSTPROCESS_COMMAND += "function; ... "
7193
7194      If you need to pass an SDK path to a command within a function, you
7195      can use ``${SDK_DIR}``, which points to the parent directory used by
7196      the OpenEmbedded build system when creating SDK output. See the
7197      :term:`SDK_DIR` variable for more information.
7198
7199   :term:`SDK_PREFIX`
7200      The toolchain binary prefix used for
7201      :ref:`ref-classes-nativesdk` recipes. The
7202      OpenEmbedded build system uses the :term:`SDK_PREFIX` value to set the
7203      :term:`TARGET_PREFIX` when building
7204      ``nativesdk`` recipes. The default value is "${SDK_SYS}-".
7205
7206   :term:`SDK_RECRDEP_TASKS`
7207      A list of shared state tasks added to the extensible SDK. By default,
7208      the following tasks are added:
7209
7210      - :ref:`ref-tasks-populate_lic`
7211      - :ref:`ref-tasks-package_qa`
7212      - :ref:`ref-tasks-populate_sysroot`
7213      - :ref:`ref-tasks-deploy`
7214
7215      Despite the default value of "" for the
7216      :term:`SDK_RECRDEP_TASKS` variable, the above four tasks are always added
7217      to the SDK. To specify tasks beyond these four, you need to use the
7218      :term:`SDK_RECRDEP_TASKS` variable (e.g. you are defining additional
7219      tasks that are needed in order to build
7220      :term:`SDK_TARGETS`).
7221
7222   :term:`SDK_SYS`
7223      Specifies the system, including the architecture and the operating
7224      system, for which the SDK will be built.
7225
7226      The OpenEmbedded build system automatically sets this variable based
7227      on :term:`SDK_ARCH`,
7228      :term:`SDK_VENDOR`, and
7229      :term:`SDK_OS`. You do not need to set the :term:`SDK_SYS`
7230      variable yourself.
7231
7232   :term:`SDK_TARGET_MANIFEST`
7233      The manifest file for the target part of the SDK. This file lists all
7234      the installed packages that make up the target part of the SDK. The
7235      file contains package information on a line-per-package basis as
7236      follows::
7237
7238         packagename packagearch version
7239
7240      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
7241      defines the manifest file as follows::
7242
7243         SDK_TARGET_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.target.manifest"
7244
7245      The location is derived using the :term:`SDK_DEPLOY` and
7246      :term:`TOOLCHAIN_OUTPUTNAME` variables.
7247
7248   :term:`SDK_TARGETS`
7249      A list of targets to install from shared state as part of the
7250      standard or extensible SDK installation. The default value is "${PN}"
7251      (i.e. the image from which the SDK is built).
7252
7253      The :term:`SDK_TARGETS` variable is an internal variable and typically
7254      would not be changed.
7255
7256   :term:`SDK_TITLE`
7257      The title to be printed when running the SDK installer. By default,
7258      this title is based on the :term:`DISTRO_NAME` or
7259      :term:`DISTRO` variable and is set in the
7260      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
7261      follows::
7262
7263         SDK_TITLE ??= "${@d.getVar('DISTRO_NAME') or d.getVar('DISTRO')} SDK"
7264
7265      For the default distribution "poky",
7266      :term:`SDK_TITLE` is set to "Poky (Yocto Project Reference Distro)".
7267
7268      For information on how to change this default title, see the
7269      ":ref:`sdk-manual/appendix-customizing:changing the extensible sdk installer title`"
7270      section in the Yocto Project Application Development and the
7271      Extensible Software Development Kit (eSDK) manual.
7272
7273   :term:`SDK_TOOLCHAIN_LANGS`
7274      Specifies programming languages to support in the SDK, as a
7275      space-separated list. Currently supported items are ``rust`` and ``go``.
7276
7277   :term:`SDK_UPDATE_URL`
7278      An optional URL for an update server for the extensible SDK. If set,
7279      the value is used as the default update server when running
7280      ``devtool sdk-update`` within the extensible SDK.
7281
7282   :term:`SDK_VENDOR`
7283      Specifies the name of the SDK vendor.
7284
7285   :term:`SDK_VERSION`
7286      Specifies the version of the SDK. The Poky distribution configuration file
7287      (``/meta-poky/conf/distro/poky.conf``) sets the default
7288      :term:`SDK_VERSION` as follows::
7289
7290         SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"
7291
7292      For additional information, see the
7293      :term:`DISTRO_VERSION` and
7294      :term:`METADATA_REVISION` variables.
7295
7296   :term:`SDK_ZIP_OPTIONS`
7297      Specifies extra options to pass to the ``zip`` command when zipping the SDK
7298      (i.e. when :term:`SDK_ARCHIVE_TYPE` is set to "zip"). The default value is
7299      "-y".
7300
7301   :term:`SDKEXTPATH`
7302      The default installation directory for the Extensible SDK. By
7303      default, this directory is based on the :term:`DISTRO`
7304      variable and is set in the
7305      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
7306      follows::
7307
7308         SDKEXTPATH ??= "~/${@d.getVar('DISTRO')}_sdk"
7309
7310      For the
7311      default distribution "poky", the :term:`SDKEXTPATH` is set to "poky_sdk".
7312
7313      For information on how to change this default directory, see the
7314      ":ref:`sdk-manual/appendix-customizing:changing the default sdk installation directory`"
7315      section in the Yocto Project Application Development and the
7316      Extensible Software Development Kit (eSDK) manual.
7317
7318   :term:`SDKIMAGE_FEATURES`
7319      Equivalent to :term:`IMAGE_FEATURES`. However, this variable applies to
7320      the SDK generated from an image using the following command::
7321
7322         $ bitbake -c populate_sdk imagename
7323
7324   :term:`SDKMACHINE`
7325      The machine for which the SDK is built. In other words, the SDK is built
7326      such that it runs on the target you specify with the :term:`SDKMACHINE`
7327      value. The value points to a corresponding ``.conf`` file under
7328      ``conf/machine-sdk/`` in the enabled layers, for example ``aarch64``,
7329      ``i586``, ``i686``, ``ppc64``, ``ppc64le``, and ``x86_64`` are
7330      :oe_git:`available in OpenEmbedded-Core </openembedded-core/tree/meta/conf/machine-sdk>`.
7331
7332      The variable defaults to :term:`BUILD_ARCH` so that SDKs are built for the
7333      architecture of the build machine.
7334
7335      .. note::
7336
7337         You cannot set the :term:`SDKMACHINE`
7338         variable in your distribution configuration file. If you do, the
7339         configuration will not take effect.
7340
7341   :term:`SDKPATH`
7342      Defines the path offered to the user for installation of the SDK that
7343      is generated by the OpenEmbedded build system. The path appears as
7344      the default location for installing the SDK when you run the SDK's
7345      installation script. You can override the offered path when you run
7346      the script.
7347
7348   :term:`SDKTARGETSYSROOT`
7349      The full path to the sysroot used for cross-compilation within an SDK
7350      as it will be when installed into the default
7351      :term:`SDKPATH`.
7352
7353   :term:`SECTION`
7354      The section in which packages should be categorized. Package
7355      management utilities can make use of this variable.
7356
7357   :term:`SELECTED_OPTIMIZATION`
7358      Specifies the optimization flags passed to the C compiler when
7359      building for the target. The flags are passed through the default
7360      value of the :term:`TARGET_CFLAGS` variable.
7361
7362      The :term:`SELECTED_OPTIMIZATION` variable takes the value of
7363      :term:`FULL_OPTIMIZATION` unless :term:`DEBUG_BUILD` = "1", in which
7364      case the value of :term:`DEBUG_OPTIMIZATION` is used.
7365
7366   :term:`SERIAL_CONSOLES`
7367      Defines a serial console (TTY) to enable using
7368      :wikipedia:`getty <Getty_(Unix)>`. Provide a value that specifies the
7369      baud rate followed by the TTY device name separated by a semicolon.
7370      Use spaces to separate multiple devices::
7371
7372         SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
7373
7374   :term:`SERIAL_CONSOLES_CHECK`
7375      Specifies serial consoles, which must be listed in
7376      :term:`SERIAL_CONSOLES`, to check against
7377      ``/proc/console`` before enabling them using getty. This variable
7378      allows aliasing in the format: <device>:<alias>. If a device was
7379      listed as "sclp_line0" in ``/dev/`` and "ttyS0" was listed in
7380      ``/proc/console``, you would do the following::
7381
7382         SERIAL_CONSOLES_CHECK = "slcp_line0:ttyS0"
7383
7384      This variable is currently only supported with SysVinit (i.e. not
7385      with systemd). Note that :term:`SERIAL_CONSOLES_CHECK` also requires
7386      ``/etc/inittab`` to be writable when used with SysVinit. This makes it
7387      incompatible with customizations such as the following::
7388
7389         EXTRA_IMAGE_FEATURES += "read-only-rootfs"
7390
7391   :term:`SETUPTOOLS_BUILD_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 build`` in the ``setuptools3_do_compile()`` task.
7395
7396   :term:`SETUPTOOLS_INSTALL_ARGS`
7397      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7398      class, this variable can be used to specify additional arguments to be
7399      passed to ``setup.py install`` in the ``setuptools3_do_install()`` task.
7400
7401   :term:`SETUPTOOLS_SETUP_PATH`
7402      When used by recipes that inherit the :ref:`ref-classes-setuptools3`
7403      class, this variable should be used to specify the directory in which
7404      the ``setup.py`` file is located if it is not at the root of the source
7405      tree (as specified by :term:`S`). For example, in a recipe where the
7406      sources are fetched from a Git repository and ``setup.py`` is in a
7407      ``python/pythonmodule`` subdirectory, you would have this::
7408
7409         S = "${WORKDIR}/git"
7410         SETUPTOOLS_SETUP_PATH = "${S}/python/pythonmodule"
7411
7412   :term:`SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS`
7413      A list of recipe dependencies that should not be used to determine
7414      signatures of tasks from one recipe when they depend on tasks from
7415      another recipe. For example::
7416
7417         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
7418
7419      In the previous example, ``intone`` depends on ``mplayer2``.
7420
7421      You can use the special token ``"*"`` on the left-hand side of the
7422      dependency to match all recipes except the one on the right-hand
7423      side. Here is an example::
7424
7425         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "*->quilt-native"
7426
7427      In the previous example, all recipes except ``quilt-native`` ignore
7428      task signatures from the ``quilt-native`` recipe when determining
7429      their task signatures.
7430
7431      Use of this variable is one mechanism to remove dependencies that
7432      affect task signatures and thus force rebuilds when a recipe changes.
7433
7434      .. note::
7435
7436         If you add an inappropriate dependency for a recipe relationship,
7437         the software might break during runtime if the interface of the
7438         second recipe was changed after the first recipe had been built.
7439
7440   :term:`SIGGEN_EXCLUDERECIPES_ABISAFE`
7441      A list of recipes that are completely stable and will never change.
7442      The ABI for the recipes in the list are presented by output from the
7443      tasks run to build the recipe. Use of this variable is one way to
7444      remove dependencies from one recipe on another that affect task
7445      signatures and thus force rebuilds when the recipe changes.
7446
7447      .. note::
7448
7449         If you add an inappropriate variable to this list, the software
7450         might break at runtime if the interface of the recipe was changed
7451         after the other had been built.
7452
7453   :term:`SITEINFO_BITS`
7454      Specifies the number of bits for the target system CPU. The value
7455      should be either "32" or "64".
7456
7457   :term:`SITEINFO_ENDIANNESS`
7458      Specifies the endian byte order of the target system. The value
7459      should be either "le" for little-endian or "be" for big-endian.
7460
7461   :term:`SKIP_FILEDEPS`
7462      Enables removal of all files from the "Provides" section of an RPM
7463      package. Removal of these files is required for packages containing
7464      prebuilt binaries and libraries such as ``libstdc++`` and ``glibc``.
7465
7466      To enable file removal, set the variable to "1" in your
7467      ``conf/local.conf`` configuration file in your:
7468      :term:`Build Directory`::
7469
7470         SKIP_FILEDEPS = "1"
7471
7472   :term:`SKIP_RECIPE`
7473      Used to prevent the OpenEmbedded build system from building a given
7474      recipe. Specify the :term:`PN` value as a variable flag (``varflag``)
7475      and provide a reason, which will be reported when attempting to
7476      build the recipe.
7477
7478      To prevent a recipe from being built, use the :term:`SKIP_RECIPE`
7479      variable in your ``local.conf`` file or distribution configuration.
7480      Here is an example which prevents ``myrecipe`` from being built::
7481
7482         SKIP_RECIPE[myrecipe] = "Not supported by our organization."
7483
7484   :term:`SOC_FAMILY`
7485      Groups together machines based upon the same family of SOC (System On
7486      Chip). You typically set this variable in a common ``.inc`` file that
7487      you include in the configuration files of all the machines.
7488
7489      .. note::
7490
7491         You must include ``conf/machine/include/soc-family.inc`` for this
7492         variable to appear in :term:`MACHINEOVERRIDES`.
