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
130      :ref:`features_check <ref-classes-features_check>`
131      class, this variable identifies a list of distribution features where
132      at least one must be enabled in the current configuration in order
133      for the OpenEmbedded build system to build the recipe. In other words,
134      if none of the features listed in :term:`ANY_OF_DISTRO_FEATURES`
135      appear in :term:`DISTRO_FEATURES` within the current configuration, then
136      the recipe will be skipped, and if the build system attempts to build
137      the recipe then an error will be triggered.
138
139
140   :term:`APPEND`
141      An override list of append strings for each target specified with
142      :term:`LABELS`.
143
144      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
145      information on how this variable is used.
146
147   :term:`AR`
148      The minimal command and arguments used to run ``ar``.
149
150   :term:`ARCHIVER_MODE`
151      When used with the :ref:`archiver <ref-classes-archiver>` class,
152      determines the type of information used to create a released archive.
153      You can use this variable to create archives of patched source,
154      original source, configured source, and so forth by employing the
155      following variable flags (varflags)::
156
157         ARCHIVER_MODE[src] = "original"                   # Uses original (unpacked) source files.
158         ARCHIVER_MODE[src] = "patched"                    # Uses patched source files. This is the default.
159         ARCHIVER_MODE[src] = "configured"                 # Uses configured source files.
160         ARCHIVER_MODE[diff] = "1"                         # Uses patches between do_unpack and do_patch.
161         ARCHIVER_MODE[diff-exclude] ?= "file file ..."    # Lists files and directories to exclude from diff.
162         ARCHIVER_MODE[dumpdata] = "1"                     # Uses environment data.
163         ARCHIVER_MODE[recipe] = "1"                       # Uses recipe and include files.
164         ARCHIVER_MODE[srpm] = "1"                         # Uses RPM package files.
165
166      For information on how the variable works, see the
167      ``meta/classes/archiver.bbclass`` file in the :term:`Source Directory`.
168
169   :term:`AS`
170      Minimal command and arguments needed to run the assembler.
171
172   :term:`ASSUME_PROVIDED`
173      Lists recipe names (:term:`PN` values) BitBake does not
174      attempt to build. Instead, BitBake assumes these recipes have already
175      been built.
176
177      In OpenEmbedded-Core, :term:`ASSUME_PROVIDED` mostly specifies native
178      tools that should not be built. An example is ``git-native``, which
179      when specified, allows for the Git binary from the host to be used
180      rather than building ``git-native``.
181
182   :term:`ASSUME_SHLIBS`
183      Provides additional ``shlibs`` provider mapping information, which
184      adds to or overwrites the information provided automatically by the
185      system. Separate multiple entries using spaces.
186
187      As an example, use the following form to add an ``shlib`` provider of
188      shlibname in packagename with the optional version::
189
190         shlibname:packagename[_version]
191
192      Here is an example that adds a shared library named ``libEGL.so.1``
193      as being provided by the ``libegl-implementation`` package::
194
195         ASSUME_SHLIBS = "libEGL.so.1:libegl-implementation"
196
197   :term:`AUTHOR`
198      The email address used to contact the original author or authors in
199      order to send patches and forward bugs.
200
201   :term:`AUTO_LIBNAME_PKGS`
202      When the :ref:`debian <ref-classes-debian>` class is inherited,
203      which is the default behavior, :term:`AUTO_LIBNAME_PKGS` specifies which
204      packages should be checked for libraries and renamed according to
205      Debian library package naming.
206
207      The default value is "${PACKAGES}", which causes the debian class to
208      act on all packages that are explicitly generated by the recipe.
209
210   :term:`AUTOREV`
211      When :term:`SRCREV` is set to the value of this variable, it specifies to
212      use the latest source revision in the repository. Here is an example::
213
214         SRCREV = "${AUTOREV}"
215
216      If you use the previous statement to retrieve the latest version of
217      software, you need to be sure :term:`PV` contains
218      ``${``\ :term:`SRCPV`\ ``}``. For example, suppose you
219      have a kernel recipe that inherits the
220      :ref:`kernel <ref-classes-kernel>` class and you use the previous
221      statement. In this example, ``${SRCPV}`` does not automatically get
222      into :term:`PV`. Consequently, you need to change :term:`PV` in your recipe
223      so that it does contain ``${SRCPV}``.
224
225      For more information see the
226      ":ref:`dev-manual/common-tasks:automatically incrementing a package version number`"
227      section in the Yocto Project Development Tasks Manual.
228
229   :term:`AUTO_SYSLINUXMENU`
230      Enables creating an automatic menu for the syslinux bootloader. You
231      must set this variable in your recipe. The
232      :ref:`syslinux <ref-classes-syslinux>` class checks this variable.
233
234   :term:`AVAILTUNES`
235      The list of defined CPU and Application Binary Interface (ABI)
236      tunings (i.e. "tunes") available for use by the OpenEmbedded build
237      system.
238
239      The list simply presents the tunes that are available. Not all tunes
240      may be compatible with a particular machine configuration, or with
241      each other in a
242      :ref:`Multilib <dev-manual/common-tasks:combining multiple versions of library files into one image>`
243      configuration.
244
245      To add a tune to the list, be sure to append it with spaces using the
246      "+=" BitBake operator. Do not simply replace the list by using the
247      "=" operator. See the
248      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:basic syntax`" section in the BitBake
249      User Manual for more information.
250
251   :term:`AZ_SAS`
252      Azure Storage Shared Access Signature, when using the
253      :ref:`Azure Storage fetcher (az://) <bitbake:bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
254      This variable can be defined to be used by the fetcher to authenticate
255      and gain access to non-public artifacts.
256      ::
257
258         AZ_SAS = ""se=2021-01-01&sp=r&sv=2018-11-09&sr=c&skoid=<skoid>&sig=<signature>""
259
260      For more information see Microsoft's Azure Storage documentation at
261      https://docs.microsoft.com/en-us/azure/storage/common/storage-sas-overview
262
263   :term:`B`
264      The directory within the :term:`Build Directory` in
265      which the OpenEmbedded build system places generated objects during a
266      recipe's build process. By default, this directory is the same as the
267      :term:`S` directory, which is defined as::
268
269         S = "${WORKDIR}/${BP}"
270
271      You can separate the (:term:`S`) directory and the directory pointed to
272      by the :term:`B` variable. Most Autotools-based recipes support
273      separating these directories. The build system defaults to using
274      separate directories for ``gcc`` and some kernel recipes.
275
276   :term:`BAD_RECOMMENDATIONS`
277      Lists "recommended-only" packages to not install. Recommended-only
278      packages are packages installed only through the
279      :term:`RRECOMMENDS` variable. You can prevent any
280      of these "recommended" packages from being installed by listing them
281      with the :term:`BAD_RECOMMENDATIONS` variable::
282
283         BAD_RECOMMENDATIONS = "package_name package_name package_name ..."
284
285      You can set this variable globally in your ``local.conf`` file or you
286      can attach it to a specific image recipe by using the recipe name
287      override::
288
289         BAD_RECOMMENDATIONS:pn-target_image = "package_name"
290
291      It is important to realize that if you choose to not install packages
292      using this variable and some other packages are dependent on them
293      (i.e. listed in a recipe's :term:`RDEPENDS`
294      variable), the OpenEmbedded build system ignores your request and
295      will install the packages to avoid dependency errors.
296
297      This variable is supported only when using the IPK and RPM
298      packaging backends. DEB is not supported.
299
300      See the :term:`NO_RECOMMENDATIONS` and the
301      :term:`PACKAGE_EXCLUDE` variables for related
302      information.
303
304   :term:`BASE_LIB`
305      The library directory name for the CPU or Application Binary
306      Interface (ABI) tune. The :term:`BASE_LIB` applies only in the Multilib
307      context. See the ":ref:`dev-manual/common-tasks:combining multiple versions of library files into one image`"
308      section in the Yocto Project Development Tasks Manual for information
309      on Multilib.
310
311      The :term:`BASE_LIB` variable is defined in the machine include files in
312      the :term:`Source Directory`. If Multilib is not
313      being used, the value defaults to "lib".
314
315   :term:`BASE_WORKDIR`
316      Points to the base of the work directory for all recipes. The default
317      value is "${TMPDIR}/work".
318
319   :term:`BB_ALLOWED_NETWORKS`
320      Specifies a space-delimited list of hosts that the fetcher is allowed
321      to use to obtain the required source code. Following are
322      considerations surrounding this variable:
323
324      -  This host list is only used if :term:`BB_NO_NETWORK` is either not set
325         or set to "0".
326
327      -  There is limited support for wildcard matching against the beginning of
328         host names. For example, the following setting matches
329         ``git.gnu.org``, ``ftp.gnu.org``, and ``foo.git.gnu.org``.
330         ::
331
332            BB_ALLOWED_NETWORKS = "*.gnu.org"
333
334         .. note::
335
336            The use of the "``*``" character only works at the beginning of
337            a host name and it must be isolated from the remainder of the
338            host name. You cannot use the wildcard character in any other
339            location of the name or combined with the front part of the
340            name.
341
342            For example, ``*.foo.bar`` is supported, while ``*aa.foo.bar``
343            is not.
344
345      -  Mirrors not in the host list are skipped and logged in debug.
346
347      -  Attempts to access networks not in the host list cause a failure.
348
349      Using :term:`BB_ALLOWED_NETWORKS` in conjunction with
350      :term:`PREMIRRORS` is very useful. Adding the host
351      you want to use to :term:`PREMIRRORS` results in the source code being
352      fetched from an allowed location and avoids raising an error when a
353      host that is not allowed is in a :term:`SRC_URI`
354      statement. This is because the fetcher does not attempt to use the
355      host listed in :term:`SRC_URI` after a successful fetch from the
356      :term:`PREMIRRORS` occurs.
357
358   :term:`BB_DANGLINGAPPENDS_WARNONLY`
359      Defines how BitBake handles situations where an append file
360      (``.bbappend``) has no corresponding recipe file (``.bb``). This
361      condition often occurs when layers get out of sync (e.g. ``oe-core``
362      bumps a recipe version and the old recipe no longer exists and the
363      other layer has not been updated to the new version of the recipe
364      yet).
365
366      The default fatal behavior is safest because it is the sane reaction
367      given something is out of sync. It is important to realize when your
368      changes are no longer being applied.
369
370      You can change the default behavior by setting this variable to "1",
371      "yes", or "true" in your ``local.conf`` file, which is located in the
372      :term:`Build Directory`: Here is an example::
373
374         BB_DANGLINGAPPENDS_WARNONLY = "1"
375
376   :term:`BB_DISKMON_DIRS`
377      Monitors disk space and available inodes during the build and allows
378      you to control the build based on these parameters.
379
380      Disk space monitoring is disabled by default. To enable monitoring,
381      add the :term:`BB_DISKMON_DIRS` variable to your ``conf/local.conf`` file
382      found in the :term:`Build Directory`. Use the
383      following form:
384
385      .. code-block:: none
386
387         BB_DISKMON_DIRS = "action,dir,threshold [...]"
388
389         where:
390
391            action is:
392               ABORT:     Immediately stop the build when
393                          a threshold is broken.
394               STOPTASKS: Stop the build after the currently
395                          executing tasks have finished when
396                          a threshold is broken.
397               WARN:      Issue a warning but continue the
398                          build when a threshold is broken.
399                          Subsequent warnings are issued as
400                          defined by the BB_DISKMON_WARNINTERVAL
401                          variable, which must be defined in
402                          the conf/local.conf file.
403
404            dir is:
405               Any directory you choose. You can specify one or
406               more directories to monitor by separating the
407               groupings with a space.  If two directories are
408               on the same device, only the first directory
409               is monitored.
410
411            threshold is:
412               Either the minimum available disk space,
413               the minimum number of free inodes, or
414               both.  You must specify at least one.  To
415               omit one or the other, simply omit the value.
416               Specify the threshold using G, M, K for Gbytes,
417               Mbytes, and Kbytes, respectively. If you do
418               not specify G, M, or K, Kbytes is assumed by
419               default.  Do not use GB, MB, or KB.
420
421      Here are some examples::
422
423         BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K"
424         BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G"
425         BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
426
427      The first example works only if you also provide the
428      :term:`BB_DISKMON_WARNINTERVAL`
429      variable in the ``conf/local.conf``. This example causes the build
430      system to immediately stop when either the disk space in
431      ``${TMPDIR}`` drops below 1 Gbyte or the available free inodes drops
432      below 100 Kbytes. Because two directories are provided with the
433      variable, the build system also issue a warning when the disk space
434      in the ``${SSTATE_DIR}`` directory drops below 1 Gbyte or the number
435      of free inodes drops below 100 Kbytes. Subsequent warnings are issued
436      during intervals as defined by the :term:`BB_DISKMON_WARNINTERVAL`
437      variable.
438
439      The second example stops the build after all currently executing
440      tasks complete when the minimum disk space in the ``${TMPDIR}``
441      directory drops below 1 Gbyte. No disk monitoring occurs for the free
442      inodes in this case.
443
444      The final example immediately stops the build when the number of
445      free inodes in the ``${TMPDIR}`` directory drops below 100 Kbytes. No
446      disk space monitoring for the directory itself occurs in this case.
447
448   :term:`BB_DISKMON_WARNINTERVAL`
449      Defines the disk space and free inode warning intervals. To set these
450      intervals, define the variable in your ``conf/local.conf`` file in
451      the :term:`Build Directory`.
452
453      If you are going to use the :term:`BB_DISKMON_WARNINTERVAL` variable, you
454      must also use the :term:`BB_DISKMON_DIRS`
455      variable and define its action as "WARN". During the build,
456      subsequent warnings are issued each time disk space or number of free
457      inodes further reduces by the respective interval.
458
459      If you do not provide a :term:`BB_DISKMON_WARNINTERVAL` variable and you
460      do use :term:`BB_DISKMON_DIRS` with the "WARN" action, the disk
461      monitoring interval defaults to the following::
462
463         BB_DISKMON_WARNINTERVAL = "50M,5K"
464
465      When specifying the variable in your configuration file, use the
466      following form:
467
468      .. code-block:: none
469
470         BB_DISKMON_WARNINTERVAL = "disk_space_interval,disk_inode_interval"
471
472         where:
473
474            disk_space_interval is:
475               An interval of memory expressed in either
476               G, M, or K for Gbytes, Mbytes, or Kbytes,
477               respectively. You cannot use GB, MB, or KB.
478
479            disk_inode_interval is:
480               An interval of free inodes expressed in either
481               G, M, or K for Gbytes, Mbytes, or Kbytes,
482               respectively. You cannot use GB, MB, or KB.
483
484      Here is an example::
485
486         BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K"
487         BB_DISKMON_WARNINTERVAL = "50M,5K"
488
489      These variables cause the
490      OpenEmbedded build system to issue subsequent warnings each time the
491      available disk space further reduces by 50 Mbytes or the number of
492      free inodes further reduces by 5 Kbytes in the ``${SSTATE_DIR}``
493      directory. Subsequent warnings based on the interval occur each time
494      a respective interval is reached beyond the initial warning (i.e. 1
495      Gbytes and 100 Kbytes).
496
497   :term:`BB_GENERATE_MIRROR_TARBALLS`
498      Causes tarballs of the source control repositories (e.g. Git
499      repositories), including metadata, to be placed in the
500      :term:`DL_DIR` directory.
501
502      For performance reasons, creating and placing tarballs of these
503      repositories is not the default action by the OpenEmbedded build
504      system.
505      ::
506
507         BB_GENERATE_MIRROR_TARBALLS = "1"
508
509      Set this variable in your
510      ``local.conf`` file in the :term:`Build Directory`.
511
512      Once you have the tarballs containing your source files, you can
513      clean up your :term:`DL_DIR` directory by deleting any Git or other
514      source control work directories.
515
516   :term:`BB_NUMBER_THREADS`
517      The maximum number of tasks BitBake should run in parallel at any one
518      time. The OpenEmbedded build system automatically configures this
519      variable to be equal to the number of cores on the build system. For
520      example, a system with a dual core processor that also uses
521      hyper-threading causes the :term:`BB_NUMBER_THREADS` variable to default
522      to "4".
523
524      For single socket systems (i.e. one CPU), you should not have to
525      override this variable to gain optimal parallelism during builds.
526      However, if you have very large systems that employ multiple physical
527      CPUs, you might want to make sure the :term:`BB_NUMBER_THREADS` variable
528      is not set higher than "20".
529
530      For more information on speeding up builds, see the
531      ":ref:`dev-manual/common-tasks:speeding up a build`"
532      section in the Yocto Project Development Tasks Manual.
533
534   :term:`BB_SERVER_TIMEOUT`
535      Specifies the time (in seconds) after which to unload the BitBake
536      server due to inactivity. Set :term:`BB_SERVER_TIMEOUT` to determine how
537      long the BitBake server stays resident between invocations.
538
539      For example, the following statement in your ``local.conf`` file
540      instructs the server to be unloaded after 20 seconds of inactivity::
541
542         BB_SERVER_TIMEOUT = "20"
543
544      If you want the server to never be unloaded,
545      set :term:`BB_SERVER_TIMEOUT` to "-1".
546
547   :term:`BBCLASSEXTEND`
548      Allows you to extend a recipe so that it builds variants of the
549      software. There are common variants for recipes as "natives" like
550      ``quilt-native``, which is a copy of Quilt built to run on the build
551      system; "crosses" such as ``gcc-cross``, which is a compiler built to
552      run on the build machine but produces binaries that run on the target
553      :term:`MACHINE`; "nativesdk", which targets the SDK
554      machine instead of :term:`MACHINE`; and "mulitlibs" in the form
555      "``multilib:``\ multilib_name".
556
557      To build a different variant of the recipe with a minimal amount of
558      code, it usually is as simple as adding the following to your recipe::
559
560         BBCLASSEXTEND =+ "native nativesdk"
561         BBCLASSEXTEND =+ "multilib:multilib_name"
562
563      .. note::
564
565         Internally, the :term:`BBCLASSEXTEND` mechanism generates recipe
566         variants by rewriting variable values and applying overrides such
567         as ``:class-native``. For example, to generate a native version of
568         a recipe, a :term:`DEPENDS` on "foo" is rewritten
569         to a :term:`DEPENDS` on "foo-native".
570
571         Even when using :term:`BBCLASSEXTEND`, the recipe is only parsed once.
572         Parsing once adds some limitations. For example, it is not
573         possible to include a different file depending on the variant,
574         since ``include`` statements are processed when the recipe is
575         parsed.
576
577   :term:`BBFILE_COLLECTIONS`
578      Lists the names of configured layers. These names are used to find
579      the other ``BBFILE_*`` variables. Typically, each layer will append
580      its name to this variable in its ``conf/layer.conf`` file.
581
582   :term:`BBFILE_PATTERN`
583      Variable that expands to match files from
584      :term:`BBFILES` in a particular layer. This variable
585      is used in the ``conf/layer.conf`` file and must be suffixed with the
586      name of the specific layer (e.g. ``BBFILE_PATTERN_emenlow``).
587
588   :term:`BBFILE_PRIORITY`
589      Assigns the priority for recipe files in each layer.
590
591      This variable is useful in situations where the same recipe appears
592      in more than one layer. Setting this variable allows you to
593      prioritize a layer against other layers that contain the same recipe
594      --- effectively letting you control the precedence for the multiple
595      layers. The precedence established through this variable stands
596      regardless of a recipe's version (:term:`PV` variable). For
597      example, a layer that has a recipe with a higher :term:`PV` value but for
598      which the :term:`BBFILE_PRIORITY` is set to have a lower precedence still
599      has a lower precedence.
600
601      A larger value for the :term:`BBFILE_PRIORITY` variable results in a
602      higher precedence. For example, the value 6 has a higher precedence
603      than the value 5. If not specified, the :term:`BBFILE_PRIORITY` variable
604      is set based on layer dependencies (see the :term:`LAYERDEPENDS` variable
605      for more information. The default priority, if unspecified for a
606      layer with no dependencies, is the lowest defined priority + 1 (or 1
607      if no priorities are defined).
608
609      .. tip::
610
611         You can use the command ``bitbake-layers show-layers``
612         to list all configured layers along with their priorities.
613
614   :term:`BBFILES`
615      A space-separated list of recipe files BitBake uses to build
616      software.
617
618      When specifying recipe files, you can pattern match using Python's
619      `glob <https://docs.python.org/3/library/glob.html>`_ syntax.
620      For details on the syntax, see the documentation by following the
621      previous link.
622
623   :term:`BBFILES_DYNAMIC`
624      Activates content when identified layers are present. You identify
625      the layers by the collections that the layers define.
626
627      Use the :term:`BBFILES_DYNAMIC` variable to avoid ``.bbappend`` files
628      whose corresponding ``.bb`` file is in a layer that attempts to
629      modify other layers through ``.bbappend`` but does not want to
630      introduce a hard dependency on those other layers.
631
632      Use the following form for :term:`BBFILES_DYNAMIC`:
633      ``collection_name:filename_pattern``.
634
635      The following example identifies two collection names and two
636      filename patterns::
637
638         BBFILES_DYNAMIC += " \
639            clang-layer:${LAYERDIR}/bbappends/meta-clang/*/*/*.bbappend \
640            core:${LAYERDIR}/bbappends/openembedded-core/meta/*/*/*.bbappend \
641            "
642
643      This next example shows an error message that occurs because invalid
644      entries are found, which cause parsing to fail:
645
646      .. code-block:: none
647
648         ERROR: BBFILES_DYNAMIC entries must be of the form <collection name>:<filename pattern>, not:
649             /work/my-layer/bbappends/meta-security-isafw/*/*/*.bbappend
650             /work/my-layer/bbappends/openembedded-core/meta/*/*/*.bbappend
651
652   :term:`BBINCLUDELOGS`
653      Variable that controls how BitBake displays logs on build failure.
654
655   :term:`BBINCLUDELOGS_LINES`
656      If :term:`BBINCLUDELOGS` is set, specifies the
657      maximum number of lines from the task log file to print when
658      reporting a failed task. If you do not set :term:`BBINCLUDELOGS_LINES`,
659      the entire log is printed.
660
661   :term:`BBLAYERS`
662      Lists the layers to enable during the build. This variable is defined
663      in the ``bblayers.conf`` configuration file in the :term:`Build Directory`.
664      Here is an example::
665
666         BBLAYERS = " \
667             /home/scottrif/poky/meta \
668             /home/scottrif/poky/meta-poky \
669             /home/scottrif/poky/meta-yocto-bsp \
670             /home/scottrif/poky/meta-mykernel \
671             "
672
673      This example enables four layers, one of which is a custom,
674      user-defined layer named ``meta-mykernel``.
675
676   :term:`BBMASK`
677      Prevents BitBake from processing recipes and recipe append files.
678
679      You can use the :term:`BBMASK` variable to "hide" these ``.bb`` and
680      ``.bbappend`` files. BitBake ignores any recipe or recipe append
681      files that match any of the expressions. It is as if BitBake does not
682      see them at all. Consequently, matching files are not parsed or
683      otherwise used by BitBake.
684
685      The values you provide are passed to Python's regular expression
686      compiler. Consequently, the syntax follows Python's Regular
687      Expression (re) syntax. The expressions are compared against the full
688      paths to the files. For complete syntax information, see Python's
689      documentation at https://docs.python.org/3/library/re.html#regular-expression-syntax.
690
691      The following example uses a complete regular expression to tell
692      BitBake to ignore all recipe and recipe append files in the
693      ``meta-ti/recipes-misc/`` directory::
694
695         BBMASK = "meta-ti/recipes-misc/"
696
697      If you want to mask out multiple directories or recipes, you can
698      specify multiple regular expression fragments. This next example
699      masks out multiple directories and individual recipes::
700
701         BBMASK += "/meta-ti/recipes-misc/ meta-ti/recipes-ti/packagegroup/"
702         BBMASK += "/meta-oe/recipes-support/"
703         BBMASK += "/meta-foo/.*/openldap"
704         BBMASK += "opencv.*\.bbappend"
705         BBMASK += "lzma"
706
707      .. note::
708
709         When specifying a directory name, use the trailing slash character
710         to ensure you match just that directory name.
711
712   :term:`BBMULTICONFIG`
713      Specifies each additional separate configuration when you are
714      building targets with multiple configurations. Use this variable in
715      your ``conf/local.conf`` configuration file. Specify a
716      multiconfigname for each configuration file you are using. For
717      example, the following line specifies three configuration files::
718
719         BBMULTICONFIG = "configA configB configC"
720
721      Each configuration file you use must reside in a ``multiconfig``
722      subdirectory of a configuration directory within a layer, or
723      within the :term:`Build Directory` (e.g.
724      ``build_directory/conf/multiconfig/configA.conf`` or
725      ``mylayer/conf/multiconfig/configB.conf``).
726
727      For information on how to use :term:`BBMULTICONFIG` in an environment
728      that supports building targets with multiple configurations, see the
729      ":ref:`dev-manual/common-tasks:building images for multiple targets using multiple configurations`"
730      section in the Yocto Project Development Tasks Manual.
731
732   :term:`BBPATH`
733      Used by BitBake to locate ``.bbclass`` and configuration files. This
734      variable is analogous to the ``PATH`` variable.
735
736      .. note::
737
738         If you run BitBake from a directory outside of the
739         :term:`Build Directory`, you must be sure to set :term:`BBPATH`
740         to point to the Build Directory. Set the variable as you would any
741         environment variable and then run BitBake::
742
743                 $ BBPATH = "build_directory"
744                 $ export BBPATH
745                 $ bitbake target
746
747
748   :term:`BBSERVER`
749      If defined in the BitBake environment, :term:`BBSERVER` points to the
750      BitBake remote server.
751
752      Use the following format to export the variable to the BitBake
753      environment::
754
755         export BBSERVER=localhost:$port
756
757      By default, :term:`BBSERVER` also appears in :term:`BB_BASEHASH_IGNORE_VARS`.
758      Consequently, :term:`BBSERVER` is excluded from checksum and dependency
759      data.
760
761   :term:`BINCONFIG`
762      When inheriting the
763      :ref:`binconfig-disabled <ref-classes-binconfig-disabled>` class,
764      this variable specifies binary configuration scripts to disable in
765      favor of using ``pkg-config`` to query the information. The
766      :ref:`binconfig-disabled <ref-classes-binconfig-disabled>` class will modify the specified scripts to
767      return an error so that calls to them can be easily found and
768      replaced.
769
770      To add multiple scripts, separate them by spaces. Here is an example
771      from the ``libpng`` recipe::
772
773         BINCONFIG = "${bindir}/libpng-config ${bindir}/libpng16-config"
774
775   :term:`BINCONFIG_GLOB`
776      When inheriting the :ref:`binconfig <ref-classes-binconfig>` class,
777      this variable specifies a wildcard for configuration scripts that
778      need editing. The scripts are edited to correct any paths that have
779      been set up during compilation so that they are correct for use when
780      installed into the sysroot and called by the build processes of other
781      recipes.
782
783      .. note::
784
785         The :term:`BINCONFIG_GLOB` variable uses
786         `shell globbing <https://tldp.org/LDP/abs/html/globbingref.html>`__,
787         which is recognition and expansion of wildcards during pattern
788         matching. Shell globbing is very similar to
789         `fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__
790         and `glob <https://docs.python.org/3/library/glob.html>`__.
791
792      For more information on how this variable works, see
793      ``meta/classes/binconfig.bbclass`` in the :term:`Source Directory`.
794      You can also find general
795      information on the class in the
796      ":ref:`ref-classes-binconfig`" section.
797
798   :term:`BP`
799      The base recipe name and version but without any special recipe name
800      suffix (i.e. ``-native``, ``lib64-``, and so forth). :term:`BP` is
801      comprised of the following::
802
803         ${BPN}-${PV}
804
805   :term:`BPN`
806      This variable is a version of the :term:`PN` variable with
807      common prefixes and suffixes removed, such as ``nativesdk-``,
808      ``-cross``, ``-native``, and multilib's ``lib64-`` and ``lib32-``.
809      The exact lists of prefixes and suffixes removed are specified by the
810      :term:`MLPREFIX` and
811      :term:`SPECIAL_PKGSUFFIX` variables,
812      respectively.
813
814   :term:`BUGTRACKER`
815      Specifies a URL for an upstream bug tracking website for a recipe.
816      The OpenEmbedded build system does not use this variable. Rather, the
817      variable is a useful pointer in case a bug in the software being
818      built needs to be manually reported.
819
820   :term:`BUILD_ARCH`
821      Specifies the architecture of the build host (e.g. ``i686``). The
822      OpenEmbedded build system sets the value of :term:`BUILD_ARCH` from the
823      machine name reported by the ``uname`` command.
824
825   :term:`BUILD_AS_ARCH`
826      Specifies the architecture-specific assembler flags for the build
827      host. By default, the value of :term:`BUILD_AS_ARCH` is empty.
828
829   :term:`BUILD_CC_ARCH`
830      Specifies the architecture-specific C compiler flags for the build
831      host. By default, the value of :term:`BUILD_CC_ARCH` is empty.
832
833   :term:`BUILD_CCLD`
834      Specifies the linker command to be used for the build host when the C
835      compiler is being used as the linker. By default, :term:`BUILD_CCLD`
836      points to GCC and passes as arguments the value of
837      :term:`BUILD_CC_ARCH`, assuming
838      :term:`BUILD_CC_ARCH` is set.
839
840   :term:`BUILD_CFLAGS`
841      Specifies the flags to pass to the C compiler when building for the
842      build host. When building in the ``-native`` context,
843      :term:`CFLAGS` is set to the value of this variable by
844      default.
845
846   :term:`BUILD_CPPFLAGS`
847      Specifies the flags to pass to the C preprocessor (i.e. to both the C
848      and the C++ compilers) when building for the build host. When
849      building in the ``-native`` context, :term:`CPPFLAGS`
850      is set to the value of this variable by default.
851
852   :term:`BUILD_CXXFLAGS`
853      Specifies the flags to pass to the C++ compiler when building for the
854      build host. When building in the ``-native`` context,
855      :term:`CXXFLAGS` is set to the value of this variable
856      by default.
857
858   :term:`BUILD_FC`
859      Specifies the Fortran compiler command for the build host. By
860      default, :term:`BUILD_FC` points to Gfortran and passes as arguments the
861      value of :term:`BUILD_CC_ARCH`, assuming
862      :term:`BUILD_CC_ARCH` is set.
863
864   :term:`BUILD_LD`
865      Specifies the linker command for the build host. By default,
866      :term:`BUILD_LD` points to the GNU linker (ld) and passes as arguments
867      the value of :term:`BUILD_LD_ARCH`, assuming
868      :term:`BUILD_LD_ARCH` is set.
869
870   :term:`BUILD_LD_ARCH`
871      Specifies architecture-specific linker flags for the build host. By
872      default, the value of :term:`BUILD_LD_ARCH` is empty.
873
874   :term:`BUILD_LDFLAGS`
875      Specifies the flags to pass to the linker when building for the build
876      host. When building in the ``-native`` context,
877      :term:`LDFLAGS` is set to the value of this variable
878      by default.
879
880   :term:`BUILD_OPTIMIZATION`
881      Specifies the optimization flags passed to the C compiler when
882      building for the build host or the SDK. The flags are passed through
883      the :term:`BUILD_CFLAGS` and
884      :term:`BUILDSDK_CFLAGS` default values.
885
886      The default value of the :term:`BUILD_OPTIMIZATION` variable is "-O2
887      -pipe".
888
889   :term:`BUILD_OS`
890      Specifies the operating system in use on the build host (e.g.
891      "linux"). The OpenEmbedded build system sets the value of
892      :term:`BUILD_OS` from the OS reported by the ``uname`` command --- the
893      first word, converted to lower-case characters.
894
895   :term:`BUILD_PREFIX`
896      The toolchain binary prefix used for native recipes. The OpenEmbedded
897      build system uses the :term:`BUILD_PREFIX` value to set the
898      :term:`TARGET_PREFIX` when building for
899      ``native`` recipes.
900
901   :term:`BUILD_STRIP`
902      Specifies the command to be used to strip debugging symbols from
903      binaries produced for the build host. By default, :term:`BUILD_STRIP`
904      points to
905      ``${``\ :term:`BUILD_PREFIX`\ ``}strip``.
906
907   :term:`BUILD_SYS`
908      Specifies the system, including the architecture and the operating
909      system, to use when building for the build host (i.e. when building
910      ``native`` recipes).
911
912      The OpenEmbedded build system automatically sets this variable based
913      on :term:`BUILD_ARCH`,
914      :term:`BUILD_VENDOR`, and
915      :term:`BUILD_OS`. You do not need to set the
916      :term:`BUILD_SYS` variable yourself.
917
918   :term:`BUILD_VENDOR`
919      Specifies the vendor name to use when building for the build host.
920      The default value is an empty string ("").
921
922   :term:`BUILDDIR`
923      Points to the location of the :term:`Build Directory`.
924      You can define this directory indirectly through the
925      :ref:`structure-core-script` script by passing in a Build
926      Directory path when you run the script. If you run the script and do
927      not provide a Build Directory path, the :term:`BUILDDIR` defaults to
928      ``build`` in the current directory.
929
930   :term:`BUILDHISTORY_COMMIT`
931      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
932      class, this variable specifies whether or not to commit the build
933      history output in a local Git repository. If set to "1", this local
934      repository will be maintained automatically by the :ref:`buildhistory <ref-classes-buildhistory>`
935      class and a commit will be created on every build for changes to each
936      top-level subdirectory of the build history output (images, packages,
937      and sdk). If you want to track changes to build history over time,
938      you should set this value to "1".
939
940      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class does not commit the build
941      history output in a local Git repository::
942
943         BUILDHISTORY_COMMIT ?= "0"
944
945   :term:`BUILDHISTORY_COMMIT_AUTHOR`
946      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
947      class, this variable specifies the author to use for each Git commit.