7493
7494   :term:`SOLIBS`
7495      Defines the suffix for shared libraries used on the target platform.
7496      By default, this suffix is ".so.*" for all Linux-based systems and is
7497      defined in the ``meta/conf/bitbake.conf`` configuration file.
7498
7499      You will see this variable referenced in the default values of
7500      ``FILES:${PN}``.
7501
7502   :term:`SOLIBSDEV`
7503      Defines the suffix for the development symbolic link (symlink) for
7504      shared libraries on the target platform. By default, this suffix is
7505      ".so" for Linux-based systems and is defined in the
7506      ``meta/conf/bitbake.conf`` configuration file.
7507
7508      You will see this variable referenced in the default values of
7509      ``FILES:${PN}-dev``.
7510
7511   :term:`SOURCE_DATE_EPOCH`
7512      This defines a date expressed in number of seconds since
7513      the UNIX EPOCH (01 Jan 1970 00:00:00 UTC), which is used by
7514      multiple build systems to force a timestamp in built binaries.
7515      Many upstream projects already support this variable.
7516
7517      You will find more details in the `official specifications
7518      <https://reproducible-builds.org/specs/source-date-epoch/>`__.
7519
7520      A value for each recipe is computed from the sources by
7521      :oe_git:`meta/lib/oe/reproducible.py </openembedded-core/tree/meta/lib/oe/reproducible.py>`.
7522
7523      If a recipe wishes to override the default behavior, it should set its
7524      own :term:`SOURCE_DATE_EPOCH` value::
7525
7526          SOURCE_DATE_EPOCH = "1613559011"
7527
7528   :term:`SOURCE_MIRROR_FETCH`
7529      When you are fetching files to create a mirror of sources (i.e.
7530      creating a source mirror), setting :term:`SOURCE_MIRROR_FETCH` to "1" in
7531      your ``local.conf`` configuration file ensures the source for all
7532      recipes are fetched regardless of whether or not a recipe is
7533      compatible with the configuration. A recipe is considered
7534      incompatible with the currently configured machine when either or
7535      both the :term:`COMPATIBLE_MACHINE`
7536      variable and :term:`COMPATIBLE_HOST` variables
7537      specify compatibility with a machine other than that of the current
7538      machine or host.
7539
7540      .. note::
7541
7542         Do not set the :term:`SOURCE_MIRROR_FETCH`
7543         variable unless you are creating a source mirror. In other words,
7544         do not set the variable during a normal build.
7545
7546   :term:`SOURCE_MIRROR_URL`
7547      Defines your own :term:`PREMIRRORS` from which to
7548      first fetch source before attempting to fetch from the upstream
7549      specified in :term:`SRC_URI`.
7550
7551      To use this variable, you must globally inherit the
7552      :ref:`ref-classes-own-mirrors` class and then provide
7553      the URL to your mirrors. Here is the general syntax::
7554
7555         INHERIT += "own-mirrors"
7556         SOURCE_MIRROR_URL = "http://example.com/my_source_mirror"
7557
7558      .. note::
7559
7560         You can specify only a single URL in :term:`SOURCE_MIRROR_URL`.
7561
7562   :term:`SPDX_ARCHIVE_PACKAGED`
7563      This option allows to add to :term:`SPDX` output compressed archives
7564      of the files in the generated target packages.
7565
7566      Such archives are available in
7567      ``tmp/deploy/spdx/MACHINE/packages/packagename.tar.zst``
7568      under the :term:`Build Directory`.
7569
7570      Enable this option as follows::
7571
7572         SPDX_ARCHIVE_PACKAGED = "1"
7573
7574      According to our tests on release 4.1 "langdale", building
7575      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling this
7576      option multiplied the size of the ``tmp/deploy/spdx`` directory by a
7577      factor of 13 (+1.6 GiB for this image), compared to just using the
7578      :ref:`ref-classes-create-spdx` class with no option.
7579
7580      Note that this option doesn't increase the size of :term:`SPDX`
7581      files in ``tmp/deploy/images/MACHINE``.
7582
7583   :term:`SPDX_ARCHIVE_SOURCES`
7584      This option allows to add to :term:`SPDX` output compressed archives
7585      of the sources for packages installed on the target. It currently
7586      only works when :term:`SPDX_INCLUDE_SOURCES` is set.
7587
7588      This is one way of fulfilling "source code access" license
7589      requirements.
7590
7591      Such source archives are available in
7592      ``tmp/deploy/spdx/MACHINE/recipes/recipe-packagename.tar.zst``
7593      under the :term:`Build Directory`.
7594
7595      Enable this option as follows::
7596
7597         SPDX_INCLUDE_SOURCES = "1"
7598         SPDX_ARCHIVE_SOURCES = "1"
7599
7600      According to our tests on release 4.1 "langdale", building
7601      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling
7602      these options multiplied the size of the ``tmp/deploy/spdx``
7603      directory by a factor of 11 (+1.4 GiB for this image),
7604      compared to just using the :ref:`ref-classes-create-spdx`
7605      class with no option.
7606
7607      Note that using this option only marginally increases the size
7608      of the :term:`SPDX` output in ``tmp/deploy/images/MACHINE/``
7609      (+ 0.07\% with the tested image), compared to just enabling
7610      :term:`SPDX_INCLUDE_SOURCES`.
7611
7612   :term:`SPDX_CUSTOM_ANNOTATION_VARS`
7613      This option allows to associate `SPDX annotations
7614      <https://spdx.github.io/spdx-spec/v2.3/annotations/>`__ to a recipe,
7615      using the values of variables in the recipe::
7616
7617         ANNOTATION1 = "First annotation for recipe"
7618         ANNOTATION2 = "Second annotation for recipe"
7619         SPDX_CUSTOM_ANNOTATION_VARS = "ANNOTATION1 ANNOTATION2"
7620
7621      This will add a new block to the recipe ``.sdpx.json`` output::
7622
7623         "annotations": [
7624           {
7625             "annotationDate": "2023-04-18T08:32:12Z",
7626             "annotationType": "OTHER",
7627             "annotator": "Tool: oe-spdx-creator - 1.0",
7628             "comment": "ANNOTATION1=First annotation for recipe"
7629           },
7630           {
7631             "annotationDate": "2023-04-18T08:32:12Z",
7632             "annotationType": "OTHER",
7633             "annotator": "Tool: oe-spdx-creator - 1.0",
7634             "comment": "ANNOTATION2=Second annotation for recipe"
7635           }
7636         ],
7637
7638   :term:`SPDX_INCLUDE_SOURCES`
7639      This option allows to add a description of the source files used to build
7640      the host tools and the target packages, to the ``spdx.json`` files in
7641      ``tmp/deploy/spdx/MACHINE/recipes/`` under the :term:`Build Directory`.
7642      As a consequence, the ``spdx.json`` files under the ``by-namespace`` and
7643      ``packages`` subdirectories in ``tmp/deploy/spdx/MACHINE`` are also
7644      modified to include references to such source file descriptions.
7645
7646      Enable this option as follows::
7647
7648         SPDX_INCLUDE_SOURCES = "1"
7649
7650      According to our tests on release 4.1 "langdale", building
7651      ``core-image-minimal`` for the ``qemux86-64`` machine, enabling
7652      this option multiplied the total size of the ``tmp/deploy/spdx``
7653      directory by a factor of 3  (+291 MiB for this image),
7654      and the size of the ``IMAGE-MACHINE.spdx.tar.zst`` in
7655      ``tmp/deploy/images/MACHINE`` by a factor of 130 (+15 MiB for this
7656      image), compared to just using the :ref:`ref-classes-create-spdx` class
7657      with no option.
7658
7659   :term:`SPDX_PRETTY`
7660      This option makes the SPDX output more human-readable, using
7661      identation and newlines, instead of the default output in a
7662      single line::
7663
7664         SPDX_PRETTY = "1"
7665
7666      The generated SPDX files are approximately 20% bigger, but
7667      this option is recommended if you want to inspect the SPDX
7668      output files with a text editor.
7669
7670   :term:`SPDXLICENSEMAP`
7671      Maps commonly used license names to their SPDX counterparts found in
7672      ``meta/files/common-licenses/``. For the default :term:`SPDXLICENSEMAP`
7673      mappings, see the ``meta/conf/licenses.conf`` file.
7674
7675      For additional information, see the :term:`LICENSE`
7676      variable.
7677
7678   :term:`SPECIAL_PKGSUFFIX`
7679      A list of prefixes for :term:`PN` used by the OpenEmbedded
7680      build system to create variants of recipes or packages. The list
7681      specifies the prefixes to strip off during certain circumstances such
7682      as the generation of the :term:`BPN` variable.
7683
7684   :term:`SPL_BINARY`
7685      The file type for the Secondary Program Loader (SPL). Some devices
7686      use an SPL from which to boot (e.g. the BeagleBone development
7687      board). For such cases, you can declare the file type of the SPL
7688      binary in the ``u-boot.inc`` include file, which is used in the
7689      U-Boot recipe.
7690
7691      The SPL file type is set to "null" by default in the ``u-boot.inc``
7692      file as follows::
7693
7694         # Some versions of u-boot build an SPL (Second Program Loader) image that
7695         # should be packaged along with the u-boot binary as well as placed in the
7696         # deploy directory. For those versions they can set the following variables
7697         # to allow packaging the SPL.
7698         SPL_BINARY ?= ""
7699         SPL_BINARYNAME ?= "${@os.path.basename(d.getVar("SPL_BINARY"))}"
7700         SPL_IMAGE ?= "${SPL_BINARYNAME}-${MACHINE}-${PV}-${PR}"
7701         SPL_SYMLINK ?= "${SPL_BINARYNAME}-${MACHINE}"
7702
7703      The :term:`SPL_BINARY` variable helps form
7704      various ``SPL_*`` variables used by the OpenEmbedded build system.
7705
7706      See the BeagleBone machine configuration example in the
7707      ":ref:`dev-manual/layers:adding a layer using the \`\`bitbake-layers\`\` script`"
7708      section in the Yocto Project Board Support Package Developer's Guide
7709      for additional information.
7710
7711   :term:`SRCREV_FORMAT`
7712      See :term:`bitbake:SRCREV_FORMAT` in the BitBake manual.
7713
7714   :term:`SRC_URI`
7715
7716      See the BitBake manual for the initial description for this variable:
7717      :term:`bitbake:SRC_URI`.
7718
7719      The following features are added by OpenEmbedded and the Yocto Project.
7720
7721      There are standard and recipe-specific options. Here are standard ones:
7722
7723      -  ``apply`` --- whether to apply the patch or not. The default
7724         action is to apply the patch.
7725
7726      -  ``striplevel`` --- which striplevel to use when applying the
7727         patch. The default level is 1.
7728
7729      -  ``patchdir`` --- specifies the directory in which the patch should
7730         be applied. The default is ``${``\ :term:`S`\ ``}``.
7731
7732      Here are options specific to recipes building code from a revision
7733      control system:
7734
7735      -  ``mindate`` --- apply the patch only if
7736         :term:`SRCDATE` is equal to or greater than
7737         ``mindate``.
7738
7739      -  ``maxdate`` --- apply the patch only if :term:`SRCDATE` is not later
7740         than ``maxdate``.
7741
7742      -  ``minrev`` --- apply the patch only if :term:`SRCREV` is equal to or
7743         greater than ``minrev``.
7744
7745      -  ``maxrev`` --- apply the patch only if :term:`SRCREV` is not later
7746         than ``maxrev``.
7747
7748      -  ``rev`` --- apply the patch only if :term:`SRCREV` is equal to
7749         ``rev``.
7750
7751      -  ``notrev`` --- apply the patch only if :term:`SRCREV` is not equal to
7752         ``rev``.
7753
7754      .. note::
7755
7756         If you want the build system to pick up files specified through
7757         a :term:`SRC_URI` statement from your append file, you need to be
7758         sure to extend the :term:`FILESPATH` variable by also using the
7759         :term:`FILESEXTRAPATHS` variable from within your append file.
7760
7761   :term:`SRC_URI_OVERRIDES_PACKAGE_ARCH`
7762      By default, the OpenEmbedded build system automatically detects
7763      whether :term:`SRC_URI` contains files that are machine-specific. If so,
7764      the build system automatically changes :term:`PACKAGE_ARCH`. Setting this
7765      variable to "0" disables this behavior.
7766
7767   :term:`SRCDATE`
7768      The date of the source code used to build the package. This variable
7769      applies only if the source was fetched from a Source Code Manager
7770      (SCM).
7771
7772   :term:`SRCPV`
7773      Returns the version string of the current package. This string is
7774      used to help define the value of :term:`PV`.
7775
7776      The :term:`SRCPV` variable is defined in the ``meta/conf/bitbake.conf``
7777      configuration file in the :term:`Source Directory` as
7778      follows::
7779
7780         SRCPV = "${@bb.fetch2.get_srcrev(d)}"
7781
7782      Recipes that need to define :term:`PV` do so with the help of the
7783      :term:`SRCPV`. For example, the ``ofono`` recipe (``ofono_git.bb``)
7784      located in ``meta/recipes-connectivity`` in the Source Directory
7785      defines :term:`PV` as follows::
7786
7787         PV = "0.12-git${SRCPV}"
7788
7789   :term:`SRCREV`
7790      The revision of the source code used to build the package. This
7791      variable applies to Subversion, Git, Mercurial, and Bazaar only. Note
7792      that if you want to build a fixed revision and you want to avoid
7793      performing a query on the remote repository every time BitBake parses
7794      your recipe, you should specify a :term:`SRCREV` that is a full revision
7795      identifier and not just a tag.
7796
7797      .. note::
7798
7799         For information on limitations when inheriting the latest revision
7800         of software using :term:`SRCREV`, see the :term:`AUTOREV` variable
7801         description and the
7802         ":ref:`dev-manual/packages:automatically incrementing a package version number`"
7803         section, which is in the Yocto Project Development Tasks Manual.
7804
7805   :term:`SRCTREECOVEREDTASKS`
7806      A list of tasks that are typically not relevant (and therefore skipped)
7807      when building using the :ref:`ref-classes-externalsrc`
7808      class. The default value as set in that class file is the set of tasks
7809      that are rarely needed when using external source::
7810
7811         SRCTREECOVEREDTASKS ?= "do_patch do_unpack do_fetch"
7812
7813      The notable exception is when processing external kernel source as
7814      defined in the :ref:`ref-classes-kernel-yocto` class file (formatted for
7815      aesthetics)::
7816
7817         SRCTREECOVEREDTASKS += "\
7818           do_validate_branches \
7819           do_kernel_configcheck \
7820           do_kernel_checkout \
7821           do_fetch \
7822           do_unpack \
7823           do_patch \
7824         "
7825
7826      See the associated :term:`EXTERNALSRC` and :term:`EXTERNALSRC_BUILD`
7827      variables for more information.
7828
7829   :term:`SSTATE_DIR`
7830      The directory for the shared state cache.
7831
7832   :term:`SSTATE_EXCLUDEDEPS_SYSROOT`
7833      This variable allows to specify indirect dependencies to exclude
7834      from sysroots, for example to avoid the situations when a dependency on
7835      any ``-native`` recipe will pull in all dependencies of that recipe
7836      in the recipe sysroot. This behaviour might not always be wanted,
7837      for example when that ``-native`` recipe depends on build tools
7838      that are not relevant for the current recipe.
7839
7840      This way, irrelevant dependencies are ignored, which could have
7841      prevented the reuse of prebuilt artifacts stored in the Shared
7842      State Cache.
7843
7844      :term:`SSTATE_EXCLUDEDEPS_SYSROOT` is evaluated as two regular
7845      expressions of recipe and dependency to ignore. An example
7846      is the rule in :oe_git:`meta/conf/layer.conf </openembedded-core/tree/meta/conf/layer.conf>`::
7847
7848         # Nothing needs to depend on libc-initial
7849         # base-passwd/shadow-sysroot don't need their dependencies
7850         SSTATE_EXCLUDEDEPS_SYSROOT += "\
7851             .*->.*-initial.* \
7852             .*(base-passwd|shadow-sysroot)->.* \
7853         "
7854
7855      The ``->`` substring represents the dependency between
7856      the two regular expressions.
7857
7858   :term:`SSTATE_MIRROR_ALLOW_NETWORK`
7859      If set to "1", allows fetches from mirrors that are specified in
7860      :term:`SSTATE_MIRRORS` to work even when
7861      fetching from the network is disabled by setting :term:`BB_NO_NETWORK` to
7862      "1". Using the :term:`SSTATE_MIRROR_ALLOW_NETWORK` variable is useful if
7863      you have set :term:`SSTATE_MIRRORS` to point to an internal server for
7864      your shared state cache, but you want to disable any other fetching
7865      from the network.
7866
7867   :term:`SSTATE_MIRRORS`
7868      Configures the OpenEmbedded build system to search other mirror
7869      locations for prebuilt cache data objects before building out the
7870      data. This variable works like fetcher :term:`MIRRORS`
7871      and :term:`PREMIRRORS` and points to the cache
7872      locations to check for the shared state (sstate) objects.
7873
7874      You can specify a filesystem directory or a remote URL such as HTTP
7875      or FTP. The locations you specify need to contain the shared state
7876      cache (sstate-cache) results from previous builds. The sstate-cache
7877      you point to can also be from builds on other machines.
7878
7879      When pointing to sstate build artifacts on another machine that uses
7880      a different GCC version for native builds, you must configure
7881      :term:`SSTATE_MIRRORS` with a regular expression that maps local search
7882      paths to server paths. The paths need to take into account
7883      :term:`NATIVELSBSTRING` set by the :ref:`ref-classes-uninative` class.
7884      For example, the following maps the local search path ``universal-4.9``
7885      to the server-provided path server_url_sstate_path::
7886
7887         SSTATE_MIRRORS ?= "file://universal-4.9/(.*) https://server_url_sstate_path/universal-4.8/\1"
7888
7889      If a mirror uses the same structure as
7890      :term:`SSTATE_DIR`, you need to add "PATH" at the
7891      end as shown in the examples below. The build system substitutes the
7892      correct path within the directory structure::
7893
7894         SSTATE_MIRRORS ?= "\
7895             file://.* https://someserver.tld/share/sstate/PATH;downloadfilename=PATH \
7896             file://.* file:///some-local-dir/sstate/PATH"
7897
7898   :term:`SSTATE_SCAN_FILES`
7899      Controls the list of files the OpenEmbedded build system scans for
7900      hardcoded installation paths. The variable uses a space-separated
7901      list of filenames (not paths) with standard wildcard characters
7902      allowed.
7903
7904      During a build, the OpenEmbedded build system creates a shared state
7905      (sstate) object during the first stage of preparing the sysroots.
7906      That object is scanned for hardcoded paths for original installation
7907      locations. The list of files that are scanned for paths is controlled
7908      by the :term:`SSTATE_SCAN_FILES` variable. Typically, recipes add files
7909      they want to be scanned to the value of :term:`SSTATE_SCAN_FILES` rather
7910      than the variable being comprehensively set. The
7911      :ref:`ref-classes-sstate` class specifies the default list of files.
7912
7913      For details on the process, see the :ref:`ref-classes-staging` class.
7914
7915   :term:`STAGING_BASE_LIBDIR_NATIVE`
7916      Specifies the path to the ``/lib`` subdirectory of the sysroot
7917      directory for the build host.
7918
7919   :term:`STAGING_BASELIBDIR`
7920      Specifies the path to the ``/lib`` 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`
7925      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7926      directory for the target for which the current recipe is being built
7927      (:term:`STAGING_DIR_HOST`).
7928
7929   :term:`STAGING_BINDIR_CROSS`
7930      Specifies the path to the directory containing binary configuration
7931      scripts. These scripts provide configuration information for other
7932      software that wants to make use of libraries or include files
7933      provided by the software associated with the script.
7934
7935      .. note::
7936
7937         This style of build configuration has been largely replaced by
7938         ``pkg-config``. Consequently, if ``pkg-config`` is supported by the
7939         library to which you are linking, it is recommended you use
7940         ``pkg-config`` instead of a provided configuration script.
7941
7942   :term:`STAGING_BINDIR_NATIVE`
7943      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7944      directory for the build host.
7945
7946   :term:`STAGING_DATADIR`
7947      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7948      directory for the target for which the current recipe is being built
7949      (:term:`STAGING_DIR_HOST`).
7950
7951   :term:`STAGING_DATADIR_NATIVE`
7952      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7953      directory for the build host.
7954
7955   :term:`STAGING_DIR`
7956      Helps construct the ``recipe-sysroots`` directory, which is used
7957      during packaging.
7958
7959      For information on how staging for recipe-specific sysroots occurs,
7960      see the :ref:`ref-tasks-populate_sysroot`
7961      task, the ":ref:`sdk-manual/extensible:sharing files between recipes`"
7962      section in the Yocto Project Development Tasks Manual, the
7963      ":ref:`overview-manual/concepts:configuration, compilation, and staging`"
7964      section in the Yocto Project Overview and Concepts Manual, and the
7965      :term:`SYSROOT_DIRS` variable.
7966
7967      .. note::
7968
7969         Recipes should never write files directly under the :term:`STAGING_DIR`
7970         directory because the OpenEmbedded build system manages the
7971         directory automatically. Instead, files should be installed to
7972         ``${``\ :term:`D`\ ``}`` within your recipe's :ref:`ref-tasks-install`
7973         task and then the OpenEmbedded build system will stage a subset of
7974         those files into the sysroot.
7975
7976   :term:`STAGING_DIR_HOST`
7977      Specifies the path to the sysroot directory for the system on which
7978      the component is built to run (the system that hosts the component).
7979      For most recipes, this sysroot is the one in which that recipe's
7980      :ref:`ref-tasks-populate_sysroot` task copies
7981      files. Exceptions include ``-native`` recipes, where the
7982      :ref:`ref-tasks-populate_sysroot` task instead uses
7983      :term:`STAGING_DIR_NATIVE`. Depending on
7984      the type of recipe and the build target, :term:`STAGING_DIR_HOST` can
7985      have the following values:
7986
7987      -  For recipes building for the target machine, the value is
7988         "${:term:`STAGING_DIR`}/${:term:`MACHINE`}".
7989
7990      -  For native recipes building for the build host, the value is empty
7991         given the assumption that when building for the build host, the
7992         build host's own directories should be used.
7993
7994         .. note::
7995
7996            ``-native`` recipes are not installed into host paths like such
7997            as ``/usr``. Rather, these recipes are installed into
7998            :term:`STAGING_DIR_NATIVE`. When compiling ``-native`` recipes,
7999            standard build environment variables such as
8000            :term:`CPPFLAGS` and
8001            :term:`CFLAGS` are set up so that both host paths
8002            and :term:`STAGING_DIR_NATIVE` are searched for libraries and
8003            headers using, for example, GCC's ``-isystem`` option.
8004
8005            Thus, the emphasis is that the ``STAGING_DIR*`` variables
8006            should be viewed as input variables by tasks such as
8007            :ref:`ref-tasks-configure`,
8008            :ref:`ref-tasks-compile`, and
8009            :ref:`ref-tasks-install`. Having the real system
8010            root correspond to :term:`STAGING_DIR_HOST` makes conceptual sense
8011            for ``-native`` recipes, as they make use of host headers and
8012            libraries.
8013
8014   :term:`STAGING_DIR_NATIVE`
8015      Specifies the path to the sysroot directory used when building
8016      components that run on the build host itself.
8017
8018   :term:`STAGING_DIR_TARGET`
8019      Specifies the path to the sysroot used for the system for which the
8020      component generates code. For components that do not generate code,
8021      which is the majority, :term:`STAGING_DIR_TARGET` is set to match
8022      :term:`STAGING_DIR_HOST`.
8023
8024      Some recipes build binaries that can run on the target system but those
8025      binaries in turn generate code for another different system (e.g.
8026      :ref:`ref-classes-cross-canadian` recipes). Using terminology from GNU,
8027      the primary system is referred to as the "HOST" and the secondary, or
8028      different, system is referred to as the "TARGET". Thus, the binaries
8029      run on the "HOST" system and generate binaries for the "TARGET"
8030      system. The :term:`STAGING_DIR_HOST` variable points to the sysroot used
8031      for the "HOST" system, while :term:`STAGING_DIR_TARGET` points to the
8032      sysroot used for the "TARGET" system.
8033
8034   :term:`STAGING_ETCDIR_NATIVE`
8035      Specifies the path to the ``/etc`` subdirectory of the sysroot
8036      directory for the build host.
8037
8038   :term:`STAGING_EXECPREFIXDIR`
8039      Specifies the path to the ``/usr`` subdirectory of the sysroot
8040      directory for the target for which the current recipe is being built
8041      (:term:`STAGING_DIR_HOST`).
8042
8043   :term:`STAGING_INCDIR`
8044      Specifies the path to the ``/usr/include`` subdirectory of the
8045      sysroot directory for the target for which the current recipe being
8046      built (:term:`STAGING_DIR_HOST`).
8047
8048   :term:`STAGING_INCDIR_NATIVE`
8049      Specifies the path to the ``/usr/include`` subdirectory of the
8050      sysroot directory for the build host.
8051
8052   :term:`STAGING_KERNEL_BUILDDIR`
8053      Points to the directory containing the kernel build artifacts.
8054      Recipes building software that needs to access kernel build artifacts
8055      (e.g. ``systemtap-uprobes``) can look in the directory specified with
8056      the :term:`STAGING_KERNEL_BUILDDIR` variable to find these artifacts
8057      after the kernel has been built.
8058
8059   :term:`STAGING_KERNEL_DIR`
8060      The directory with kernel headers that are required to build
8061      out-of-tree modules.