948      In order for the :term:`BUILDHISTORY_COMMIT_AUTHOR` variable to work, the
949      :term:`BUILDHISTORY_COMMIT` variable must
950      be set to "1".
951
952      Git requires that the value you provide for the
953      :term:`BUILDHISTORY_COMMIT_AUTHOR` variable takes the form of "name
954      email@host". Providing an email address or host that is not valid
955      does not produce an error.
956
957      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the variable as follows::
958
959         BUILDHISTORY_COMMIT_AUTHOR ?= "buildhistory <buildhistory@${DISTRO}>"
960
961   :term:`BUILDHISTORY_DIR`
962      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
963      class, this variable specifies the directory in which build history
964      information is kept. For more information on how the variable works,
965      see the :ref:`ref-classes-buildhistory` class.
966
967      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the directory as follows::
968
969         BUILDHISTORY_DIR ?= "${TOPDIR}/buildhistory"
970
971   :term:`BUILDHISTORY_FEATURES`
972      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
973      class, this variable specifies the build history features to be
974      enabled. For more information on how build history works, see the
975      ":ref:`dev-manual/common-tasks:maintaining build output quality`"
976      section in the Yocto Project Development Tasks Manual.
977
978      You can specify these features in the form of a space-separated list:
979
980      -  *image:* Analysis of the contents of images, which includes the
981         list of installed packages among other things.
982
983      -  *package:* Analysis of the contents of individual packages.
984
985      -  *sdk:* Analysis of the contents of the software development kit
986         (SDK).
987
988      -  *task:* Save output file signatures for
989         :ref:`shared state <overview-manual/concepts:shared state cache>`
990         (sstate) tasks.
991         This saves one file per task and lists the SHA-256 checksums for
992         each file staged (i.e. the output of the task).
993
994      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class enables the following
995      features::
996
997         BUILDHISTORY_FEATURES ?= "image package sdk"
998
999   :term:`BUILDHISTORY_IMAGE_FILES`
1000      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1001      class, this variable specifies a list of paths to files copied from
1002      the image contents into the build history directory under an
1003      "image-files" directory in the directory for the image, so that you
1004      can track the contents of each file. The default is to copy
1005      ``/etc/passwd`` and ``/etc/group``, which allows you to monitor for
1006      changes in user and group entries. You can modify the list to include
1007      any file. Specifying an invalid path does not produce an error.
1008      Consequently, you can include files that might not always be present.
1009
1010      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class provides paths to the
1011      following files::
1012
1013         BUILDHISTORY_IMAGE_FILES ?= "/etc/passwd /etc/group"
1014
1015   :term:`BUILDHISTORY_PATH_PREFIX_STRIP`
1016      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1017      class, this variable specifies a common path prefix that should be
1018      stripped off the beginning of paths in the task signature list when the
1019      ``task`` feature is active in :term:`BUILDHISTORY_FEATURES`. This can be
1020      useful when build history is populated from multiple sources that may not
1021      all use the same top level directory.
1022
1023      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the variable as follows::
1024
1025         BUILDHISTORY_PATH_PREFIX_STRIP ?= ""
1026
1027      In this case, no prefixes will be stripped.
1028
1029   :term:`BUILDHISTORY_PUSH_REPO`
1030      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1031      class, this variable optionally specifies a remote repository to
1032      which build history pushes Git changes. In order for
1033      :term:`BUILDHISTORY_PUSH_REPO` to work,
1034      :term:`BUILDHISTORY_COMMIT` must be set to
1035      "1".
1036
1037      The repository should correspond to a remote address that specifies a
1038      repository as understood by Git, or alternatively to a remote name
1039      that you have set up manually using ``git remote`` within the local
1040      repository.
1041
1042      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the variable as follows::
1043
1044         BUILDHISTORY_PUSH_REPO ?= ""
1045
1046   :term:`BUILDSDK_CFLAGS`
1047      Specifies the flags to pass to the C compiler when building for the
1048      SDK. When building in the ``nativesdk-`` context,
1049      :term:`CFLAGS` is set to the value of this variable by
1050      default.
1051
1052   :term:`BUILDSDK_CPPFLAGS`
1053      Specifies the flags to pass to the C pre-processor (i.e. to both the
1054      C and the C++ compilers) when building for the SDK. When building in
1055      the ``nativesdk-`` context, :term:`CPPFLAGS` is set
1056      to the value of this variable by default.
1057
1058   :term:`BUILDSDK_CXXFLAGS`
1059      Specifies the flags to pass to the C++ compiler when building for the
1060      SDK. When building in the ``nativesdk-`` context,
1061      :term:`CXXFLAGS` is set to the value of this variable
1062      by default.
1063
1064   :term:`BUILDSDK_LDFLAGS`
1065      Specifies the flags to pass to the linker when building for the SDK.
1066      When building in the ``nativesdk-`` context,
1067      :term:`LDFLAGS` is set to the value of this variable
1068      by default.
1069
1070   :term:`BUILDSTATS_BASE`
1071      Points to the location of the directory that holds build statistics
1072      when you use and enable the
1073      :ref:`buildstats <ref-classes-buildstats>` class. The
1074      :term:`BUILDSTATS_BASE` directory defaults to
1075      ``${``\ :term:`TMPDIR`\ ``}/buildstats/``.
1076
1077   :term:`BUSYBOX_SPLIT_SUID`
1078      For the BusyBox recipe, specifies whether to split the output
1079      executable file into two parts: one for features that require
1080      ``setuid root``, and one for the remaining features (i.e. those that
1081      do not require ``setuid root``).
1082
1083      The :term:`BUSYBOX_SPLIT_SUID` variable defaults to "1", which results in
1084      splitting the output executable file. Set the variable to "0" to get
1085      a single output executable file.
1086
1087   :term:`CACHE`
1088      Specifies the directory BitBake uses to store a cache of the
1089      :term:`Metadata` so it does not need to be parsed every time
1090      BitBake is started.
1091
1092   :term:`CC`
1093      The minimal command and arguments used to run the C compiler.
1094
1095   :term:`CFLAGS`
1096      Specifies the flags to pass to the C compiler. This variable is
1097      exported to an environment variable and thus made visible to the
1098      software being built during the compilation step.
1099
1100      Default initialization for :term:`CFLAGS` varies depending on what is
1101      being built:
1102
1103      -  :term:`TARGET_CFLAGS` when building for the
1104         target
1105
1106      -  :term:`BUILD_CFLAGS` when building for the
1107         build host (i.e. ``-native``)
1108
1109      -  :term:`BUILDSDK_CFLAGS` when building for
1110         an SDK (i.e. ``nativesdk-``)
1111
1112   :term:`CLASSOVERRIDE`
1113      An internal variable specifying the special class override that
1114      should currently apply (e.g. "class-target", "class-native", and so
1115      forth). The classes that use this variable (e.g.
1116      :ref:`native <ref-classes-native>`,
1117      :ref:`nativesdk <ref-classes-nativesdk>`, and so forth) set the
1118      variable to appropriate values.
1119
1120      .. note::
1121
1122         :term:`CLASSOVERRIDE` gets its default "class-target" value from the
1123         ``bitbake.conf`` file.
1124
1125      As an example, the following override allows you to install extra
1126      files, but only when building for the target::
1127
1128         do_install:append:class-target() {
1129             install my-extra-file ${D}${sysconfdir}
1130         }
1131
1132      Here is an example where ``FOO`` is set to
1133      "native" when building for the build host, and to "other" when not
1134      building for the build host::
1135
1136         FOO:class-native = "native"
1137         FOO = "other"
1138
1139      The underlying mechanism behind :term:`CLASSOVERRIDE` is simply
1140      that it is included in the default value of
1141      :term:`OVERRIDES`.
1142
1143   :term:`CLEANBROKEN`
1144      If set to "1" within a recipe, :term:`CLEANBROKEN` specifies that the
1145      ``make clean`` command does not work for the software being built.
1146      Consequently, the OpenEmbedded build system will not try to run
1147      ``make clean`` during the :ref:`ref-tasks-configure`
1148      task, which is the default behavior.
1149
1150   :term:`COMBINED_FEATURES`
1151      Provides a list of hardware features that are enabled in both
1152      :term:`MACHINE_FEATURES` and
1153      :term:`DISTRO_FEATURES`. This select list of
1154      features contains features that make sense to be controlled both at
1155      the machine and distribution configuration level. For example, the
1156      "bluetooth" feature requires hardware support but should also be
1157      optional at the distribution level, in case the hardware supports
1158      Bluetooth but you do not ever intend to use it.
1159
1160   :term:`COMMON_LICENSE_DIR`
1161      Points to ``meta/files/common-licenses`` in the
1162      :term:`Source Directory`, which is where generic license
1163      files reside.
1164
1165   :term:`COMPATIBLE_HOST`
1166      A regular expression that resolves to one or more hosts (when the
1167      recipe is native) or one or more targets (when the recipe is
1168      non-native) with which a recipe is compatible. The regular expression
1169      is matched against :term:`HOST_SYS`. You can use the
1170      variable to stop recipes from being built for classes of systems with
1171      which the recipes are not compatible. Stopping these builds is
1172      particularly useful with kernels. The variable also helps to increase
1173      parsing speed since the build system skips parsing recipes not
1174      compatible with the current system.
1175
1176   :term:`COMPATIBLE_MACHINE`
1177      A regular expression that resolves to one or more target machines
1178      with which a recipe is compatible. The regular expression is matched
1179      against :term:`MACHINEOVERRIDES`. You can use
1180      the variable to stop recipes from being built for machines with which
1181      the recipes are not compatible. Stopping these builds is particularly
1182      useful with kernels. The variable also helps to increase parsing
1183      speed since the build system skips parsing recipes not compatible
1184      with the current machine.
1185
1186   :term:`COMPLEMENTARY_GLOB`
1187      Defines wildcards to match when installing a list of complementary
1188      packages for all the packages explicitly (or implicitly) installed in
1189      an image.
1190
1191      .. note::
1192
1193         The :term:`COMPLEMENTARY_GLOB` variable uses Unix filename pattern matching
1194         (`fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__),
1195         which is similar to the Unix style pathname pattern expansion
1196         (`glob <https://docs.python.org/3/library/glob.html>`__).
1197
1198      The resulting list of complementary packages is associated with an
1199      item that can be added to
1200      :term:`IMAGE_FEATURES`. An example usage of
1201      this is the "dev-pkgs" item that when added to :term:`IMAGE_FEATURES`
1202      will install -dev packages (containing headers and other development
1203      files) for every package in the image.
1204
1205      To add a new feature item pointing to a wildcard, use a variable flag
1206      to specify the feature item name and use the value to specify the
1207      wildcard. Here is an example::
1208
1209         COMPLEMENTARY_GLOB[dev-pkgs] = '*-dev'
1210
1211   :term:`COMPONENTS_DIR`
1212      Stores sysroot components for each recipe. The OpenEmbedded build
1213      system uses :term:`COMPONENTS_DIR` when constructing recipe-specific
1214      sysroots for other recipes.
1215
1216      The default is
1217      "``${``\ :term:`STAGING_DIR`\ ``}-components``."
1218      (i.e.
1219      "``${``\ :term:`TMPDIR`\ ``}/sysroots-components``").
1220
1221   :term:`CONF_VERSION`
1222      Tracks the version of the local configuration file (i.e.
1223      ``local.conf``). The value for :term:`CONF_VERSION` increments each time
1224      ``build/conf/`` compatibility changes.
1225
1226   :term:`CONFFILES`
1227      Identifies editable or configurable files that are part of a package.
1228      If the Package Management System (PMS) is being used to update
1229      packages on the target system, it is possible that configuration
1230      files you have changed after the original installation and that you
1231      now want to remain unchanged are overwritten. In other words,
1232      editable files might exist in the package that you do not want reset
1233      as part of the package update process. You can use the :term:`CONFFILES`
1234      variable to list the files in the package that you wish to prevent
1235      the PMS from overwriting during this update process.
1236
1237      To use the :term:`CONFFILES` variable, provide a package name override
1238      that identifies the resulting package. Then, provide a
1239      space-separated list of files. Here is an example::
1240
1241         CONFFILES:${PN} += "${sysconfdir}/file1 \
1242             ${sysconfdir}/file2 ${sysconfdir}/file3"
1243
1244      There is a relationship between the :term:`CONFFILES` and :term:`FILES`
1245      variables. The files listed within :term:`CONFFILES` must be a subset of
1246      the files listed within :term:`FILES`. Because the configuration files
1247      you provide with :term:`CONFFILES` are simply being identified so that
1248      the PMS will not overwrite them, it makes sense that the files must
1249      already be included as part of the package through the :term:`FILES`
1250      variable.
1251
1252      .. note::
1253
1254         When specifying paths as part of the :term:`CONFFILES` variable, it is
1255         good practice to use appropriate path variables.
1256         For example, ``${sysconfdir}`` rather than ``/etc`` or ``${bindir}``
1257         rather than ``/usr/bin``. You can find a list of these variables at
1258         the top of the ``meta/conf/bitbake.conf`` file in the
1259         :term:`Source Directory`.
1260
1261   :term:`CONFIG_INITRAMFS_SOURCE`
1262      Identifies the initial RAM filesystem (initramfs) source files. The
1263      OpenEmbedded build system receives and uses this kernel Kconfig
1264      variable as an environment variable. By default, the variable is set
1265      to null ("").
1266
1267      The :term:`CONFIG_INITRAMFS_SOURCE` can be either a single cpio archive
1268      with a ``.cpio`` suffix or a space-separated list of directories and
1269      files for building the initramfs image. A cpio archive should contain
1270      a filesystem archive to be used as an initramfs image. Directories
1271      should contain a filesystem layout to be included in the initramfs
1272      image. Files should contain entries according to the format described
1273      by the ``usr/gen_init_cpio`` program in the kernel tree.
1274
1275      If you specify multiple directories and files, the initramfs image
1276      will be the aggregate of all of them.
1277
1278      For information on creating an initramfs, see the
1279      ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
1280      in the Yocto Project Development Tasks Manual.
1281
1282   :term:`CONFIG_SITE`
1283      A list of files that contains ``autoconf`` test results relevant to
1284      the current build. This variable is used by the Autotools utilities
1285      when running ``configure``.
1286
1287   :term:`CONFIGURE_FLAGS`
1288      The minimal arguments for GNU configure.
1289
1290   :term:`CONFLICT_DISTRO_FEATURES`
1291      When inheriting the
1292      :ref:`features_check <ref-classes-features_check>`
1293      class, this variable identifies distribution features that would be
1294      in conflict should the recipe be built. In other words, if the
1295      :term:`CONFLICT_DISTRO_FEATURES` variable lists a feature that also
1296      appears in :term:`DISTRO_FEATURES` within the current configuration, then
1297      the recipe will be skipped, and if the build system attempts to build
1298      the recipe then an error will be triggered.
1299
1300   :term:`CONVERSION_CMD`
1301      This variable is used for storing image conversion commands.
1302      Image conversion can convert an image into different objects like:
1303
1304      -   Compressed version of the image
1305
1306      -   Checksums for the image
1307
1308      An example of :term:`CONVERSION_CMD` from :ref:`image-types
1309      <ref-classes-image_types>` class is::
1310
1311         CONVERSION_CMD:lzo = "lzop -9 ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}"
1312
1313   :term:`COPY_LIC_DIRS`
1314      If set to "1" along with the
1315      :term:`COPY_LIC_MANIFEST` variable, the
1316      OpenEmbedded build system copies into the image the license files,
1317      which are located in ``/usr/share/common-licenses``, for each
1318      package. The license files are placed in directories within the image
1319      itself during build time.
1320
1321      .. note::
1322
1323         The :term:`COPY_LIC_DIRS` does not offer a path for adding licenses for
1324         newly installed packages to an image, which might be most suitable for
1325         read-only filesystems that cannot be upgraded. See the
1326         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1327         You can also reference the ":ref:`dev-manual/common-tasks:providing license text`"
1328         section in the Yocto Project Development Tasks Manual for
1329         information on providing license text.
1330
1331   :term:`COPY_LIC_MANIFEST`
1332      If set to "1", the OpenEmbedded build system copies the license
1333      manifest for the image to
1334      ``/usr/share/common-licenses/license.manifest`` within the image
1335      itself during build time.
1336
1337      .. note::
1338
1339         The :term:`COPY_LIC_MANIFEST` does not offer a path for adding licenses for
1340         newly installed packages to an image, which might be most suitable for
1341         read-only filesystems that cannot be upgraded. See the
1342         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1343         You can also reference the ":ref:`dev-manual/common-tasks:providing license text`"
1344         section in the Yocto Project Development Tasks Manual for
1345         information on providing license text.
1346
1347   :term:`COPYLEFT_LICENSE_EXCLUDE`
1348      A space-separated list of licenses to exclude from the source
1349      archived by the :ref:`archiver <ref-classes-archiver>` class. In
1350      other words, if a license in a recipe's
1351      :term:`LICENSE` value is in the value of
1352      :term:`COPYLEFT_LICENSE_EXCLUDE`, then its source is not archived by the
1353      class.
1354
1355      .. note::
1356
1357         The :term:`COPYLEFT_LICENSE_EXCLUDE` variable takes precedence over the
1358         :term:`COPYLEFT_LICENSE_INCLUDE` variable.
1359
1360      The default value, which is "CLOSED Proprietary", for
1361      :term:`COPYLEFT_LICENSE_EXCLUDE` is set by the
1362      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1363      is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1364
1365   :term:`COPYLEFT_LICENSE_INCLUDE`
1366      A space-separated list of licenses to include in the source archived
1367      by the :ref:`archiver <ref-classes-archiver>` class. In other
1368      words, if a license in a recipe's :term:`LICENSE`
1369      value is in the value of :term:`COPYLEFT_LICENSE_INCLUDE`, then its
1370      source is archived by the class.
1371
1372      The default value is set by the
1373      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1374      is inherited by the :ref:`archiver <ref-classes-archiver>` class. The default value includes
1375      "GPL*", "LGPL*", and "AGPL*".
1376
1377   :term:`COPYLEFT_PN_EXCLUDE`
1378      A list of recipes to exclude in the source archived by the
1379      :ref:`archiver <ref-classes-archiver>` class. The
1380      :term:`COPYLEFT_PN_EXCLUDE` variable overrides the license inclusion and
1381      exclusion caused through the
1382      :term:`COPYLEFT_LICENSE_INCLUDE` and
1383      :term:`COPYLEFT_LICENSE_EXCLUDE`
1384      variables, respectively.
1385
1386      The default value, which is "" indicating to not explicitly exclude
1387      any recipes by name, for :term:`COPYLEFT_PN_EXCLUDE` is set by the
1388      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1389      is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1390
1391   :term:`COPYLEFT_PN_INCLUDE`
1392      A list of recipes to include in the source archived by the
1393      :ref:`archiver <ref-classes-archiver>` class. The
1394      :term:`COPYLEFT_PN_INCLUDE` variable overrides the license inclusion and
1395      exclusion caused through the
1396      :term:`COPYLEFT_LICENSE_INCLUDE` and
1397      :term:`COPYLEFT_LICENSE_EXCLUDE`
1398      variables, respectively.
1399
1400      The default value, which is "" indicating to not explicitly include
1401      any recipes by name, for :term:`COPYLEFT_PN_INCLUDE` is set by the
1402      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1403      is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1404
1405   :term:`COPYLEFT_RECIPE_TYPES`
1406      A space-separated list of recipe types to include in the source
1407      archived by the :ref:`archiver <ref-classes-archiver>` class.
1408      Recipe types are ``target``, ``native``, ``nativesdk``, ``cross``,
1409      ``crosssdk``, and ``cross-canadian``.
1410
1411      The default value, which is "target*", for :term:`COPYLEFT_RECIPE_TYPES`
1412      is set by the :ref:`copyleft_filter <ref-classes-copyleft_filter>`
1413      class, which is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1414
1415   :term:`CORE_IMAGE_EXTRA_INSTALL`
1416      Specifies the list of packages to be added to the image. You should
1417      only set this variable in the ``local.conf`` configuration file found
1418      in the :term:`Build Directory`.
1419
1420      This variable replaces ``POKY_EXTRA_INSTALL``, which is no longer
1421      supported.
1422
1423   :term:`COREBASE`
1424      Specifies the parent directory of the OpenEmbedded-Core Metadata
1425      layer (i.e. ``meta``).
1426
1427      It is an important distinction that :term:`COREBASE` points to the parent
1428      of this layer and not the layer itself. Consider an example where you
1429      have cloned the Poky Git repository and retained the ``poky`` name
1430      for your local copy of the repository. In this case, :term:`COREBASE`
1431      points to the ``poky`` folder because it is the parent directory of
1432      the ``poky/meta`` layer.
1433
1434   :term:`COREBASE_FILES`
1435      Lists files from the :term:`COREBASE` directory that
1436      should be copied other than the layers listed in the
1437      ``bblayers.conf`` file. The :term:`COREBASE_FILES` variable allows
1438      to copy metadata from the OpenEmbedded build system
1439      into the extensible SDK.
1440
1441      Explicitly listing files in :term:`COREBASE` is needed because it
1442      typically contains build directories and other files that should not
1443      normally be copied into the extensible SDK. Consequently, the value
1444      of :term:`COREBASE_FILES` is used in order to only copy the files that
1445      are actually needed.
1446
1447   :term:`CPP`
1448      The minimal command and arguments used to run the C preprocessor.
1449
1450   :term:`CPPFLAGS`
1451      Specifies the flags to pass to the C pre-processor (i.e. to both the
1452      C and the C++ compilers). This variable is exported to an environment
1453      variable and thus made visible to the software being built during the
1454      compilation step.
1455
1456      Default initialization for :term:`CPPFLAGS` varies depending on what is
1457      being built:
1458
1459      -  :term:`TARGET_CPPFLAGS` when building for
1460         the target
1461
1462      -  :term:`BUILD_CPPFLAGS` when building for the
1463         build host (i.e. ``-native``)
1464
1465      -  :term:`BUILDSDK_CPPFLAGS` when building
1466         for an SDK (i.e. ``nativesdk-``)
1467
1468   :term:`CROSS_COMPILE`
1469      The toolchain binary prefix for the target tools. The
1470      :term:`CROSS_COMPILE` variable is the same as the
1471      :term:`TARGET_PREFIX` variable.
1472
1473      .. note::
1474
1475         The OpenEmbedded build system sets the :term:`CROSS_COMPILE`
1476         variable only in certain contexts (e.g. when building for kernel
1477         and kernel module recipes).
1478
1479   :term:`CVE_CHECK_IGNORE`
1480      The list of CVE IDs which are ignored. Here is
1481      an example from the :oe_layerindex:`Python3 recipe</layerindex/recipe/23823>`::
1482
1483         # This is windows only issue.
1484         CVE_CHECK_IGNORE += "CVE-2020-15523"
1485
1486   :term:`CVE_CHECK_SKIP_RECIPE`
1487      The list of package names (:term:`PN`) for which
1488      CVEs (Common Vulnerabilities and Exposures) are ignored.
1489
1490   :term:`CVE_PRODUCT`
1491      In a recipe, defines the name used to match the recipe name
1492      against the name in the upstream `NIST CVE database <https://nvd.nist.gov/>`__.
1493
1494      The default is ${:term:`BPN`}. If it does not match the name in the NIST CVE
1495      database or matches with multiple entries in the database, the default
1496      value needs to be changed.
1497
1498      Here is an example from the :oe_layerindex:`Berkeley DB recipe </layerindex/recipe/544>`::
1499
1500         CVE_PRODUCT = "oracle_berkeley_db berkeley_db"
1501
1502      Sometimes the product name is not specific enough, for example
1503      "tar" has been matching CVEs for the GNU ``tar`` package and also
1504      the ``node-tar`` node.js extension. To avoid this problem, use the
1505      vendor name as a prefix. The syntax for this is::
1506
1507         CVE_PRODUCT = "vendor:package"
1508
1509   :term:`CVSDIR`
1510      The directory in which files checked out under the CVS system are
1511      stored.
1512
1513   :term:`CXX`
1514      The minimal command and arguments used to run the C++ compiler.
1515
1516   :term:`CXXFLAGS`
1517      Specifies the flags to pass to the C++ compiler. This variable is
1518      exported to an environment variable and thus made visible to the
1519      software being built during the compilation step.
1520
1521      Default initialization for :term:`CXXFLAGS` varies depending on what is
1522      being built:
1523
1524      -  :term:`TARGET_CXXFLAGS` when building for
1525         the target
1526
1527      -  :term:`BUILD_CXXFLAGS` when building for the
1528         build host (i.e. ``-native``)
1529
1530      -  :term:`BUILDSDK_CXXFLAGS` when building
1531         for an SDK (i.e. ``nativesdk-``)
1532
1533   :term:`D`
1534      The destination directory. The location in the :term:`Build Directory`
1535      where components are installed by the
1536      :ref:`ref-tasks-install` task. This location defaults
1537      to::
1538
1539         ${WORKDIR}/image
1540
1541      .. note::
1542
1543         Tasks that read from or write to this directory should run under
1544         :ref:`fakeroot <overview-manual/concepts:fakeroot and pseudo>`.
1545
1546   :term:`DATE`
1547      The date the build was started. Dates appear using the year, month,
1548      and day (YMD) format (e.g. "20150209" for February 9th, 2015).
1549
1550   :term:`DATETIME`
1551      The date and time on which the current build started. The format is
1552      suitable for timestamps.
1553
1554   :term:`DEBIAN_NOAUTONAME`
1555      When the :ref:`debian <ref-classes-debian>` class is inherited,
1556      which is the default behavior, :term:`DEBIAN_NOAUTONAME` specifies a
1557      particular package should not be renamed according to Debian library
1558      package naming. You must use the package name as an override when you
1559      set this variable. Here is an example from the ``fontconfig`` recipe::
1560
1561         DEBIAN_NOAUTONAME:fontconfig-utils = "1"
1562
1563   :term:`DEBIANNAME`
1564      When the :ref:`debian <ref-classes-debian>` class is inherited,
1565      which is the default behavior, :term:`DEBIANNAME` allows you to override
1566      the library name for an individual package. Overriding the library
1567      name in these cases is rare. You must use the package name as an
1568      override when you set this variable. Here is an example from the
1569      ``dbus`` recipe::
1570
1571         DEBIANNAME:${PN} = "dbus-1"
1572
1573   :term:`DEBUG_BUILD`
1574      Specifies to build packages with debugging information. This
1575      influences the value of the :term:`SELECTED_OPTIMIZATION` variable.
1576
1577   :term:`DEBUG_OPTIMIZATION`
1578      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
1579      compiling a system for debugging. This variable defaults to "-O
1580      -fno-omit-frame-pointer ${DEBUG_FLAGS} -pipe".
1581
1582   :term:`DEBUG_PREFIX_MAP`
1583      Allows to set C compiler options, such as ``-fdebug-prefix-map``,
1584      ``-fmacro-prefix-map``, and ``-ffile-prefix-map``, which allow to
1585      replace build-time paths by install-time ones in the debugging sections
1586      of binaries.  This makes compiler output files location independent,
1587      at the cost of having to pass an extra command to tell the debugger
1588      where source files are.
1589
1590      This is used by the Yocto Project to guarantee
1591      :doc:`/test-manual/reproducible-builds` even when the source code of
1592      a package uses the ``__FILE__`` or ``assert()`` macros. See the
1593      `reproducible-builds.org <https://reproducible-builds.org/docs/build-path/>`__
1594      website for details.
1595
1596      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1597      not intended to be user-configurable.
1598
1599   :term:`DEFAULT_PREFERENCE`
1600      Specifies a weak bias for recipe selection priority.
1601
1602      The most common usage of this is variable is to set it to "-1" within
1603      a recipe for a development version of a piece of software. Using the
1604      variable in this way causes the stable version of the recipe to build
1605      by default in the absence of :term:`PREFERRED_VERSION` being used to
1606      build the development version.
1607
1608      .. note::
1609
1610         The bias provided by :term:`DEFAULT_PREFERENCE` is weak and is overridden
1611         by :term:`BBFILE_PRIORITY` if that variable is different between two
1612         layers that contain different versions of the same recipe.
1613
1614   :term:`DEFAULTTUNE`
1615      The default CPU and Application Binary Interface (ABI) tunings (i.e.
1616      the "tune") used by the OpenEmbedded build system. The
1617      :term:`DEFAULTTUNE` helps define
1618      :term:`TUNE_FEATURES`.
1619
1620      The default tune is either implicitly or explicitly set by the
1621      machine (:term:`MACHINE`). However, you can override
1622      the setting using available tunes as defined with
1623      :term:`AVAILTUNES`.
1624
1625   :term:`DEPENDS`
1626      Lists a recipe's build-time dependencies. These are dependencies on
1627      other recipes whose contents (e.g. headers and shared libraries) are
1628      needed by the recipe at build time.
1629
1630      As an example, consider a recipe ``foo`` that contains the following
1631      assignment::
1632
1633          DEPENDS = "bar"
1634
1635      The practical effect of the previous
1636      assignment is that all files installed by bar will be available in
1637      the appropriate staging sysroot, given by the
1638      :term:`STAGING_DIR* <STAGING_DIR>` variables, by the time the
1639      :ref:`ref-tasks-configure` task for ``foo`` runs.
1640      This mechanism is implemented by having ``do_configure`` depend on
1641      the :ref:`ref-tasks-populate_sysroot` task of
1642      each recipe listed in :term:`DEPENDS`, through a
1643      ``[``\ :ref:`deptask <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]``
1644      declaration in the :ref:`base <ref-classes-base>` class.
1645
1646      .. note::
1647
1648         It seldom is necessary to reference, for example, :term:`STAGING_DIR_HOST`
1649         explicitly. The standard classes and build-related variables are
1650         configured to automatically use the appropriate staging sysroots.
1651
1652      As another example, :term:`DEPENDS` can also be used to add utilities
1653      that run on the build machine during the build. For example, a recipe
1654      that makes use of a code generator built by the recipe ``codegen``
1655      might have the following::
1656
1657         DEPENDS = "codegen-native"
1658
1659      For more
1660      information, see the :ref:`native <ref-classes-native>` class and
1661      the :term:`EXTRANATIVEPATH` variable.
1662
1663      .. note::
1664
1665         -  :term:`DEPENDS` is a list of recipe names. Or, to be more precise,
1666            it is a list of :term:`PROVIDES` names, which
1667            usually match recipe names. Putting a package name such as
1668            "foo-dev" in :term:`DEPENDS` does not make sense. Use "foo"
1669            instead, as this will put files from all the packages that make
1670            up ``foo``, which includes those from ``foo-dev``, into the
1671            sysroot.
1672
1673         -  One recipe having another recipe in :term:`DEPENDS` does not by
1674            itself add any runtime dependencies between the packages
1675            produced by the two recipes. However, as explained in the
1676            ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
1677            section in the Yocto Project Overview and Concepts Manual,
1678            runtime dependencies will often be added automatically, meaning
1679            :term:`DEPENDS` alone is sufficient for most recipes.
1680
1681         -  Counterintuitively, :term:`DEPENDS` is often necessary even for
1682            recipes that install precompiled components. For example, if
1683            ``libfoo`` is a precompiled library that links against
1684            ``libbar``, then linking against ``libfoo`` requires both
1685            ``libfoo`` and ``libbar`` to be available in the sysroot.
1686            Without a :term:`DEPENDS` from the recipe that installs ``libfoo``
1687            to the recipe that installs ``libbar``, other recipes might
1688            fail to link against ``libfoo``.
1689
1690      For information on runtime dependencies, see the
1691      :term:`RDEPENDS` variable. You can also see the
1692      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
1693      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
1694      BitBake User Manual for additional information on tasks and
1695      dependencies.
1696
1697   :term:`DEPLOY_DIR`
1698      Points to the general area that the OpenEmbedded build system uses to
1699      place images, packages, SDKs, and other output files that are ready
1700      to be used outside of the build system. By default, this directory
1701      resides within the :term:`Build Directory` as
1702      ``${TMPDIR}/deploy``.
1703
1704      For more information on the structure of the Build Directory, see
1705      ":ref:`ref-manual/structure:the build directory --- \`\`build/\`\``" section.
1706      For more detail on the contents of the ``deploy`` directory, see the
1707      ":ref:`overview-manual/concepts:images`",
1708      ":ref:`overview-manual/concepts:package feeds`", and
1709      ":ref:`overview-manual/concepts:application development sdk`" sections all in the
1710      Yocto Project Overview and Concepts Manual.
1711
1712   :term:`DEPLOY_DIR_DEB`
1713      Points to the area that the OpenEmbedded build system uses to place
1714      Debian packages that are ready to be used outside of the build
1715      system. This variable applies only when
1716      :term:`PACKAGE_CLASSES` contains
1717      "package_deb".
1718
1719      The BitBake configuration file initially defines the
1720      :term:`DEPLOY_DIR_DEB` variable as a sub-folder of
1721      :term:`DEPLOY_DIR`::
1722
1723         DEPLOY_DIR_DEB = "${DEPLOY_DIR}/deb"
1724
1725      The :ref:`package_deb <ref-classes-package_deb>` class uses the
1726      :term:`DEPLOY_DIR_DEB` variable to make sure the
1727      :ref:`ref-tasks-package_write_deb` task
1728      writes Debian packages into the appropriate folder. For more
1729      information on how packaging works, see the
1730      ":ref:`overview-manual/concepts:package feeds`" section
1731      in the Yocto Project Overview and Concepts Manual.
1732
1733   :term:`DEPLOY_DIR_IMAGE`
1734      Points to the area that the OpenEmbedded build system uses to place
1735      images and other associated output files that are ready to be
1736      deployed onto the target machine. The directory is machine-specific
1737      as it contains the ``${MACHINE}`` name. By default, this directory
1738      resides within the :term:`Build Directory` as
1739      ``${DEPLOY_DIR}/images/${MACHINE}/``.
1740
1741      It must not be used directly in recipes when deploying files. Instead,
1742      it's only useful when a recipe needs to "read" a file already deployed
1743      by a dependency. So, it should be filled with the contents of
1744      :term:`DEPLOYDIR` by the :ref:`deploy <ref-classes-deploy>` class or
1745      with the contents of :term:`IMGDEPLOYDIR` by the :ref:`image
1746      <ref-classes-image>` class.
1747
1748      For more information on the structure of the Build Directory, see
1749      ":ref:`ref-manual/structure:the build directory --- \`\`build/\`\``" section.
1750      For more detail on the contents of the ``deploy`` directory, see the
1751      ":ref:`overview-manual/concepts:images`" and
1752      ":ref:`overview-manual/concepts:application development sdk`" sections both in
1753      the Yocto Project Overview and Concepts Manual.
1754
1755   :term:`DEPLOY_DIR_IPK`
1756      Points to the area that the OpenEmbedded build system uses to place
1757      IPK packages that are ready to be used outside of the build system.
1758      This variable applies only when
1759      :term:`PACKAGE_CLASSES` contains
1760      "package_ipk".
1761
1762      The BitBake configuration file initially defines this variable as a
1763      sub-folder of :term:`DEPLOY_DIR`::
1764
1765         DEPLOY_DIR_IPK = "${DEPLOY_DIR}/ipk"
1766
1767      The :ref:`package_ipk <ref-classes-package_ipk>` class uses the
1768      :term:`DEPLOY_DIR_IPK` variable to make sure the
1769      :ref:`ref-tasks-package_write_ipk` task
1770      writes IPK packages into the appropriate folder. For more information
1771      on how packaging works, see the
1772      ":ref:`overview-manual/concepts:package feeds`" section
1773      in the Yocto Project Overview and Concepts Manual.
1774
1775   :term:`DEPLOY_DIR_RPM`
1776      Points to the area that the OpenEmbedded build system uses to place
1777      RPM packages that are ready to be used outside of the build system.
1778      This variable applies only when
1779      :term:`PACKAGE_CLASSES` contains
1780      "package_rpm".
1781
1782      The BitBake configuration file initially defines this variable as a
1783      sub-folder of :term:`DEPLOY_DIR`::
1784
1785         DEPLOY_DIR_RPM = "${DEPLOY_DIR}/rpm"
1786
1787      The :ref:`package_rpm <ref-classes-package_rpm>` class uses the
1788      :term:`DEPLOY_DIR_RPM` variable to make sure the
1789      :ref:`ref-tasks-package_write_rpm` task
1790      writes RPM packages into the appropriate folder. For more information
1791      on how packaging works, see the
1792      ":ref:`overview-manual/concepts:package feeds`" section
1793      in the Yocto Project Overview and Concepts Manual.
1794
1795   :term:`DEPLOY_DIR_TAR`
1796      Points to the area that the OpenEmbedded build system uses to place
1797      tarballs that are ready to be used outside of the build system. This
1798      variable applies only when
1799      :term:`PACKAGE_CLASSES` contains
1800      "package_tar".
1801
1802      The BitBake configuration file initially defines this variable as a
1803      sub-folder of :term:`DEPLOY_DIR`::
1804
1805         DEPLOY_DIR_TAR = "${DEPLOY_DIR}/tar"
1806
1807      The :ref:`package_tar <ref-classes-package_tar>` class uses the
1808      :term:`DEPLOY_DIR_TAR` variable to make sure the
1809      :ref:`ref-tasks-package_write_tar` task
1810      writes TAR packages into the appropriate folder. For more information
1811      on how packaging works, see the
1812      ":ref:`overview-manual/concepts:package feeds`" section
1813      in the Yocto Project Overview and Concepts Manual.
1814
1815   :term:`DEPLOYDIR`
1816      When inheriting the :ref:`deploy <ref-classes-deploy>` class, the
1817      :term:`DEPLOYDIR` points to a temporary work area for deployed files that
1818      is set in the :ref:`deploy <ref-classes-deploy>` class as follows::
1819
1820         DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
1821
1822      Recipes inheriting the :ref:`deploy <ref-classes-deploy>` class should copy files to be
1823      deployed into :term:`DEPLOYDIR`, and the class will take care of copying
1824      them into :term:`DEPLOY_DIR_IMAGE`
1825      afterwards.
1826
1827   :term:`DESCRIPTION`
1828      The package description used by package managers. If not set,
1829      :term:`DESCRIPTION` takes the value of the :term:`SUMMARY`
1830      variable.
1831
1832   :term:`DISTRO`
1833      The short name of the distribution. For information on the long name
1834      of the distribution, see the :term:`DISTRO_NAME`
1835      variable.
1836
1837      The :term:`DISTRO` variable corresponds to a distribution configuration
1838      file whose root name is the same as the variable's argument and whose
1839      filename extension is ``.conf``. For example, the distribution
1840      configuration file for the Poky distribution is named ``poky.conf``
1841      and resides in the ``meta-poky/conf/distro`` directory of the
1842      :term:`Source Directory`.
1843
1844      Within that ``poky.conf`` file, the :term:`DISTRO` variable is set as
1845      follows::
1846
1847         DISTRO = "poky"
1848
1849      Distribution configuration files are located in a ``conf/distro``
1850      directory within the :term:`Metadata` that contains the
1851      distribution configuration. The value for :term:`DISTRO` must not contain
1852      spaces, and is typically all lower-case.
1853
1854      .. note::
1855
1856         If the :term:`DISTRO` variable is blank, a set of default configurations
1857         are used, which are specified within
1858         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
1859
1860   :term:`DISTRO_CODENAME`
1861      Specifies a codename for the distribution being built.
1862
1863   :term:`DISTRO_EXTRA_RDEPENDS`
1864      Specifies a list of distro-specific packages to add to all images.
1865      This variable takes effect through ``packagegroup-base`` so the
1866      variable only really applies to the more full-featured images that
1867      include ``packagegroup-base``. You can use this variable to keep
1868      distro policy out of generic images. As with all other distro
1869      variables, you set this variable in the distro ``.conf`` file.
1870
1871   :term:`DISTRO_EXTRA_RRECOMMENDS`
1872      Specifies a list of distro-specific packages to add to all images if
1873      the packages exist. The packages might not exist or be empty (e.g.
1874      kernel modules). The list of packages are automatically installed but
1875      you can remove them.
1876
1877   :term:`DISTRO_FEATURES`
1878      The software support you want in your distribution for various
1879      features. You define your distribution features in the distribution
1880      configuration file.
1881
1882      In most cases, the presence or absence of a feature in
1883      :term:`DISTRO_FEATURES` is translated to the appropriate option supplied
1884      to the configure script during the
1885      :ref:`ref-tasks-configure` task for recipes that
1886      optionally support the feature. For example, specifying "x11" in
1887      :term:`DISTRO_FEATURES`, causes every piece of software built for the
1888      target that can optionally support X11 to have its X11 support
1889      enabled. Note: just enabling :term:`DISTRO_FEATURES` alone doesn't
1890      enable feature support for packages, mechanisms such as making
1891      :term:`PACKAGECONFIG` track :term:`DISTRO_FEATURES` are used
1892      to enable/disable package features.
1893
1894      Two more examples are Bluetooth and NFS support. For a more complete
1895      list of features that ships with the Yocto Project and that you can
1896      provide with this variable, see the ":ref:`ref-features-distro`" section.
1897
1898   :term:`DISTRO_FEATURES_BACKFILL`
1899      Features to be added to :term:`DISTRO_FEATURES` if not also present in
1900      :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`.
1901
1902      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1903      not intended to be user-configurable. It is best to just reference
1904      the variable to see which distro features are being backfilled for
1905      all distro configurations. See the ":ref:`ref-features-backfill`" section
1906      for more information.
1907
1908   :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`
1909      Features from :term:`DISTRO_FEATURES_BACKFILL` that should not be
1910      backfilled (i.e. added to :term:`DISTRO_FEATURES`) during the build. See
1911      the ":ref:`ref-features-backfill`" section for more information.
1912
1913   :term:`DISTRO_FEATURES_DEFAULT`
1914      A convenience variable that gives you the default list of distro
1915      features with the exception of any features specific to the C library
1916      (``libc``).
1917
1918      When creating a custom distribution, you might find it useful to be
1919      able to reuse the default
1920      :term:`DISTRO_FEATURES` options without the
1921      need to write out the full set. Here is an example that uses
1922      :term:`DISTRO_FEATURES_DEFAULT` from a custom distro configuration file::
1923
1924         DISTRO_FEATURES ?= "${DISTRO_FEATURES_DEFAULT} myfeature"
1925
1926   :term:`DISTRO_FEATURES_FILTER_NATIVE`
1927      Specifies a list of features that if present in the target
1928      :term:`DISTRO_FEATURES` value should be
1929      included in :term:`DISTRO_FEATURES` when building native recipes. This
1930      variable is used in addition to the features filtered using the
1931      :term:`DISTRO_FEATURES_NATIVE`
1932      variable.
1933
1934   :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
1935      Specifies a list of features that if present in the target
1936      :term:`DISTRO_FEATURES` value should be
1937      included in :term:`DISTRO_FEATURES` when building nativesdk recipes. This
1938      variable is used in addition to the features filtered using the
1939      :term:`DISTRO_FEATURES_NATIVESDK`
1940      variable.
1941
1942   :term:`DISTRO_FEATURES_NATIVE`
1943      Specifies a list of features that should be included in
1944      :term:`DISTRO_FEATURES` when building native
1945      recipes. This variable is used in addition to the features filtered
1946      using the
1947      :term:`DISTRO_FEATURES_FILTER_NATIVE`
1948      variable.
1949
1950   :term:`DISTRO_FEATURES_NATIVESDK`
1951      Specifies a list of features that should be included in
1952      :term:`DISTRO_FEATURES` when building
1953      nativesdk recipes. This variable is used in addition to the features
1954      filtered using the
1955      :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
1956      variable.
1957
1958   :term:`DISTRO_NAME`
1959      The long name of the distribution. For information on the short name
1960      of the distribution, see the :term:`DISTRO` variable.
1961
1962      The :term:`DISTRO_NAME` variable corresponds to a distribution
1963      configuration file whose root name is the same as the variable's
1964      argument and whose filename extension is ``.conf``. For example, the
1965      distribution configuration file for the Poky distribution is named
1966      ``poky.conf`` and resides in the ``meta-poky/conf/distro`` directory
1967      of the :term:`Source Directory`.
1968
1969      Within that ``poky.conf`` file, the :term:`DISTRO_NAME` variable is set
1970      as follows::
1971
1972         DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
1973
1974      Distribution configuration files are located in a ``conf/distro``
1975      directory within the :term:`Metadata` that contains the
1976      distribution configuration.
1977
1978      .. note::
1979
1980         If the :term:`DISTRO_NAME` variable is blank, a set of default
1981         configurations are used, which are specified within
1982         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
1983
1984   :term:`DISTRO_VERSION`
1985      The version of the distribution.
1986
1987   :term:`DISTROOVERRIDES`
1988      A colon-separated list of overrides specific to the current
1989      distribution. By default, this list includes the value of
1990      :term:`DISTRO`.
1991
1992      You can extend :term:`DISTROOVERRIDES` to add extra overrides that should
1993      apply to the distribution.
1994
1995      The underlying mechanism behind :term:`DISTROOVERRIDES` is simply that it
1996      is included in the default value of
1997      :term:`OVERRIDES`.
1998
1999   :term:`DL_DIR`
2000      The central download directory used by the build process to store
2001      downloads. By default, :term:`DL_DIR` gets files suitable for mirroring
2002      for everything except Git repositories. If you want tarballs of Git
2003      repositories, use the
2004      :term:`BB_GENERATE_MIRROR_TARBALLS`
2005      variable.
2006
2007      You can set this directory by defining the :term:`DL_DIR` variable in the
2008      ``conf/local.conf`` file. This directory is self-maintaining and you
2009      should not have to touch it. By default, the directory is
2010      ``downloads`` in the :term:`Build Directory`.
2011      ::
2012
2013         #DL_DIR ?= "${TOPDIR}/downloads"
2014
2015      To specify a different download directory,
2016      simply remove the comment from the line and provide your directory.
2017
2018      During a first build, the system downloads many different source code
2019      tarballs from various upstream projects. Downloading can take a
2020      while, particularly if your network connection is slow. Tarballs are
2021      all stored in the directory defined by :term:`DL_DIR` and the build
2022      system looks there first to find source tarballs.
2023
2024      .. note::
2025
2026         When wiping and rebuilding, you can preserve this directory to
2027         speed up this part of subsequent builds.
2028
2029      You can safely share this directory between multiple builds on the
2030      same development machine. For additional information on how the build
2031      process gets source files when working behind a firewall or proxy
2032      server, see this specific question in the ":doc:`faq`"
2033      chapter. You can also refer to the
2034      ":yocto_wiki:`Working Behind a Network Proxy </Working_Behind_a_Network_Proxy>`"
2035      Wiki page.
2036
2037   :term:`DOC_COMPRESS`
2038      When inheriting the :ref:`compress_doc <ref-classes-compress_doc>`
2039      class, this variable sets the compression policy used when the
2040      OpenEmbedded build system compresses man pages and info pages. By
2041      default, the compression method used is gz (gzip). Other policies
2042      available are xz and bz2.
2043
2044      For information on policies and on how to use this variable, see the
2045      comments in the ``meta/classes/compress_doc.bbclass`` file.
2046
2047   :term:`EFI_PROVIDER`
2048      When building bootable images (i.e. where ``hddimg``, ``iso``, or
2049      ``wic.vmdk`` is in :term:`IMAGE_FSTYPES`), the
2050      :term:`EFI_PROVIDER` variable specifies the EFI bootloader to use. The
2051      default is "grub-efi", but "systemd-boot" can be used instead.
2052
2053      See the :ref:`systemd-boot <ref-classes-systemd-boot>` and
2054      :ref:`image-live <ref-classes-image-live>` classes for more
2055      information.
2056
2057   :term:`ENABLE_BINARY_LOCALE_GENERATION`
2058      Variable that controls which locales for ``glibc`` are generated
2059      during the build (useful if the target device has 64Mbytes of RAM or
2060      less).
2061
2062   :term:`ERR_REPORT_DIR`
2063      When used with the :ref:`report-error <ref-classes-report-error>`
2064      class, specifies the path used for storing the debug files created by
2065      the :ref:`error reporting
2066      tool <dev-manual/common-tasks:using the error reporting tool>`, which
2067      allows you to submit build errors you encounter to a central
2068      database. By default, the value of this variable is
2069      ``${``\ :term:`LOG_DIR`\ ``}/error-report``.
2070
2071      You can set :term:`ERR_REPORT_DIR` to the path you want the error
2072      reporting tool to store the debug files as follows in your
2073      ``local.conf`` file::
2074
2075         ERR_REPORT_DIR = "path"
2076
2077   :term:`ERROR_QA`
2078      Specifies the quality assurance checks whose failures are reported as
2079      errors by the OpenEmbedded build system. You set this variable in
2080      your distribution configuration file. For a list of the checks you
2081      can control with this variable, see the
2082      ":ref:`ref-classes-insane`" section.
2083
2084   :term:`ESDK_CLASS_INHERIT_DISABLE`
2085      A list of classes to remove from the :term:`INHERIT`
2086      value globally within the extensible SDK configuration. The
2087      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class sets the
2088      default value::
2089
2090         ESDK_CLASS_INHERIT_DISABLE ?= "buildhistory icecc"
2091
2092      Some classes are not generally applicable within the extensible SDK
2093      context. You can use this variable to disable those classes.
2094
2095      For additional information on how to customize the extensible SDK's
2096      configuration, see the
2097      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2098      section in the Yocto Project Application Development and the
2099      Extensible Software Development Kit (eSDK) manual.
2100
2101   :term:`ESDK_LOCALCONF_ALLOW`
2102      A list of variables allowed through from the OpenEmbedded build
2103      system configuration into the extensible SDK configuration. By
2104      default, the list of variables is empty and is set in the
2105      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class.
2106
2107      This list overrides the variables specified using the
2108      :term:`ESDK_LOCALCONF_REMOVE` variable as well as
2109      other variables automatically added due to the "/" character
2110      being found at the start of the
2111      value, which is usually indicative of being a path and thus might not
2112      be valid on the system where the SDK is installed.
2113
2114      For additional information on how to customize the extensible SDK's
2115      configuration, see the
2116      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2117      section in the Yocto Project Application Development and the
2118      Extensible Software Development Kit (eSDK) manual.
2119
2120   :term:`ESDK_LOCALCONF_REMOVE`
2121      A list of variables not allowed through from the OpenEmbedded build
2122      system configuration into the extensible SDK configuration. Usually,
2123      these are variables that are specific to the machine on which the
2124      build system is running and thus would be potentially problematic
2125      within the extensible SDK.
2126
2127      By default, :term:`ESDK_LOCALCONF_REMOVE` is set in the
2128      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class and
2129      excludes the following variables:
2130
2131      - :term:`CONF_VERSION`
2132      - :term:`BB_NUMBER_THREADS`
2133      - :term:`BB_NUMBER_PARSE_THREADS`
2134      - :term:`PARALLEL_MAKE`
2135      - :term:`PRSERV_HOST`
2136      - :term:`SSTATE_MIRRORS` :term:`DL_DIR`
2137      - :term:`SSTATE_DIR` :term:`TMPDIR`
2138      - :term:`BB_SERVER_TIMEOUT`
2139
2140      For additional information on how to customize the extensible SDK's
2141      configuration, see the
2142      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2143      section in the Yocto Project Application Development and the
2144      Extensible Software Development Kit (eSDK) manual.
2145
2146   :term:`EXCLUDE_FROM_SHLIBS`
2147      Triggers the OpenEmbedded build system's shared libraries resolver to
2148      exclude an entire package when scanning for shared libraries.
2149
2150      .. note::
2151
2152         The shared libraries resolver's functionality results in part from
2153         the internal function ``package_do_shlibs``, which is part of the
2154         :ref:`ref-tasks-package` task. You should be aware that the shared
2155         libraries resolver might implicitly define some dependencies between
2156         packages.
2157
2158      The :term:`EXCLUDE_FROM_SHLIBS` variable is similar to the
2159      :term:`PRIVATE_LIBS` variable, which excludes a
2160      package's particular libraries only and not the whole package.
2161
2162      Use the :term:`EXCLUDE_FROM_SHLIBS` variable by setting it to "1" for a
2163      particular package::
2164
2165         EXCLUDE_FROM_SHLIBS = "1"
2166
2167   :term:`EXCLUDE_FROM_WORLD`
2168      Directs BitBake to exclude a recipe from world builds (i.e.
2169      ``bitbake world``). During world builds, BitBake locates, parses and
2170      builds all recipes found in every layer exposed in the
2171      ``bblayers.conf`` configuration file.
2172
2173      To exclude a recipe from a world build using this variable, set the
2174      variable to "1" in the recipe.
2175
2176      .. note::
2177
2178         Recipes added to :term:`EXCLUDE_FROM_WORLD` may still be built during a
2179         world build in order to satisfy dependencies of other recipes. Adding
2180         a recipe to :term:`EXCLUDE_FROM_WORLD` only ensures that the recipe is not
2181         explicitly added to the list of build targets in a world build.
2182
2183   :term:`EXTENDPE`
2184      Used with file and pathnames to create a prefix for a recipe's
2185      version based on the recipe's :term:`PE` value. If :term:`PE`
2186      is set and greater than zero for a recipe, :term:`EXTENDPE` becomes that
2187      value (e.g if :term:`PE` is equal to "1" then :term:`EXTENDPE` becomes "1").
2188      If a recipe's :term:`PE` is not set (the default) or is equal to zero,
2189      :term:`EXTENDPE` becomes "".
2190
2191      See the :term:`STAMP` variable for an example.
2192
2193   :term:`EXTENDPKGV`
2194      The full package version specification as it appears on the final
2195      packages produced by a recipe. The variable's value is normally used
2196      to fix a runtime dependency to the exact same version of another
2197      package in the same recipe::
2198
2199         RDEPENDS:${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
2200
2201      The dependency relationships are intended to force the package
2202      manager to upgrade these types of packages in lock-step.
2203
2204   :term:`EXTERNAL_KERNEL_TOOLS`
2205      When set, the :term:`EXTERNAL_KERNEL_TOOLS` variable indicates that these
2206      tools are not in the source tree.
2207
2208      When kernel tools are available in the tree, they are preferred over
2209      any externally installed tools. Setting the :term:`EXTERNAL_KERNEL_TOOLS`
2210      variable tells the OpenEmbedded build system to prefer the installed
2211      external tools. See the
2212      :ref:`kernel-yocto <ref-classes-kernel-yocto>` class in
2213      ``meta/classes`` to see how the variable is used.
2214
2215   :term:`EXTERNALSRC`
2216      When inheriting the :ref:`externalsrc <ref-classes-externalsrc>`
2217      class, this variable points to the source tree, which is outside of
2218      the OpenEmbedded build system. When set, this variable sets the
2219      :term:`S` variable, which is what the OpenEmbedded build
2220      system uses to locate unpacked recipe source code.
2221
2222      See the ":ref:`ref-classes-externalsrc`" section for details. You
2223      can also find information on how to use this variable in the
2224      ":ref:`dev-manual/common-tasks:building software from an external source`"
2225      section in the Yocto Project Development Tasks Manual.
2226
2227   :term:`EXTERNALSRC_BUILD`
2228      When inheriting the :ref:`externalsrc <ref-classes-externalsrc>`
2229      class, this variable points to the directory in which the recipe's
2230      source code is built, which is outside of the OpenEmbedded build
2231      system. When set, this variable sets the :term:`B` variable,
2232      which is what the OpenEmbedded build system uses to locate the Build
2233      Directory.
2234
2235      See the ":ref:`ref-classes-externalsrc`" section for details. You
2236      can also find information on how to use this variable in the
2237      ":ref:`dev-manual/common-tasks:building software from an external source`"
2238      section in the Yocto Project Development Tasks Manual.
2239
2240   :term:`EXTRA_AUTORECONF`
2241      For recipes inheriting the :ref:`autotools <ref-classes-autotools>`
2242      class, you can use :term:`EXTRA_AUTORECONF` to specify extra options to
2243      pass to the ``autoreconf`` command that is executed during the
2244      :ref:`ref-tasks-configure` task.
2245
2246      The default value is "--exclude=autopoint".
2247
2248   :term:`EXTRA_IMAGE_FEATURES`
2249      A list of additional features to include in an image. When listing
2250      more than one feature, separate them with a space.
2251
2252      Typically, you configure this variable in your ``local.conf`` file,
2253      which is found in the :term:`Build Directory`.
2254      Although you can use this variable from within a recipe, best
2255      practices dictate that you do not.
2256
2257      .. note::
2258
2259         To enable primary features from within the image recipe, use the
2260         :term:`IMAGE_FEATURES` variable.
2261
2262      Here are some examples of features you can add:
2263
2264        - "dbg-pkgs" --- adds -dbg packages for all installed packages including
2265          symbol information for debugging and profiling.
2266
2267        - "debug-tweaks" --- makes an image suitable for debugging. For example, allows root logins without passwords and
2268          enables post-installation logging. See the 'allow-empty-password' and
2269          'post-install-logging' features in the ":ref:`ref-features-image`"
2270          section for more information.
2271        - "dev-pkgs" --- adds -dev packages for all installed packages. This is
2272          useful if you want to develop against the libraries in the image.
2273        - "read-only-rootfs" --- creates an image whose root filesystem is
2274          read-only. See the
2275          ":ref:`dev-manual/common-tasks:creating a read-only root filesystem`"
2276          section in the Yocto Project Development Tasks Manual for more
2277          information
2278        - "tools-debug" --- adds debugging tools such as gdb and strace.
2279        - "tools-sdk" --- adds development tools such as gcc, make,
2280          pkgconfig and so forth.
2281        - "tools-testapps" --- adds useful testing tools
2282          such as ts_print, aplay, arecord and so forth.
2283
2284      For a complete list of image features that ships with the Yocto
2285      Project, see the ":ref:`ref-features-image`" section.
2286
2287      For an example that shows how to customize your image by using this
2288      variable, see the ":ref:`dev-manual/common-tasks:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
2289      section in the Yocto Project Development Tasks Manual.
2290
2291   :term:`EXTRA_IMAGECMD`
2292      Specifies additional options for the image creation command that has
2293      been specified in :term:`IMAGE_CMD`. When setting
2294      this variable, use an override for the associated image type. Here is
2295      an example::
2296
2297         EXTRA_IMAGECMD:ext3 ?= "-i 4096"
2298
2299   :term:`EXTRA_IMAGEDEPENDS`
2300      A list of recipes to build that do not provide packages for
2301      installing into the root filesystem.
2302
2303      Sometimes a recipe is required to build the final image but is not
2304      needed in the root filesystem. You can use the :term:`EXTRA_IMAGEDEPENDS`
2305      variable to list these recipes and thus specify the dependencies. A
2306      typical example is a required bootloader in a machine configuration.
2307
2308      .. note::
2309
2310         To add packages to the root filesystem, see the various
2311         :term:`RDEPENDS` and :term:`RRECOMMENDS` variables.
2312
2313   :term:`EXTRA_OECMAKE`
2314      Additional `CMake <https://cmake.org/overview/>`__ options. See the
2315      :ref:`cmake <ref-classes-cmake>` class for additional information.
2316
2317   :term:`EXTRA_OECONF`
2318      Additional ``configure`` script options. See
2319      :term:`PACKAGECONFIG_CONFARGS` for
2320      additional information on passing configure script options.
2321
2322   :term:`EXTRA_OEMAKE`
2323      Additional GNU ``make`` options.
2324
2325      Because the :term:`EXTRA_OEMAKE` defaults to "", you need to set the
2326      variable to specify any required GNU options.
2327
2328      :term:`PARALLEL_MAKE` and
2329      :term:`PARALLEL_MAKEINST` also make use of
2330      :term:`EXTRA_OEMAKE` to pass the required flags.
2331
2332   :term:`EXTRA_OESCONS`
2333      When inheriting the :ref:`scons <ref-classes-scons>` class, this
2334      variable specifies additional configuration options you want to pass
2335      to the ``scons`` command line.
2336
2337   :term:`EXTRA_USERS_PARAMS`
2338      When inheriting the :ref:`extrausers <ref-classes-extrausers>`
2339      class, this variable provides image level user and group operations.
2340      This is a more global method of providing user and group
2341      configuration as compared to using the
2342      :ref:`useradd <ref-classes-useradd>` class, which ties user and
2343      group configurations to a specific recipe.
2344
2345      The set list of commands you can configure using the
2346      :term:`EXTRA_USERS_PARAMS` is shown in the :ref:`extrausers <ref-classes-extrausers>` class. These
2347      commands map to the normal Unix commands of the same names::
2348
2349         # EXTRA_USERS_PARAMS = "\
2350         # useradd -p '' tester; \
2351         # groupadd developers; \
2352         # userdel nobody; \
2353         # groupdel -g video; \
2354         # groupmod -g 1020 developers; \
2355         # usermod -s /bin/sh tester; \
2356         # "
2357
2358      Hardcoded passwords are supported via the ``-p`` parameters for
2359      ``useradd`` or ``usermod``, but only hashed.
2360
2361      Here is an example that adds two users named "tester-jim" and "tester-sue" and assigns
2362      passwords. First on host, create the (escaped) password hash::
2363
2364         printf "%q" $(mkpasswd -m sha256crypt tester01)
2365
2366      The resulting hash is set to a variable and used in ``useradd`` command parameters::
2367
2368         inherit extrausers
2369         PASSWD = "\$X\$ABC123\$A-Long-Hash"
2370         EXTRA_USERS_PARAMS = "\
2371             useradd -p '${PASSWD}' tester-jim; \
2372             useradd -p '${PASSWD}' tester-sue; \
2373             "
2374
2375      Finally, here is an example that sets the root password::
2376
2377         inherit extrausers
2378         EXTRA_USERS_PARAMS = "\
2379             usermod -p '${PASSWD}' root; \
2380             "
2381
2382      .. note::
2383
2384         From a security perspective, hardcoding a default password is not
2385         generally a good idea or even legal in some jurisdictions. It is
2386         recommended that you do not do this if you are building a production
2387         image.
2388
2389      Additionally there is a special ``passwd-expire`` command that will
2390      cause the password for a user to be expired and thus force changing it
2391      on first login, for example::
2392
2393         EXTRA_USERS_PARAMS += " useradd myuser; passwd-expire myuser;"
2394
2395      .. note::
2396
2397         At present, ``passwd-expire`` may only work for remote logins when
2398         using OpenSSH and not dropbear as an SSH server.
2399
2400   :term:`EXTRANATIVEPATH`
2401      A list of subdirectories of
2402      ``${``\ :term:`STAGING_BINDIR_NATIVE`\ ``}``
2403      added to the beginning of the environment variable ``PATH``. As an
2404      example, the following prepends
2405      "${STAGING_BINDIR_NATIVE}/foo:${STAGING_BINDIR_NATIVE}/bar:" to
2406      ``PATH``::
2407
2408         EXTRANATIVEPATH = "foo bar"
2409
2410   :term:`FEATURE_PACKAGES`
2411      Defines one or more packages to include in an image when a specific
2412      item is included in :term:`IMAGE_FEATURES`.
2413      When setting the value, :term:`FEATURE_PACKAGES` should have the name of
2414      the feature item as an override. Here is an example::
2415
2416         FEATURE_PACKAGES_widget = "package1 package2"
2417
2418      In this example, if "widget" were added to :term:`IMAGE_FEATURES`,
2419      package1 and package2 would be included in the image.
2420
2421      .. note::
2422
2423         Packages installed by features defined through :term:`FEATURE_PACKAGES`
2424         are often package groups. While similarly named, you should not
2425         confuse the :term:`FEATURE_PACKAGES` variable with package groups, which
2426         are discussed elsewhere in the documentation.
2427
2428   :term:`FEED_DEPLOYDIR_BASE_URI`
2429      Points to the base URL of the server and location within the
2430      document-root that provides the metadata and packages required by
2431      OPKG to support runtime package management of IPK packages. You set
2432      this variable in your ``local.conf`` file.
2433
2434      Consider the following example::
2435
2436         FEED_DEPLOYDIR_BASE_URI = "http://192.168.7.1/BOARD-dir"
2437
2438      This example assumes you are serving
2439      your packages over HTTP and your databases are located in a directory
2440      named ``BOARD-dir``, which is underneath your HTTP server's
2441      document-root. In this case, the OpenEmbedded build system generates
2442      a set of configuration files for you in your target that work with
2443      the feed.
2444
2445   :term:`FILES`
2446      The list of files and directories that are placed in a package. The
2447      :term:`PACKAGES` variable lists the packages
2448      generated by a recipe.
2449
2450      To use the :term:`FILES` variable, provide a package name override that
2451      identifies the resulting package. Then, provide a space-separated
2452      list of files or paths that identify the files you want included as
2453      part of the resulting package. Here is an example::
2454
2455         FILES:${PN} += "${bindir}/mydir1 ${bindir}/mydir2/myfile"
2456
2457      .. note::
2458
2459         -  When specifying files or paths, you can pattern match using
2460            Python's
2461            `glob <https://docs.python.org/3/library/glob.html>`_
2462            syntax. For details on the syntax, see the documentation by
2463            following the previous link.
2464
2465         -  When specifying paths as part of the :term:`FILES` variable, it is
2466            good practice to use appropriate path variables. For example,
2467            use ``${sysconfdir}`` rather than ``/etc``, or ``${bindir}``
2468            rather than ``/usr/bin``. You can find a list of these
2469            variables at the top of the ``meta/conf/bitbake.conf`` file in
2470            the :term:`Source Directory`. You will also
2471            find the default values of the various ``FILES:*`` variables in
2472            this file.
2473
2474      If some of the files you provide with the :term:`FILES` variable are
2475      editable and you know they should not be overwritten during the
2476      package update process by the Package Management System (PMS), you
2477      can identify these files so that the PMS will not overwrite them. See
2478      the :term:`CONFFILES` variable for information on
2479      how to identify these files to the PMS.
2480
2481   :term:`FILES_SOLIBSDEV`
2482      Defines the file specification to match
2483      :term:`SOLIBSDEV`. In other words,
2484      :term:`FILES_SOLIBSDEV` defines the full path name of the development
2485      symbolic link (symlink) for shared libraries on the target platform.
2486
2487      The following statement from the ``bitbake.conf`` shows how it is
2488      set::
2489
2490         FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}"
2491
2492   :term:`FILESEXTRAPATHS`
2493      Extends the search path the OpenEmbedded build system uses when
2494      looking for files and patches as it processes recipes and append
2495      files. The default directories BitBake uses when it processes recipes
2496      are initially defined by the :term:`FILESPATH`
2497      variable. You can extend :term:`FILESPATH` variable by using
2498      :term:`FILESEXTRAPATHS`.
2499
2500      Best practices dictate that you accomplish this by using
2501      :term:`FILESEXTRAPATHS` from within a ``.bbappend`` file and that you
2502      prepend paths as follows::
2503
2504         FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
2505
2506      In the above example, the build system first
2507      looks for files in a directory that has the same name as the
2508      corresponding append file.
2509
2510      .. note::
2511
2512         When extending :term:`FILESEXTRAPATHS`, be sure to use the immediate
2513         expansion (``:=``) operator. Immediate expansion makes sure that
2514         BitBake evaluates :term:`THISDIR` at the time the
2515         directive is encountered rather than at some later time when
2516         expansion might result in a directory that does not contain the
2517         files you need.