8062
8063   :term:`STAGING_LIBDIR`
8064      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
8065      directory for the target for which the current recipe is being built
8066      (:term:`STAGING_DIR_HOST`).
8067
8068   :term:`STAGING_LIBDIR_NATIVE`
8069      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
8070      directory for the build host.
8071
8072   :term:`STAMP`
8073      Specifies the base path used to create recipe stamp files. The path
8074      to an actual stamp file is constructed by evaluating this string and
8075      then appending additional information. Currently, the default
8076      assignment for :term:`STAMP` as set in the ``meta/conf/bitbake.conf``
8077      file is::
8078
8079         STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
8080
8081      For information on how BitBake uses stamp files to determine if a
8082      task should be rerun, see the
8083      ":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`"
8084      section in the Yocto Project Overview and Concepts Manual.
8085
8086      See :term:`STAMPS_DIR`,
8087      :term:`MULTIMACH_TARGET_SYS`,
8088      :term:`PN`, :term:`EXTENDPE`,
8089      :term:`PV`, and :term:`PR` for related variable
8090      information.
8091
8092   :term:`STAMPCLEAN`
8093      See :term:`bitbake:STAMPCLEAN` in the BitBake manual.
8094
8095   :term:`STAMPS_DIR`
8096      Specifies the base directory in which the OpenEmbedded build system
8097      places stamps. The default directory is ``${TMPDIR}/stamps``.
8098
8099   :term:`STRIP`
8100      The minimal command and arguments to run ``strip``, which is used to
8101      strip symbols.
8102
8103   :term:`SUMMARY`
8104      The short (72 characters or less) summary of the binary package for
8105      packaging systems such as ``opkg``, ``rpm``, or ``dpkg``. By default,
8106      :term:`SUMMARY` is used to define the
8107      :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
8108      not set in the recipe.
8109
8110   :term:`SVNDIR`
8111      The directory in which files checked out of a Subversion system are
8112      stored.
8113
8114   :term:`SYSLINUX_DEFAULT_CONSOLE`
8115      Specifies the kernel boot default console. If you want to use a
8116      console other than the default, set this variable in your recipe as
8117      follows where "X" is the console number you want to use::
8118
8119         SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
8120
8121      The :ref:`ref-classes-syslinux` class initially sets
8122      this variable to null but then checks for a value later.
8123
8124   :term:`SYSLINUX_OPTS`
8125      Lists additional options to add to the syslinux file. You need to set
8126      this variable in your recipe. If you want to list multiple options,
8127      separate the options with a semicolon character (``;``).
8128
8129      The :ref:`ref-classes-syslinux` class uses this variable
8130      to create a set of options.
8131
8132   :term:`SYSLINUX_SERIAL`
8133      Specifies the alternate serial port or turns it off. To turn off
8134      serial, set this variable to an empty string in your recipe. The
8135      variable's default value is set in the
8136      :ref:`ref-classes-syslinux` class as follows::
8137
8138         SYSLINUX_SERIAL ?= "0 115200"
8139
8140      The class checks for and uses the variable as needed.
8141
8142   :term:`SYSLINUX_SERIAL_TTY`
8143      Specifies the alternate console=tty... kernel boot argument. The
8144      variable's default value is set in the :ref:`ref-classes-syslinux`
8145      class as follows::
8146
8147         SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
8148
8149      The class checks for and uses the variable as needed.
8150
8151   :term:`SYSLINUX_SPLASH`
8152      An ``.LSS`` file used as the background for the VGA boot menu when
8153      you use the boot menu. You need to set this variable in your recipe.
8154
8155      The :ref:`ref-classes-syslinux` class checks for this
8156      variable and if found, the OpenEmbedded build system installs the
8157      splash screen.
8158
8159   :term:`SYSROOT_DESTDIR`
8160      Points to the temporary directory under the work directory (default
8161      "``${``\ :term:`WORKDIR`\ ``}/sysroot-destdir``")
8162      where the files populated into the sysroot are assembled during the
8163      :ref:`ref-tasks-populate_sysroot` task.
8164
8165   :term:`SYSROOT_DIRS`
8166      Directories that are staged into the sysroot by the
8167      :ref:`ref-tasks-populate_sysroot` task. By
8168      default, the following directories are staged::
8169
8170         SYSROOT_DIRS = " \
8171             ${includedir} \
8172             ${libdir} \
8173             ${base_libdir} \
8174             ${nonarch_base_libdir} \
8175             ${datadir} \
8176             /sysroot-only \
8177             "
8178
8179   :term:`SYSROOT_DIRS_IGNORE`
8180      Directories that are not staged into the sysroot by the
8181      :ref:`ref-tasks-populate_sysroot` task. You
8182      can use this variable to exclude certain subdirectories of
8183      directories listed in :term:`SYSROOT_DIRS` from
8184      staging. By default, the following directories are not staged::
8185
8186         SYSROOT_DIRS_IGNORE = " \
8187             ${mandir} \
8188             ${docdir} \
8189             ${infodir} \
8190             ${datadir}/X11/locale \
8191             ${datadir}/applications \
8192             ${datadir}/bash-completion \
8193             ${datadir}/fonts \
8194             ${datadir}/gtk-doc/html \
8195             ${datadir}/installed-tests \
8196             ${datadir}/locale \
8197             ${datadir}/pixmaps \
8198             ${datadir}/terminfo \
8199             ${libdir}/${BPN}/ptest \
8200             "
8201
8202   :term:`SYSROOT_DIRS_NATIVE`
8203      Extra directories staged into the sysroot by the
8204      :ref:`ref-tasks-populate_sysroot` task for
8205      ``-native`` recipes, in addition to those specified in
8206      :term:`SYSROOT_DIRS`. By default, the following
8207      extra directories are staged::
8208
8209         SYSROOT_DIRS_NATIVE = " \
8210             ${bindir} \
8211             ${sbindir} \
8212             ${base_bindir} \
8213             ${base_sbindir} \
8214             ${libexecdir} \
8215             ${sysconfdir} \
8216             ${localstatedir} \
8217             "
8218
8219      .. note::
8220
8221         Programs built by ``-native`` recipes run directly from the sysroot
8222         (:term:`STAGING_DIR_NATIVE`), which is why additional directories
8223         containing program executables and supporting files need to be staged.
8224
8225   :term:`SYSROOT_PREPROCESS_FUNCS`
8226      A list of functions to execute after files are staged into the
8227      sysroot. These functions are usually used to apply additional
8228      processing on the staged files, or to stage additional files.
8229
8230   :term:`SYSTEMD_AUTO_ENABLE`
8231      When inheriting the :ref:`ref-classes-systemd` class,
8232      this variable specifies whether the specified service in
8233      :term:`SYSTEMD_SERVICE` should start
8234      automatically or not. By default, the service is enabled to
8235      automatically start at boot time. The default setting is in the
8236      :ref:`ref-classes-systemd` class as follows::
8237
8238         SYSTEMD_AUTO_ENABLE ??= "enable"
8239
8240      You can disable the service by setting the variable to "disable".
8241
8242   :term:`SYSTEMD_BOOT_CFG`
8243      When :term:`EFI_PROVIDER` is set to
8244      "systemd-boot", the :term:`SYSTEMD_BOOT_CFG` variable specifies the
8245      configuration file that should be used. By default, the
8246      :ref:`ref-classes-systemd-boot` class sets the
8247      :term:`SYSTEMD_BOOT_CFG` as follows::
8248
8249         SYSTEMD_BOOT_CFG ?= "${S}/loader.conf"
8250
8251      For information on Systemd-boot, see the `Systemd-boot
8252      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8253
8254   :term:`SYSTEMD_BOOT_ENTRIES`
8255      When :term:`EFI_PROVIDER` is set to
8256      "systemd-boot", the :term:`SYSTEMD_BOOT_ENTRIES` variable specifies a
8257      list of entry files (``*.conf``) to install that contain one boot
8258      entry per file. By default, the :ref:`ref-classes-systemd-boot` class
8259      sets the :term:`SYSTEMD_BOOT_ENTRIES` as follows::
8260
8261          SYSTEMD_BOOT_ENTRIES ?= ""
8262
8263      For information on Systemd-boot, see the `Systemd-boot
8264      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8265
8266   :term:`SYSTEMD_BOOT_TIMEOUT`
8267      When :term:`EFI_PROVIDER` is set to
8268      "systemd-boot", the :term:`SYSTEMD_BOOT_TIMEOUT` variable specifies the
8269      boot menu timeout in seconds. By default, the
8270      :ref:`ref-classes-systemd-boot` class sets the
8271      :term:`SYSTEMD_BOOT_TIMEOUT` as follows::
8272
8273         SYSTEMD_BOOT_TIMEOUT ?= "10"
8274
8275      For information on Systemd-boot, see the `Systemd-boot
8276      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
8277
8278   :term:`SYSTEMD_DEFAULT_TARGET`
8279
8280      This variable allows to set the default unit that systemd starts at bootup.
8281      Usually, this is either ``multi-user.target`` or ``graphical.target``.
8282      This works by creating a ``default.target`` symbolic link to the chosen systemd
8283      target file.
8284
8285      See `systemd's documentation
8286      <https://www.freedesktop.org/software/systemd/man/systemd.special.html>`__
8287      for details.
8288
8289      For example, this variable is used in the :oe_git:`core-image-minimal-xfce.bb
8290      </meta-openembedded/tree/meta-xfce/recipes-core/images/core-image-minimal-xfce.bb>`
8291      recipe::
8292
8293          SYSTEMD_DEFAULT_TARGET = "graphical.target"
8294
8295   :term:`SYSTEMD_PACKAGES`
8296      When inheriting the :ref:`ref-classes-systemd` class,
8297      this variable locates the systemd unit files when they are not found
8298      in the main recipe's package. By default, the :term:`SYSTEMD_PACKAGES`
8299      variable is set such that the systemd unit files are assumed to
8300      reside in the recipes main package::
8301
8302         SYSTEMD_PACKAGES ?= "${PN}"
8303
8304      If these unit files are not in this recipe's main package, you need
8305      to use :term:`SYSTEMD_PACKAGES` to list the package or packages in which
8306      the build system can find the systemd unit files.
8307
8308   :term:`SYSTEMD_SERVICE`
8309      When inheriting the :ref:`ref-classes-systemd` class,
8310      this variable specifies the systemd service name for a package.
8311
8312      Multiple services can be specified, each one separated by a space.
8313
8314      When you specify this file in your recipe, use a package name
8315      override to indicate the package to which the value applies. Here is
8316      an example from the connman recipe::
8317
8318         SYSTEMD_SERVICE:${PN} = "connman.service"
8319
8320      The package overrides that can be specified are directly related to the value of
8321      :term:`SYSTEMD_PACKAGES`. Overrides not included in :term:`SYSTEMD_PACKAGES`
8322      will be silently ignored.
8323
8324   :term:`SYSVINIT_ENABLED_GETTYS`
8325      When using :ref:`SysVinit <dev-manual/new-recipe:enabling system services>`,
8326      specifies a space-separated list of the virtual terminals that should
8327      run a :wikipedia:`getty <Getty_(Unix)>` (allowing login), assuming
8328      :term:`USE_VT` is not set to "0".
8329
8330      The default value for :term:`SYSVINIT_ENABLED_GETTYS` is "1" (i.e. only
8331      run a getty on the first virtual terminal).
8332
8333   :term:`T`
8334      This variable points to a directory were BitBake places temporary
8335      files, which consist mostly of task logs and scripts, when building a
8336      particular recipe. The variable is typically set as follows::
8337
8338         T = "${WORKDIR}/temp"
8339
8340      The :term:`WORKDIR` is the directory into which
8341      BitBake unpacks and builds the recipe. The default ``bitbake.conf``
8342      file sets this variable.
8343
8344      The :term:`T` variable is not to be confused with the
8345      :term:`TMPDIR` variable, which points to the root of
8346      the directory tree where BitBake places the output of an entire
8347      build.
8348
8349   :term:`TARGET_ARCH`
8350      The target machine's architecture. The OpenEmbedded build system
8351      supports many architectures. Here is an example list of architectures
8352      supported. This list is by no means complete as the architecture is
8353      configurable:
8354
8355      - arm
8356      - i586
8357      - x86_64
8358      - powerpc
8359      - powerpc64
8360      - mips
8361      - mipsel
8362
8363      For additional information on machine architectures, see the
8364      :term:`TUNE_ARCH` variable.
8365
8366   :term:`TARGET_AS_ARCH`
8367      Specifies architecture-specific assembler flags for the target
8368      system. :term:`TARGET_AS_ARCH` is initialized from
8369      :term:`TUNE_ASARGS` by default in the BitBake
8370      configuration file (``meta/conf/bitbake.conf``)::
8371
8372         TARGET_AS_ARCH = "${TUNE_ASARGS}"
8373
8374   :term:`TARGET_CC_ARCH`
8375      Specifies architecture-specific C compiler flags for the target
8376      system. :term:`TARGET_CC_ARCH` is initialized from
8377      :term:`TUNE_CCARGS` by default.
8378
8379      .. note::
8380
8381         It is a common workaround to append :term:`LDFLAGS` to
8382         :term:`TARGET_CC_ARCH` in recipes that build software for the target that
8383         would not otherwise respect the exported :term:`LDFLAGS` variable.
8384
8385   :term:`TARGET_CC_KERNEL_ARCH`
8386      This is a specific kernel compiler flag for a CPU or Application
8387      Binary Interface (ABI) tune. The flag is used rarely and only for
8388      cases where a userspace :term:`TUNE_CCARGS` is not
8389      compatible with the kernel compilation. The :term:`TARGET_CC_KERNEL_ARCH`
8390      variable allows the kernel (and associated modules) to use a
8391      different configuration. See the
8392      ``meta/conf/machine/include/arm/feature-arm-thumb.inc`` file in the
8393      :term:`Source Directory` for an example.
8394
8395   :term:`TARGET_CFLAGS`
8396      Specifies the flags to pass to the C compiler when building for the
8397      target. When building in the target context,
8398      :term:`CFLAGS` is set to the value of this variable by
8399      default.
8400
8401      Additionally, the SDK's environment setup script sets the :term:`CFLAGS`
8402      variable in the environment to the :term:`TARGET_CFLAGS` value so that
8403      executables built using the SDK also have the flags applied.
8404
8405   :term:`TARGET_CPPFLAGS`
8406      Specifies the flags to pass to the C pre-processor (i.e. to both the
8407      C and the C++ compilers) when building for the target. When building
8408      in the target context, :term:`CPPFLAGS` is set to the
8409      value of this variable by default.
8410
8411      Additionally, the SDK's environment setup script sets the
8412      :term:`CPPFLAGS` variable in the environment to the :term:`TARGET_CPPFLAGS`
8413      value so that executables built using the SDK also have the flags
8414      applied.
8415
8416   :term:`TARGET_CXXFLAGS`
8417      Specifies the flags to pass to the C++ compiler when building for the
8418      target. When building in the target context,
8419      :term:`CXXFLAGS` is set to the value of this variable
8420      by default.
8421
8422      Additionally, the SDK's environment setup script sets the
8423      :term:`CXXFLAGS` variable in the environment to the :term:`TARGET_CXXFLAGS`
8424      value so that executables built using the SDK also have the flags
8425      applied.
8426
8427   :term:`TARGET_FPU`
8428      Specifies the method for handling FPU code. For FPU-less targets,
8429      which include most ARM CPUs, the variable must be set to "soft". If
8430      not, the kernel emulation gets used, which results in a performance
8431      penalty.
8432
8433   :term:`TARGET_LD_ARCH`
8434      Specifies architecture-specific linker flags for the target system.
8435      :term:`TARGET_LD_ARCH` is initialized from
8436      :term:`TUNE_LDARGS` by default in the BitBake
8437      configuration file (``meta/conf/bitbake.conf``)::
8438
8439         TARGET_LD_ARCH = "${TUNE_LDARGS}"
8440
8441   :term:`TARGET_LDFLAGS`
8442      Specifies the flags to pass to the linker when building for the
8443      target. When building in the target context,
8444      :term:`LDFLAGS` is set to the value of this variable
8445      by default.
8446
8447      Additionally, the SDK's environment setup script sets the
8448      :term:`LDFLAGS` variable in the environment to the
8449      :term:`TARGET_LDFLAGS` value so that executables built using the SDK also
8450      have the flags applied.
8451
8452   :term:`TARGET_OS`
8453      Specifies the target's operating system. The variable can be set to
8454      "linux" for glibc-based systems (GNU C Library) and to "linux-musl"
8455      for musl libc. For ARM/EABI targets, the possible values are
8456      "linux-gnueabi" and "linux-musleabi".
8457
8458   :term:`TARGET_PREFIX`
8459      Specifies the prefix used for the toolchain binary target tools.
8460
8461      Depending on the type of recipe and the build target,
8462      :term:`TARGET_PREFIX` is set as follows:
8463
8464      -  For recipes building for the target machine, the value is
8465         "${:term:`TARGET_SYS`}-".
8466
8467      -  For native recipes, the build system sets the variable to the
8468         value of :term:`BUILD_PREFIX`.
8469
8470      -  For native SDK recipes (:ref:`ref-classes-nativesdk`),
8471         the build system sets the variable to the value of :term:`SDK_PREFIX`.
8472
8473   :term:`TARGET_SYS`
8474      Specifies the system, including the architecture and the operating
8475      system, for which the build is occurring in the context of the
8476      current recipe.
8477
8478      The OpenEmbedded build system automatically sets this variable based
8479      on :term:`TARGET_ARCH`,
8480      :term:`TARGET_VENDOR`, and
8481      :term:`TARGET_OS` variables.
8482
8483      .. note::
8484
8485         You do not need to set the :term:`TARGET_SYS` variable yourself.
8486
8487      Consider these two examples:
8488
8489      -  Given a native recipe on a 32-bit, x86 machine running Linux, the
8490         value is "i686-linux".
8491
8492      -  Given a recipe being built for a little-endian, MIPS target
8493         running Linux, the value might be "mipsel-linux".
8494
8495   :term:`TARGET_VENDOR`
8496      Specifies the name of the target vendor.
8497
8498   :term:`TCLIBC`
8499      Specifies the GNU standard C library (``libc``) variant to use during
8500      the build process.
8501
8502      You can select "glibc", "musl", "newlib", or "baremetal".
8503
8504   :term:`TCLIBCAPPEND`
8505      Specifies a suffix to be appended onto the :term:`TMPDIR` value. The
8506      suffix identifies the ``libc`` variant for building. When you are
8507      building for multiple variants with the same :term:`Build Directory`,
8508      this mechanism ensures that output for different ``libc`` variants is
8509      kept separate to avoid potential conflicts.
8510
8511      In the ``defaultsetup.conf`` file, the default value of
8512      :term:`TCLIBCAPPEND` is "-${TCLIBC}". However, distros such as poky,
8513      which normally only support one ``libc`` variant, set
8514      :term:`TCLIBCAPPEND` to "" in their distro configuration file resulting
8515      in no suffix being applied.
8516
8517   :term:`TCMODE`
8518      Specifies the toolchain selector. :term:`TCMODE` controls the
8519      characteristics of the generated packages and images by telling the
8520      OpenEmbedded build system which toolchain profile to use. By default,
8521      the OpenEmbedded build system builds its own internal toolchain. The
8522      variable's default value is "default", which uses that internal
8523      toolchain.
8524
8525      .. note::
8526
8527         If :term:`TCMODE` is set to a value other than "default", then it is your
8528         responsibility to ensure that the toolchain is compatible with the
8529         default toolchain. Using older or newer versions of these
8530         components might cause build problems. See
8531         :doc:`Release Information </migration-guides/index>` for your
8532         version of the Yocto Project, to find the specific components with
8533         which the toolchain must be compatible.
8534
8535      The :term:`TCMODE` variable is similar to :term:`TCLIBC`,
8536      which controls the variant of the GNU standard C library (``libc``)
8537      used during the build process: ``glibc`` or ``musl``.
8538
8539      With additional layers, it is possible to use a pre-compiled external
8540      toolchain. One example is the Sourcery G++ Toolchain. The support for
8541      this toolchain resides in the separate Mentor Graphics
8542      ``meta-sourcery`` layer at
8543      https://github.com/MentorEmbedded/meta-sourcery/.
8544
8545      The layer's ``README`` file contains information on how to use the
8546      Sourcery G++ Toolchain as an external toolchain. You will have to
8547      add the layer to your ``bblayers.conf`` file and then set the
8548      :term:`EXTERNAL_TOOLCHAIN` variable in your ``local.conf`` file to
8549      the location of the toolchain.
8550
8551      The fundamentals used for this example apply to any external
8552      toolchain. You can use ``meta-sourcery`` as a template for adding
8553      support for other external toolchains.
8554
8555      In addition to toolchain configuration, you will also need a
8556      corresponding toolchain recipe file. This recipe file needs to package
8557      up any pre-built objects in the toolchain such as ``libgcc``,
8558      ``libstdcc++``, any locales, and ``libc``.
8559
8560   :term:`TC_CXX_RUNTIME`
8561      Specifies the C/C++ STL and runtime variant to use during
8562      the build process. Default value is 'gnu'
8563
8564      You can select "gnu", "llvm", or "android".
8565
8566   :term:`TEMPLATECONF`
8567      Specifies the directory used by the build system to find templates
8568      from which to build the ``bblayers.conf`` and ``local.conf`` files.
8569      Use this variable if you wish to customize such files, and the default
8570      BitBake targets shown when sourcing the ``oe-init-build-env`` script.
8571
8572      For details, see the
8573      :ref:`dev-manual/custom-template-configuration-directory:creating a custom template configuration directory`
8574      section in the Yocto Project Development Tasks manual.
8575
8576      .. note::
8577
8578         You must set this variable in the external environment in order
8579         for it to work.
8580
8581   :term:`TEST_EXPORT_DIR`
8582      The location the OpenEmbedded build system uses to export tests when
8583      the :term:`TEST_EXPORT_ONLY` variable is set
8584      to "1".
8585
8586      The :term:`TEST_EXPORT_DIR` variable defaults to
8587      ``"${TMPDIR}/testimage/${PN}"``.
8588
8589   :term:`TEST_EXPORT_ONLY`
8590      Specifies to export the tests only. Set this variable to "1" if you
8591      do not want to run the tests but you want them to be exported in a
8592      manner that you to run them outside of the build system.
8593
8594   :term:`TEST_LOG_DIR`
8595      Holds the SSH log and the boot log for QEMU machines. The
8596      :term:`TEST_LOG_DIR` variable defaults to ``"${WORKDIR}/testimage"``.
8597
8598      .. note::
8599
8600         Actual test results reside in the task log (``log.do_testimage``),
8601         which is in the ``${WORKDIR}/temp/`` directory.
8602
8603   :term:`TEST_POWERCONTROL_CMD`
8604      For automated hardware testing, specifies the command to use to
8605      control the power of the target machine under test. Typically, this
8606      command would point to a script that performs the appropriate action
8607      (e.g. interacting with a web-enabled power strip). The specified
8608      command should expect to receive as the last argument "off", "on" or
8609      "cycle" specifying to power off, on, or cycle (power off and then
8610      power on) the device, respectively.
8611
8612   :term:`TEST_POWERCONTROL_EXTRA_ARGS`
8613      For automated hardware testing, specifies additional arguments to
8614      pass through to the command specified in
8615      :term:`TEST_POWERCONTROL_CMD`. Setting
8616      :term:`TEST_POWERCONTROL_EXTRA_ARGS` is optional. You can use it if you
8617      wish, for example, to separate the machine-specific and
8618      non-machine-specific parts of the arguments.
8619
8620   :term:`TEST_QEMUBOOT_TIMEOUT`
8621      The time in seconds allowed for an image to boot before automated
8622      runtime tests begin to run against an image. The default timeout
8623      period to allow the boot process to reach the login prompt is 500
8624      seconds. You can specify a different value in the ``local.conf``
8625      file.
8626
8627      For more information on testing images, see the
8628      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8629      section in the Yocto Project Development Tasks Manual.
8630
8631   :term:`TEST_SERIALCONTROL_CMD`
8632      For automated hardware testing, specifies the command to use to
8633      connect to the serial console of the target machine under test. This
8634      command simply needs to connect to the serial console and forward
8635      that connection to standard input and output as any normal terminal
8636      program does.
8637
8638      For example, to use the Picocom terminal program on serial device
8639      ``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows::
8640
8641         TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
8642
8643   :term:`TEST_SERIALCONTROL_EXTRA_ARGS`
8644      For automated hardware testing, specifies additional arguments to
8645      pass through to the command specified in
8646      :term:`TEST_SERIALCONTROL_CMD`. Setting
8647      :term:`TEST_SERIALCONTROL_EXTRA_ARGS` is optional. You can use it if you
8648      wish, for example, to separate the machine-specific and
8649      non-machine-specific parts of the command.
8650
8651   :term:`TEST_SERVER_IP`
8652      The IP address of the build machine (host machine). This IP address
8653      is usually automatically detected. However, if detection fails, this
8654      variable needs to be set to the IP address of the build machine (i.e.
8655      where the build is taking place).
8656
8657      .. note::
8658
8659         The :term:`TEST_SERVER_IP` variable is only used for a small number of
8660         tests such as the "dnf" test suite, which needs to download packages
8661         from ``WORKDIR/oe-rootfs-repo``.
8662
8663   :term:`TEST_SUITES`
8664      An ordered list of tests (modules) to run against an image when
8665      performing automated runtime testing.
8666
8667      The OpenEmbedded build system provides a core set of tests that can
8668      be used against images.