2518
2519         Also, include the trailing separating colon character if you are
2520         prepending. The trailing colon character is necessary because you
2521         are directing BitBake to extend the path by prepending directories
2522         to the search path.
2523
2524      Here is another common use::
2525
2526         FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
2527
2528      In this example, the build system extends the
2529      :term:`FILESPATH` variable to include a directory named ``files`` that is
2530      in the same directory as the corresponding append file.
2531
2532      This next example specifically adds three paths::
2533
2534         FILESEXTRAPATHS:prepend := "path_1:path_2:path_3:"
2535
2536      A final example shows how you can extend the search path and include
2537      a :term:`MACHINE`-specific override, which is useful
2538      in a BSP layer::
2539
2540          FILESEXTRAPATHS:prepend:intel-x86-common := "${THISDIR}/${PN}:"
2541
2542      The previous statement appears in the
2543      ``linux-yocto-dev.bbappend`` file, which is found in the
2544      :ref:`overview-manual/development-environment:yocto project source repositories` in
2545      ``meta-intel/common/recipes-kernel/linux``. Here, the machine
2546      override is a special :term:`PACKAGE_ARCH`
2547      definition for multiple ``meta-intel`` machines.
2548
2549      .. note::
2550
2551         For a layer that supports a single BSP, the override could just be
2552         the value of :term:`MACHINE`.
2553
2554      By prepending paths in ``.bbappend`` files, you allow multiple append
2555      files that reside in different layers but are used for the same
2556      recipe to correctly extend the path.
2557
2558   :term:`FILESOVERRIDES`
2559      A subset of :term:`OVERRIDES` used by the
2560      OpenEmbedded build system for creating
2561      :term:`FILESPATH`. The :term:`FILESOVERRIDES` variable
2562      uses overrides to automatically extend the
2563      :term:`FILESPATH` variable. For an example of how
2564      that works, see the :term:`FILESPATH` variable
2565      description. Additionally, you find more information on how overrides
2566      are handled in the
2567      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
2568      section of the BitBake User Manual.
2569
2570      By default, the :term:`FILESOVERRIDES` variable is defined as::
2571
2572         FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
2573
2574      .. note::
2575
2576         Do not hand-edit the :term:`FILESOVERRIDES` variable. The values match up
2577         with expected overrides and are used in an expected manner by the
2578         build system.
2579
2580   :term:`FILESPATH`
2581      The default set of directories the OpenEmbedded build system uses
2582      when searching for patches and files.
2583
2584      During the build process, BitBake searches each directory in
2585      :term:`FILESPATH` in the specified order when looking for files and
2586      patches specified by each ``file://`` URI in a recipe's
2587      :term:`SRC_URI` statements.
2588
2589      The default value for the :term:`FILESPATH` variable is defined in the
2590      :ref:`ref-classes-base` class found in ``meta/classes`` in the
2591      :term:`Source Directory`::
2592
2593         FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
2594             "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
2595
2596      The
2597      :term:`FILESPATH` variable is automatically extended using the overrides
2598      from the :term:`FILESOVERRIDES` variable.
2599
2600      .. note::
2601
2602         -  Do not hand-edit the :term:`FILESPATH` variable. If you want the
2603            build system to look in directories other than the defaults,
2604            extend the :term:`FILESPATH` variable by using the
2605            :term:`FILESEXTRAPATHS` variable.
2606
2607         -  Be aware that the default :term:`FILESPATH` directories do not map
2608            to directories in custom layers where append files
2609            (``.bbappend``) are used. If you want the build system to find
2610            patches or files that reside with your append files, you need
2611            to extend the :term:`FILESPATH` variable by using the
2612            :term:`FILESEXTRAPATHS` variable.
2613
2614      You can take advantage of this searching behavior in useful ways. For
2615      example, consider a case where there is the following directory structure
2616      for general and machine-specific configurations::
2617
2618         files/defconfig
2619         files/MACHINEA/defconfig
2620         files/MACHINEB/defconfig
2621
2622      Also in the example, the :term:`SRC_URI` statement contains
2623      "file://defconfig". Given this scenario, you can set
2624      :term:`MACHINE` to "MACHINEA" and cause the build
2625      system to use files from ``files/MACHINEA``. Set :term:`MACHINE` to
2626      "MACHINEB" and the build system uses files from ``files/MACHINEB``.
2627      Finally, for any machine other than "MACHINEA" and "MACHINEB", the
2628      build system uses files from ``files/defconfig``.
2629
2630      You can find out more about the patching process in the
2631      ":ref:`overview-manual/concepts:patching`" section
2632      in the Yocto Project Overview and Concepts Manual and the
2633      ":ref:`dev-manual/common-tasks:patching code`" section in
2634      the Yocto Project Development Tasks Manual. See the
2635      :ref:`ref-tasks-patch` task as well.
2636
2637   :term:`FILESYSTEM_PERMS_TABLES`
2638      Allows you to define your own file permissions settings table as part
2639      of your configuration for the packaging process. For example, suppose
2640      you need a consistent set of custom permissions for a set of groups
2641      and users across an entire work project. It is best to do this in the
2642      packages themselves but this is not always possible.
2643
2644      By default, the OpenEmbedded build system uses the ``fs-perms.txt``,
2645      which is located in the ``meta/files`` folder in the :term:`Source Directory`.
2646      If you create your own file
2647      permissions setting table, you should place it in your layer or the
2648      distro's layer.
2649
2650      You define the :term:`FILESYSTEM_PERMS_TABLES` variable in the
2651      ``conf/local.conf`` file, which is found in the :term:`Build Directory`,
2652      to point to your custom
2653      ``fs-perms.txt``. You can specify more than a single file permissions
2654      setting table. The paths you specify to these files must be defined
2655      within the :term:`BBPATH` variable.
2656
2657      For guidance on how to create your own file permissions settings
2658      table file, examine the existing ``fs-perms.txt``.
2659
2660   :term:`FIT_DESC`
2661      Specifies the description string encoded into a fitImage. The default
2662      value is set by the :ref:`kernel-fitimage <ref-classes-kernel-fitimage>`
2663      class as follows::
2664
2665         FIT_DESC ?= "U-Boot fitImage for ${DISTRO_NAME}/${PV}/${MACHINE}"
2666
2667   :term:`FIT_GENERATE_KEYS`
2668      Decides whether to generate the keys for signing fitImage if they
2669      don't already exist. The keys are created in :term:`UBOOT_SIGN_KEYDIR`.
2670      The default value is 0.
2671
2672   :term:`FIT_HASH_ALG`
2673      Specifies the hash algorithm used in creating the FIT Image. For e.g. sha256.
2674
2675   :term:`FIT_KERNEL_COMP_ALG`
2676      Compression algorithm to use for the kernel image inside the FIT Image.
2677      At present, the only supported values are "gzip" (default) or "none"
2678      If you set this variable to anything other than "none" you may also need
2679      to set :term:`FIT_KERNEL_COMP_ALG_EXTENSION`.
2680
2681   :term:`FIT_KERNEL_COMP_ALG_EXTENSION`
2682      File extension corresponding to :term:`FIT_KERNEL_COMP_ALG`. The default
2683      value is ".gz".
2684
2685   :term:`FIT_KEY_GENRSA_ARGS`
2686      Arguments to openssl genrsa for generating RSA private key for signing
2687      fitImage. The default value is "-F4". i.e. the public exponent 65537 to
2688      use.
2689
2690   :term:`FIT_KEY_REQ_ARGS`
2691      Arguments to openssl req for generating certificate for signing fitImage.
2692      The default value is "-batch -new". batch for non interactive mode
2693      and new for generating new keys.
2694
2695   :term:`FIT_KEY_SIGN_PKCS`
2696      Format for public key certificate used in signing fitImage.
2697      The default value is "x509".
2698
2699   :term:`FIT_SIGN_ALG`
2700      Specifies the signature algorithm used in creating the FIT Image.
2701      For e.g. rsa2048.
2702
2703   :term:`FIT_SIGN_INDIVIDUAL`
2704      If set to "1", then the :ref:`kernel-fitimage <ref-classes-kernel-fitimage>`
2705      class will sign the kernel, dtb and ramdisk images individually in addition
2706      to signing the fitImage itself. This could be useful if you are
2707      intending to verify signatures in another context than booting via
2708      U-Boot.
2709
2710   :term:`FIT_SIGN_NUMBITS`
2711      Size of private key in number of bits used in fitImage. The default
2712      value is "2048".
2713
2714   :term:`FONT_EXTRA_RDEPENDS`
2715      When inheriting the :ref:`fontcache <ref-classes-fontcache>` class,
2716      this variable specifies the runtime dependencies for font packages.
2717      By default, the :term:`FONT_EXTRA_RDEPENDS` is set to "fontconfig-utils".
2718
2719   :term:`FONT_PACKAGES`
2720      When inheriting the :ref:`fontcache <ref-classes-fontcache>` class,
2721      this variable identifies packages containing font files that need to
2722      be cached by Fontconfig. By default, the :ref:`fontcache <ref-classes-fontcache>` class assumes
2723      that fonts are in the recipe's main package (i.e.
2724      ``${``\ :term:`PN`\ ``}``). Use this variable if fonts you
2725      need are in a package other than that main package.
2726
2727   :term:`FORCE_RO_REMOVE`
2728      Forces the removal of the packages listed in ``ROOTFS_RO_UNNEEDED``
2729      during the generation of the root filesystem.
2730
2731      Set the variable to "1" to force the removal of these packages.
2732
2733   :term:`FULL_OPTIMIZATION`
2734      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
2735      compiling an optimized system. This variable defaults to "-O2 -pipe
2736      ${DEBUG_FLAGS}".
2737
2738   :term:`GCCPIE`
2739      Enables Position Independent Executables (PIE) within the GNU C
2740      Compiler (GCC). Enabling PIE in the GCC makes Return Oriented
2741      Programming (ROP) attacks much more difficult to execute.
2742
2743      By default the ``security_flags.inc`` file enables PIE by setting the
2744      variable as follows::
2745
2746         GCCPIE ?= "--enable-default-pie"
2747
2748   :term:`GCCVERSION`
2749      Specifies the default version of the GNU C Compiler (GCC) used for
2750      compilation. By default, :term:`GCCVERSION` is set to "8.x" in the
2751      ``meta/conf/distro/include/tcmode-default.inc`` include file::
2752
2753         GCCVERSION ?= "8.%"
2754
2755      You can override this value by setting it in a
2756      configuration file such as the ``local.conf``.
2757
2758   :term:`GDB`
2759      The minimal command and arguments to run the GNU Debugger.
2760
2761   :term:`GIR_EXTRA_LIBS_PATH`
2762      Allows to specify an extra search path for ``.so`` files
2763      in GLib related recipes using GObject introspection,
2764      and which do not compile without this setting.
2765      See the ":ref:`dev-manual/common-tasks:enabling gobject introspection support`"
2766      section for details.
2767
2768   :term:`GITDIR`
2769      The directory in which a local copy of a Git repository is stored
2770      when it is cloned.
2771
2772   :term:`GLIBC_GENERATE_LOCALES`
2773      Specifies the list of GLIBC locales to generate should you not wish
2774      to generate all LIBC locals, which can be time consuming.
2775
2776      .. note::
2777
2778         If you specifically remove the locale ``en_US.UTF-8``, you must set
2779         :term:`IMAGE_LINGUAS` appropriately.
2780
2781      You can set :term:`GLIBC_GENERATE_LOCALES` in your ``local.conf`` file.
2782      By default, all locales are generated.
2783      ::
2784
2785         GLIBC_GENERATE_LOCALES = "en_GB.UTF-8 en_US.UTF-8"
2786
2787   :term:`GROUPADD_PARAM`
2788      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
2789      this variable specifies for a package what parameters should be
2790      passed to the ``groupadd`` command if you wish to add a group to the
2791      system when the package is installed.
2792
2793      Here is an example from the ``dbus`` recipe::
2794
2795         GROUPADD_PARAM:${PN} = "-r netdev"
2796
2797      For information on the standard Linux shell command
2798      ``groupadd``, see https://linux.die.net/man/8/groupadd.
2799
2800   :term:`GROUPMEMS_PARAM`
2801      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
2802      this variable specifies for a package what parameters should be
2803      passed to the ``groupmems`` command if you wish to modify the members
2804      of a group when the package is installed.
2805
2806      For information on the standard Linux shell command ``groupmems``,
2807      see https://linux.die.net/man/8/groupmems.
2808
2809   :term:`GRUB_GFXSERIAL`
2810      Configures the GNU GRand Unified Bootloader (GRUB) to have graphics
2811      and serial in the boot menu. Set this variable to "1" in your
2812      ``local.conf`` or distribution configuration file to enable graphics
2813      and serial in the menu.
2814
2815      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
2816      information on how this variable is used.
2817
2818   :term:`GRUB_OPTS`
2819      Additional options to add to the GNU GRand Unified Bootloader (GRUB)
2820      configuration. Use a semi-colon character (``;``) to separate
2821      multiple options.
2822
2823      The :term:`GRUB_OPTS` variable is optional. See the
2824      :ref:`grub-efi <ref-classes-grub-efi>` class for more information
2825      on how this variable is used.
2826
2827   :term:`GRUB_TIMEOUT`
2828      Specifies the timeout before executing the default ``LABEL`` in the
2829      GNU GRand Unified Bootloader (GRUB).
2830
2831      The :term:`GRUB_TIMEOUT` variable is optional. See the
2832      :ref:`grub-efi <ref-classes-grub-efi>` class for more information
2833      on how this variable is used.
2834
2835   :term:`GTKIMMODULES_PACKAGES`
2836      When inheriting the
2837      :ref:`gtk-immodules-cache <ref-classes-gtk-immodules-cache>` class,
2838      this variable specifies the packages that contain the GTK+ input
2839      method modules being installed when the modules are in packages other
2840      than the main package.
2841
2842   :term:`HOMEPAGE`
2843      Website where more information about the software the recipe is
2844      building can be found.
2845
2846   :term:`HOST_ARCH`
2847      The name of the target architecture, which is normally the same as
2848      :term:`TARGET_ARCH`. The OpenEmbedded build system
2849      supports many architectures. Here is an example list of architectures
2850      supported. This list is by no means complete as the architecture is
2851      configurable:
2852
2853      - arm
2854      - i586
2855      - x86_64
2856      - powerpc
2857      - powerpc64
2858      - mips
2859      - mipsel
2860
2861   :term:`HOST_CC_ARCH`
2862      Specifies architecture-specific compiler flags that are passed to the
2863      C compiler.
2864
2865      Default initialization for :term:`HOST_CC_ARCH` varies depending on what
2866      is being built:
2867
2868      -  :term:`TARGET_CC_ARCH` when building for the
2869         target
2870
2871      -  :term:`BUILD_CC_ARCH` when building for the build host (i.e.
2872         ``-native``)
2873
2874      -  ``BUILDSDK_CC_ARCH`` when building for an SDK (i.e.
2875         ``nativesdk-``)
2876
2877   :term:`HOST_OS`
2878      Specifies the name of the target operating system, which is normally
2879      the same as the :term:`TARGET_OS`. The variable can
2880      be set to "linux" for ``glibc``-based systems and to "linux-musl" for
2881      ``musl``. For ARM/EABI targets, there are also "linux-gnueabi" and
2882      "linux-musleabi" values possible.
2883
2884   :term:`HOST_PREFIX`
2885      Specifies the prefix for the cross-compile toolchain. :term:`HOST_PREFIX`
2886      is normally the same as :term:`TARGET_PREFIX`.
2887
2888   :term:`HOST_SYS`
2889      Specifies the system, including the architecture and the operating
2890      system, for which the build is occurring in the context of the
2891      current recipe.
2892
2893      The OpenEmbedded build system automatically sets this variable based
2894      on :term:`HOST_ARCH`,
2895      :term:`HOST_VENDOR`, and
2896      :term:`HOST_OS` variables.
2897
2898      .. note::
2899
2900         You do not need to set the variable yourself.
2901
2902      Consider these two examples:
2903
2904      -  Given a native recipe on a 32-bit x86 machine running Linux, the
2905         value is "i686-linux".
2906
2907      -  Given a recipe being built for a little-endian MIPS target running
2908         Linux, the value might be "mipsel-linux".
2909
2910   :term:`HOST_VENDOR`
2911      Specifies the name of the vendor. :term:`HOST_VENDOR` is normally the
2912      same as :term:`TARGET_VENDOR`.
2913
2914   :term:`HOSTTOOLS`
2915      A space-separated list (filter) of tools on the build host that
2916      should be allowed to be called from within build tasks. Using this
2917      filter helps reduce the possibility of host contamination. If a tool
2918      specified in the value of :term:`HOSTTOOLS` is not found on the build
2919      host, the OpenEmbedded build system produces an error and the build
2920      is not started.
2921
2922      For additional information, see
2923      :term:`HOSTTOOLS_NONFATAL`.
2924
2925   :term:`HOSTTOOLS_NONFATAL`
2926      A space-separated list (filter) of tools on the build host that
2927      should be allowed to be called from within build tasks. Using this
2928      filter helps reduce the possibility of host contamination. Unlike
2929      :term:`HOSTTOOLS`, the OpenEmbedded build system
2930      does not produce an error if a tool specified in the value of
2931      :term:`HOSTTOOLS_NONFATAL` is not found on the build host. Thus, you can
2932      use :term:`HOSTTOOLS_NONFATAL` to filter optional host tools.
2933
2934   :term:`ICECC_CLASS_DISABLE`
2935      Identifies user classes that you do not want the Icecream distributed
2936      compile support to consider. This variable is used by the
2937      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2938      your ``local.conf`` file.
2939
2940      When you list classes using this variable, the recipes inheriting
2941      those classes will not benefit from distributed compilation across
2942      remote hosts. Instead they will be built locally.
2943
2944   :term:`ICECC_DISABLED`
2945      Disables or enables the ``icecc`` (Icecream) function. For more
2946      information on this function and best practices for using this
2947      variable, see the ":ref:`ref-classes-icecc`"
2948      section.
2949
2950      Setting this variable to "1" in your ``local.conf`` disables the
2951      function::
2952
2953         ICECC_DISABLED ??= "1"
2954
2955      To enable the function, set the variable as follows::
2956
2957         ICECC_DISABLED = ""
2958
2959   :term:`ICECC_ENV_EXEC`
2960      Points to the ``icecc-create-env`` script that you provide. This
2961      variable is used by the :ref:`icecc <ref-classes-icecc>` class. You
2962      set this variable in your ``local.conf`` file.
2963
2964      If you do not point to a script that you provide, the OpenEmbedded
2965      build system uses the default script provided by the
2966      ``icecc-create-env.bb`` recipe, which is a modified version and not
2967      the one that comes with ``icecc``.
2968
2969   :term:`ICECC_PARALLEL_MAKE`
2970      Extra options passed to the ``make`` command during the
2971      :ref:`ref-tasks-compile` task that specify parallel
2972      compilation. This variable usually takes the form of "-j x", where x
2973      represents the maximum number of parallel threads ``make`` can run.
2974
2975      .. note::
2976
2977         The options passed affect builds on all enabled machines on the
2978         network, which are machines running the ``iceccd`` daemon.
2979
2980      If your enabled machines support multiple cores, coming up with the
2981      maximum number of parallel threads that gives you the best
2982      performance could take some experimentation since machine speed,
2983      network lag, available memory, and existing machine loads can all
2984      affect build time. Consequently, unlike the
2985      :term:`PARALLEL_MAKE` variable, there is no
2986      rule-of-thumb for setting :term:`ICECC_PARALLEL_MAKE` to achieve optimal
2987      performance.
2988
2989      If you do not set :term:`ICECC_PARALLEL_MAKE`, the build system does not
2990      use it (i.e. the system does not detect and assign the number of
2991      cores as is done with :term:`PARALLEL_MAKE`).
2992
2993   :term:`ICECC_PATH`
2994      The location of the ``icecc`` binary. You can set this variable in
2995      your ``local.conf`` file. If your ``local.conf`` file does not define
2996      this variable, the :ref:`icecc <ref-classes-icecc>` class attempts
2997      to define it by locating ``icecc`` using ``which``.
2998
2999   :term:`ICECC_RECIPE_DISABLE`
3000      Identifies user recipes that you do not want the Icecream distributed
3001      compile support to consider. This variable is used by the
3002      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
3003      your ``local.conf`` file.
3004
3005      When you list recipes using this variable, you are excluding them
3006      from distributed compilation across remote hosts. Instead they will
3007      be built locally.
3008
3009   :term:`ICECC_RECIPE_ENABLE`
3010      Identifies user recipes that use an empty
3011      :term:`PARALLEL_MAKE` variable that you want to
3012      force remote distributed compilation on using the Icecream
3013      distributed compile support. This variable is used by the
3014      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
3015      your ``local.conf`` file.
3016
3017   :term:`IMAGE_BASENAME`
3018      The base name of image output files. This variable defaults to the
3019      recipe name (``${``\ :term:`PN`\ ``}``).
3020
3021   :term:`IMAGE_BOOT_FILES`
3022      A space-separated list of files installed into the boot partition
3023      when preparing an image using the Wic tool with the
3024      ``bootimg-partition`` source plugin. By default,
3025      the files are
3026      installed under the same name as the source files. To change the
3027      installed name, separate it from the original name with a semi-colon
3028      (;). Source files need to be located in
3029      :term:`DEPLOY_DIR_IMAGE`. Here are two
3030      examples::
3031
3032         IMAGE_BOOT_FILES = "u-boot.img uImage;kernel"
3033         IMAGE_BOOT_FILES = "u-boot.${UBOOT_SUFFIX} ${KERNEL_IMAGETYPE}"
3034
3035      Alternatively, source files can be picked up using a glob pattern. In
3036      this case, the destination file must have the same name as the base
3037      name of the source file path. To install files into a directory
3038      within the target location, pass its name after a semi-colon (;).
3039      Here are two examples::
3040
3041         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*"
3042         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*;boot/"
3043
3044      The first example
3045      installs all files from ``${DEPLOY_DIR_IMAGE}/bcm2835-bootfiles``
3046      into the root of the target partition. The second example installs
3047      the same files into a ``boot`` directory within the target partition.
3048
3049      You can find information on how to use the Wic tool in the
3050      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
3051      section of the Yocto Project Development Tasks Manual. Reference
3052      material for Wic is located in the
3053      ":doc:`/ref-manual/kickstart`" chapter.
3054
3055   :term:`IMAGE_CLASSES`
3056      A list of classes that all images should inherit. You typically use
3057      this variable to specify the list of classes that register the
3058      different types of images the OpenEmbedded build system creates.
3059
3060      The default value for :term:`IMAGE_CLASSES` is ``image_types``. You can
3061      set this variable in your ``local.conf`` or in a distribution
3062      configuration file.
3063
3064      For more information, see ``meta/classes/image_types.bbclass`` in the
3065      :term:`Source Directory`.
3066
3067   :term:`IMAGE_CMD`
3068      Specifies the command to create the image file for a specific image
3069      type, which corresponds to the value set in
3070      :term:`IMAGE_FSTYPES`, (e.g. ``ext3``,
3071      ``btrfs``, and so forth). When setting this variable, you should use
3072      an override for the associated type. Here is an example::
3073
3074         IMAGE_CMD:jffs2 = "mkfs.jffs2 --root=${IMAGE_ROOTFS} --faketime \
3075             --output=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.jffs2 \
3076             ${EXTRA_IMAGECMD}"
3077
3078      You typically do not need to set this variable unless you are adding
3079      support for a new image type. For more examples on how to set this
3080      variable, see the :ref:`image_types <ref-classes-image_types>`
3081      class file, which is ``meta/classes/image_types.bbclass``.
3082
3083   :term:`IMAGE_DEVICE_TABLES`
3084      Specifies one or more files that contain custom device tables that
3085      are passed to the ``makedevs`` command as part of creating an image.
3086      These files list basic device nodes that should be created under
3087      ``/dev`` within the image. If :term:`IMAGE_DEVICE_TABLES` is not set,
3088      ``files/device_table-minimal.txt`` is used, which is located by
3089      :term:`BBPATH`. For details on how you should write
3090      device table files, see ``meta/files/device_table-minimal.txt`` as an
3091      example.
3092
3093   :term:`IMAGE_EFI_BOOT_FILES`
3094      A space-separated list of files installed into the boot partition
3095      when preparing an image using the Wic tool with the
3096      ``bootimg-efi`` source plugin. By default,
3097      the files are
3098      installed under the same name as the source files. To change the
3099      installed name, separate it from the original name with a semi-colon
3100      (;). Source files need to be located in
3101      :term:`DEPLOY_DIR_IMAGE`. Here are two
3102      examples::
3103
3104         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE};bz2"
3105         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE} microcode.cpio"
3106
3107      Alternatively, source files can be picked up using a glob pattern. In
3108      this case, the destination file must have the same name as the base
3109      name of the source file path. To install files into a directory
3110      within the target location, pass its name after a semi-colon (;).
3111      Here are two examples::
3112
3113         IMAGE_EFI_BOOT_FILES = "boot/loader/*"
3114         IMAGE_EFI_BOOT_FILES = "boot/loader/*;boot/"
3115
3116      The first example
3117      installs all files from ``${DEPLOY_DIR_IMAGE}/boot/loader/``
3118      into the root of the target partition. The second example installs
3119      the same files into a ``boot`` directory within the target partition.
3120
3121      You can find information on how to use the Wic tool in the
3122      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
3123      section of the Yocto Project Development Tasks Manual. Reference
3124      material for Wic is located in the
3125      ":doc:`/ref-manual/kickstart`" chapter.
3126
3127   :term:`IMAGE_FEATURES`
3128      The primary list of features to include in an image. Typically, you
3129      configure this variable in an image recipe. Although you can use this
3130      variable from your ``local.conf`` file, which is found in the
3131      :term:`Build Directory`, best practices dictate that you do
3132      not.
3133
3134      .. note::
3135
3136         To enable extra features from outside the image recipe, use the
3137         :term:`EXTRA_IMAGE_FEATURES` variable.
3138
3139      For a list of image features that ships with the Yocto Project, see
3140      the ":ref:`ref-features-image`" section.
3141
3142      For an example that shows how to customize your image by using this
3143      variable, see the ":ref:`dev-manual/common-tasks:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
3144      section in the Yocto Project Development Tasks Manual.
3145
3146   :term:`IMAGE_FSTYPES`
3147      Specifies the formats the OpenEmbedded build system uses during the
3148      build when creating the root filesystem. For example, setting
3149      :term:`IMAGE_FSTYPES` as follows causes the build system to create root
3150      filesystems using two formats: ``.ext3`` and ``.tar.bz2``::
3151
3152         IMAGE_FSTYPES = "ext3 tar.bz2"
3153
3154      For the complete list of supported image formats from which you can
3155      choose, see :term:`IMAGE_TYPES`.
3156
3157      .. note::
3158
3159         -  If an image recipe uses the "inherit image" line and you are
3160            setting :term:`IMAGE_FSTYPES` inside the recipe, you must set
3161            :term:`IMAGE_FSTYPES` prior to using the "inherit image" line.
3162
3163         -  Due to the way the OpenEmbedded build system processes this
3164            variable, you cannot update its contents by using ``:append``
3165            or ``:prepend``. You must use the ``+=`` operator to add one or
3166            more options to the :term:`IMAGE_FSTYPES` variable.
3167
3168   :term:`IMAGE_INSTALL`
3169      Used by recipes to specify the packages to install into an image
3170      through the :ref:`image <ref-classes-image>` class. Use the
3171      :term:`IMAGE_INSTALL` variable with care to avoid ordering issues.
3172
3173      Image recipes set :term:`IMAGE_INSTALL` to specify the packages to
3174      install into an image through :ref:`ref-classes-image`. Additionally,
3175      there are "helper" classes such as the
3176      :ref:`core-image <ref-classes-core-image>` class which can
3177      take lists used with :term:`IMAGE_FEATURES` and turn them into
3178      auto-generated entries in :term:`IMAGE_INSTALL` in addition to its
3179      default contents.
3180
3181      When you use this variable, it is best to use it as follows::
3182
3183         IMAGE_INSTALL:append = " package-name"
3184
3185      Be sure to include the space
3186      between the quotation character and the start of the package name or
3187      names.
3188
3189      .. note::
3190
3191         -  When working with a
3192            :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
3193            image, do not use the :term:`IMAGE_INSTALL` variable to specify
3194            packages for installation. Instead, use the
3195            :term:`PACKAGE_INSTALL` variable, which
3196            allows the initial RAM filesystem (initramfs) recipe to use a
3197            fixed set of packages and not be affected by :term:`IMAGE_INSTALL`.
3198            For information on creating an initramfs, see the
3199            ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`"
3200            section in the Yocto Project Development Tasks Manual.
3201
3202         -  Using :term:`IMAGE_INSTALL` with the
3203            :ref:`+= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:appending (+=) and prepending (=+) with spaces>`
3204            BitBake operator within the ``/conf/local.conf`` file or from
3205            within an image recipe is not recommended. Use of this operator
3206            in these ways can cause ordering issues. Since
3207            :ref:`ref-classes-core-image` sets :term:`IMAGE_INSTALL` to a default
3208            value using the
3209            :ref:`?= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:setting a default value (?=)>`
3210            operator, using a ``+=`` operation against :term:`IMAGE_INSTALL`
3211            results in unexpected behavior when used within
3212            ``conf/local.conf``. Furthermore, the same operation from
3213            within an image recipe may or may not succeed depending on the
3214            specific situation. In both these cases, the behavior is
3215            contrary to how most users expect the ``+=`` operator to work.
3216
3217   :term:`IMAGE_LINGUAS`
3218      Specifies the list of locales to install into the image during the
3219      root filesystem construction process. The OpenEmbedded build system
3220      automatically splits locale files, which are used for localization,
3221      into separate packages. Setting the :term:`IMAGE_LINGUAS` variable
3222      ensures that any locale packages that correspond to packages already
3223      selected for installation into the image are also installed. Here is
3224      an example::
3225
3226         IMAGE_LINGUAS = "pt-br de-de"
3227
3228      In this example, the build system ensures any Brazilian Portuguese
3229      and German locale files that correspond to packages in the image are
3230      installed (i.e. ``*-locale-pt-br`` and ``*-locale-de-de`` as well as
3231      ``*-locale-pt`` and ``*-locale-de``, since some software packages
3232      only provide locale files by language and not by country-specific
3233      language).
3234
3235      See the :term:`GLIBC_GENERATE_LOCALES`
3236      variable for information on generating GLIBC locales.
3237
3238
3239   :term:`IMAGE_LINK_NAME`
3240      The name of the output image symlink (which does not include
3241      the version part as :term:`IMAGE_NAME` does). The default value
3242      is derived using the :term:`IMAGE_BASENAME` and :term:`MACHINE`
3243      variables::
3244
3245         IMAGE_LINK_NAME ?= "${IMAGE_BASENAME}-${MACHINE}"
3246
3247
3248   :term:`IMAGE_MANIFEST`
3249      The manifest file for the image. This file lists all the installed
3250      packages that make up the image. The file contains package
3251      information on a line-per-package basis as follows::
3252
3253          packagename packagearch version
3254
3255      The :ref:`rootfs-postcommands <ref-classes-rootfs*>` class defines the manifest
3256      file as follows::
3257
3258         IMAGE_MANIFEST ="${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.manifest"
3259
3260      The location is
3261      derived using the :term:`IMGDEPLOYDIR`
3262      and :term:`IMAGE_NAME` variables. You can find
3263      information on how the image is created in the ":ref:`overview-manual/concepts:image generation`"
3264      section in the Yocto Project Overview and Concepts Manual.
3265
3266   :term:`IMAGE_NAME`
3267      The name of the output image files minus the extension. This variable
3268      is derived using the :term:`IMAGE_BASENAME`,
3269      :term:`MACHINE`, and :term:`IMAGE_VERSION_SUFFIX`
3270      variables::
3271
3272         IMAGE_NAME ?= "${IMAGE_BASENAME}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3273
3274   :term:`IMAGE_NAME_SUFFIX`
3275      Suffix used for the image output filename --- defaults to ``".rootfs"``
3276      to distinguish the image file from other files created during image
3277      building; however if this suffix is redundant or not desired you can
3278      clear the value of this variable (set the value to ""). For example,
3279      this is typically cleared in initramfs image recipes.
3280
3281   :term:`IMAGE_OVERHEAD_FACTOR`
3282      Defines a multiplier that the build system applies to the initial
3283      image size for cases when the multiplier times the returned disk
3284      usage value for the image is greater than the sum of
3285      :term:`IMAGE_ROOTFS_SIZE` and :term:`IMAGE_ROOTFS_EXTRA_SPACE`. The result of
3286      the multiplier applied to the initial image size creates free disk
3287      space in the image as overhead. By default, the build process uses a
3288      multiplier of 1.3 for this variable. This default value results in
3289      30% free disk space added to the image when this method is used to
3290      determine the final generated image size. You should be aware that
3291      post install scripts and the package management system uses disk
3292      space inside this overhead area. Consequently, the multiplier does
3293      not produce an image with all the theoretical free disk space. See
3294      :term:`IMAGE_ROOTFS_SIZE` for information on how the build system
3295      determines the overall image size.
3296
3297      The default 30% free disk space typically gives the image enough room
3298      to boot and allows for basic post installs while still leaving a
3299      small amount of free disk space. If 30% free space is inadequate, you
3300      can increase the default value. For example, the following setting
3301      gives you 50% free space added to the image::
3302
3303         IMAGE_OVERHEAD_FACTOR = "1.5"
3304
3305      Alternatively, you can ensure a specific amount of free disk space is
3306      added to the image by using the :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3307      variable.