8669
8670      .. note::
8671
8672         Currently, there is only support for running these tests under
8673         QEMU.
8674
8675      Tests include ``ping``, ``ssh``, ``df`` among others. You can add
8676      your own tests to the list of tests by appending :term:`TEST_SUITES` as
8677      follows::
8678
8679         TEST_SUITES:append = " mytest"
8680
8681      Alternatively, you can
8682      provide the "auto" option to have all applicable tests run against
8683      the image::
8684
8685         TEST_SUITES:append = " auto"
8686
8687      Using this option causes the
8688      build system to automatically run tests that are applicable to the
8689      image. Tests that are not applicable are skipped.
8690
8691      The order in which tests are run is important. Tests that depend on
8692      another test must appear later in the list than the test on which
8693      they depend. For example, if you append the list of tests with two
8694      tests (``test_A`` and ``test_B``) where ``test_B`` is dependent on
8695      ``test_A``, then you must order the tests as follows::
8696
8697         TEST_SUITES = "test_A test_B"
8698
8699      For more information on testing images, see the
8700      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8701      section in the Yocto Project Development Tasks Manual.
8702
8703   :term:`TEST_TARGET`
8704      Specifies the target controller to use when running tests against a
8705      test image. The default controller to use is "qemu"::
8706
8707         TEST_TARGET = "qemu"
8708
8709      A target controller is a class that defines how an image gets
8710      deployed on a target and how a target is started. A layer can extend
8711      the controllers by adding a module in the layer's
8712      ``/lib/oeqa/controllers`` directory and by inheriting the
8713      ``BaseTarget`` class, which is an abstract class that cannot be used
8714      as a value of :term:`TEST_TARGET`.
8715
8716      You can provide the following arguments with :term:`TEST_TARGET`:
8717
8718      -  *"qemu":* Boots a QEMU image and runs the tests. See the
8719         ":ref:`dev-manual/runtime-testing:enabling runtime tests on qemu`" section
8720         in the Yocto Project Development Tasks Manual for more
8721         information.
8722
8723      -  *"simpleremote":* Runs the tests on target hardware that is
8724         already up and running. The hardware can be on the network or it
8725         can be a device running an image on QEMU. You must also set
8726         :term:`TEST_TARGET_IP` when you use
8727         "simpleremote".
8728
8729         .. note::
8730
8731            This argument is defined in
8732            ``meta/lib/oeqa/controllers/simpleremote.py``.
8733
8734      For information on running tests on hardware, see the
8735      ":ref:`dev-manual/runtime-testing:enabling runtime tests on hardware`"
8736      section in the Yocto Project Development Tasks Manual.
8737
8738   :term:`TEST_TARGET_IP`
8739      The IP address of your hardware under test. The :term:`TEST_TARGET_IP`
8740      variable has no effect when :term:`TEST_TARGET` is
8741      set to "qemu".
8742
8743      When you specify the IP address, you can also include a port. Here is
8744      an example::
8745
8746         TEST_TARGET_IP = "192.168.1.4:2201"
8747
8748      Specifying a port is
8749      useful when SSH is started on a non-standard port or in cases when
8750      your hardware under test is behind a firewall or network that is not
8751      directly accessible from your host and you need to do port address
8752      translation.
8753
8754   :term:`TESTIMAGE_AUTO`
8755      Automatically runs the series of automated tests for images when an
8756      image is successfully built. Setting :term:`TESTIMAGE_AUTO` to "1" causes
8757      any image that successfully builds to automatically boot under QEMU.
8758      Using the variable also adds in dependencies so that any SDK for
8759      which testing is requested is automatically built first.
8760
8761      These tests are written in Python making use of the ``unittest``
8762      module, and the majority of them run commands on the target system
8763      over ``ssh``. You can set this variable to "1" in your ``local.conf``
8764      file in the :term:`Build Directory` to have the
8765      OpenEmbedded build system automatically run these tests after an
8766      image successfully builds:
8767
8768         TESTIMAGE_AUTO = "1"
8769
8770      For more information
8771      on enabling, running, and writing these tests, see the
8772      ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
8773      section in the Yocto Project Development Tasks Manual and the
8774      ":ref:`ref-classes-testimage`" section.
8775
8776   :term:`THISDIR`
8777      The directory in which the file BitBake is currently parsing is
8778      located. Do not manually set this variable.
8779
8780   :term:`TIME`
8781      The time the build was started. Times appear using the hour, minute,
8782      and second (HMS) format (e.g. "140159" for one minute and fifty-nine
8783      seconds past 1400 hours).
8784
8785   :term:`TMPDIR`
8786      This variable is the base directory the OpenEmbedded build system
8787      uses for all build output and intermediate files (other than the
8788      shared state cache). By default, the :term:`TMPDIR` variable points to
8789      ``tmp`` within the :term:`Build Directory`.
8790
8791      If you want to establish this directory in a location other than the
8792      default, you can uncomment and edit the following statement in the
8793      ``conf/local.conf`` file in the :term:`Source Directory`::
8794
8795         #TMPDIR = "${TOPDIR}/tmp"
8796
8797      An example use for this scenario is to set :term:`TMPDIR` to a local disk,
8798      which does not use NFS, while having the :term:`Build Directory` use NFS.
8799
8800      The filesystem used by :term:`TMPDIR` must have standard filesystem
8801      semantics (i.e. mixed-case files are unique, POSIX file locking, and
8802      persistent inodes). Due to various issues with NFS and bugs in some
8803      implementations, NFS does not meet this minimum requirement.
8804      Consequently, :term:`TMPDIR` cannot be on NFS.
8805
8806   :term:`TOOLCHAIN_HOST_TASK`
8807      This variable lists packages the OpenEmbedded build system uses when
8808      building an SDK, which contains a cross-development environment. The
8809      packages specified by this variable are part of the toolchain set
8810      that runs on the :term:`SDKMACHINE`, and each
8811      package should usually have the prefix ``nativesdk-``. For example,
8812      consider the following command when building an SDK::
8813
8814         $ bitbake -c populate_sdk imagename
8815
8816      In this case, a default list of packages is
8817      set in this variable, but you can add additional packages to the
8818      list. See the
8819      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8820      in the Yocto Project Application Development and the Extensible
8821      Software Development Kit (eSDK) manual for more information.
8822
8823      For background information on cross-development toolchains in the
8824      Yocto Project development environment, see the
8825      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8826      section in the Yocto Project Overview and Concepts Manual. For
8827      information on setting up a cross-development environment, see the
8828      :doc:`/sdk-manual/index` manual.
8829
8830      Note that this variable applies to building an SDK, not an eSDK,
8831      in which case the :term:`TOOLCHAIN_HOST_TASK_ESDK` setting should be
8832      used instead.
8833
8834   :term:`TOOLCHAIN_HOST_TASK_ESDK`
8835      This variable allows to extend what is installed in the host
8836      portion of an eSDK. This is similar to :term:`TOOLCHAIN_HOST_TASK`
8837      applying to SDKs.
8838
8839   :term:`TOOLCHAIN_OUTPUTNAME`
8840      This variable defines the name used for the toolchain output. The
8841      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class sets
8842      the :term:`TOOLCHAIN_OUTPUTNAME` variable as follows::
8843
8844         TOOLCHAIN_OUTPUTNAME ?= "${SDK_NAME}-toolchain-${SDK_VERSION}"
8845
8846      See
8847      the :term:`SDK_NAME` and
8848      :term:`SDK_VERSION` variables for additional
8849      information.
8850
8851   :term:`TOOLCHAIN_TARGET_TASK`
8852      This variable lists packages the OpenEmbedded build system uses when
8853      it creates the target part of an SDK (i.e. the part built for the
8854      target hardware), which includes libraries and headers. Use this
8855      variable to add individual packages to the part of the SDK that runs
8856      on the target. See the
8857      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8858      in the Yocto Project Application Development and the Extensible
8859      Software Development Kit (eSDK) manual for more information.
8860
8861      For background information on cross-development toolchains in the
8862      Yocto Project development environment, see the
8863      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8864      section in the Yocto Project Overview and Concepts Manual. For
8865      information on setting up a cross-development environment, see the
8866      :doc:`/sdk-manual/index` manual.
8867
8868   :term:`TOPDIR`
8869      See :term:`bitbake:TOPDIR` in the BitBake manual.
8870
8871   :term:`TRANSLATED_TARGET_ARCH`
8872      A sanitized version of :term:`TARGET_ARCH`. This
8873      variable is used where the architecture is needed in a value where
8874      underscores are not allowed, for example within package filenames. In
8875      this case, dash characters replace any underscore characters used in
8876      :term:`TARGET_ARCH`.
8877
8878      Do not edit this variable.
8879
8880   :term:`TUNE_ARCH`
8881      The GNU canonical architecture for a specific architecture (i.e.
8882      ``arm``, ``armeb``, ``mips``, ``mips64``, and so forth). BitBake uses
8883      this value to setup configuration.
8884
8885      :term:`TUNE_ARCH` definitions are specific to a given architecture. The
8886      definitions can be a single static definition, or can be dynamically
8887      adjusted. You can see details for a given CPU family by looking at
8888      the architecture's ``README`` file. For example, the
8889      ``meta/conf/machine/include/mips/README`` file in the
8890      :term:`Source Directory` provides information for
8891      :term:`TUNE_ARCH` specific to the ``mips`` architecture.
8892
8893      :term:`TUNE_ARCH` is tied closely to
8894      :term:`TARGET_ARCH`, which defines the target
8895      machine's architecture. The BitBake configuration file
8896      (``meta/conf/bitbake.conf``) sets :term:`TARGET_ARCH` as follows::
8897
8898         TARGET_ARCH = "${TUNE_ARCH}"
8899
8900      The following list, which is by no means complete since architectures
8901      are configurable, shows supported machine architectures:
8902
8903      - arm
8904      - i586
8905      - x86_64
8906      - powerpc
8907      - powerpc64
8908      - mips
8909      - mipsel
8910
8911   :term:`TUNE_ASARGS`
8912      Specifies architecture-specific assembler flags for the target
8913      system. The set of flags is based on the selected tune features.
8914      :term:`TUNE_ASARGS` is set using the tune include files, which are
8915      typically under ``meta/conf/machine/include/`` and are influenced
8916      through :term:`TUNE_FEATURES`. For example, the
8917      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8918      for the x86 architecture as follows::
8919
8920         TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
8921
8922      .. note::
8923
8924         Board Support Packages (BSPs) select the tune. The selected tune,
8925         in turn, affects the tune variables themselves (i.e. the tune can
8926         supply its own set of flags).
8927
8928   :term:`TUNE_CCARGS`
8929      Specifies architecture-specific C compiler flags for the target
8930      system. The set of flags is based on the selected tune features.
8931      :term:`TUNE_CCARGS` is set using the tune include files, which are
8932      typically under ``meta/conf/machine/include/`` and are influenced
8933      through :term:`TUNE_FEATURES`.
8934
8935      .. note::
8936
8937         Board Support Packages (BSPs) select the tune. The selected tune,
8938         in turn, affects the tune variables themselves (i.e. the tune can
8939         supply its own set of flags).
8940
8941   :term:`TUNE_FEATURES`
8942      Features used to "tune" a compiler for optimal use given a specific
8943      processor. The features are defined within the tune files and allow
8944      arguments (i.e. ``TUNE_*ARGS``) to be dynamically generated based on
8945      the features.
8946
8947      The OpenEmbedded build system verifies the features to be sure they
8948      are not conflicting and that they are supported.
8949
8950      The BitBake configuration file (``meta/conf/bitbake.conf``) defines
8951      :term:`TUNE_FEATURES` as follows::
8952
8953         TUNE_FEATURES ??= "${TUNE_FEATURES:tune-${DEFAULTTUNE}}"
8954
8955      See the :term:`DEFAULTTUNE` variable for more information.
8956
8957   :term:`TUNE_LDARGS`
8958      Specifies architecture-specific linker flags for the target system.
8959      The set of flags is based on the selected tune features.
8960      :term:`TUNE_LDARGS` is set using the tune include files, which are
8961      typically under ``meta/conf/machine/include/`` and are influenced
8962      through :term:`TUNE_FEATURES`. For example, the
8963      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8964      for the x86 architecture as follows::
8965
8966         TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
8967
8968      .. note::
8969
8970         Board Support Packages (BSPs) select the tune. The selected tune,
8971         in turn, affects the tune variables themselves (i.e. the tune can
8972         supply its own set of flags).
8973
8974   :term:`TUNE_PKGARCH`
8975      The package architecture understood by the packaging system to define
8976      the architecture, ABI, and tuning of output packages. The specific
8977      tune is defined using the "_tune" override as follows::
8978
8979         TUNE_PKGARCH:tune-tune = "tune"
8980
8981      These tune-specific package architectures are defined in the machine
8982      include files. Here is an example of the "core2-32" tuning as used in
8983      the ``meta/conf/machine/include/x86/tune-core2.inc`` file::
8984
8985         TUNE_PKGARCH:tune-core2-32 = "core2-32"
8986
8987   :term:`TUNECONFLICTS[feature]`
8988      Specifies CPU or Application Binary Interface (ABI) tuning features
8989      that conflict with feature.