3308
3309   :term:`IMAGE_PKGTYPE`
3310      Defines the package type (i.e. DEB, RPM, IPK, or TAR) used by the
3311      OpenEmbedded build system. The variable is defined appropriately by
3312      the :ref:`package_deb <ref-classes-package_deb>`,
3313      :ref:`package_rpm <ref-classes-package_rpm>`,
3314      :ref:`package_ipk <ref-classes-package_ipk>`, or
3315      :ref:`package_tar <ref-classes-package_tar>` class.
3316
3317      .. note::
3318
3319         The ``package_tar`` class is broken and is not supported. It is
3320         recommended that you do not use it.
3321
3322      The :ref:`populate_sdk_* <ref-classes-populate-sdk-*>` and
3323      :ref:`image <ref-classes-image>` classes use the :term:`IMAGE_PKGTYPE`
3324      for packaging up images and SDKs.
3325
3326      You should not set the :term:`IMAGE_PKGTYPE` manually. Rather, the
3327      variable is set indirectly through the appropriate
3328      :ref:`package_* <ref-classes-package>` class using the
3329      :term:`PACKAGE_CLASSES` variable. The
3330      OpenEmbedded build system uses the first package type (e.g. DEB, RPM,
3331      or IPK) that appears with the variable
3332
3333      .. note::
3334
3335         Files using the ``.tar`` format are never used as a substitute
3336         packaging format for DEB, RPM, and IPK formatted files for your image
3337         or SDK.
3338
3339   :term:`IMAGE_POSTPROCESS_COMMAND`
3340      Specifies a list of functions to call once the OpenEmbedded build
3341      system creates the final image output files. You can specify
3342      functions separated by semicolons::
3343
3344         IMAGE_POSTPROCESS_COMMAND += "function; ... "
3345
3346      If you need to pass the root filesystem path to a command within the
3347      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3348      directory that becomes the root filesystem image. See the
3349      :term:`IMAGE_ROOTFS` variable for more
3350      information.
3351
3352   :term:`IMAGE_PREPROCESS_COMMAND`
3353      Specifies a list of functions to call before the OpenEmbedded build
3354      system creates the final image output files. You can specify
3355      functions separated by semicolons::
3356
3357         IMAGE_PREPROCESS_COMMAND += "function; ... "
3358
3359      If you need to pass the root filesystem path to a command within the
3360      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3361      directory that becomes the root filesystem image. See the
3362      :term:`IMAGE_ROOTFS` variable for more
3363      information.
3364
3365   :term:`IMAGE_ROOTFS`
3366      The location of the root filesystem while it is under construction
3367      (i.e. during the :ref:`ref-tasks-rootfs` task). This
3368      variable is not configurable. Do not change it.
3369
3370   :term:`IMAGE_ROOTFS_ALIGNMENT`
3371      Specifies the alignment for the output image file in Kbytes. If the
3372      size of the image is not a multiple of this value, then the size is
3373      rounded up to the nearest multiple of the value. The default value is
3374      "1". See :term:`IMAGE_ROOTFS_SIZE` for
3375      additional information.
3376
3377   :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3378      Defines additional free disk space created in the image in Kbytes. By
3379      default, this variable is set to "0". This free disk space is added
3380      to the image after the build system determines the image size as
3381      described in :term:`IMAGE_ROOTFS_SIZE`.
3382
3383      This variable is particularly useful when you want to ensure that a
3384      specific amount of free disk space is available on a device after an
3385      image is installed and running. For example, to be sure 5 Gbytes of
3386      free disk space is available, set the variable as follows::
3387
3388         IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
3389
3390      For example, the Yocto Project Build Appliance specifically requests
3391      40 Gbytes of extra space with the line::
3392
3393         IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
3394
3395   :term:`IMAGE_ROOTFS_SIZE`
3396      Defines the size in Kbytes for the generated image. The OpenEmbedded
3397      build system determines the final size for the generated image using
3398      an algorithm that takes into account the initial disk space used for
3399      the generated image, a requested size for the image, and requested
3400      additional free disk space to be added to the image. Programatically,
3401      the build system determines the final size of the generated image as
3402      follows::
3403
3404         if (image-du * overhead) < rootfs-size:
3405             internal-rootfs-size = rootfs-size + xspace
3406         else:
3407             internal-rootfs-size = (image-du * overhead) + xspace
3408         where:
3409             image-du = Returned value of the du command on the image.
3410             overhead = IMAGE_OVERHEAD_FACTOR
3411             rootfs-size = IMAGE_ROOTFS_SIZE
3412             internal-rootfs-size = Initial root filesystem size before any modifications.
3413             xspace = IMAGE_ROOTFS_EXTRA_SPACE
3414
3415      See the :term:`IMAGE_OVERHEAD_FACTOR`
3416      and :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3417      variables for related information.
3418
3419   :term:`IMAGE_TYPEDEP`
3420      Specifies a dependency from one image type on another. Here is an
3421      example from the :ref:`image-live <ref-classes-image-live>` class::
3422
3423         IMAGE_TYPEDEP:live = "ext3"
3424
3425      In the previous example, the variable ensures that when "live" is
3426      listed with the :term:`IMAGE_FSTYPES` variable,
3427      the OpenEmbedded build system produces an ``ext3`` image first since
3428      one of the components of the live image is an ``ext3`` formatted
3429      partition containing the root filesystem.
3430
3431   :term:`IMAGE_TYPES`
3432      Specifies the complete list of supported image types by default:
3433
3434      - btrfs
3435      - container
3436      - cpio
3437      - cpio.gz
3438      - cpio.lz4
3439      - cpio.lzma
3440      - cpio.xz
3441      - cramfs
3442      - erofs
3443      - erofs-lz4
3444      - erofs-lz4hc
3445      - ext2
3446      - ext2.bz2
3447      - ext2.gz
3448      - ext2.lzma
3449      - ext3
3450      - ext3.gz
3451      - ext4
3452      - ext4.gz
3453      - f2fs
3454      - hddimg
3455      - iso
3456      - jffs2
3457      - jffs2.sum
3458      - multiubi
3459      - squashfs
3460      - squashfs-lz4
3461      - squashfs-lzo
3462      - squashfs-xz
3463      - tar
3464      - tar.bz2
3465      - tar.gz
3466      - tar.lz4
3467      - tar.xz
3468      - tar.zst
3469      - ubi
3470      - ubifs
3471      - wic
3472      - wic.bz2
3473      - wic.gz
3474      - wic.lzma
3475
3476      For more information about these types of images, see
3477      ``meta/classes/image_types*.bbclass`` in the :term:`Source Directory`.
3478
3479   :term:`IMAGE_VERSION_SUFFIX`
3480      Version suffix that is part of the default :term:`IMAGE_NAME` and
3481      :term:`KERNEL_ARTIFACT_NAME` values.
3482      Defaults to ``"-${DATETIME}"``, however you could set this to a
3483      version string that comes from your external build environment if
3484      desired, and this suffix would then be used consistently across
3485      the build artifacts.
3486
3487   :term:`IMGDEPLOYDIR`
3488      When inheriting the :ref:`image <ref-classes-image>` class directly or
3489      through the :ref:`core-image <ref-classes-core-image>` class, the
3490      :term:`IMGDEPLOYDIR` points to a temporary work area for deployed files
3491      that is set in the ``image`` class as follows::
3492
3493         IMGDEPLOYDIR = "${WORKDIR}/deploy-${PN}-image-complete"
3494
3495      Recipes inheriting the ``image`` class should copy files to be
3496      deployed into :term:`IMGDEPLOYDIR`, and the class will take care of
3497      copying them into :term:`DEPLOY_DIR_IMAGE` afterwards.
3498
3499   :term:`INC_PR`
3500      Helps define the recipe revision for recipes that share a common
3501      ``include`` file. You can think of this variable as part of the
3502      recipe revision as set from within an include file.
3503
3504      Suppose, for example, you have a set of recipes that are used across
3505      several projects. And, within each of those recipes the revision (its
3506      :term:`PR` value) is set accordingly. In this case, when
3507      the revision of those recipes changes, the burden is on you to find
3508      all those recipes and be sure that they get changed to reflect the
3509      updated version of the recipe. In this scenario, it can get
3510      complicated when recipes that are used in many places and provide
3511      common functionality are upgraded to a new revision.
3512
3513      A more efficient way of dealing with this situation is to set the
3514      :term:`INC_PR` variable inside the ``include`` files that the recipes
3515      share and then expand the :term:`INC_PR` variable within the recipes to
3516      help define the recipe revision.
3517
3518      The following provides an example that shows how to use the
3519      :term:`INC_PR` variable given a common ``include`` file that defines the
3520      variable. Once the variable is defined in the ``include`` file, you
3521      can use the variable to set the :term:`PR` values in each recipe. You
3522      will notice that when you set a recipe's :term:`PR` you can provide more
3523      granular revisioning by appending values to the :term:`INC_PR` variable::
3524
3525         recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2"
3526         recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1"
3527         recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0"
3528         recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
3529
3530      The
3531      first line of the example establishes the baseline revision to be
3532      used for all recipes that use the ``include`` file. The remaining
3533      lines in the example are from individual recipes and show how the
3534      :term:`PR` value is set.
3535
3536   :term:`INCOMPATIBLE_LICENSE`
3537      Specifies a space-separated list of license names (as they would
3538      appear in :term:`LICENSE`) that should be excluded
3539      from the build. Recipes that provide no alternatives to listed
3540      incompatible licenses are not built. Packages that are individually
3541      licensed with the specified incompatible licenses will be deleted.
3542
3543      There is some support for wildcards in this variable's value,
3544      however it is restricted to specific licenses. Currently only
3545      these wildcards are allowed and expand as follows:
3546
3547      - ``AGPL-3.0*"``: ``AGPL-3.0-only``, ``AGPL-3.0-or-later``
3548      - ``GPL-3.0*``: ``GPL-3.0-only``, ``GPL-3.0-or-later``
3549      - ``LGPL-3.0*``: ``LGPL-3.0-only``, ``LGPL-3.0-or-later``
3550
3551      .. note::
3552
3553         This functionality is only regularly tested using the following
3554         setting::
3555
3556                 INCOMPATIBLE_LICENSE = "GPL-3.0* LGPL-3.0* AGPL-3.0*"
3557
3558
3559         Although you can use other settings, you might be required to
3560         remove dependencies on or provide alternatives to components that
3561         are required to produce a functional system image.
3562
3563   :term:`INCOMPATIBLE_LICENSE_EXCEPTIONS`
3564      Specifies a space-separated list of package and license pairs that
3565      are allowed to be used even if the license is specified in
3566      :term:`INCOMPATIBLE_LICENSE`. The package and license pairs are
3567      separated using a colon. Example::
3568
3569         INCOMPATIBLE_LICENSE_EXCEPTIONS = "gdbserver:GPL-3.0-only gdbserver:LGPL-3.0-only"
3570
3571   :term:`INHERIT`
3572      Causes the named class or classes to be inherited globally. Anonymous
3573      functions in the class or classes are not executed for the base
3574      configuration and in each individual recipe. The OpenEmbedded build
3575      system ignores changes to :term:`INHERIT` in individual recipes.
3576
3577      For more information on :term:`INHERIT`, see the
3578      :ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:\`\`inherit\`\` configuration directive`"
3579      section in the BitBake User Manual.
3580
3581   :term:`INHERIT_DISTRO`
3582      Lists classes that will be inherited at the distribution level. It is
3583      unlikely that you want to edit this variable.
3584
3585      The default value of the variable is set as follows in the
3586      ``meta/conf/distro/defaultsetup.conf`` file::
3587
3588         INHERIT_DISTRO ?= "debian devshell sstate license"
3589
3590   :term:`INHIBIT_DEFAULT_DEPS`
3591      Prevents the default dependencies, namely the C compiler and standard
3592      C library (libc), from being added to :term:`DEPENDS`.
3593      This variable is usually used within recipes that do not require any
3594      compilation using the C compiler.
3595
3596      Set the variable to "1" to prevent the default dependencies from
3597      being added.
3598
3599   :term:`INHIBIT_PACKAGE_DEBUG_SPLIT`
3600      Prevents the OpenEmbedded build system from splitting out debug
3601      information during packaging. By default, the build system splits out
3602      debugging information during the
3603      :ref:`ref-tasks-package` task. For more information on
3604      how debug information is split out, see the
3605      :term:`PACKAGE_DEBUG_SPLIT_STYLE`
3606      variable.
3607
3608      To prevent the build system from splitting out debug information
3609      during packaging, set the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable as
3610      follows::
3611
3612         INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
3613
3614   :term:`INHIBIT_PACKAGE_STRIP`
3615      If set to "1", causes the build to not strip binaries in resulting
3616      packages and prevents the ``-dbg`` package from containing the source
3617      files.
3618
3619      By default, the OpenEmbedded build system strips binaries and puts
3620      the debugging symbols into ``${``\ :term:`PN`\ ``}-dbg``.
3621      Consequently, you should not set :term:`INHIBIT_PACKAGE_STRIP` when you
3622      plan to debug in general.
3623
3624   :term:`INHIBIT_SYSROOT_STRIP`
3625      If set to "1", causes the build to not strip binaries in the
3626      resulting sysroot.
3627
3628      By default, the OpenEmbedded build system strips binaries in the
3629      resulting sysroot. When you specifically set the
3630      :term:`INHIBIT_SYSROOT_STRIP` variable to "1" in your recipe, you inhibit
3631      this stripping.
3632
3633      If you want to use this variable, include the
3634      :ref:`staging <ref-classes-staging>` class. This class uses a
3635      ``sys_strip()`` function to test for the variable and acts
3636      accordingly.
3637
3638      .. note::
3639
3640         Use of the :term:`INHIBIT_SYSROOT_STRIP` variable occurs in rare and
3641         special circumstances. For example, suppose you are building
3642         bare-metal firmware by using an external GCC toolchain. Furthermore,
3643         even if the toolchain's binaries are strippable, there are other files
3644         needed for the build that are not strippable.
3645
3646   :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
3647      Indicates the deploy directory used by ``do_bundle_initramfs`` where the
3648      :term:`INITRAMFS_IMAGE` will be fetched from.
3649      This variable is set by default to ``${DEPLOY_DIR_IMAGE}`` in the
3650      :ref:`kernel <ref-classes-kernel>` class and it's only meant to be changed
3651      when building an initramfs image from a separate multiconfig via :term:`INITRAMFS_MULTICONFIG`.
3652
3653   :term:`INITRAMFS_FSTYPES`
3654      Defines the format for the output image of an initial RAM filesystem
3655      (initramfs), which is used during boot. Supported formats are the
3656      same as those supported by the
3657      :term:`IMAGE_FSTYPES` variable.
3658
3659      The default value of this variable, which is set in the
3660      ``meta/conf/bitbake.conf`` configuration file in the
3661      :term:`Source Directory`, is "cpio.gz". The Linux kernel's
3662      initramfs mechanism, as opposed to the initial RAM filesystem
3663      `initrd <https://en.wikipedia.org/wiki/Initrd>`__ mechanism, expects
3664      an optionally compressed cpio archive.
3665
3666   :term:`INITRAMFS_IMAGE`
3667      Specifies the :term:`PROVIDES` name of an image
3668      recipe that is used to build an initial RAM filesystem (initramfs)
3669      image. In other words, the :term:`INITRAMFS_IMAGE` variable causes an
3670      additional recipe to be built as a dependency to whatever root
3671      filesystem recipe you might be using (e.g. ``core-image-sato``). The
3672      initramfs image recipe you provide should set
3673      :term:`IMAGE_FSTYPES` to
3674      :term:`INITRAMFS_FSTYPES`.
3675
3676      An initramfs image provides a temporary root filesystem used for
3677      early system initialization (e.g. loading of modules needed to locate
3678      and mount the "real" root filesystem).
3679
3680      .. note::
3681
3682         See the ``meta/recipes-core/images/core-image-minimal-initramfs.bb``
3683         recipe in the :term:`Source Directory`
3684         for an example initramfs recipe. To select this sample recipe as
3685         the one built to provide the initramfs image, set :term:`INITRAMFS_IMAGE`
3686         to "core-image-minimal-initramfs".
3687
3688      You can also find more information by referencing the
3689      ``meta-poky/conf/local.conf.sample.extended`` configuration file in
3690      the Source Directory, the :ref:`image <ref-classes-image>` class,
3691      and the :ref:`kernel <ref-classes-kernel>` class to see how to use
3692      the :term:`INITRAMFS_IMAGE` variable.
3693
3694      If :term:`INITRAMFS_IMAGE` is empty, which is the default, then no
3695      initramfs image is built.
3696
3697      For more information, you can also see the
3698      :term:`INITRAMFS_IMAGE_BUNDLE`
3699      variable, which allows the generated image to be bundled inside the
3700      kernel image. Additionally, for information on creating an initramfs
3701      image, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
3702      in the Yocto Project Development Tasks Manual.
3703
3704   :term:`INITRAMFS_IMAGE_BUNDLE`
3705      Controls whether or not the image recipe specified by
3706      :term:`INITRAMFS_IMAGE` is run through an
3707      extra pass
3708      (:ref:`ref-tasks-bundle_initramfs`) during
3709      kernel compilation in order to build a single binary that contains
3710      both the kernel image and the initial RAM filesystem (initramfs)
3711      image. This makes use of the
3712      :term:`CONFIG_INITRAMFS_SOURCE` kernel
3713      feature.
3714
3715      .. note::
3716
3717         Bundling the initramfs with the kernel conflates the code in the
3718         initramfs with the GPLv2 licensed Linux kernel binary. Thus only GPLv2
3719         compatible software may be part of a bundled initramfs.
3720
3721      .. note::
3722
3723         Using an extra compilation pass to bundle the initramfs avoids a
3724         circular dependency between the kernel recipe and the initramfs
3725         recipe should the initramfs include kernel modules. Should that be
3726         the case, the initramfs recipe depends on the kernel for the
3727         kernel modules, and the kernel depends on the initramfs recipe
3728         since the initramfs is bundled inside the kernel image.
3729
3730      The combined binary is deposited into the ``tmp/deploy`` directory,
3731      which is part of the :term:`Build Directory`.
3732
3733      Setting the variable to "1" in a configuration file causes the
3734      OpenEmbedded build system to generate a kernel image with the
3735      initramfs specified in :term:`INITRAMFS_IMAGE` bundled within::
3736
3737         INITRAMFS_IMAGE_BUNDLE = "1"
3738
3739      By default, the
3740      :ref:`kernel <ref-classes-kernel>` class sets this variable to a
3741      null string as follows::
3742
3743         INITRAMFS_IMAGE_BUNDLE ?= ""
3744
3745      .. note::
3746
3747         You must set the :term:`INITRAMFS_IMAGE_BUNDLE` variable in a
3748         configuration file. You cannot set the variable in a recipe file.
3749
3750      See the
3751      :yocto_git:`local.conf.sample.extended </poky/tree/meta-poky/conf/local.conf.sample.extended>`
3752      file for additional information. Also, for information on creating an
3753      initramfs, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
3754      in the Yocto Project Development Tasks Manual.
3755
3756   :term:`INITRAMFS_LINK_NAME`
3757      The link name of the initial RAM filesystem image. This variable is
3758      set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3759      follows::
3760
3761         INITRAMFS_LINK_NAME ?= "initramfs-${KERNEL_ARTIFACT_LINK_NAME}"
3762
3763      The value of the
3764      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
3765      file, has the following value::
3766
3767         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
3768
3769      See the :term:`MACHINE` variable for additional
3770      information.
3771
3772   :term:`INITRAMFS_MULTICONFIG`
3773      Defines the multiconfig to create a multiconfig dependency to be used by the :ref:`kernel <ref-classes-kernel>` class.
3774
3775      This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
3776      a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
3777
3778      For more information on how to bundle an initramfs image from a separate
3779      multiconfig see the ":ref:`dev-manual/common-tasks:Bundling an Initramfs Image From a Separate Multiconfig`"
3780      section in the Yocto Project Development Tasks Manual.
3781
3782   :term:`INITRAMFS_NAME`
3783      The base name of the initial RAM filesystem image. This variable is
3784      set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3785      follows::
3786
3787         INITRAMFS_NAME ?= "initramfs-${KERNEL_ARTIFACT_NAME}"
3788
3789      The value of the :term:`KERNEL_ARTIFACT_NAME`
3790      variable, which is set in the same file, has the following value::
3791
3792         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3793
3794   :term:`INITRD`
3795      Indicates list of filesystem images to concatenate and use as an
3796      initial RAM disk (``initrd``).
3797
3798      The :term:`INITRD` variable is an optional variable used with the
3799      :ref:`image-live <ref-classes-image-live>` class.
3800
3801   :term:`INITRD_IMAGE`
3802      When building a "live" bootable image (i.e. when
3803      :term:`IMAGE_FSTYPES` contains "live"),
3804      :term:`INITRD_IMAGE` specifies the image recipe that should be built to
3805      provide the initial RAM disk image. The default value is
3806      "core-image-minimal-initramfs".
3807
3808      See the :ref:`image-live <ref-classes-image-live>` class for more
3809      information.
3810
3811   :term:`INITSCRIPT_NAME`
3812      The filename of the initialization script as installed to
3813      ``${sysconfdir}/init.d``.
3814
3815      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
3816      The variable is mandatory.
3817
3818   :term:`INITSCRIPT_PACKAGES`
3819      A list of the packages that contain initscripts. If multiple packages
3820      are specified, you need to append the package name to the other
3821      ``INITSCRIPT_*`` as an override.
3822
3823      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
3824      The variable is optional and defaults to the :term:`PN`
3825      variable.
3826
3827   :term:`INITSCRIPT_PARAMS`
3828      Specifies the options to pass to ``update-rc.d``. Here is an example::
3829
3830         INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
3831
3832      In this example, the script has a runlevel of 99, starts the script
3833      in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
3834
3835      The variable's default value is "defaults", which is set in the
3836      :ref:`update-rc.d <ref-classes-update-rc.d>` class.
3837
3838      The value in :term:`INITSCRIPT_PARAMS` is passed through to the
3839      ``update-rc.d`` command. For more information on valid parameters,
3840      please see the ``update-rc.d`` manual page at
3841      https://manpages.debian.org/buster/init-system-helpers/update-rc.d.8.en.html
3842
3843   :term:`INSANE_SKIP`
3844      Specifies the QA checks to skip for a specific package within a
3845      recipe. For example, to skip the check for symbolic link ``.so``
3846      files in the main package of a recipe, add the following to the
3847      recipe. The package name override must be used, which in this example
3848      is ``${PN}``::
3849
3850         INSANE_SKIP:${PN} += "dev-so"
3851
3852      See the ":ref:`ref-classes-insane`" section for a
3853      list of the valid QA checks you can specify using this variable.
3854
3855   :term:`INSTALL_TIMEZONE_FILE`
3856      By default, the ``tzdata`` recipe packages an ``/etc/timezone`` file.
3857      Set the :term:`INSTALL_TIMEZONE_FILE` variable to "0" at the
3858      configuration level to disable this behavior.
3859
3860   :term:`IPK_FEED_URIS`
3861      When the IPK backend is in use and package management is enabled on
3862      the target, you can use this variable to set up ``opkg`` in the
3863      target image to point to package feeds on a nominated server. Once
3864      the feed is established, you can perform installations or upgrades
3865      using the package manager at runtime.
3866
3867   :term:`KARCH`
3868      Defines the kernel architecture used when assembling the
3869      configuration. Architectures supported for this release are:
3870
3871      - powerpc
3872      - i386
3873      - x86_64
3874      - arm
3875      - qemu
3876      - mips
3877
3878      You define the :term:`KARCH` variable in the :ref:`kernel-dev/advanced:bsp descriptions`.
3879
3880   :term:`KBRANCH`
3881      A regular expression used by the build process to explicitly identify
3882      the kernel branch that is validated, patched, and configured during a
3883      build. You must set this variable to ensure the exact kernel branch
3884      you want is being used by the build process.
3885
3886      Values for this variable are set in the kernel's recipe file and the
3887      kernel's append file. For example, if you are using the
3888      ``linux-yocto_4.12`` kernel, the kernel recipe file is the
3889      ``meta/recipes-kernel/linux/linux-yocto_4.12.bb`` file. :term:`KBRANCH`
3890      is set as follows in that kernel recipe file::
3891
3892         KBRANCH ?= "standard/base"
3893
3894      This variable is also used from the kernel's append file to identify
3895      the kernel branch specific to a particular machine or target
3896      hardware. Continuing with the previous kernel example, the kernel's
3897      append file (i.e. ``linux-yocto_4.12.bbappend``) is located in the
3898      BSP layer for a given machine. For example, the append file for the
3899      Beaglebone, EdgeRouter, and generic versions of both 32 and 64-bit IA
3900      machines (``meta-yocto-bsp``) is named
3901      ``meta-yocto-bsp/recipes-kernel/linux/linux-yocto_4.12.bbappend``.
3902      Here are the related statements from that append file::
3903
3904         KBRANCH:genericx86 = "standard/base"
3905         KBRANCH:genericx86-64 = "standard/base"
3906         KBRANCH:edgerouter = "standard/edgerouter"
3907         KBRANCH:beaglebone = "standard/beaglebone"
3908
3909      The :term:`KBRANCH` statements
3910      identify the kernel branch to use when building for each supported
3911      BSP.
3912
3913   :term:`KBUILD_DEFCONFIG`
3914      When used with the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
3915      class, specifies an "in-tree" kernel configuration file for use
3916      during a kernel build.
3917
3918      Typically, when using a ``defconfig`` to configure a kernel during a
3919      build, you place the file in your layer in the same manner as you
3920      would place patch files and configuration fragment files (i.e.
3921      "out-of-tree"). However, if you want to use a ``defconfig`` file that
3922      is part of the kernel tree (i.e. "in-tree"), you can use the
3923      :term:`KBUILD_DEFCONFIG` variable and append the
3924      :term:`KMACHINE` variable to point to the
3925      ``defconfig`` file.
3926
3927      To use the variable, set it in the append file for your kernel recipe
3928      using the following form::
3929
3930         KBUILD_DEFCONFIG_KMACHINE ?= defconfig_file
3931
3932      Here is an example from a "raspberrypi2" :term:`KMACHINE` build that uses
3933      a ``defconfig`` file named "bcm2709_defconfig"::
3934
3935         KBUILD_DEFCONFIG:raspberrypi2 = "bcm2709_defconfig"
3936
3937      As an alternative, you can use the following within your append file::
3938
3939         KBUILD_DEFCONFIG:pn-linux-yocto ?= "defconfig_file"
3940
3941      For more
3942      information on how to use the :term:`KBUILD_DEFCONFIG` variable, see the
3943      ":ref:`kernel-dev/common:using an "in-tree" \`\`defconfig\`\` file`"
3944      section in the Yocto Project Linux Kernel Development Manual.
3945
3946   :term:`KCONFIG_MODE`
3947      When used with the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
3948      class, specifies the kernel configuration values to use for options
3949      not specified in the provided ``defconfig`` file. Valid options are::
3950
3951         KCONFIG_MODE = "alldefconfig"
3952         KCONFIG_MODE = "allnoconfig"
3953
3954      In ``alldefconfig`` mode the options not explicitly specified will be
3955      assigned their Kconfig default value. In ``allnoconfig`` mode the
3956      options not explicitly specified will be disabled in the kernel
3957      config.
3958
3959      In case :term:`KCONFIG_MODE` is not set the behaviour will depend on where
3960      the ``defconfig`` file is coming from. An "in-tree" ``defconfig`` file
3961      will be handled in ``alldefconfig`` mode, a ``defconfig`` file placed
3962      in ``${WORKDIR}`` through a meta-layer will be handled in
3963      ``allnoconfig`` mode.
3964
3965      An "in-tree" ``defconfig`` file can be selected via the
3966      :term:`KBUILD_DEFCONFIG` variable. :term:`KCONFIG_MODE` does not need to
3967      be explicitly set.
3968
3969      A ``defconfig`` file compatible with ``allnoconfig`` mode can be
3970      generated by copying the ``.config`` file from a working Linux kernel
3971      build, renaming it to ``defconfig`` and placing it into the Linux
3972      kernel ``${WORKDIR}`` through your meta-layer. :term:`KCONFIG_MODE` does
3973      not need to be explicitly set.
3974
3975      A ``defconfig`` file compatible with ``alldefconfig`` mode can be
3976      generated using the
3977      :ref:`ref-tasks-savedefconfig`
3978      task and placed into the Linux kernel ``${WORKDIR}`` through your
3979      meta-layer. Explicitely set :term:`KCONFIG_MODE`::
3980
3981         KCONFIG_MODE = "alldefconfig"
3982
3983
3984   :term:`KERNEL_ALT_IMAGETYPE`
3985      Specifies an alternate kernel image type for creation in addition to
3986      the kernel image type specified using the
3987      :term:`KERNEL_IMAGETYPE` variable.
3988
3989   :term:`KERNEL_ARTIFACT_NAME`
3990      Specifies the name of all of the build artifacts. You can change the
3991      name of the artifacts by changing the :term:`KERNEL_ARTIFACT_NAME`
3992      variable.
3993
3994      The value of :term:`KERNEL_ARTIFACT_NAME`, which is set in the
3995      ``meta/classes/kernel-artifact-names.bbclass`` file, has the
3996      following default value::
3997
3998         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3999
4000      See the :term:`PKGE`, :term:`PKGV`, :term:`PKGR`, :term:`MACHINE`
4001      and :term:`IMAGE_VERSION_SUFFIX` variables for additional information.
4002
4003   :term:`KERNEL_CLASSES`
4004      A list of classes defining kernel image types that the
4005      :ref:`kernel <ref-classes-kernel>` class should inherit. You
4006      typically append this variable to enable extended image types. An
4007      example is the "kernel-fitimage", which enables fitImage support and
4008      resides in ``meta/classes/kernel-fitimage.bbclass``. You can register
4009      custom kernel image types with the :ref:`kernel <ref-classes-kernel>` class using this
4010      variable.
4011
4012   :term:`KERNEL_DEBUG_TIMESTAMPS`
4013      If set to "1", enables timestamping functionality during building
4014      the kernel. The default is "0" to disable this for reproducibility
4015      reasons.
4016
4017   :term:`KERNEL_DEVICETREE`
4018      Specifies the name of the generated Linux kernel device tree (i.e.
4019      the ``.dtb``) file.
4020
4021      .. note::
4022
4023         There is legacy support for specifying the full path to the device
4024         tree. However, providing just the ``.dtb`` file is preferred.
4025
4026      In order to use this variable, the
4027      :ref:`kernel-devicetree <ref-classes-kernel-devicetree>` class must
4028      be inherited.
4029
4030   :term:`KERNEL_DTB_LINK_NAME`
4031      The link name of the kernel device tree binary (DTB). This variable
4032      is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
4033      follows::
4034
4035         KERNEL_DTB_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4036
4037      The
4038      value of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in
4039      the same file, has the following value::
4040
4041         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4042
4043      See the :term:`MACHINE` variable for additional
4044      information.
4045
4046   :term:`KERNEL_DTB_NAME`
4047      The base name of the kernel device tree binary (DTB). This variable
4048      is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
4049      follows::
4050
4051         KERNEL_DTB_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4052
4053      The value of the :term:`KERNEL_ARTIFACT_NAME`
4054      variable, which is set in the same file, has the following value::
4055
4056         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4057
4058   :term:`KERNEL_DTC_FLAGS`
4059      Specifies the ``dtc`` flags that are passed to the Linux kernel build
4060      system when generating the device trees (via ``DTC_FLAGS`` environment
4061      variable).
4062
4063      In order to use this variable, the
4064      :ref:`kernel-devicetree <ref-classes-kernel-devicetree>` class must
4065      be inherited.
4066
4067   :term:`KERNEL_EXTRA_ARGS`
4068      Specifies additional ``make`` command-line arguments the OpenEmbedded
4069      build system passes on when compiling the kernel.
4070
4071   :term:`KERNEL_FEATURES`
4072      Includes additional kernel metadata. In the OpenEmbedded build
4073      system, the default Board Support Packages (BSPs)
4074      :term:`Metadata` is provided through the
4075      :term:`KMACHINE` and :term:`KBRANCH`
4076      variables. You can use the :term:`KERNEL_FEATURES` variable from within
4077      the kernel recipe or kernel append file to further add metadata for
4078      all BSPs or specific BSPs.
4079
4080      The metadata you add through this variable includes config fragments
4081      and features descriptions, which usually includes patches as well as
4082      config fragments. You typically override the :term:`KERNEL_FEATURES`
4083      variable for a specific machine. In this way, you can provide
4084      validated, but optional, sets of kernel configurations and features.
4085
4086      For example, the following example from the ``linux-yocto-rt_4.12``
4087      kernel recipe adds "netfilter" and "taskstats" features to all BSPs
4088      as well as "virtio" configurations to all QEMU machines. The last two
4089      statements add specific configurations to targeted machine types::
4090
4091         KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc features/taskstats/taskstats.scc"
4092         KERNEL_FEATURES:append = " ${KERNEL_EXTRA_FEATURES}"
4093         KERNEL_FEATURES:append:qemuall = " cfg/virtio.scc"
4094         KERNEL_FEATURES:append:qemux86 = "  cfg/sound.scc cfg/paravirt_kvm.scc"
4095         KERNEL_FEATURES:append:qemux86-64 = " cfg/sound.scc"
4096
4097   :term:`KERNEL_FIT_LINK_NAME`
4098      The link name of the kernel flattened image tree (FIT) image. This
4099      variable is set in the ``meta/classes/kernel-artifact-names.bbclass``
4100      file as follows::
4101
4102         KERNEL_FIT_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4103
4104      The value of the
4105      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4106      file, has the following value::
4107
4108         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4109
4110      See the :term:`MACHINE` variable for additional
4111      information.
4112
4113   :term:`KERNEL_FIT_NAME`
4114      The base name of the kernel flattened image tree (FIT) image. This
4115      variable is set in the ``meta/classes/kernel-artifact-names.bbclass``
4116      file as follows::
4117
4118         KERNEL_FIT_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4119
4120      The value of the :term:`KERNEL_ARTIFACT_NAME`
4121      variable, which is set in the same file, has the following value::
4122
4123         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4124
4125   :term:`KERNEL_IMAGE_LINK_NAME`
4126      The link name for the kernel image. This variable is set in the
4127      ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4128
4129         KERNEL_IMAGE_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4130
4131      The value of
4132      the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4133      file, has the following value::
4134
4135         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4136
4137      See the :term:`MACHINE` variable for additional
4138      information.
4139
4140   :term:`KERNEL_IMAGE_MAXSIZE`
4141      Specifies the maximum size of the kernel image file in kilobytes. If
4142      :term:`KERNEL_IMAGE_MAXSIZE` is set, the size of the kernel image file is
4143      checked against the set value during the
4144      :ref:`ref-tasks-sizecheck` task. The task fails if
4145      the kernel image file is larger than the setting.
4146
4147      :term:`KERNEL_IMAGE_MAXSIZE` is useful for target devices that have a
4148      limited amount of space in which the kernel image must be stored.
4149
4150      By default, this variable is not set, which means the size of the
4151      kernel image is not checked.
4152
4153   :term:`KERNEL_IMAGE_NAME`
4154      The base name of the kernel image. This variable is set in the
4155      ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4156
4157         KERNEL_IMAGE_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4158
4159      The value of the
4160      :term:`KERNEL_ARTIFACT_NAME` variable,
4161      which is set in the same file, has the following value::
4162
4163         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4164
4165   :term:`KERNEL_IMAGETYPE`
4166      The type of kernel to build for a device, usually set by the machine
4167      configuration files and defaults to "zImage". This variable is used
4168      when building the kernel and is passed to ``make`` as the target to
4169      build.
4170
4171      If you want to build an alternate kernel image type in addition to that
4172      specified by :term:`KERNEL_IMAGETYPE`, use the :term:`KERNEL_ALT_IMAGETYPE`
4173      variable.
4174
4175   :term:`KERNEL_MODULE_AUTOLOAD`
4176      Lists kernel modules that need to be auto-loaded during boot.
4177
4178      .. note::
4179
4180         This variable replaces the deprecated :term:`module_autoload`
4181         variable.
4182
4183      You can use the :term:`KERNEL_MODULE_AUTOLOAD` variable anywhere that it
4184      can be recognized by the kernel recipe or by an out-of-tree kernel
4185      module recipe (e.g. a machine configuration file, a distribution
4186      configuration file, an append file for the recipe, or the recipe
4187      itself).
4188
4189      Specify it as follows::
4190
4191         KERNEL_MODULE_AUTOLOAD += "module_name1 module_name2 module_name3"
4192
4193      Including :term:`KERNEL_MODULE_AUTOLOAD` causes the OpenEmbedded build
4194      system to populate the ``/etc/modules-load.d/modname.conf`` file with
4195      the list of modules to be auto-loaded on boot. The modules appear
4196      one-per-line in the file. Here is an example of the most common use
4197      case::
4198
4199         KERNEL_MODULE_AUTOLOAD += "module_name"
4200
4201      For information on how to populate the ``modname.conf`` file with
4202      ``modprobe.d`` syntax lines, see the :term:`KERNEL_MODULE_PROBECONF` variable.
4203
4204   :term:`KERNEL_MODULE_PROBECONF`
4205      Provides a list of modules for which the OpenEmbedded build system
4206      expects to find ``module_conf_``\ modname values that specify
4207      configuration for each of the modules. For information on how to
4208      provide those module configurations, see the
4209      :term:`module_conf_* <module_conf>` variable.
4210
4211   :term:`KERNEL_PATH`
4212      The location of the kernel sources. This variable is set to the value
4213      of the :term:`STAGING_KERNEL_DIR` within
4214      the :ref:`module <ref-classes-module>` class. For information on
4215      how this variable is used, see the
4216      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4217      section in the Yocto Project Linux Kernel Development Manual.
4218
4219      To help maximize compatibility with out-of-tree drivers used to build
4220      modules, the OpenEmbedded build system also recognizes and uses the
4221      :term:`KERNEL_SRC` variable, which is identical to
4222      the :term:`KERNEL_PATH` variable. Both variables are common variables
4223      used by external Makefiles to point to the kernel source directory.
4224
4225   :term:`KERNEL_SRC`
4226      The location of the kernel sources. This variable is set to the value
4227      of the :term:`STAGING_KERNEL_DIR` within
4228      the :ref:`module <ref-classes-module>` class. For information on
4229      how this variable is used, see the
4230      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4231      section in the Yocto Project Linux Kernel Development Manual.
4232
4233      To help maximize compatibility with out-of-tree drivers used to build
4234      modules, the OpenEmbedded build system also recognizes and uses the
4235      :term:`KERNEL_PATH` variable, which is identical
4236      to the :term:`KERNEL_SRC` variable. Both variables are common variables
4237      used by external Makefiles to point to the kernel source directory.
4238
4239   :term:`KERNEL_VERSION`
4240      Specifies the version of the kernel as extracted from ``version.h``
4241      or ``utsrelease.h`` within the kernel sources. Effects of setting
4242      this variable do not take effect until the kernel has been
4243      configured. Consequently, attempting to refer to this variable in
4244      contexts prior to configuration will not work.
4245
4246   :term:`KERNELDEPMODDEPEND`
4247      Specifies whether the data referenced through
4248      :term:`PKGDATA_DIR` is needed or not.
4249      :term:`KERNELDEPMODDEPEND` does not control whether or not that data
4250      exists, but simply whether or not it is used. If you do not need to
4251      use the data, set the :term:`KERNELDEPMODDEPEND` variable in your
4252      ``initramfs`` recipe. Setting the variable there when the data is not
4253      needed avoids a potential dependency loop.
4254
4255   :term:`KFEATURE_DESCRIPTION`
4256      Provides a short description of a configuration fragment. You use
4257      this variable in the ``.scc`` file that describes a configuration
4258      fragment file. Here is the variable used in a file named ``smp.scc``
4259      to describe SMP being enabled::
4260
4261          define KFEATURE_DESCRIPTION "Enable SMP"
4262
4263   :term:`KMACHINE`
4264      The machine as known by the kernel. Sometimes the machine name used
4265      by the kernel does not match the machine name used by the
4266      OpenEmbedded build system. For example, the machine name that the
4267      OpenEmbedded build system understands as ``core2-32-intel-common``
4268      goes by a different name in the Linux Yocto kernel. The kernel
4269      understands that machine as ``intel-core2-32``. For cases like these,
4270      the :term:`KMACHINE` variable maps the kernel machine name to the
4271      OpenEmbedded build system machine name.
4272
4273      These mappings between different names occur in the Yocto Linux
4274      Kernel's ``meta`` branch. As an example take a look in the
4275      ``common/recipes-kernel/linux/linux-yocto_3.19.bbappend`` file::
4276
4277         LINUX_VERSION:core2-32-intel-common = "3.19.0"
4278         COMPATIBLE_MACHINE:core2-32-intel-common = "${MACHINE}"
4279         SRCREV_meta:core2-32-intel-common = "8897ef68b30e7426bc1d39895e71fb155d694974"
4280         SRCREV_machine:core2-32-intel-common = "43b9eced9ba8a57add36af07736344dcc383f711"
4281         KMACHINE:core2-32-intel-common = "intel-core2-32"
4282         KBRANCH:core2-32-intel-common = "standard/base"
4283         KERNEL_FEATURES:append:core2-32-intel-common = " ${KERNEL_FEATURES_INTEL_COMMON}"
4284
4285      The :term:`KMACHINE` statement says
4286      that the kernel understands the machine name as "intel-core2-32".
4287      However, the OpenEmbedded build system understands the machine as
4288      "core2-32-intel-common".
4289
4290   :term:`KTYPE`
4291      Defines the kernel type to be used in assembling the configuration.
4292      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4293      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4294      section in the
4295      Yocto Project Linux Kernel Development Manual for more information on
4296      kernel types.
4297
4298      You define the :term:`KTYPE` variable in the
4299      :ref:`kernel-dev/advanced:bsp descriptions`. The
4300      value you use must match the value used for the
4301      :term:`LINUX_KERNEL_TYPE` value used by the
4302      kernel recipe.
4303
4304   :term:`LABELS`
4305      Provides a list of targets for automatic configuration.
4306
4307      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
4308      information on how this variable is used.
4309
4310   :term:`LAYERDEPENDS`
4311      Lists the layers, separated by spaces, on which this recipe depends.
4312      Optionally, you can specify a specific layer version for a dependency
4313      by adding it to the end of the layer name. Here is an example::
4314
4315         LAYERDEPENDS_mylayer = "anotherlayer (=3)"
4316
4317      In this previous example,
4318      version 3 of "anotherlayer" is compared against
4319      :term:`LAYERVERSION`\ ``_anotherlayer``.
4320
4321      An error is produced if any dependency is missing or the version
4322      numbers (if specified) do not match exactly. This variable is used in
4323      the ``conf/layer.conf`` file and must be suffixed with the name of
4324      the specific layer (e.g. ``LAYERDEPENDS_mylayer``).
4325
4326   :term:`LAYERDIR`
4327      When used inside the ``layer.conf`` configuration file, this variable
4328      provides the path of the current layer. This variable is not
4329      available outside of ``layer.conf`` and references are expanded
4330      immediately when parsing of the file completes.
4331
4332   :term:`LAYERRECOMMENDS`
4333      Lists the layers, separated by spaces, recommended for use with this
4334      layer.
4335
4336      Optionally, you can specify a specific layer version for a
4337      recommendation by adding the version to the end of the layer name.
4338      Here is an example::
4339
4340         LAYERRECOMMENDS_mylayer = "anotherlayer (=3)"
4341
4342      In this previous example, version 3 of "anotherlayer" is compared
4343      against ``LAYERVERSION_anotherlayer``.
4344
4345      This variable is used in the ``conf/layer.conf`` file and must be
4346      suffixed with the name of the specific layer (e.g.
4347      ``LAYERRECOMMENDS_mylayer``).
4348
4349   :term:`LAYERSERIES_COMPAT`
4350      Lists the versions of the :term:`OpenEmbedded-Core (OE-Core)` for which
4351      a layer is compatible. Using the :term:`LAYERSERIES_COMPAT` variable
4352      allows the layer maintainer to indicate which combinations of the
4353      layer and OE-Core can be expected to work. The variable gives the
4354      system a way to detect when a layer has not been tested with new
4355      releases of OE-Core (e.g. the layer is not maintained).
4356
4357      To specify the OE-Core versions for which a layer is compatible, use
4358      this variable in your layer's ``conf/layer.conf`` configuration file.
4359      For the list, use the Yocto Project
4360      :yocto_wiki:`Release Name </Releases>` (e.g.
4361      &DISTRO_NAME_NO_CAP;). To specify multiple OE-Core versions for the
4362      layer, use a space-separated list::
4363
4364         LAYERSERIES_COMPAT_layer_root_name = "&DISTRO_NAME_NO_CAP; &DISTRO_NAME_NO_CAP_MINUS_ONE;"
4365
4366      .. note::
4367
4368         Setting :term:`LAYERSERIES_COMPAT` is required by the Yocto Project
4369         Compatible version 2 standard.
4370         The OpenEmbedded build system produces a warning if the variable
4371         is not set for any given layer.
4372
4373      See the ":ref:`dev-manual/common-tasks:creating your own layer`"
4374      section in the Yocto Project Development Tasks Manual.
4375
4376   :term:`LAYERVERSION`
4377      Optionally specifies the version of a layer as a single number. You
4378      can use this within :term:`LAYERDEPENDS` for
4379      another layer in order to depend on a specific version of the layer.
4380      This variable is used in the ``conf/layer.conf`` file and must be
4381      suffixed with the name of the specific layer (e.g.
4382      ``LAYERVERSION_mylayer``).
4383
4384   :term:`LD`
4385      The minimal command and arguments used to run the linker.
4386
4387   :term:`LDFLAGS`
4388      Specifies the flags to pass to the linker. This variable is exported
4389      to an environment variable and thus made visible to the software
4390      being built during the compilation step.
4391
4392      Default initialization for :term:`LDFLAGS` varies depending on what is
4393      being built:
4394
4395      -  :term:`TARGET_LDFLAGS` when building for the
4396         target
4397
4398      -  :term:`BUILD_LDFLAGS` when building for the
4399         build host (i.e. ``-native``)
4400
4401      -  :term:`BUILDSDK_LDFLAGS` when building for
4402         an SDK (i.e. ``nativesdk-``)
4403
4404   :term:`LEAD_SONAME`
4405      Specifies the lead (or primary) compiled library file (i.e. ``.so``)
4406      that the :ref:`debian <ref-classes-debian>` class applies its
4407      naming policy to given a recipe that packages multiple libraries.
4408
4409      This variable works in conjunction with the :ref:`debian <ref-classes-debian>` class.
4410
4411   :term:`LIC_FILES_CHKSUM`
4412      Checksums of the license text in the recipe source code.
4413
4414      This variable tracks changes in license text of the source code
4415      files. If the license text is changed, it will trigger a build
4416      failure, which gives the developer an opportunity to review any
4417      license change.
4418
4419      This variable must be defined for all recipes (unless
4420      :term:`LICENSE` is set to "CLOSED").
4421
4422      For more information, see the ":ref:`dev-manual/common-tasks:tracking license changes`"
4423      section in the Yocto Project Development Tasks Manual.
4424
4425   :term:`LICENSE`
4426      The list of source licenses for the recipe. Follow these rules:
4427
4428      -  Do not use spaces within individual license names.
4429
4430      -  Separate license names using \| (pipe) when there is a choice
4431         between licenses.
4432
4433      -  Separate license names using & (ampersand) when there are
4434         multiple licenses for different parts of the source.
4435
4436      -  You can use spaces between license names.
4437
4438      -  For standard licenses, use the names of the files in
4439         ``meta/files/common-licenses/`` or the
4440         :term:`SPDXLICENSEMAP` flag names defined in
4441         ``meta/conf/licenses.conf``.
4442
4443      Here are some examples::
4444
4445         LICENSE = "LGPL-2.1-only | GPL-3.0-only"
4446         LICENSE = "MPL-1.0 & LGPL-2.1-only"
4447         LICENSE = "GPL-2.0-or-later"
4448
4449      The first example is from the
4450      recipes for Qt, which the user may choose to distribute under either
4451      the LGPL version 2.1 or GPL version 3. The second example is from
4452      Cairo where two licenses cover different parts of the source code.
4453      The final example is from ``sysstat``, which presents a single
4454      license.
4455
4456      You can also specify licenses on a per-package basis to handle
4457      situations where components of the output have different licenses.
4458      For example, a piece of software whose code is licensed under GPLv2
4459      but has accompanying documentation licensed under the GNU Free
4460      Documentation License 1.2 could be specified as follows::
4461
4462         LICENSE = "GFDL-1.2 & GPL-2.0-only"
4463         LICENSE:${PN} = "GPL-2.0.only"
4464         LICENSE:${PN}-doc = "GFDL-1.2"
4465
4466   :term:`LICENSE_CREATE_PACKAGE`
4467      Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
4468      build system to create an extra package (i.e.
4469      ``${``\ :term:`PN`\ ``}-lic``) for each recipe and to add
4470      those packages to the
4471      :term:`RRECOMMENDS`\ ``:${PN}``.
4472
4473      The ``${PN}-lic`` package installs a directory in
4474      ``/usr/share/licenses`` named ``${PN}``, which is the recipe's base
4475      name, and installs files in that directory that contain license and
4476      copyright information (i.e. copies of the appropriate license files
4477      from ``meta/common-licenses`` that match the licenses specified in
4478      the :term:`LICENSE` variable of the recipe metadata
4479      and copies of files marked in
4480      :term:`LIC_FILES_CHKSUM` as containing
4481      license text).
4482
4483      For related information on providing license text, see the
4484      :term:`COPY_LIC_DIRS` variable, the
4485      :term:`COPY_LIC_MANIFEST` variable, and the
4486      ":ref:`dev-manual/common-tasks:providing license text`"
4487      section in the Yocto Project Development Tasks Manual.
4488
4489   :term:`LICENSE_FLAGS`
4490      Specifies additional flags for a recipe you must allow through
4491      :term:`LICENSE_FLAGS_ACCEPTED` in
4492      order for the recipe to be built. When providing multiple flags,
4493      separate them with spaces.
4494
4495      This value is independent of :term:`LICENSE` and is
4496      typically used to mark recipes that might require additional licenses
4497      in order to be used in a commercial product. For more information,
4498      see the
4499      ":ref:`dev-manual/common-tasks:enabling commercially licensed recipes`"
4500      section in the Yocto Project Development Tasks Manual.
4501
4502   :term:`LICENSE_FLAGS_ACCEPTED`
4503      Lists license flags that when specified in
4504      :term:`LICENSE_FLAGS` within a recipe should not
4505      prevent that recipe from being built.  For more information, see the
4506      ":ref:`dev-manual/common-tasks:enabling commercially licensed recipes`"
4507      section in the Yocto Project Development Tasks Manual.
4508
4509   :term:`LICENSE_PATH`
4510      Path to additional licenses used during the build. By default, the
4511      OpenEmbedded build system uses :term:`COMMON_LICENSE_DIR` to define the
4512      directory that holds common license text used during the build. The
4513      :term:`LICENSE_PATH` variable allows you to extend that location to other
4514      areas that have additional licenses::
4515
4516         LICENSE_PATH += "path-to-additional-common-licenses"
4517
4518   :term:`LINUX_KERNEL_TYPE`
4519      Defines the kernel type to be used in assembling the configuration.
4520      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4521      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4522      section in the
4523      Yocto Project Linux Kernel Development Manual for more information on
4524      kernel types.
4525
4526      If you do not specify a :term:`LINUX_KERNEL_TYPE`, it defaults to
4527      "standard". Together with :term:`KMACHINE`, the
4528      :term:`LINUX_KERNEL_TYPE` variable defines the search arguments used by
4529      the kernel tools to find the appropriate description within the
4530      kernel :term:`Metadata` with which to build out the sources
4531      and configuration.
4532
4533   :term:`LINUX_VERSION`
4534      The Linux version from ``kernel.org`` on which the Linux kernel image
4535      being built using the OpenEmbedded build system is based. You define
4536      this variable in the kernel recipe. For example, the
4537      ``linux-yocto-3.4.bb`` kernel recipe found in
4538      ``meta/recipes-kernel/linux`` defines the variables as follows::
4539
4540         LINUX_VERSION ?= "3.4.24"
4541
4542      The :term:`LINUX_VERSION` variable is used to define :term:`PV`
4543      for the recipe::
4544
4545         PV = "${LINUX_VERSION}+git${SRCPV}"
4546
4547   :term:`LINUX_VERSION_EXTENSION`
4548      A string extension compiled into the version string of the Linux
4549      kernel built with the OpenEmbedded build system. You define this
4550      variable in the kernel recipe. For example, the linux-yocto kernel
4551      recipes all define the variable as follows::
4552
4553         LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
4554
4555      Defining this variable essentially sets the Linux kernel
4556      configuration item ``CONFIG_LOCALVERSION``, which is visible through
4557      the ``uname`` command. Here is an example that shows the extension
4558      assuming it was set as previously shown::
4559
4560         $ uname -r
4561         3.7.0-rc8-custom
4562
4563   :term:`LOG_DIR`
4564      Specifies the directory to which the OpenEmbedded build system writes
4565      overall log files. The default directory is ``${TMPDIR}/log``.
4566
4567      For the directory containing logs specific to each task, see the
4568      :term:`T` variable.
4569
4570   :term:`MACHINE`
4571      Specifies the target device for which the image is built. You define
4572      :term:`MACHINE` in the ``local.conf`` file found in the
4573      :term:`Build Directory`. By default, :term:`MACHINE` is set to
4574      "qemux86", which is an x86-based architecture machine to be emulated
4575      using QEMU::
4576
4577         MACHINE ?= "qemux86"
4578
4579      The variable corresponds to a machine configuration file of the same
4580      name, through which machine-specific configurations are set. Thus,
4581      when :term:`MACHINE` is set to "qemux86", the corresponding
4582      ``qemux86.conf`` machine configuration file can be found in
4583      the :term:`Source Directory` in
4584      ``meta/conf/machine``.
4585
4586      The list of machines supported by the Yocto Project as shipped
4587      include the following::
4588
4589         MACHINE ?= "qemuarm"
4590         MACHINE ?= "qemuarm64"
4591         MACHINE ?= "qemumips"
4592         MACHINE ?= "qemumips64"
4593         MACHINE ?= "qemuppc"
4594         MACHINE ?= "qemux86"
4595         MACHINE ?= "qemux86-64"
4596         MACHINE ?= "genericx86"
4597         MACHINE ?= "genericx86-64"
4598         MACHINE ?= "beaglebone"
4599         MACHINE ?= "edgerouter"
4600
4601      The last five are Yocto Project reference hardware
4602      boards, which are provided in the ``meta-yocto-bsp`` layer.
4603
4604      .. note::
4605
4606         Adding additional Board Support Package (BSP) layers to your
4607         configuration adds new possible settings for :term:`MACHINE`.
4608
4609   :term:`MACHINE_ARCH`
4610      Specifies the name of the machine-specific architecture. This
4611      variable is set automatically from :term:`MACHINE` or
4612      :term:`TUNE_PKGARCH`. You should not hand-edit
4613      the :term:`MACHINE_ARCH` variable.
4614
4615   :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4616      A list of required machine-specific packages to install as part of
4617      the image being built. The build process depends on these packages
4618      being present. Furthermore, because this is a "machine-essential"
4619      variable, the list of packages are essential for the machine to boot.
4620      The impact of this variable affects images based on
4621      ``packagegroup-core-boot``, including the ``core-image-minimal``
4622      image.
4623
4624      This variable is similar to the
4625      :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` variable with the exception
4626      that the image being built has a build dependency on the variable's
4627      list of packages. In other words, the image will not build if a file
4628      in this list is not found.
4629
4630      As an example, suppose the machine for which you are building
4631      requires ``example-init`` to be run during boot to initialize the
4632      hardware. In this case, you would use the following in the machine's
4633      ``.conf`` configuration file::
4634
4635         MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
4636
4637   :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS`
4638      A list of recommended machine-specific packages to install as part of
4639      the image being built. The build process does not depend on these
4640      packages being present. However, because this is a
4641      "machine-essential" variable, the list of packages are essential for
4642      the machine to boot. The impact of this variable affects images based
4643      on ``packagegroup-core-boot``, including the ``core-image-minimal``
4644      image.
4645
4646      This variable is similar to the :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4647      variable with the exception that the image being built does not have
4648      a build dependency on the variable's list of packages. In other
4649      words, the image will still build if a package in this list is not
4650      found. Typically, this variable is used to handle essential kernel
4651      modules, whose functionality may be selected to be built into the
4652      kernel rather than as a module, in which case a package will not be
4653      produced.
4654
4655      Consider an example where you have a custom kernel where a specific
4656      touchscreen driver is required for the machine to be usable. However,
4657      the driver can be built as a module or into the kernel depending on
4658      the kernel configuration. If the driver is built as a module, you
4659      want it to be installed. But, when the driver is built into the
4660      kernel, you still want the build to succeed. This variable sets up a
4661      "recommends" relationship so that in the latter case, the build will
4662      not fail due to the missing package. To accomplish this, assuming the
4663      package for the module was called ``kernel-module-ab123``, you would
4664      use the following in the machine's ``.conf`` configuration file::
4665
4666         MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
4667
4668      .. note::
4669
4670         In this example, the ``kernel-module-ab123`` recipe needs to
4671         explicitly set its :term:`PACKAGES` variable to ensure that BitBake
4672         does not use the kernel recipe's :term:`PACKAGES_DYNAMIC` variable to
4673         satisfy the dependency.
4674
4675      Some examples of these machine essentials are flash, screen,
4676      keyboard, mouse, or touchscreen drivers (depending on the machine).
4677
4678   :term:`MACHINE_EXTRA_RDEPENDS`
4679      A list of machine-specific packages to install as part of the image
4680      being built that are not essential for the machine to boot. However,
4681      the build process for more fully-featured images depends on the
4682      packages being present.
4683
4684      This variable affects all images based on ``packagegroup-base``,
4685      which does not include the ``core-image-minimal`` or
4686      ``core-image-full-cmdline`` images.
4687
4688      The variable is similar to the :term:`MACHINE_EXTRA_RRECOMMENDS` variable
4689      with the exception that the image being built has a build dependency
4690      on the variable's list of packages. In other words, the image will
4691      not build if a file in this list is not found.
4692
4693      An example is a machine that has WiFi capability but is not essential
4694      for the machine to boot the image. However, if you are building a
4695      more fully-featured image, you want to enable the WiFi. The package
4696      containing the firmware for the WiFi hardware is always expected to
4697      exist, so it is acceptable for the build process to depend upon
4698      finding the package. In this case, assuming the package for the
4699      firmware was called ``wifidriver-firmware``, you would use the
4700      following in the ``.conf`` file for the machine::
4701
4702         MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
4703
4704   :term:`MACHINE_EXTRA_RRECOMMENDS`
4705      A list of machine-specific packages to install as part of the image
4706      being built that are not essential for booting the machine. The image
4707      being built has no build dependency on this list of packages.
4708
4709      This variable affects only images based on ``packagegroup-base``,
4710      which does not include the ``core-image-minimal`` or
4711      ``core-image-full-cmdline`` images.
4712
4713      This variable is similar to the :term:`MACHINE_EXTRA_RDEPENDS` variable
4714      with the exception that the image being built does not have a build
4715      dependency on the variable's list of packages. In other words, the
4716      image will build if a file in this list is not found.
4717
4718      An example is a machine that has WiFi capability but is not essential
4719      For the machine to boot the image. However, if you are building a
4720      more fully-featured image, you want to enable WiFi. In this case, the
4721      package containing the WiFi kernel module will not be produced if the
4722      WiFi driver is built into the kernel, in which case you still want
4723      the build to succeed instead of failing as a result of the package
4724      not being found. To accomplish this, assuming the package for the
4725      module was called ``kernel-module-examplewifi``, you would use the
4726      following in the ``.conf`` file for the machine::
4727
4728         MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
4729
4730   :term:`MACHINE_FEATURES`
4731      Specifies the list of hardware features the
4732      :term:`MACHINE` is capable of supporting. For related
4733      information on enabling features, see the
4734      :term:`DISTRO_FEATURES`,
4735      :term:`COMBINED_FEATURES`, and
4736      :term:`IMAGE_FEATURES` variables.
4737
4738      For a list of hardware features supported by the Yocto Project as
4739      shipped, see the ":ref:`ref-features-machine`" section.
4740
4741   :term:`MACHINE_FEATURES_BACKFILL`
4742      Features to be added to :term:`MACHINE_FEATURES` if not also present in
4743      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`.
4744
4745      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
4746      not intended to be user-configurable. It is best to just reference
4747      the variable to see which machine features are being backfilled for
4748      all machine configurations. See the ":ref:`ref-features-backfill`"
4749      section for more information.
4750
4751   :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`
4752      Features from :term:`MACHINE_FEATURES_BACKFILL` that should not be
4753      backfilled (i.e. added to :term:`MACHINE_FEATURES`) during the build. See
4754      the ":ref:`ref-features-backfill`" section for more information.
4755
4756   :term:`MACHINEOVERRIDES`
4757      A colon-separated list of overrides that apply to the current
4758      machine. By default, this list includes the value of
4759      :term:`MACHINE`.
4760
4761      You can extend :term:`MACHINEOVERRIDES` to add extra overrides that
4762      should apply to a machine. For example, all machines emulated in QEMU
4763      (e.g. ``qemuarm``, ``qemux86``, and so forth) include a file named
4764      ``meta/conf/machine/include/qemu.inc`` that prepends the following
4765      override to :term:`MACHINEOVERRIDES`::
4766
4767         MACHINEOVERRIDES =. "qemuall:"
4768
4769      This
4770      override allows variables to be overridden for all machines emulated
4771      in QEMU, like in the following example from the ``connman-conf``
4772      recipe::
4773
4774         SRC_URI:append:qemuall = " file://wired.config \
4775             file://wired-setup \
4776             "
4777
4778      The underlying mechanism behind
4779      :term:`MACHINEOVERRIDES` is simply that it is included in the default
4780      value of :term:`OVERRIDES`.
4781
4782   :term:`MAINTAINER`
4783      The email address of the distribution maintainer.
4784
4785   :term:`METADATA_BRANCH`
4786      The branch currently checked out for the OpenEmbedded-Core layer (path
4787      determined by :term:`COREBASE`).
4788
4789   :term:`METADATA_REVISION`
4790      The revision currently checked out for the OpenEmbedded-Core layer (path
4791      determined by :term:`COREBASE`).
4792
4793   :term:`MIRRORS`
4794      Specifies additional paths from which the OpenEmbedded build system
4795      gets source code. When the build system searches for source code, it
4796      first tries the local download directory. If that location fails, the
4797      build system tries locations defined by
4798      :term:`PREMIRRORS`, the upstream source, and then
4799      locations specified by :term:`MIRRORS` in that order.
4800
4801      Assuming your distribution (:term:`DISTRO`) is "poky",
4802      the default value for :term:`MIRRORS` is defined in the
4803      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
4804
4805   :term:`MLPREFIX`
4806      Specifies a prefix has been added to :term:`PN` to create a
4807      special version of a recipe or package (i.e. a Multilib version). The
4808      variable is used in places where the prefix needs to be added to or
4809      removed from a the name (e.g. the :term:`BPN` variable).
4810      :term:`MLPREFIX` gets set when a prefix has been added to :term:`PN`.
4811
4812      .. note::
4813
4814         The "ML" in :term:`MLPREFIX` stands for "MultiLib". This representation is
4815         historical and comes from a time when ``nativesdk`` was a suffix
4816         rather than a prefix on the recipe name. When ``nativesdk`` was turned
4817         into a prefix, it made sense to set :term:`MLPREFIX` for it as well.
4818
4819      To help understand when :term:`MLPREFIX` might be needed, consider when
4820      :term:`BBCLASSEXTEND` is used to provide a
4821      ``nativesdk`` version of a recipe in addition to the target version.
4822      If that recipe declares build-time dependencies on tasks in other
4823      recipes by using :term:`DEPENDS`, then a dependency on
4824      "foo" will automatically get rewritten to a dependency on
4825      "nativesdk-foo". However, dependencies like the following will not
4826      get rewritten automatically::
4827
4828         do_foo[depends] += "recipe:do_foo"
4829
4830      If you want such a dependency to also get transformed, you can do the
4831      following::
4832
4833         do_foo[depends] += "${MLPREFIX}recipe:do_foo"
4834
4835   :term:`module_autoload`
4836      This variable has been replaced by the :term:`KERNEL_MODULE_AUTOLOAD`
4837      variable. You should replace all occurrences of :term:`module_autoload`
4838      with additions to :term:`KERNEL_MODULE_AUTOLOAD`, for example::
4839
4840         module_autoload_rfcomm = "rfcomm"
4841
4842      should now be replaced with::
4843
4844         KERNEL_MODULE_AUTOLOAD += "rfcomm"
4845
4846      See the :term:`KERNEL_MODULE_AUTOLOAD` variable for more information.
4847
4848   :term:`module_conf`
4849      Specifies `modprobe.d <https://linux.die.net/man/5/modprobe.d>`_
4850      syntax lines for inclusion in the ``/etc/modprobe.d/modname.conf``
4851      file.
4852
4853      You can use this variable anywhere that it can be recognized by the
4854      kernel recipe or out-of-tree kernel module recipe (e.g. a machine
4855      configuration file, a distribution configuration file, an append file
4856      for the recipe, or the recipe itself). If you use this variable, you
4857      must also be sure to list the module name in the
4858      :term:`KERNEL_MODULE_PROBECONF`
4859      variable.
4860
4861      Here is the general syntax::
4862
4863         module_conf_module_name = "modprobe.d-syntax"
4864
4865      You must use the kernel module name override.
4866
4867      Run ``man modprobe.d`` in the shell to find out more information on
4868      the exact syntax you want to provide with :term:`module_conf`.
4869
4870      Including :term:`module_conf` causes the OpenEmbedded build system to
4871      populate the ``/etc/modprobe.d/modname.conf`` file with
4872      ``modprobe.d`` syntax lines. Here is an example that adds the options
4873      ``arg1`` and ``arg2`` to a module named ``mymodule``::
4874
4875         module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
4876
4877      For information on how to specify kernel modules to auto-load on
4878      boot, see the :term:`KERNEL_MODULE_AUTOLOAD` variable.
4879
4880   :term:`MODULE_TARBALL_DEPLOY`
4881      Controls creation of the ``modules-*.tgz`` file. Set this variable to
4882      "0" to disable creation of this file, which contains all of the
4883      kernel modules resulting from a kernel build.
4884
4885   :term:`MODULE_TARBALL_LINK_NAME`
4886      The link name of the kernel module tarball. This variable is set in
4887      the ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4888
4889         MODULE_TARBALL_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4890
4891      The value
4892      of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the
4893      same file, has the following value::
4894
4895         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4896
4897      See the :term:`MACHINE` variable for additional information.
4898
4899   :term:`MODULE_TARBALL_NAME`
4900      The base name of the kernel module tarball. This variable is set in
4901      the ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4902
4903         MODULE_TARBALL_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4904
4905      The value of the :term:`KERNEL_ARTIFACT_NAME` variable,
4906      which is set in the same file, has the following value::
4907
4908         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4909
4910   :term:`MULTIMACH_TARGET_SYS`
4911      Uniquely identifies the type of the target system for which packages
4912      are being built. This variable allows output for different types of
4913      target systems to be put into different subdirectories of the same
4914      output directory.