8990
8991      Known tuning conflicts are specified in the machine include files in
8992      the :term:`Source Directory`. Here is an example from
8993      the ``meta/conf/machine/include/mips/arch-mips.inc`` include file
8994      that lists the "o32" and "n64" features as conflicting with the "n32"
8995      feature::
8996
8997         TUNECONFLICTS[n32] = "o32 n64"
8998
8999   :term:`TUNEVALID[feature]`
9000      Specifies a valid CPU or Application Binary Interface (ABI) tuning
9001      feature. The specified feature is stored as a flag. Valid features
9002      are specified in the machine include files (e.g.
9003      ``meta/conf/machine/include/arm/arch-arm.inc``). Here is an example
9004      from that file::
9005
9006         TUNEVALID[bigendian] = "Enable big-endian mode."
9007
9008      See the machine include files in the :term:`Source Directory`
9009      for these features.
9010
9011   :term:`UBOOT_CONFIG`
9012      Configures the :term:`UBOOT_MACHINE` and can
9013      also define :term:`IMAGE_FSTYPES` for individual
9014      cases.
9015
9016      Following is an example from the ``meta-fsl-arm`` layer. ::
9017
9018         UBOOT_CONFIG ??= "sd"
9019         UBOOT_CONFIG[sd] = "mx6qsabreauto_config,sdcard"
9020         UBOOT_CONFIG[eimnor] = "mx6qsabreauto_eimnor_config"
9021         UBOOT_CONFIG[nand] = "mx6qsabreauto_nand_config,ubifs"
9022         UBOOT_CONFIG[spinor] = "mx6qsabreauto_spinor_config"
9023
9024      In this example, "sd" is selected as the configuration of the possible four for the
9025      :term:`UBOOT_MACHINE`. The "sd" configuration defines
9026      "mx6qsabreauto_config" as the value for :term:`UBOOT_MACHINE`, while the
9027      "sdcard" specifies the :term:`IMAGE_FSTYPES` to use for the U-Boot image.
9028
9029      For more information on how the :term:`UBOOT_CONFIG` is handled, see the
9030      :ref:`ref-classes-uboot-config` class.
9031
9032   :term:`UBOOT_DTB_LOADADDRESS`
9033      Specifies the load address for the dtb image used by U-Boot. During FIT
9034      image creation, the :term:`UBOOT_DTB_LOADADDRESS` variable is used in
9035      :ref:`ref-classes-kernel-fitimage` class to specify the load address to be
9036      used in creating the dtb sections of Image Tree Source for the FIT image.
9037
9038   :term:`UBOOT_DTBO_LOADADDRESS`
9039      Specifies the load address for the dtbo image used by U-Boot.  During FIT
9040      image creation, the :term:`UBOOT_DTBO_LOADADDRESS` variable is used in
9041      :ref:`ref-classes-kernel-fitimage` class to specify the load address to be
9042      used in creating the dtbo sections of Image Tree Source for the FIT image.
9043
9044   :term:`UBOOT_ENTRYPOINT`
9045      Specifies the entry point for the U-Boot image. During U-Boot image
9046      creation, the :term:`UBOOT_ENTRYPOINT` variable is passed as a
9047      command-line parameter to the ``uboot-mkimage`` utility.
9048
9049   :term:`UBOOT_LOADADDRESS`
9050      Specifies the load address for the U-Boot image. During U-Boot image
9051      creation, the :term:`UBOOT_LOADADDRESS` variable is passed as a
9052      command-line parameter to the ``uboot-mkimage`` utility.
9053
9054   :term:`UBOOT_LOCALVERSION`
9055      Appends a string to the name of the local version of the U-Boot
9056      image. For example, assuming the version of the U-Boot image built
9057      was "2013.10", the full version string reported by U-Boot would be
9058      "2013.10-yocto" given the following statement::
9059
9060         UBOOT_LOCALVERSION = "-yocto"
9061
9062   :term:`UBOOT_MACHINE`
9063      Specifies the value passed on the ``make`` command line when building
9064      a U-Boot image. The value indicates the target platform
9065      configuration. You typically set this variable from the machine
9066      configuration file (i.e. ``conf/machine/machine_name.conf``).
9067
9068      Please see the "Selection of Processor Architecture and Board Type"
9069      section in the U-Boot README for valid values for this variable.
9070
9071   :term:`UBOOT_MAKE_TARGET`
9072      Specifies the target called in the ``Makefile``. The default target
9073      is "all".
9074
9075   :term:`UBOOT_MKIMAGE`
9076      Specifies the name of the mkimage command as used by the
9077      :ref:`ref-classes-kernel-fitimage` class to assemble
9078      the FIT image. This can be used to substitute an alternative command, wrapper
9079      script or function if desired. The default is "uboot-mkimage".
9080
9081   :term:`UBOOT_MKIMAGE_DTCOPTS`
9082      Options for the device tree compiler passed to mkimage '-D' feature while
9083      creating FIT image in :ref:`ref-classes-kernel-fitimage` class. If
9084      :term:`UBOOT_MKIMAGE_DTCOPTS` is not set then
9085      :ref:`ref-classes-kernel-fitimage` will not pass the ``-D`` option to
9086      mkimage.
9087
9088   :term:`UBOOT_MKIMAGE_KERNEL_TYPE`
9089      Specifies the type argument for the kernel as passed to ``uboot-mkimage``.
9090      The default value is "kernel".
9091
9092   :term:`UBOOT_MKIMAGE_SIGN`
9093      Specifies the name of the mkimage command as used by the
9094      :ref:`ref-classes-kernel-fitimage` class to sign
9095      the FIT image after it has been assembled (if enabled). This can be used
9096      to substitute an alternative command, wrapper script or function if
9097      desired. The default is "${:term:`UBOOT_MKIMAGE`}".
9098
9099   :term:`UBOOT_MKIMAGE_SIGN_ARGS`
9100      Optionally specifies additional arguments for the
9101      :ref:`ref-classes-kernel-fitimage` class to pass to the
9102      mkimage command when signing the FIT image.
9103
9104   :term:`UBOOT_RD_ENTRYPOINT`
9105      Specifies the entrypoint for the RAM disk image. During FIT image
9106      creation, the :term:`UBOOT_RD_ENTRYPOINT` variable is used in
9107      :ref:`ref-classes-kernel-fitimage` class to specify the entrypoint to be
9108      used in creating the Image Tree Source for the FIT image.
9109
9110   :term:`UBOOT_RD_LOADADDRESS`
9111      Specifies the load address for the RAM disk image. During FIT image
9112      creation, the :term:`UBOOT_RD_LOADADDRESS` variable is used in
9113      :ref:`ref-classes-kernel-fitimage` class to specify the load address to
9114      be used in creating the Image Tree Source for the FIT image.
9115
9116   :term:`UBOOT_SIGN_ENABLE`
9117      Enable signing of FIT image. The default value is "0".
9118
9119   :term:`UBOOT_SIGN_KEYDIR`
9120      Location of the directory containing the RSA key and
9121      certificate used for signing FIT image.
9122
9123   :term:`UBOOT_SIGN_KEYNAME`
9124      The name of keys used for signing U-Boot FIT image stored in
9125      :term:`UBOOT_SIGN_KEYDIR` directory. For e.g. dev.key key and dev.crt
9126      certificate stored in :term:`UBOOT_SIGN_KEYDIR` directory will have
9127      :term:`UBOOT_SIGN_KEYNAME` set to "dev".
9128
9129   :term:`UBOOT_SUFFIX`
9130      Points to the generated U-Boot extension. For example, ``u-boot.sb``
9131      has a ``.sb`` extension.
9132
9133      The default U-Boot extension is ``.bin``
9134
9135   :term:`UBOOT_TARGET`
9136      Specifies the target used for building U-Boot. The target is passed
9137      directly as part of the "make" command (e.g. SPL and AIS). If you do
9138      not specifically set this variable, the OpenEmbedded build process
9139      passes and uses "all" for the target during the U-Boot building
9140      process.
9141
9142   :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`
9143      Specifies a list of options that, if reported by the configure script
9144      as being invalid, should not generate a warning during the
9145      :ref:`ref-tasks-configure` task. Normally, invalid
9146      configure options are simply not passed to the configure script (e.g.
9147      should be removed from :term:`EXTRA_OECONF` or
9148      :term:`PACKAGECONFIG_CONFARGS`).
9149      However, there are common options that are passed to all
9150      configure scripts at a class level, but might not be valid for some
9151      configure scripts. Therefore warnings about these options are useless.
9152      For these cases, the options are added to :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`.
9153
9154      The configure arguments check that uses
9155      :term:`UNKNOWN_CONFIGURE_OPT_IGNORE` is part of the
9156      :ref:`ref-classes-insane` class and is only enabled if the
9157      recipe inherits the :ref:`ref-classes-autotools` class.
9158
9159   :term:`UPDATERCPN`
9160      For recipes inheriting the
9161      :ref:`ref-classes-update-rc.d` class, :term:`UPDATERCPN`
9162      specifies the package that contains the initscript that is enabled.
9163
9164      The default value is "${PN}". Given that almost all recipes that
9165      install initscripts package them in the main package for the recipe,
9166      you rarely need to set this variable in individual recipes.
9167
9168   :term:`UPSTREAM_CHECK_COMMITS`
9169      You can perform a per-recipe check for what the latest upstream
9170      source code version is by calling ``devtool latest-version recipe``. If
9171      the recipe source code is provided from Git repositories, but
9172      releases are not identified by Git tags, set :term:`UPSTREAM_CHECK_COMMITS`
9173      to ``1`` in the recipe, and the OpenEmbedded build system
9174      will compare the latest commit with the one currently specified
9175      by the recipe (:term:`SRCREV`)::
9176
9177         UPSTREAM_CHECK_COMMITS = "1"
9178
9179   :term:`UPSTREAM_CHECK_GITTAGREGEX`
9180      You can perform a per-recipe check for what the latest upstream
9181      source code version is by calling ``devtool latest-version recipe``. If
9182      the recipe source code is provided from Git repositories, the
9183      OpenEmbedded build system determines the latest upstream version by
9184      picking the latest tag from the list of all repository tags.
9185
9186      You can use the :term:`UPSTREAM_CHECK_GITTAGREGEX` variable to provide a
9187      regular expression to filter only the relevant tags should the
9188      default filter not work correctly::
9189
9190         UPSTREAM_CHECK_GITTAGREGEX = "git_tag_regex"
9191
9192   :term:`UPSTREAM_CHECK_REGEX`
9193      Use the :term:`UPSTREAM_CHECK_REGEX` variable to specify a different
9194      regular expression instead of the default one when the package
9195      checking system is parsing the page found using
9196      :term:`UPSTREAM_CHECK_URI`::
9197
9198         UPSTREAM_CHECK_REGEX = "package_regex"
9199
9200   :term:`UPSTREAM_CHECK_URI`
9201      You can perform a per-recipe check for what the latest upstream
9202      source code version is by calling ``devtool latest-version recipe``. If
9203      the source code is provided from tarballs, the latest version is
9204      determined by fetching the directory listing where the tarball is and
9205      attempting to find a later tarball. When this approach does not work,
9206      you can use :term:`UPSTREAM_CHECK_URI` to provide a different URI that
9207      contains the link to the latest tarball::
9208
9209         UPSTREAM_CHECK_URI = "recipe_url"
9210
9211   :term:`UPSTREAM_VERSION_UNKNOWN`
9212      You can perform a per-recipe check for what the latest upstream
9213      source code version is by calling ``devtool latest-version recipe``.
9214      If no combination of the :term:`UPSTREAM_CHECK_URI`, :term:`UPSTREAM_CHECK_REGEX`,
9215      :term:`UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
9216      the recipe allows to determine what the latest upstream version is,
9217      you can set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1`` in the recipe
9218      to acknowledge that the check cannot be performed::
9219
9220         UPSTREAM_VERSION_UNKNOWN = "1"
9221
9222   :term:`USE_DEVFS`
9223      Determines if ``devtmpfs`` is used for ``/dev`` population. The
9224      default value used for :term:`USE_DEVFS` is "1" when no value is
9225      specifically set. Typically, you would set :term:`USE_DEVFS` to "0" for a
9226      statically populated ``/dev`` directory.
9227
9228      See the ":ref:`dev-manual/device-manager:selecting a device manager`" section in
9229      the Yocto Project Development Tasks Manual for information on how to
9230      use this variable.
9231
9232   :term:`USE_VT`
9233      When using
9234      :ref:`SysVinit <dev-manual/new-recipe:enabling system services>`,
9235      determines whether or not to run a :wikipedia:`getty <Getty_(Unix)>`
9236      on any virtual terminals in order to enable logging in through those
9237      terminals.
9238
9239      The default value used for :term:`USE_VT` is "1" when no default value is
9240      specifically set. Typically, you would set :term:`USE_VT` to "0" in the
9241      machine configuration file for machines that do not have a graphical
9242      display attached and therefore do not need virtual terminal
9243      functionality.
9244
9245   :term:`USER_CLASSES`
9246      A list of classes to globally inherit. These classes are used by the
9247      OpenEmbedded build system to enable extra features.
9248
9249      Classes inherited using :term:`USER_CLASSES` must be located in the
9250      ``classes-global/`` or ``classes/`` subdirectories.
9251
9252      The default list is set in your ``local.conf`` file::
9253
9254         USER_CLASSES ?= "buildstats"
9255
9256      For more information, see
9257      ``meta-poky/conf/templates/default/local.conf.sample`` in the
9258      :term:`Source Directory`.
9259
9260   :term:`USERADD_ERROR_DYNAMIC`
9261      If set to ``error``, forces the OpenEmbedded build system to produce
9262      an error if the user identification (``uid``) and group
9263      identification (``gid``) values are not defined in any of the files
9264      listed in :term:`USERADD_UID_TABLES` and
9265      :term:`USERADD_GID_TABLES`. If set to
9266      ``warn``, a warning will be issued instead.
9267
9268      The default behavior for the build system is to dynamically apply
9269      ``uid`` and ``gid`` values. Consequently, the
9270      :term:`USERADD_ERROR_DYNAMIC` variable is by default not set. If you plan
9271      on using statically assigned ``gid`` and ``uid`` values, you should
9272      set the :term:`USERADD_ERROR_DYNAMIC` variable in your ``local.conf``
9273      file as follows::
9274
9275         USERADD_ERROR_DYNAMIC = "error"
9276
9277      Overriding the
9278      default behavior implies you are going to also take steps to set
9279      static ``uid`` and ``gid`` values through use of the
9280      :term:`USERADDEXTENSION`,
9281      :term:`USERADD_UID_TABLES`, and
9282      :term:`USERADD_GID_TABLES` variables.
9283
9284      .. note::
9285
9286         There is a difference in behavior between setting
9287         :term:`USERADD_ERROR_DYNAMIC` to ``error`` and setting it to ``warn``.
9288         When it is set to ``warn``, the build system will report a warning for
9289         every undefined ``uid`` and ``gid`` in any recipe. But when it is set
9290         to ``error``, it will only report errors for recipes that are actually
9291         built.
9292         This saves you from having to add static IDs for recipes that you
9293         know will never be built.
9294
9295   :term:`USERADD_GID_TABLES`
9296      Specifies a password file to use for obtaining static group
9297      identification (``gid``) values when the OpenEmbedded build system
9298      adds a group to the system during package installation.
9299
9300      When applying static group identification (``gid``) values, the
9301      OpenEmbedded build system looks in :term:`BBPATH` for a
9302      ``files/group`` file and then applies those ``uid`` values. Set the
9303      variable as follows in your ``local.conf`` file::
9304
9305
9306         USERADD_GID_TABLES = "files/group"
9307
9308      .. note::
9309
9310         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
9311         causes the build system to use static ``gid`` values.
9312
9313   :term:`USERADD_PACKAGES`
9314      When inheriting the :ref:`ref-classes-useradd` class,
9315      this variable specifies the individual packages within the recipe
9316      that require users and/or groups to be added.
9317
9318      You must set this variable if the recipe inherits the class. For
9319      example, the following enables adding a user for the main package in
9320      a recipe::
9321
9322         USERADD_PACKAGES = "${PN}"
9323
9324      .. note::
9325
9326         It follows that if you are going to use the :term:`USERADD_PACKAGES`
9327         variable, you need to set one or more of the :term:`USERADD_PARAM`,
9328         :term:`GROUPADD_PARAM`, or :term:`GROUPMEMS_PARAM` variables.
9329
9330   :term:`USERADD_PARAM`
9331      When inheriting the :ref:`ref-classes-useradd` class,
9332      this variable specifies for a package what parameters should pass to
9333      the ``useradd`` command if you add a user to the system when the
9334      package is installed.
9335
9336      Here is an example from the ``dbus`` recipe::
9337
9338         USERADD_PARAM:${PN} = "--system --home ${localstatedir}/lib/dbus \
9339                                --no-create-home --shell /bin/false \
9340                                --user-group messagebus"
9341
9342      For information on the
9343      standard Linux shell command ``useradd``, see
9344      https://linux.die.net/man/8/useradd.
9345
9346   :term:`USERADD_UID_TABLES`
9347      Specifies a password file to use for obtaining static user
9348      identification (``uid``) values when the OpenEmbedded build system
9349      adds a user to the system during package installation.
9350
9351      When applying static user identification (``uid``) values, the
9352      OpenEmbedded build system looks in :term:`BBPATH` for a
9353      ``files/passwd`` file and then applies those ``uid`` values. Set the
9354      variable as follows in your ``local.conf`` file::
9355
9356         USERADD_UID_TABLES = "files/passwd"
9357
9358      .. note::
9359
9360         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
9361         causes the build system to use static ``uid`` values.
9362
9363   :term:`USERADDEXTENSION`
9364      When set to "useradd-staticids", causes the OpenEmbedded build system
9365      to base all user and group additions on a static ``passwd`` and
9366      ``group`` files found in :term:`BBPATH`.
9367
9368      To use static user identification (``uid``) and group identification
9369      (``gid``) values, set the variable as follows in your ``local.conf``
9370      file: USERADDEXTENSION = "useradd-staticids"
9371
9372      .. note::
9373
9374         Setting this variable to use static ``uid`` and ``gid``
9375         values causes the OpenEmbedded build system to employ the
9376         :ref:`ref-classes-useradd` class.
9377
9378      If you use static ``uid`` and ``gid`` information, you must also
9379      specify the ``files/passwd`` and ``files/group`` files by setting the
9380      :term:`USERADD_UID_TABLES` and
9381      :term:`USERADD_GID_TABLES` variables.
9382      Additionally, you should also set the
9383      :term:`USERADD_ERROR_DYNAMIC` variable.
9384
9385   :term:`VOLATILE_LOG_DIR`
9386      Specifies the persistence of the target's ``/var/log`` directory,
9387      which is used to house postinstall target log files.
9388
9389      By default, :term:`VOLATILE_LOG_DIR` is set to "yes", which means the
9390      file is not persistent. You can override this setting by setting the
9391      variable to "no" to make the log directory persistent.
9392
9393   :term:`VOLATILE_TMP_DIR`
9394      Specifies the persistence of the target's ``/tmp`` directory.
9395
9396      By default, :term:`VOLATILE_TMP_DIR` is set to "yes", in which case
9397      ``/tmp`` links to a directory which resides in RAM in a ``tmpfs``
9398      filesystem.
9399
9400      If instead, you want the ``/tmp`` directory to be persistent, set the
9401      variable to "no" to make it a regular directory in the root filesystem.
9402
9403      This supports both sysvinit and systemd based systems.
9404
9405   :term:`WARN_QA`
9406      Specifies the quality assurance checks whose failures are reported as
9407      warnings by the OpenEmbedded build system. You set this variable in
9408      your distribution configuration file. For a list of the checks you
9409      can control with this variable, see the
9410      ":ref:`ref-classes-insane`" section.
9411
9412   :term:`WATCHDOG_TIMEOUT`
9413      Specifies the timeout in seconds used by the ``watchdog`` recipe and
9414      also by ``systemd`` during reboot. The default is 60 seconds.
9415
9416   :term:`WIRELESS_DAEMON`
9417      For ``connman`` and ``packagegroup-base``, specifies the wireless
9418      daemon to use. The default is "wpa-supplicant" (note that the value
9419      uses a dash and not an underscore).
9420
9421   :term:`WKS_FILE`
9422      Specifies the location of the Wic kickstart file that is used by the
9423      OpenEmbedded build system to create a partitioned image
9424      (``image.wic``). For information on how to create a partitioned
9425      image, see the
9426      ":ref:`dev-manual/wic:creating partitioned images using wic`"
9427      section in the Yocto Project Development Tasks Manual. For details on
9428      the kickstart file format, see the ":doc:`/ref-manual/kickstart`" Chapter.
9429
9430   :term:`WKS_FILE_DEPENDS`
9431      When placed in the recipe that builds your image, this variable lists
9432      build-time dependencies. The :term:`WKS_FILE_DEPENDS` variable is only
9433      applicable when Wic images are active (i.e. when
9434      :term:`IMAGE_FSTYPES` contains entries related
9435      to Wic). If your recipe does not create Wic images, the variable has
9436      no effect.
9437
9438      The :term:`WKS_FILE_DEPENDS` variable is similar to the
9439      :term:`DEPENDS` variable. When you use the variable in
9440      your recipe that builds the Wic image, dependencies you list in the
9441      :term:`WKS_FILE_DEPENDS` variable are added to the :term:`DEPENDS` variable.
9442
9443      With the :term:`WKS_FILE_DEPENDS` variable, you have the possibility to
9444      specify a list of additional dependencies (e.g. native tools,
9445      bootloaders, and so forth), that are required to build Wic images.
9446      Following is an example::
9447
9448         WKS_FILE_DEPENDS = "some-native-tool"
9449
9450      In the
9451      previous example, some-native-tool would be replaced with an actual
9452      native tool on which the build would depend.
9453
9454   :term:`WKS_FILES`
9455      Specifies a list of candidate Wic kickstart files to be used by the
9456      OpenEmbedded build system to create a partitioned image. Only the
9457      first one that is found, from left to right, will be used.
9458
9459      This is only useful when there are multiple ``.wks`` files that can be
9460      used to produce an image. A typical case is when multiple layers are
9461      used for different hardware platforms, each supplying a different
9462      ``.wks`` file. In this case, you specify all possible ones through
9463      :term:`WKS_FILES`.
9464
9465      If only one ``.wks`` file is used, set :term:`WKS_FILE` instead.
9466
9467   :term:`WORKDIR`
9468      The pathname of the work directory in which the OpenEmbedded build
9469      system builds a recipe. This directory is located within the
9470      :term:`TMPDIR` directory structure and is specific to
9471      the recipe being built and the system for which it is being built.
9472
9473      The :term:`WORKDIR` directory is defined as follows::
9474
9475         ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
9476
9477      The actual directory depends on several things:
9478
9479      -  :term:`TMPDIR`: The top-level build output directory
9480      -  :term:`MULTIMACH_TARGET_SYS`: The target system identifier
9481      -  :term:`PN`: The recipe name
9482      -  :term:`EXTENDPE`: The epoch --- if :term:`PE` is not specified, which
9483         is usually the case for most recipes, then :term:`EXTENDPE` is blank.
9484      -  :term:`PV`: The recipe version
9485      -  :term:`PR`: The recipe revision
9486
9487      As an example, assume a Source Directory top-level folder name
9488      ``poky``, a default :term:`Build Directory` at ``poky/build``, and a
9489      ``qemux86-poky-linux`` machine target system. Furthermore, suppose
9490      your recipe is named ``foo_1.3.0-r0.bb``. In this case, the work
9491      directory the build system uses to build the package would be as
9492      follows::
9493
9494         poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
9495
9496   :term:`XSERVER`
9497      Specifies the packages that should be installed to provide an X
9498      server and drivers for the current machine, assuming your image
9499      directly includes ``packagegroup-core-x11-xserver`` or, perhaps
9500      indirectly, includes "x11-base" in
9501      :term:`IMAGE_FEATURES`.
9502
9503      The default value of :term:`XSERVER`, if not specified in the machine
9504      configuration, is "xserver-xorg xf86-video-fbdev xf86-input-evdev".
9505
9506   :term:`XZ_THREADS`
9507      Specifies the number of parallel threads that should be used when
9508      using xz compression.
9509
9510      By default this scales with core count, but is never set less than 2
9511      to ensure that multi-threaded mode is always used so that the output
9512      file contents are deterministic. Builds will work with a value of 1
9513      but the output will differ compared to the output from the compression
9514      generated when more than one thread is used.
9515
9516      On systems where many tasks run in parallel, setting a limit to this
9517      can be helpful in controlling system resource usage.
9518
9519   :term:`XZ_MEMLIMIT`
9520      Specifies the maximum memory the xz compression should use as a percentage
9521      of system memory. If unconstrained the xz compressor can use large amounts of
9522      memory and become problematic with parallelism elsewhere in the build.
9523      "50%" has been found to be a good value.
9524
9525   :term:`ZSTD_THREADS`
9526      Specifies the number of parallel threads that should be used when
9527      using ZStandard compression.
9528
9529      By default this scales with core count, but is never set less than 2
9530      to ensure that multi-threaded mode is always used so that the output
9531      file contents are deterministic. Builds will work with a value of 1
9532      but the output will differ compared to the output from the compression
9533      generated when more than one thread is used.
9534
9535      On systems where many tasks run in parallel, setting a limit to this
9536      can be helpful in controlling system resource usage.
9537