4915
4916      The default value of this variable is::
4917
4918         ${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}
4919
4920      Some classes (e.g.
4921      :ref:`cross-canadian <ref-classes-cross-canadian>`) modify the
4922      :term:`MULTIMACH_TARGET_SYS` value.
4923
4924      See the :term:`STAMP` variable for an example. See the
4925      :term:`STAGING_DIR_TARGET` variable for more information.
4926
4927   :term:`NATIVELSBSTRING`
4928      A string identifying the host distribution. Strings consist of the
4929      host distributor ID followed by the release, as reported by the
4930      ``lsb_release`` tool or as read from ``/etc/lsb-release``. For
4931      example, when running a build on Ubuntu 12.10, the value is
4932      "Ubuntu-12.10". If this information is unable to be determined, the
4933      value resolves to "Unknown".
4934
4935      This variable is used by default to isolate native shared state
4936      packages for different distributions (e.g. to avoid problems with
4937      ``glibc`` version incompatibilities). Additionally, the variable is
4938      checked against
4939      :term:`SANITY_TESTED_DISTROS` if that
4940      variable is set.
4941
4942   :term:`NM`
4943      The minimal command and arguments to run ``nm``.
4944
4945   :term:`NO_GENERIC_LICENSE`
4946      Avoids QA errors when you use a non-common, non-CLOSED license in a
4947      recipe. There are packages, such as the linux-firmware package, with many
4948      licenses that are not in any way common. Also, new licenses are added
4949      occasionally to avoid introducing a lot of common license files,
4950      which are only applicable to a specific package.
4951      :term:`NO_GENERIC_LICENSE` is used to allow copying a license that does
4952      not exist in common licenses.
4953
4954      The following example shows how to add :term:`NO_GENERIC_LICENSE` to a
4955      recipe::
4956
4957         NO_GENERIC_LICENSE[license_name] = "license_file_in_fetched_source"
4958
4959      Here is an example that
4960      uses the ``LICENSE.Abilis.txt`` file as the license from the fetched
4961      source::
4962
4963         NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt"
4964
4965   :term:`NO_RECOMMENDATIONS`
4966      Prevents installation of all "recommended-only" packages.
4967      Recommended-only packages are packages installed only through the
4968      :term:`RRECOMMENDS` variable). Setting the
4969      :term:`NO_RECOMMENDATIONS` variable to "1" turns this feature on::
4970
4971         NO_RECOMMENDATIONS = "1"
4972
4973      You can set this variable globally in your ``local.conf`` file or you
4974      can attach it to a specific image recipe by using the recipe name
4975      override::
4976
4977         NO_RECOMMENDATIONS:pn-target_image = "1"
4978
4979      It is important to realize that if you choose to not install packages
4980      using this variable and some other packages are dependent on them
4981      (i.e. listed in a recipe's :term:`RDEPENDS`
4982      variable), the OpenEmbedded build system ignores your request and
4983      will install the packages to avoid dependency errors.
4984
4985      .. note::
4986
4987         Some recommended packages might be required for certain system
4988         functionality, such as kernel modules. It is up to you to add
4989         packages with the :term:`IMAGE_INSTALL` variable.
4990
4991      This variable is only supported when using the IPK and RPM
4992      packaging backends. DEB is not supported.
4993
4994      See the :term:`BAD_RECOMMENDATIONS` and
4995      the :term:`PACKAGE_EXCLUDE` variables for
4996      related information.
4997
4998   :term:`NOAUTOPACKAGEDEBUG`
4999      Disables auto package from splitting ``.debug`` files. If a recipe
5000      requires ``FILES:${PN}-dbg`` to be set manually, the
5001      :term:`NOAUTOPACKAGEDEBUG` can be defined allowing you to define the
5002      content of the debug package. For example::
5003
5004         NOAUTOPACKAGEDEBUG = "1"
5005         FILES:${PN}-dev = "${includedir}/${QT_DIR_NAME}/Qt/*"
5006         FILES:${PN}-dbg = "/usr/src/debug/"
5007         FILES:${QT_BASE_NAME}-demos-doc = "${docdir}/${QT_DIR_NAME}/qch/qt.qch"
5008
5009   :term:`NON_MULTILIB_RECIPES`
5010      A list of recipes that should not be built for multilib. OE-Core's
5011      ``multilib.conf`` file defines a reasonable starting point for this
5012      list with::
5013
5014         NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot"
5015
5016   :term:`OBJCOPY`
5017      The minimal command and arguments to run ``objcopy``.
5018
5019   :term:`OBJDUMP`
5020      The minimal command and arguments to run ``objdump``.
5021
5022   :term:`OE_BINCONFIG_EXTRA_MANGLE`
5023      When inheriting the :ref:`binconfig <ref-classes-binconfig>` class,
5024      this variable specifies additional arguments passed to the "sed"
5025      command. The sed command alters any paths in configuration scripts
5026      that have been set up during compilation. Inheriting this class
5027      results in all paths in these scripts being changed to point into the
5028      ``sysroots/`` directory so that all builds that use the script will
5029      use the correct directories for the cross compiling layout.
5030
5031      See the ``meta/classes/binconfig.bbclass`` in the
5032      :term:`Source Directory` for details on how this class
5033      applies these additional sed command arguments.
5034
5035   :term:`OE_IMPORTS`
5036      An internal variable used to tell the OpenEmbedded build system what
5037      Python modules to import for every Python function run by the system.
5038
5039      .. note::
5040
5041         Do not set this variable. It is for internal use only.
5042
5043   :term:`OE_INIT_ENV_SCRIPT`
5044      The name of the build environment setup script for the purposes of
5045      setting up the environment within the extensible SDK. The default
5046      value is "oe-init-build-env".
5047
5048      If you use a custom script to set up your build environment, set the
5049      :term:`OE_INIT_ENV_SCRIPT` variable to its name.
5050
5051   :term:`OE_TERMINAL`
5052      Controls how the OpenEmbedded build system spawns interactive
5053      terminals on the host development system (e.g. using the BitBake
5054      command with the ``-c devshell`` command-line option). For more
5055      information, see the ":ref:`dev-manual/common-tasks:using a development shell`" section in
5056      the Yocto Project Development Tasks Manual.
5057
5058      You can use the following values for the :term:`OE_TERMINAL` variable:
5059
5060      - auto
5061      - gnome
5062      - xfce
5063      - rxvt
5064      - screen
5065      - konsole
5066      - none
5067
5068   :term:`OEROOT`
5069      The directory from which the top-level build environment setup script
5070      is sourced. The Yocto Project provides a top-level build environment
5071      setup script: :ref:`structure-core-script`. When you run this
5072      script, the :term:`OEROOT` variable resolves to the directory that
5073      contains the script.
5074
5075      For additional information on how this variable is used, see the
5076      initialization script.
5077
5078   :term:`OLDEST_KERNEL`
5079      Declares the oldest version of the Linux kernel that the produced
5080      binaries must support. This variable is passed into the build of the
5081      Embedded GNU C Library (``glibc``).
5082
5083      The default for this variable comes from the
5084      ``meta/conf/bitbake.conf`` configuration file. You can override this
5085      default by setting the variable in a custom distribution
5086      configuration file.
5087
5088   :term:`OVERRIDES`
5089      A colon-separated list of overrides that currently apply. Overrides
5090      are a BitBake mechanism that allows variables to be selectively
5091      overridden at the end of parsing. The set of overrides in
5092      :term:`OVERRIDES` represents the "state" during building, which includes
5093      the current recipe being built, the machine for which it is being
5094      built, and so forth.
5095
5096      As an example, if the string "an-override" appears as an element in
5097      the colon-separated list in :term:`OVERRIDES`, then the following
5098      assignment will override ``FOO`` with the value "overridden" at the
5099      end of parsing::
5100
5101         FOO:an-override = "overridden"
5102
5103      See the
5104      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
5105      section in the BitBake User Manual for more information on the
5106      overrides mechanism.
5107
5108      The default value of :term:`OVERRIDES` includes the values of the
5109      :term:`CLASSOVERRIDE`,
5110      :term:`MACHINEOVERRIDES`, and
5111      :term:`DISTROOVERRIDES` variables. Another
5112      important override included by default is ``pn-${PN}``. This override
5113      allows variables to be set for a single recipe within configuration
5114      (``.conf``) files. Here is an example::
5115
5116         FOO:pn-myrecipe = "myrecipe-specific value"
5117
5118      .. note::
5119
5120         An easy way to see what overrides apply is to search for :term:`OVERRIDES`
5121         in the output of the ``bitbake -e`` command. See the
5122         ":ref:`dev-manual/common-tasks:viewing variable values`" section in the Yocto
5123         Project Development Tasks Manual for more information.
5124
5125   :term:`P`
5126      The recipe name and version. :term:`P` is comprised of the following::
5127
5128         ${PN}-${PV}
5129
5130   :term:`PACKAGE_ADD_METADATA`
5131      This variable defines additional metadata to add to packages.
5132
5133      You may find you need to inject additional metadata into packages.
5134      This variable allows you to do that by setting the injected data as
5135      the value. Multiple fields can be added by splitting the content with
5136      the literal separator "\n".
5137
5138      The suffixes '_IPK', '_DEB', or '_RPM' can be applied to the variable
5139      to do package type specific settings. It can also be made package
5140      specific by using the package name as a suffix.
5141
5142      You can find out more about applying this variable in the
5143      ":ref:`dev-manual/common-tasks:adding custom metadata to packages`"
5144      section in the Yocto Project Development Tasks Manual.
5145
5146   :term:`PACKAGE_ARCH`
5147      The architecture of the resulting package or packages.
5148
5149      By default, the value of this variable is set to
5150      :term:`TUNE_PKGARCH` when building for the
5151      target, :term:`BUILD_ARCH` when building for the
5152      build host, and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building for the
5153      SDK.
5154
5155      .. note::
5156
5157         See :term:`SDK_ARCH` for more information.
5158
5159      However, if your recipe's output packages are built specific to the
5160      target machine rather than generally for the architecture of the
5161      machine, you should set :term:`PACKAGE_ARCH` to the value of
5162      :term:`MACHINE_ARCH` in the recipe as follows::
5163
5164         PACKAGE_ARCH = "${MACHINE_ARCH}"
5165
5166   :term:`PACKAGE_ARCHS`
5167      Specifies a list of architectures compatible with the target machine.
5168      This variable is set automatically and should not normally be
5169      hand-edited. Entries are separated using spaces and listed in order
5170      of priority. The default value for :term:`PACKAGE_ARCHS` is "all any
5171      noarch ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
5172
5173   :term:`PACKAGE_BEFORE_PN`
5174      Enables easily adding packages to :term:`PACKAGES` before ``${PN}`` so
5175      that those added packages can pick up files that would normally be
5176      included in the default package.
5177
5178   :term:`PACKAGE_CLASSES`
5179      This variable, which is set in the ``local.conf`` configuration file
5180      found in the ``conf`` folder of the
5181      :term:`Build Directory`, specifies the package manager the
5182      OpenEmbedded build system uses when packaging data.
5183
5184      You can provide one or more of the following arguments for the
5185      variable: PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk
5186      package_tar"
5187
5188      .. note::
5189
5190         While it is a legal option, the ``package_tar``
5191         class has limited functionality due to no support for package
5192         dependencies by that backend. Therefore, it is recommended that
5193         you do not use it.
5194
5195      The build system uses only the first argument in the list as the
5196      package manager when creating your image or SDK. However, packages
5197      will be created using any additional packaging classes you specify.
5198      For example, if you use the following in your ``local.conf`` file::
5199
5200         PACKAGE_CLASSES ?= "package_ipk"
5201
5202      The OpenEmbedded build system uses
5203      the IPK package manager to create your image or SDK.
5204
5205      For information on packaging and build performance effects as a
5206      result of the package manager in use, see the
5207      ":ref:`ref-classes-package`" section.
5208
5209   :term:`PACKAGE_DEBUG_SPLIT_STYLE`
5210      Determines how to split up and package debug and source information
5211      when creating debugging packages to be used with the GNU Project
5212      Debugger (GDB). In general, based on the value of this variable,
5213      you can combine the source and debug info in a single package,
5214      you can break out the source into a separate package that can be
5215      installed independently, or you can choose to not have the source
5216      packaged at all.
5217
5218      The possible values of :term:`PACKAGE_DEBUG_SPLIT_STYLE` variable:
5219
5220      -  "``.debug``": All debugging and source info is placed in a single
5221         ``*-dbg`` package; debug symbol files are placed next to the
5222         binary in a ``.debug`` directory so that, if a binary is installed
5223         into ``/bin``, the corresponding debug symbol file is installed
5224         in ``/bin/.debug``. Source files are installed in the same ``*-dbg``
5225         package under ``/usr/src/debug``.
5226
5227      -  "``debug-file-directory``": As above, all debugging and source info
5228         is placed in a single ``*-dbg`` package; debug symbol files are
5229         placed entirely under the directory ``/usr/lib/debug`` and separated
5230         by the path from where the binary is installed, so that if a binary
5231         is installed in ``/bin``, the corresponding debug symbols are installed
5232         in ``/usr/lib/debug/bin``, and so on. As above, source is installed
5233         in the same package under ``/usr/src/debug``.
5234
5235      -  "``debug-with-srcpkg``": Debugging info is placed in the standard
5236         ``*-dbg`` package as with the ``.debug`` value, while source is
5237         placed in a separate ``*-src`` package, which can be installed
5238         independently.  This is the default setting for this variable,
5239         as defined in Poky's ``bitbake.conf`` file.
5240
5241      -  "``debug-without-src``": The same behavior as with the ``.debug``
5242         setting, but no source is packaged at all.
5243
5244      .. note::
5245
5246         Much of the above package splitting can be overridden via
5247         use of the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable.
5248
5249      You can find out more about debugging using GDB by reading the
5250      ":ref:`dev-manual/common-tasks:debugging with the gnu project debugger (gdb) remotely`" section
5251      in the Yocto Project Development Tasks Manual.
5252
5253   :term:`PACKAGE_EXCLUDE`
5254      Lists packages that should not be installed into an image. For
5255      example::
5256
5257         PACKAGE_EXCLUDE = "package_name package_name package_name ..."
5258
5259      You can set this variable globally in your ``local.conf`` file or you
5260      can attach it to a specific image recipe by using the recipe name
5261      override::
5262
5263         PACKAGE_EXCLUDE:pn-target_image = "package_name"
5264
5265      If you choose to not install a package using this variable and some
5266      other package is dependent on it (i.e. listed in a recipe's
5267      :term:`RDEPENDS` variable), the OpenEmbedded build
5268      system generates a fatal installation error. Because the build system
5269      halts the process with a fatal error, you can use the variable with
5270      an iterative development process to remove specific components from a
5271      system.
5272
5273      This variable is supported only when using the IPK and RPM
5274      packaging backends. DEB is not supported.
5275
5276      See the :term:`NO_RECOMMENDATIONS` and the
5277      :term:`BAD_RECOMMENDATIONS` variables for
5278      related information.
5279
5280   :term:`PACKAGE_EXCLUDE_COMPLEMENTARY`
5281      Prevents specific packages from being installed when you are
5282      installing complementary packages.
5283
5284      You might find that you want to prevent installing certain packages
5285      when you are installing complementary packages. For example, if you
5286      are using :term:`IMAGE_FEATURES` to install
5287      ``dev-pkgs``, you might not want to install all packages from a
5288      particular multilib. If you find yourself in this situation, you can
5289      use the :term:`PACKAGE_EXCLUDE_COMPLEMENTARY` variable to specify regular
5290      expressions to match the packages you want to exclude.
5291
5292   :term:`PACKAGE_EXTRA_ARCHS`
5293      Specifies the list of architectures compatible with the device CPU.
5294      This variable is useful when you build for several different devices
5295      that use miscellaneous processors such as XScale and ARM926-EJS.
5296
5297   :term:`PACKAGE_FEED_ARCHS`
5298      Optionally specifies the package architectures used as part of the
5299      package feed URIs during the build. When used, the
5300      :term:`PACKAGE_FEED_ARCHS` variable is appended to the final package feed
5301      URI, which is constructed using the
5302      :term:`PACKAGE_FEED_URIS` and
5303      :term:`PACKAGE_FEED_BASE_PATHS`
5304      variables.
5305
5306      .. note::
5307
5308         You can use the :term:`PACKAGE_FEED_ARCHS`
5309         variable to allow specific package architectures. If you do
5310         not need to allow specific architectures, which is a common
5311         case, you can omit this variable. Omitting the variable results in
5312         all available architectures for the current machine being included
5313         into remote package feeds.
5314
5315      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5316      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5317      defined in your ``local.conf`` file::
5318
5319         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5320                              https://example.com/packagerepos/updates"
5321         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5322         PACKAGE_FEED_ARCHS = "all core2-64"
5323
5324      Given these settings, the resulting package feeds are as follows:
5325
5326      .. code-block:: none
5327
5328         https://example.com/packagerepos/release/rpm/all
5329         https://example.com/packagerepos/release/rpm/core2-64
5330         https://example.com/packagerepos/release/rpm-dev/all
5331         https://example.com/packagerepos/release/rpm-dev/core2-64
5332         https://example.com/packagerepos/updates/rpm/all
5333         https://example.com/packagerepos/updates/rpm/core2-64
5334         https://example.com/packagerepos/updates/rpm-dev/all
5335         https://example.com/packagerepos/updates/rpm-dev/core2-64
5336
5337   :term:`PACKAGE_FEED_BASE_PATHS`
5338      Specifies the base path used when constructing package feed URIs. The
5339      :term:`PACKAGE_FEED_BASE_PATHS` variable makes up the middle portion of a
5340      package feed URI used by the OpenEmbedded build system. The base path
5341      lies between the :term:`PACKAGE_FEED_URIS`
5342      and :term:`PACKAGE_FEED_ARCHS` variables.
5343
5344      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5345      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5346      defined in your ``local.conf`` file::
5347
5348         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5349                              https://example.com/packagerepos/updates"
5350         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5351         PACKAGE_FEED_ARCHS = "all core2-64"
5352
5353      Given these settings, the resulting package feeds are as follows:
5354
5355      .. code-block:: none
5356
5357         https://example.com/packagerepos/release/rpm/all
5358         https://example.com/packagerepos/release/rpm/core2-64
5359         https://example.com/packagerepos/release/rpm-dev/all
5360         https://example.com/packagerepos/release/rpm-dev/core2-64
5361         https://example.com/packagerepos/updates/rpm/all
5362         https://example.com/packagerepos/updates/rpm/core2-64
5363         https://example.com/packagerepos/updates/rpm-dev/all
5364         https://example.com/packagerepos/updates/rpm-dev/core2-64
5365
5366   :term:`PACKAGE_FEED_URIS`
5367      Specifies the front portion of the package feed URI used by the
5368      OpenEmbedded build system. Each final package feed URI is comprised
5369      of :term:`PACKAGE_FEED_URIS`,
5370      :term:`PACKAGE_FEED_BASE_PATHS`, and
5371      :term:`PACKAGE_FEED_ARCHS` variables.
5372
5373      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5374      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5375      defined in your ``local.conf`` file::
5376
5377         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5378                              https://example.com/packagerepos/updates"
5379         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5380         PACKAGE_FEED_ARCHS = "all core2-64"
5381
5382      Given these settings, the resulting package feeds are as follows:
5383
5384      .. code-block:: none
5385
5386         https://example.com/packagerepos/release/rpm/all
5387         https://example.com/packagerepos/release/rpm/core2-64
5388         https://example.com/packagerepos/release/rpm-dev/all
5389         https://example.com/packagerepos/release/rpm-dev/core2-64
5390         https://example.com/packagerepos/updates/rpm/all
5391         https://example.com/packagerepos/updates/rpm/core2-64
5392         https://example.com/packagerepos/updates/rpm-dev/all
5393         https://example.com/packagerepos/updates/rpm-dev/core2-64
5394
5395   :term:`PACKAGE_INSTALL`
5396      The final list of packages passed to the package manager for
5397      installation into the image.
5398
5399      Because the package manager controls actual installation of all
5400      packages, the list of packages passed using :term:`PACKAGE_INSTALL` is
5401      not the final list of packages that are actually installed. This
5402      variable is internal to the image construction code. Consequently, in
5403      general, you should use the
5404      :term:`IMAGE_INSTALL` variable to specify
5405      packages for installation. The exception to this is when working with
5406      the :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
5407      image. When working with an initial RAM filesystem (initramfs) image,
5408      use the :term:`PACKAGE_INSTALL` variable. For information on creating an
5409      initramfs, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
5410      in the Yocto Project Development Tasks Manual.
5411
5412   :term:`PACKAGE_INSTALL_ATTEMPTONLY`
5413      Specifies a list of packages the OpenEmbedded build system attempts
5414      to install when creating an image. If a listed package fails to
5415      install, the build system does not generate an error. This variable
5416      is generally not user-defined.
5417
5418   :term:`PACKAGE_PREPROCESS_FUNCS`
5419      Specifies a list of functions run to pre-process the
5420      :term:`PKGD` directory prior to splitting the files out
5421      to individual packages.
5422
5423   :term:`PACKAGE_WRITE_DEPS`
5424      Specifies a list of dependencies for post-installation and
5425      pre-installation scripts on native/cross tools. If your
5426      post-installation or pre-installation script can execute at root filesystem
5427      creation time rather than on the target but depends on a native tool
5428      in order to execute, you need to list the tools in
5429      :term:`PACKAGE_WRITE_DEPS`.
5430
5431      For information on running post-installation scripts, see the
5432      ":ref:`dev-manual/common-tasks:post-installation scripts`"
5433      section in the Yocto Project Development Tasks Manual.
5434
5435   :term:`PACKAGECONFIG`
5436      This variable provides a means of enabling or disabling features of a
5437      recipe on a per-recipe basis. :term:`PACKAGECONFIG` blocks are defined in
5438      recipes when you specify features and then arguments that define
5439      feature behaviors. Here is the basic block structure (broken over
5440      multiple lines for readability)::
5441
5442         PACKAGECONFIG ??= "f1 f2 f3 ..."
5443         PACKAGECONFIG[f1] = "\
5444             --with-f1, \
5445             --without-f1, \
5446             build-deps-for-f1, \
5447             runtime-deps-for-f1, \
5448             runtime-recommends-for-f1, \
5449             packageconfig-conflicts-for-f1"
5450         PACKAGECONFIG[f2] = "\
5451              ... and so on and so on ...
5452
5453      The :term:`PACKAGECONFIG` variable itself specifies a space-separated
5454      list of the features to enable. Following the features, you can
5455      determine the behavior of each feature by providing up to six
5456      order-dependent arguments, which are separated by commas. You can
5457      omit any argument you like but must retain the separating commas. The
5458      order is important and specifies the following:
5459
5460      1. Extra arguments that should be added to the configure script
5461         argument list (:term:`EXTRA_OECONF` or
5462         :term:`PACKAGECONFIG_CONFARGS`) if
5463         the feature is enabled.
5464
5465      2. Extra arguments that should be added to :term:`EXTRA_OECONF` or
5466         :term:`PACKAGECONFIG_CONFARGS` if the feature is disabled.
5467
5468      3. Additional build dependencies (:term:`DEPENDS`)
5469         that should be added if the feature is enabled.
5470
5471      4. Additional runtime dependencies (:term:`RDEPENDS`)
5472         that should be added if the feature is enabled.
5473
5474      5. Additional runtime recommendations
5475         (:term:`RRECOMMENDS`) that should be added if
5476         the feature is enabled.
5477
5478      6. Any conflicting (that is, mutually exclusive) :term:`PACKAGECONFIG`
5479         settings for this feature.
5480
5481      Consider the following :term:`PACKAGECONFIG` block taken from the
5482      ``librsvg`` recipe. In this example the feature is ``gtk``, which has
5483      three arguments that determine the feature's behavior.
5484      ::
5485
5486         PACKAGECONFIG[gtk] = "--with-gtk3,--without-gtk3,gtk+3"
5487
5488      The
5489      ``--with-gtk3`` and ``gtk+3`` arguments apply only if the feature is
5490      enabled. In this case, ``--with-gtk3`` is added to the configure
5491      script argument list and ``gtk+3`` is added to :term:`DEPENDS`. On the
5492      other hand, if the feature is disabled say through a ``.bbappend``
5493      file in another layer, then the second argument ``--without-gtk3`` is
5494      added to the configure script instead.
5495
5496      The basic :term:`PACKAGECONFIG` structure previously described holds true
5497      regardless of whether you are creating a block or changing a block.
5498      When creating a block, use the structure inside your recipe.
5499
5500      If you want to change an existing :term:`PACKAGECONFIG` block, you can do
5501      so one of two ways:
5502
5503      -  *Append file:* Create an append file named
5504         ``recipename.bbappend`` in your layer and override the value of
5505         :term:`PACKAGECONFIG`. You can either completely override the
5506         variable::
5507
5508            PACKAGECONFIG = "f4 f5"
5509
5510         Or, you can just append the variable::
5511
5512            PACKAGECONFIG:append = " f4"
5513
5514      -  *Configuration file:* This method is identical to changing the
5515         block through an append file except you edit your ``local.conf``
5516         or ``mydistro.conf`` file. As with append files previously
5517         described, you can either completely override the variable::
5518
5519            PACKAGECONFIG:pn-recipename = "f4 f5"
5520
5521         Or, you can just amend the variable::
5522
5523            PACKAGECONFIG:append:pn-recipename = " f4"
5524
5525   :term:`PACKAGECONFIG_CONFARGS`
5526      A space-separated list of configuration options generated from the
5527      :term:`PACKAGECONFIG` setting.
5528
5529      Classes such as :ref:`autotools <ref-classes-autotools>` and
5530      :ref:`cmake <ref-classes-cmake>` use :term:`PACKAGECONFIG_CONFARGS` to
5531      pass :term:`PACKAGECONFIG` options to ``configure`` and ``cmake``,
5532      respectively. If you are using :term:`PACKAGECONFIG` but not a class that
5533      handles the ``do_configure`` task, then you need to use
5534      :term:`PACKAGECONFIG_CONFARGS` appropriately.
5535
5536   :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY`
5537      For recipes inheriting the
5538      :ref:`packagegroup <ref-classes-packagegroup>` class, setting
5539      :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY` to "1" specifies that the
5540      normal complementary packages (i.e. ``-dev``, ``-dbg``, and so forth)
5541      should not be automatically created by the ``packagegroup`` recipe,
5542      which is the default behavior.
5543
5544   :term:`PACKAGES`
5545      The list of packages the recipe creates. The default value is the
5546      following::
5547
5548         ${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
5549
5550      During packaging, the :ref:`ref-tasks-package` task
5551      goes through :term:`PACKAGES` and uses the :term:`FILES`
5552      variable corresponding to each package to assign files to the
5553      package. If a file matches the :term:`FILES` variable for more than one
5554      package in :term:`PACKAGES`, it will be assigned to the earliest
5555      (leftmost) package.
5556
5557      Packages in the variable's list that are empty (i.e. where none of
5558      the patterns in ``FILES:``\ pkg match any files installed by the
5559      :ref:`ref-tasks-install` task) are not generated,
5560      unless generation is forced through the
5561      :term:`ALLOW_EMPTY` variable.
5562
5563   :term:`PACKAGES_DYNAMIC`
5564      A promise that your recipe satisfies runtime dependencies for
5565      optional modules that are found in other recipes.
5566      :term:`PACKAGES_DYNAMIC` does not actually satisfy the dependencies, it
5567      only states that they should be satisfied. For example, if a hard,
5568      runtime dependency (:term:`RDEPENDS`) of another
5569      package is satisfied at build time through the :term:`PACKAGES_DYNAMIC`
5570      variable, but a package with the module name is never actually
5571      produced, then the other package will be broken. Thus, if you attempt
5572      to include that package in an image, you will get a dependency
5573      failure from the packaging system during the
5574      :ref:`ref-tasks-rootfs` task.
5575
5576      Typically, if there is a chance that such a situation can occur and
5577      the package that is not created is valid without the dependency being
5578      satisfied, then you should use :term:`RRECOMMENDS`
5579      (a soft runtime dependency) instead of :term:`RDEPENDS`.
5580
5581      For an example of how to use the :term:`PACKAGES_DYNAMIC` variable when
5582      you are splitting packages, see the
5583      ":ref:`dev-manual/common-tasks:handling optional module packaging`"
5584      section in the Yocto Project Development Tasks Manual.
5585
5586   :term:`PACKAGESPLITFUNCS`
5587      Specifies a list of functions run to perform additional splitting of
5588      files into individual packages. Recipes can either prepend to this
5589      variable or prepend to the ``populate_packages`` function in order to
5590      perform additional package splitting. In either case, the function
5591      should set :term:`PACKAGES`,
5592      :term:`FILES`, :term:`RDEPENDS` and
5593      other packaging variables appropriately in order to perform the
5594      desired splitting.
5595
5596   :term:`PARALLEL_MAKE`
5597      Extra options passed to the ``make`` command during the
5598      :ref:`ref-tasks-compile` task in order to specify
5599      parallel compilation on the local build host. This variable is
5600      usually in the form "-j x", where x represents the maximum number of
5601      parallel threads ``make`` can run.
5602
5603      .. note::
5604
5605         In order for :term:`PARALLEL_MAKE` to be effective, ``make`` must be
5606         called with ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy way to ensure
5607         this is to use the ``oe_runmake`` function.
5608
5609      By default, the OpenEmbedded build system automatically sets this
5610      variable to be equal to the number of cores the build system uses.
5611
5612      .. note::
5613
5614         If the software being built experiences dependency issues during
5615         the ``do_compile`` task that result in race conditions, you can clear
5616         the :term:`PARALLEL_MAKE` variable within the recipe as a workaround. For
5617         information on addressing race conditions, see the
5618         ":ref:`dev-manual/common-tasks:debugging parallel make races`"
5619         section in the Yocto Project Development Tasks Manual.
5620
5621      For single socket systems (i.e. one CPU), you should not have to
5622      override this variable to gain optimal parallelism during builds.
5623      However, if you have very large systems that employ multiple physical
5624      CPUs, you might want to make sure the :term:`PARALLEL_MAKE` variable is
5625      not set higher than "-j 20".
5626
5627      For more information on speeding up builds, see the
5628      ":ref:`dev-manual/common-tasks:speeding up a build`"
5629      section in the Yocto Project Development Tasks Manual.
5630
5631   :term:`PARALLEL_MAKEINST`
5632      Extra options passed to the ``make install`` command during the
5633      :ref:`ref-tasks-install` task in order to specify
5634      parallel installation. This variable defaults to the value of
5635      :term:`PARALLEL_MAKE`.
5636
5637      .. note::
5638
5639         In order for :term:`PARALLEL_MAKEINST` to be effective, ``make`` must
5640         be called with
5641         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
5642         way to ensure this is to use the ``oe_runmake`` function.
5643
5644         If the software being built experiences dependency issues during
5645         the ``do_install`` task that result in race conditions, you can
5646         clear the :term:`PARALLEL_MAKEINST` variable within the recipe as a
5647         workaround. For information on addressing race conditions, see the
5648         ":ref:`dev-manual/common-tasks:debugging parallel make races`"
5649         section in the Yocto Project Development Tasks Manual.
5650
5651   :term:`PATCHRESOLVE`
5652      Determines the action to take when a patch fails. You can set this
5653      variable to one of two values: "noop" and "user".
5654
5655      The default value of "noop" causes the build to simply fail when the
5656      OpenEmbedded build system cannot successfully apply a patch. Setting
5657      the value to "user" causes the build system to launch a shell and
5658      places you in the right location so that you can manually resolve the
5659      conflicts.
5660
5661      Set this variable in your ``local.conf`` file.
5662
5663   :term:`PATCHTOOL`
5664      Specifies the utility used to apply patches for a recipe during the
5665      :ref:`ref-tasks-patch` task. You can specify one of
5666      three utilities: "patch", "quilt", or "git". The default utility used
5667      is "quilt" except for the quilt-native recipe itself. Because the
5668      quilt tool is not available at the time quilt-native is being
5669      patched, it uses "patch".
5670
5671      If you wish to use an alternative patching tool, set the variable in
5672      the recipe using one of the following::
5673
5674         PATCHTOOL = "patch"
5675         PATCHTOOL = "quilt"
5676         PATCHTOOL = "git"
5677
5678   :term:`PE`
5679      The epoch of the recipe. By default, this variable is unset. The
5680      variable is used to make upgrades possible when the versioning scheme
5681      changes in some backwards incompatible way.
5682
5683      :term:`PE` is the default value of the :term:`PKGE` variable.
5684
5685   :term:`PEP517_WHEEL_PATH`
5686      When used by recipes that inherit the
5687      :ref:`python_pep517 <ref-classes-python_pep517>` class,
5688      denotes the path to ``dist/`` (short for distribution) where the
5689      binary archive ``wheel`` is built.
5690
5691   :term:`PF`
5692      Specifies the recipe or package name and includes all version and
5693      revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
5694      ``bash-4.2-r1/``). This variable is comprised of the following:
5695      ${:term:`PN`}-${:term:`EXTENDPE`}${:term:`PV`}-${:term:`PR`}
5696
5697   :term:`PIXBUF_PACKAGES`
5698      When inheriting the :ref:`pixbufcache <ref-classes-pixbufcache>`
5699      class, this variable identifies packages that contain the pixbuf
5700      loaders used with ``gdk-pixbuf``. By default, the ``pixbufcache``
5701      class assumes that the loaders are in the recipe's main package (i.e.
5702      ``${``\ :term:`PN`\ ``}``). Use this variable if the
5703      loaders you need are in a package other than that main package.
5704
5705   :term:`PKG`
5706      The name of the resulting package created by the OpenEmbedded build
5707      system.
5708
5709      .. note::
5710
5711         When using the :term:`PKG` variable, you must use a package name override.
5712
5713      For example, when the :ref:`debian <ref-classes-debian>` class
5714      renames the output package, it does so by setting
5715      ``PKG:packagename``.
5716
5717   :term:`PKG_CONFIG_PATH`
5718      The path to ``pkg-config`` files for the current build context.
5719      ``pkg-config`` reads this variable from the environment.
5720
5721   :term:`PKGD`
5722      Points to the destination directory for files to be packaged before
5723      they are split into individual packages. This directory defaults to
5724      the following::
5725
5726         ${WORKDIR}/package
5727
5728      Do not change this default.
5729
5730   :term:`PKGDATA_DIR`
5731      Points to a shared, global-state directory that holds data generated
5732      during the packaging process. During the packaging process, the
5733      :ref:`ref-tasks-packagedata` task packages data
5734      for each recipe and installs it into this temporary, shared area.
5735      This directory defaults to the following, which you should not
5736      change::
5737
5738         ${STAGING_DIR_HOST}/pkgdata
5739
5740      For examples of how this data is used, see the
5741      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
5742      section in the Yocto Project Overview and Concepts Manual and the
5743      ":ref:`dev-manual/common-tasks:viewing package information with \`\`oe-pkgdata-util\`\``"
5744      section in the Yocto Project Development Tasks Manual. For more
5745      information on the shared, global-state directory, see
5746      :term:`STAGING_DIR_HOST`.
5747
5748   :term:`PKGDEST`
5749      Points to the parent directory for files to be packaged after they
5750      have been split into individual packages. This directory defaults to
5751      the following::
5752
5753         ${WORKDIR}/packages-split
5754
5755      Under this directory, the build system creates directories for each
5756      package specified in :term:`PACKAGES`. Do not change
5757      this default.
5758
5759   :term:`PKGDESTWORK`
5760      Points to a temporary work area where the
5761      :ref:`ref-tasks-package` task saves package metadata.
5762      The :term:`PKGDESTWORK` location defaults to the following::
5763
5764         ${WORKDIR}/pkgdata
5765
5766      Do not change this default.
5767
5768      The :ref:`ref-tasks-packagedata` task copies the
5769      package metadata from :term:`PKGDESTWORK` to
5770      :term:`PKGDATA_DIR` to make it available globally.
5771
5772   :term:`PKGE`
5773      The epoch of the package(s) built by the recipe. By default, :term:`PKGE`
5774      is set to :term:`PE`.
5775
5776   :term:`PKGR`
5777      The revision of the package(s) built by the recipe. By default,
5778      :term:`PKGR` is set to :term:`PR`.
5779
5780   :term:`PKGV`
5781      The version of the package(s) built by the recipe. By default,
5782      :term:`PKGV` is set to :term:`PV`.
5783
5784   :term:`PN`
5785      This variable can have two separate functions depending on the
5786      context: a recipe name or a resulting package name.
5787
5788      :term:`PN` refers to a recipe name in the context of a file used by the
5789      OpenEmbedded build system as input to create a package. The name is
5790      normally extracted from the recipe file name. For example, if the
5791      recipe is named ``expat_2.0.1.bb``, then the default value of :term:`PN`
5792      will be "expat".
5793
5794      The variable refers to a package name in the context of a file
5795      created or produced by the OpenEmbedded build system.
5796
5797      If applicable, the :term:`PN` variable also contains any special suffix
5798      or prefix. For example, using ``bash`` to build packages for the
5799      native machine, :term:`PN` is ``bash-native``. Using ``bash`` to build
5800      packages for the target and for Multilib, :term:`PN` would be ``bash``
5801      and ``lib64-bash``, respectively.
5802
5803   :term:`POPULATE_SDK_POST_HOST_COMMAND`
5804      Specifies a list of functions to call once the OpenEmbedded build
5805      system has created the host part of the SDK. You can specify
5806      functions separated by semicolons::
5807
5808          POPULATE_SDK_POST_HOST_COMMAND += "function; ... "
5809
5810      If you need to pass the SDK path to a command within a function, you
5811      can use ``${SDK_DIR}``, which points to the parent directory used by
5812      the OpenEmbedded build system when creating SDK output. See the
5813      :term:`SDK_DIR` variable for more information.
5814
5815   :term:`POPULATE_SDK_POST_TARGET_COMMAND`
5816      Specifies a list of functions to call once the OpenEmbedded build
5817      system has created the target part of the SDK. You can specify
5818      functions separated by semicolons::
5819
5820         POPULATE_SDK_POST_TARGET_COMMAND += "function; ... "
5821
5822      If you need to pass the SDK path to a command within a function, you
5823      can use ``${SDK_DIR}``, which points to the parent directory used by
5824      the OpenEmbedded build system when creating SDK output. See the
5825      :term:`SDK_DIR` variable for more information.
5826
5827   :term:`PR`
5828      The revision of the recipe. The default value for this variable is
5829      "r0". Subsequent revisions of the recipe conventionally have the
5830      values "r1", "r2", and so forth. When :term:`PV` increases,
5831      :term:`PR` is conventionally reset to "r0".
5832
5833      .. note::
5834
5835         The OpenEmbedded build system does not need the aid of :term:`PR`
5836         to know when to rebuild a recipe. The build system uses the task
5837         :ref:`input checksums <overview-manual/concepts:checksums (signatures)>` along with the
5838         :ref:`stamp <structure-build-tmp-stamps>` and
5839         :ref:`overview-manual/concepts:shared state cache`
5840         mechanisms.
5841
5842      The :term:`PR` variable primarily becomes significant when a package
5843      manager dynamically installs packages on an already built image. In
5844      this case, :term:`PR`, which is the default value of
5845      :term:`PKGR`, helps the package manager distinguish which
5846      package is the most recent one in cases where many packages have the
5847      same :term:`PV` (i.e. :term:`PKGV`). A component having many packages with
5848      the same :term:`PV` usually means that the packages all install the same
5849      upstream version, but with later (:term:`PR`) version packages including
5850      packaging fixes.
5851
5852      .. note::
5853
5854         :term:`PR` does not need to be increased for changes that do not change the
5855         package contents or metadata.
5856
5857      Because manually managing :term:`PR` can be cumbersome and error-prone,
5858      an automated solution exists. See the
5859      ":ref:`dev-manual/common-tasks:working with a pr service`" section
5860      in the Yocto Project Development Tasks Manual for more information.
5861
5862   :term:`PREFERRED_PROVIDER`
5863      If multiple recipes provide the same item, this variable determines
5864      which recipe is preferred and thus provides the item (i.e. the
5865      preferred provider). You should always suffix this variable with the
5866      name of the provided item. And, you should define the variable using
5867      the preferred recipe's name (:term:`PN`). Here is a common
5868      example::
5869
5870         PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
5871
5872      In the previous example, multiple recipes are providing "virtual/kernel".
5873      The :term:`PREFERRED_PROVIDER` variable is set with the name (:term:`PN`) of
5874      the recipe you prefer to provide "virtual/kernel".
5875
5876      Following are more examples::
5877
5878         PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
5879         PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
5880
5881      For more
5882      information, see the ":ref:`dev-manual/common-tasks:using virtual providers`"
5883      section in the Yocto Project Development Tasks Manual.
5884
5885      .. note::
5886
5887         If you use a ``virtual/\*`` item with :term:`PREFERRED_PROVIDER`, then any
5888         recipe that :term:`PROVIDES` that item but is not selected (defined)
5889         by :term:`PREFERRED_PROVIDER` is prevented from building, which is usually
5890         desirable since this mechanism is designed to select between mutually
5891         exclusive alternative providers.
5892
5893   :term:`PREFERRED_VERSION`
5894      If there are multiple versions of a recipe available, this variable
5895      determines which version should be given preference. You must always
5896      suffix the variable with the :term:`PN` you want to select (`python` in
5897      the first example below), and you should specify the :term:`PV`
5898      accordingly (`3.4.0` in the example).
5899
5900      The :term:`PREFERRED_VERSION` variable supports limited wildcard use
5901      through the "``%``" character. You can use the character to match any
5902      number of characters, which can be useful when specifying versions
5903      that contain long revision numbers that potentially change. Here are
5904      two examples::
5905
5906         PREFERRED_VERSION_python = "3.4.0"
5907         PREFERRED_VERSION_linux-yocto = "5.0%"
5908
5909      .. note::
5910
5911         The use of the "%" character is limited in that it only works at the end of the
5912         string. You cannot use the wildcard character in any other
5913         location of the string.
5914
5915      The specified version is matched against :term:`PV`, which
5916      does not necessarily match the version part of the recipe's filename.
5917      For example, consider two recipes ``foo_1.2.bb`` and ``foo_git.bb``
5918      where ``foo_git.bb`` contains the following assignment::
5919
5920         PV = "1.1+git${SRCPV}"
5921
5922      In this case, the correct way to select
5923      ``foo_git.bb`` is by using an assignment such as the following::
5924
5925         PREFERRED_VERSION_foo = "1.1+git%"
5926
5927      Compare that previous example
5928      against the following incorrect example, which does not work::
5929
5930         PREFERRED_VERSION_foo = "git"
5931
5932      Sometimes the :term:`PREFERRED_VERSION` variable can be set by
5933      configuration files in a way that is hard to change. You can use
5934      :term:`OVERRIDES` to set a machine-specific
5935      override. Here is an example::
5936
5937         PREFERRED_VERSION_linux-yocto:qemux86 = "5.0%"
5938
5939      Although not recommended, worst case, you can also use the
5940      "forcevariable" override, which is the strongest override possible.
5941      Here is an example::
5942
5943         PREFERRED_VERSION_linux-yocto:forcevariable = "5.0%"
5944
5945      .. note::
5946
5947         The ``:forcevariable`` override is not handled specially. This override
5948         only works because the default value of :term:`OVERRIDES` includes "forcevariable".
5949
5950      If a recipe with the specified version is not available, a warning
5951      message will be shown. See :term:`REQUIRED_VERSION` if you want this
5952      to be an error instead.
5953
5954   :term:`PREMIRRORS`
5955      Specifies additional paths from which the OpenEmbedded build system
5956      gets source code. When the build system searches for source code, it
5957      first tries the local download directory. If that location fails, the
5958      build system tries locations defined by :term:`PREMIRRORS`, the upstream
5959      source, and then locations specified by
5960      :term:`MIRRORS` in that order.
5961
5962      Assuming your distribution (:term:`DISTRO`) is "poky",
5963      the default value for :term:`PREMIRRORS` is defined in the
5964      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
5965
5966      Typically, you could add a specific server for the build system to
5967      attempt before any others by adding something like the following to
5968      the ``local.conf`` configuration file in the
5969      :term:`Build Directory`::
5970
5971         PREMIRRORS:prepend = "\
5972             git://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
5973             ftp://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
5974             http://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
5975             https://.*/.* &YOCTO_DL_URL;/mirror/sources/"
5976
5977      These changes cause the
5978      build system to intercept Git, FTP, HTTP, and HTTPS requests and
5979      direct them to the ``http://`` sources mirror. You can use
5980      ``file://`` URLs to point to local directories or network shares as
5981      well.
5982
5983   :term:`PRIORITY`
5984      Indicates the importance of a package.
5985
5986      :term:`PRIORITY` is considered to be part of the distribution policy
5987      because the importance of any given recipe depends on the purpose for
5988      which the distribution is being produced. Thus, :term:`PRIORITY` is not
5989      normally set within recipes.
5990
5991      You can set :term:`PRIORITY` to "required", "standard", "extra", and
5992      "optional", which is the default.
5993
5994   :term:`PRIVATE_LIBS`
5995      Specifies libraries installed within a recipe that should be ignored
5996      by the OpenEmbedded build system's shared library resolver. This
5997      variable is typically used when software being built by a recipe has
5998      its own private versions of a library normally provided by another
5999      recipe. In this case, you would not want the package containing the
6000      private libraries to be set as a dependency on other unrelated
6001      packages that should instead depend on the package providing the
6002      standard version of the library.
6003
6004      Libraries specified in this variable should be specified by their
6005      file name. For example, from the Firefox recipe in meta-browser::
6006
6007         PRIVATE_LIBS = "libmozjs.so \
6008                         libxpcom.so \
6009                         libnspr4.so \
6010                         libxul.so \
6011                         libmozalloc.so \
6012                         libplc4.so \
6013                         libplds4.so"
6014
6015      For more information, see the
6016      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6017      section in the Yocto Project Overview and Concepts Manual.
6018
6019   :term:`PROVIDES`
6020      A list of aliases by which a particular recipe can be known. By
6021      default, a recipe's own :term:`PN` is implicitly already in its
6022      :term:`PROVIDES` list and therefore does not need to mention that it
6023      provides itself. If a recipe uses :term:`PROVIDES`, the additional
6024      aliases are synonyms for the recipe and can be useful for satisfying
6025      dependencies of other recipes during the build as specified by
6026      :term:`DEPENDS`.
6027
6028      Consider the following example :term:`PROVIDES` statement from the recipe
6029      file ``eudev_3.2.9.bb``::
6030
6031         PROVIDES += "udev"
6032
6033      The :term:`PROVIDES` statement
6034      results in the "eudev" recipe also being available as simply "udev".
6035
6036      .. note::
6037
6038         A recipe's own recipe name (:term:`PN`) is always implicitly prepended
6039         to `PROVIDES`, so while using "+=" in the above example may not be
6040         strictly necessary it is recommended to avoid confusion.
6041
6042      In addition to providing recipes under alternate names, the
6043      :term:`PROVIDES` mechanism is also used to implement virtual targets. A
6044      virtual target is a name that corresponds to some particular
6045      functionality (e.g. a Linux kernel). Recipes that provide the
6046      functionality in question list the virtual target in :term:`PROVIDES`.
6047      Recipes that depend on the functionality in question can include the
6048      virtual target in :term:`DEPENDS` to leave the choice of provider open.
6049
6050      Conventionally, virtual targets have names on the form
6051      "virtual/function" (e.g. "virtual/kernel"). The slash is simply part
6052      of the name and has no syntactical significance.
6053
6054      The :term:`PREFERRED_PROVIDER` variable is
6055      used to select which particular recipe provides a virtual target.
6056
6057      .. note::
6058
6059         A corresponding mechanism for virtual runtime dependencies
6060         (packages) exists. However, the mechanism does not depend on any
6061         special functionality beyond ordinary variable assignments. For
6062         example, ``VIRTUAL-RUNTIME_dev_manager`` refers to the package of
6063         the component that manages the ``/dev`` directory.
6064
6065         Setting the "preferred provider" for runtime dependencies is as
6066         simple as using the following assignment in a configuration file::
6067
6068                 VIRTUAL-RUNTIME_dev_manager = "udev"
6069
6070
6071   :term:`PRSERV_HOST`
6072      The network based :term:`PR` service host and port.
6073
6074      The ``conf/local.conf.sample.extended`` configuration file in the
6075      :term:`Source Directory` shows how the
6076      :term:`PRSERV_HOST` variable is set::
6077
6078         PRSERV_HOST = "localhost:0"
6079
6080      You must
6081      set the variable if you want to automatically start a local :ref:`PR
6082      service <dev-manual/common-tasks:working with a pr service>`. You can
6083      set :term:`PRSERV_HOST` to other values to use a remote PR service.
6084
6085
6086   :term:`PSEUDO_IGNORE_PATHS`
6087      A comma-separated (without spaces) list of path prefixes that should be ignored
6088      by pseudo when monitoring and recording file operations, in order to avoid
6089      problems with files being written to outside of the pseudo context and
6090      reduce pseudo's overhead. A path is ignored if it matches any prefix in the list
6091      and can include partial directory (or file) names.
6092
6093
6094   :term:`PTEST_ENABLED`
6095      Specifies whether or not :ref:`Package
6096      Test <dev-manual/common-tasks:testing packages with ptest>` (ptest)
6097      functionality is enabled when building a recipe. You should not set
6098      this variable directly. Enabling and disabling building Package Tests
6099      at build time should be done by adding "ptest" to (or removing it
6100      from) :term:`DISTRO_FEATURES`.
6101
6102   :term:`PV`
6103      The version of the recipe. The version is normally extracted from the
6104      recipe filename. For example, if the recipe is named
6105      ``expat_2.0.1.bb``, then the default value of :term:`PV` will be "2.0.1".
6106      :term:`PV` is generally not overridden within a recipe unless it is
6107      building an unstable (i.e. development) version from a source code
6108      repository (e.g. Git or Subversion).
6109
6110      :term:`PV` is the default value of the :term:`PKGV` variable.
6111
6112   :term:`PYTHON_ABI`
6113      When used by recipes that inherit the
6114      :ref:`setuptools3 <ref-classes-setuptools3>` class, denotes the
6115      Application Binary Interface (ABI) currently in use for Python. By
6116      default, the ABI is "m". You do not have to set this variable as the
6117      OpenEmbedded build system sets it for you.
6118
6119      The OpenEmbedded build system uses the ABI to construct directory
6120      names used when installing the Python headers and libraries in
6121      sysroot (e.g. ``.../python3.3m/...``).
6122
6123   :term:`PYTHON_PN`
6124      When used by recipes that inherit the
6125      :ref:`setuptools3 <ref-classes-setuptools3>` classe, specifies the
6126      major Python version being built. For Python 3.x, :term:`PYTHON_PN` would
6127      be "python3". You do not have to set this variable as the
6128      OpenEmbedded build system automatically sets it for you.
6129
6130      The variable allows recipes to use common infrastructure such as the
6131      following::
6132
6133         DEPENDS += "${PYTHON_PN}-native"
6134
6135      In the previous example,
6136      the version of the dependency is :term:`PYTHON_PN`.
6137
6138   :term:`QA_EMPTY_DIRS`
6139      Specifies a list of directories that are expected to be empty when
6140      packaging; if ``empty-dirs`` appears in :term:`ERROR_QA` or
6141      :term:`WARN_QA` these will be checked and an error or warning
6142      (respectively) will be produced.
6143
6144      The default :term:`QA_EMPTY_DIRS` value is set in
6145      :ref:`insane.bbclass <ref-classes-insane>`.
6146
6147   :term:`QA_EMPTY_DIRS_RECOMMENDATION`
6148      Specifies a recommendation for why a directory must be empty,
6149      which will be included in the error message if a specific directory
6150      is found to contain files. Must be overridden with the directory
6151      path to match on.
6152
6153      If no recommendation is specified for a directory, then the default
6154      "but it is expected to be empty" will be used.
6155
6156      An example message shows if files were present in '/dev'::
6157
6158         QA_EMPTY_DIRS_RECOMMENDATION:/dev = "but all devices must be created at runtime"
6159
6160   :term:`RANLIB`
6161      The minimal command and arguments to run ``ranlib``.
6162
6163   :term:`RCONFLICTS`
6164      The list of packages that conflict with packages. Note that packages
6165      will not be installed if conflicting packages are not first removed.
6166
6167      Like all package-controlling variables, you must always use them in
6168      conjunction with a package name override. Here is an example::
6169
6170         RCONFLICTS:${PN} = "another_conflicting_package_name"
6171
6172      BitBake, which the OpenEmbedded build system uses, supports
6173      specifying versioned dependencies. Although the syntax varies
6174      depending on the packaging format, BitBake hides these differences
6175      from you. Here is the general syntax to specify versions with the
6176      :term:`RCONFLICTS` variable::
6177
6178         RCONFLICTS:${PN} = "package (operator version)"
6179
6180      For ``operator``, you can specify the following:
6181
6182      - =
6183      - <
6184      - >
6185      - <=
6186      - >=
6187
6188      For example, the following sets up a dependency on version 1.2 or
6189      greater of the package ``foo``::
6190
6191         RCONFLICTS:${PN} = "foo (>= 1.2)"
6192
6193   :term:`RDEPENDS`
6194      Lists runtime dependencies of a package. These dependencies are other
6195      packages that must be installed in order for the package to function
6196      correctly. As an example, the following assignment declares that the
6197      package ``foo`` needs the packages ``bar`` and ``baz`` to be
6198      installed::
6199
6200         RDEPENDS:foo = "bar baz"
6201
6202      The most common types of package
6203      runtime dependencies are automatically detected and added. Therefore,
6204      most recipes do not need to set :term:`RDEPENDS`. For more information,
6205      see the
6206      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6207      section in the Yocto Project Overview and Concepts Manual.
6208
6209      The practical effect of the above :term:`RDEPENDS` assignment is that
6210      ``bar`` and ``baz`` will be declared as dependencies inside the
6211      package ``foo`` when it is written out by one of the
6212      :ref:`do_package_write_\* <ref-tasks-package_write_deb>` tasks.
6213      Exactly how this is done depends on which package format is used,
6214      which is determined by
6215      :term:`PACKAGE_CLASSES`. When the
6216      corresponding package manager installs the package, it will know to
6217      also install the packages on which it depends.
6218
6219      To ensure that the packages ``bar`` and ``baz`` get built, the
6220      previous :term:`RDEPENDS` assignment also causes a task dependency to be
6221      added. This dependency is from the recipe's
6222      :ref:`ref-tasks-build` (not to be confused with
6223      :ref:`ref-tasks-compile`) task to the
6224      ``do_package_write_*`` task of the recipes that build ``bar`` and
6225      ``baz``.
6226
6227      The names of the packages you list within :term:`RDEPENDS` must be the
6228      names of other packages --- they cannot be recipe names. Although
6229      package names and recipe names usually match, the important point
6230      here is that you are providing package names within the :term:`RDEPENDS`
6231      variable. For an example of the default list of packages created from
6232      a recipe, see the :term:`PACKAGES` variable.
6233
6234      Because the :term:`RDEPENDS` variable applies to packages being built,
6235      you should always use the variable in a form with an attached package
6236      name (remember that a single recipe can build multiple packages). For
6237      example, suppose you are building a development package that depends
6238      on the ``perl`` package. In this case, you would use the following
6239      :term:`RDEPENDS` statement::
6240
6241         RDEPENDS:${PN}-dev += "perl"
6242
6243      In the example,
6244      the development package depends on the ``perl`` package. Thus, the
6245      :term:`RDEPENDS` variable has the ``${PN}-dev`` package name as part of
6246      the variable.
6247
6248      .. note::
6249
6250         ``RDEPENDS:${PN}-dev`` includes ``${``\ :term:`PN`\ ``}``
6251         by default. This default is set in the BitBake configuration file
6252         (``meta/conf/bitbake.conf``). Be careful not to accidentally remove
6253         ``${PN}`` when modifying ``RDEPENDS:${PN}-dev``. Use the "+=" operator
6254         rather than the "=" operator.
6255
6256      The package names you use with :term:`RDEPENDS` must appear as they would
6257      in the :term:`PACKAGES` variable. The :term:`PKG` variable
6258      allows a different name to be used for the final package (e.g. the
6259      :ref:`debian <ref-classes-debian>` class uses this to rename
6260      packages), but this final package name cannot be used with
6261      :term:`RDEPENDS`, which makes sense as :term:`RDEPENDS` is meant to be
6262      independent of the package format used.
6263
6264      BitBake, which the OpenEmbedded build system uses, supports
6265      specifying versioned dependencies. Although the syntax varies
6266      depending on the packaging format, BitBake hides these differences
6267      from you. Here is the general syntax to specify versions with the
6268      :term:`RDEPENDS` variable::
6269
6270         RDEPENDS:${PN} = "package (operator version)"
6271
6272      For ``operator``, you can specify the following:
6273
6274      - =
6275      - <
6276      - >
6277      - <=
6278      - >=
6279
6280      For version, provide the version number.
6281
6282      .. note::
6283
6284         You can use :term:`EXTENDPKGV` to provide a full package version
6285         specification.
6286
6287      For example, the following sets up a dependency on version 1.2 or
6288      greater of the package ``foo``::
6289
6290         RDEPENDS:${PN} = "foo (>= 1.2)"
6291
6292      For information on build-time dependencies, see the
6293      :term:`DEPENDS` variable. You can also see the
6294      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
6295      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
6296      BitBake User Manual for additional information on tasks and
6297      dependencies.
6298
6299   :term:`RECIPE_NO_UPDATE_REASON`
6300      If a recipe should not be replaced by a more recent upstream version,
6301      putting the reason why in this variable in a recipe allows
6302      ``devtool check-upgrade-status`` command to display it, as explained
6303      in the ":ref:`ref-manual/devtool-reference:checking on the upgrade status of a recipe`"
6304      section.
6305
6306   :term:`REQUIRED_DISTRO_FEATURES`
6307      When inheriting the
6308      :ref:`features_check <ref-classes-features_check>`
6309      class, this variable identifies distribution features that must exist
6310      in the current configuration in order for the OpenEmbedded build
6311      system to build the recipe. In other words, if the
6312      :term:`REQUIRED_DISTRO_FEATURES` variable lists a feature that does not
6313      appear in :term:`DISTRO_FEATURES` within the current configuration, then
6314      the recipe will be skipped, and if the build system attempts to build
6315      the recipe then an error will be triggered.
6316
6317   :term:`REQUIRED_VERSION`
6318      If there are multiple versions of a recipe available, this variable
6319      determines which version should be given preference.
6320      :term:`REQUIRED_VERSION` works in exactly the same manner as
6321      :term:`PREFERRED_VERSION`, except that if the specified version is not
6322      available then an error message is shown and the build fails
6323      immediately.
6324
6325      If both :term:`REQUIRED_VERSION` and :term:`PREFERRED_VERSION` are set
6326      for the same recipe, the :term:`REQUIRED_VERSION` value applies.
6327
6328   :term:`RM_WORK_EXCLUDE`
6329      With ``rm_work`` enabled, this variable specifies a list of recipes
6330      whose work directories should not be removed. See the
6331      ":ref:`ref-classes-rm-work`" section for more
6332      details.
6333
6334   :term:`ROOT_HOME`
6335      Defines the root home directory. By default, this directory is set as
6336      follows in the BitBake configuration file::
6337
6338         ROOT_HOME ??= "/home/root"
6339
6340      .. note::
6341
6342         This default value is likely used because some embedded solutions
6343         prefer to have a read-only root filesystem and prefer to keep
6344         writeable data in one place.
6345
6346      You can override the default by setting the variable in any layer or
6347      in the ``local.conf`` file. Because the default is set using a "weak"
6348      assignment (i.e. "??="), you can use either of the following forms to
6349      define your override::
6350
6351         ROOT_HOME = "/root"
6352         ROOT_HOME ?= "/root"
6353
6354      These
6355      override examples use ``/root``, which is probably the most commonly
6356      used override.
6357
6358   :term:`ROOTFS`
6359      Indicates a filesystem image to include as the root filesystem.
6360
6361      The :term:`ROOTFS` variable is an optional variable used with the
6362      :ref:`image-live <ref-classes-image-live>` class.
6363
6364   :term:`ROOTFS_POSTINSTALL_COMMAND`
6365      Specifies a list of functions to call after the OpenEmbedded build
6366      system has installed packages. You can specify functions separated by
6367      semicolons::
6368
6369         ROOTFS_POSTINSTALL_COMMAND += "function; ... "
6370
6371      If you need to pass the root filesystem path to a command within a
6372      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6373      directory that becomes the root filesystem image. See the
6374      :term:`IMAGE_ROOTFS` variable for more
6375      information.
6376
6377   :term:`ROOTFS_POSTPROCESS_COMMAND`
6378      Specifies a list of functions to call once the OpenEmbedded build
6379      system has created the root filesystem. You can specify functions
6380      separated by semicolons::
6381
6382         ROOTFS_POSTPROCESS_COMMAND += "function; ... "
6383
6384      If you need to pass the root filesystem path to a command within a
6385      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6386      directory that becomes the root filesystem image. See the
6387      :term:`IMAGE_ROOTFS` variable for more
6388      information.
6389
6390   :term:`ROOTFS_POSTUNINSTALL_COMMAND`
6391      Specifies a list of functions to call after the OpenEmbedded build
6392      system has removed unnecessary packages. When runtime package
6393      management is disabled in the image, several packages are removed
6394      including ``base-passwd``, ``shadow``, and ``update-alternatives``.
6395      You can specify functions separated by semicolons::
6396
6397         ROOTFS_POSTUNINSTALL_COMMAND += "function; ... "
6398
6399      If you need to pass the root filesystem path to a command within a
6400      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6401      directory that becomes the root filesystem image. See the
6402      :term:`IMAGE_ROOTFS` variable for more
6403      information.
6404
6405   :term:`ROOTFS_PREPROCESS_COMMAND`
6406      Specifies a list of functions to call before the OpenEmbedded build
6407      system has created the root filesystem. You can specify functions
6408      separated by semicolons::
6409
6410         ROOTFS_PREPROCESS_COMMAND += "function; ... "
6411
6412      If you need to pass the root filesystem path to a command within a
6413      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6414      directory that becomes the root filesystem image. See the
6415      :term:`IMAGE_ROOTFS` variable for more
6416      information.
6417
6418   :term:`RPROVIDES`
6419      A list of package name aliases that a package also provides. These
6420      aliases are useful for satisfying runtime dependencies of other
6421      packages both during the build and on the target (as specified by
6422      :term:`RDEPENDS`).
6423
6424      .. note::
6425
6426         A package's own name is implicitly already in its :term:`RPROVIDES` list.
6427
6428      As with all package-controlling variables, you must always use the
6429      variable in conjunction with a package name override. Here is an
6430      example::
6431
6432         RPROVIDES:${PN} = "widget-abi-2"
6433
6434   :term:`RRECOMMENDS`
6435      A list of packages that extends the usability of a package being
6436      built. The package being built does not depend on this list of
6437      packages in order to successfully build, but rather uses them for
6438      extended usability. To specify runtime dependencies for packages, see
6439      the :term:`RDEPENDS` variable.
6440
6441      The package manager will automatically install the :term:`RRECOMMENDS`
6442      list of packages when installing the built package. However, you can
6443      prevent listed packages from being installed by using the
6444      :term:`BAD_RECOMMENDATIONS`,
6445      :term:`NO_RECOMMENDATIONS`, and
6446      :term:`PACKAGE_EXCLUDE` variables.
6447
6448      Packages specified in :term:`RRECOMMENDS` need not actually be produced.
6449      However, there must be a recipe providing each package, either
6450      through the :term:`PACKAGES` or
6451      :term:`PACKAGES_DYNAMIC` variables or the
6452      :term:`RPROVIDES` variable, or an error will occur
6453      during the build. If such a recipe does exist and the package is not
6454      produced, the build continues without error.
6455
6456      Because the :term:`RRECOMMENDS` variable applies to packages being built,
6457      you should always attach an override to the variable to specify the
6458      particular package whose usability is being extended. For example,
6459      suppose you are building a development package that is extended to
6460      support wireless functionality. In this case, you would use the
6461      following::
6462
6463         RRECOMMENDS:${PN}-dev += "wireless_package_name"
6464
6465      In the
6466      example, the package name (``${PN}-dev``) must appear as it would in
6467      the :term:`PACKAGES` namespace before any renaming of the output package
6468      by classes such as :ref:`ref-classes-debian`.
6469
6470      BitBake, which the OpenEmbedded build system uses, supports
6471      specifying versioned recommends. Although the syntax varies depending
6472      on the packaging format, BitBake hides these differences from you.
6473      Here is the general syntax to specify versions with the
6474      :term:`RRECOMMENDS` variable::
6475
6476         RRECOMMENDS:${PN} = "package (operator version)"
6477
6478      For ``operator``, you can specify the following:
6479
6480      - =
6481      - <
6482      - >
6483      - <=
6484      - >=
6485
6486      For example, the following sets up a recommend on version 1.2 or
6487      greater of the package ``foo``::
6488
6489         RRECOMMENDS:${PN} = "foo (>= 1.2)"
6490
6491   :term:`RREPLACES`
6492      A list of packages replaced by a package. The package manager uses
6493      this variable to determine which package should be installed to
6494      replace other package(s) during an upgrade. In order to also have the
6495      other package(s) removed at the same time, you must add the name of
6496      the other package to the :term:`RCONFLICTS` variable.
6497
6498      As with all package-controlling variables, you must use this variable
6499      in conjunction with a package name override. Here is an example::
6500
6501         RREPLACES:${PN} = "other_package_being_replaced"
6502
6503      BitBake, which the OpenEmbedded build system uses, supports
6504      specifying versioned replacements. Although the syntax varies
6505      depending on the packaging format, BitBake hides these differences
6506      from you. Here is the general syntax to specify versions with the
6507      :term:`RREPLACES` variable::
6508
6509         RREPLACES:${PN} = "package (operator version)"
6510
6511      For ``operator``, you can specify the following:
6512
6513      - =
6514      - <
6515      - >
6516      - <=
6517      - >=
6518
6519      For example, the following sets up a replacement using version 1.2
6520      or greater of the package ``foo``::
6521
6522          RREPLACES:${PN} = "foo (>= 1.2)"
6523
6524   :term:`RSUGGESTS`
6525      A list of additional packages that you can suggest for installation
6526      by the package manager at the time a package is installed. Not all
6527      package managers support this functionality.
6528
6529      As with all package-controlling variables, you must always use this
6530      variable in conjunction with a package name override. Here is an
6531      example::
6532
6533         RSUGGESTS:${PN} = "useful_package another_package"
6534
6535   :term:`S`
6536      The location in the :term:`Build Directory` where
6537      unpacked recipe source code resides. By default, this directory is
6538      ``${``\ :term:`WORKDIR`\ ``}/${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
6539      where ``${BPN}`` is the base recipe name and ``${PV}`` is the recipe
6540      version. If the source tarball extracts the code to a directory named
6541      anything other than ``${BPN}-${PV}``, or if the source code is
6542      fetched from an SCM such as Git or Subversion, then you must set
6543      :term:`S` in the recipe so that the OpenEmbedded build system knows where
6544      to find the unpacked source.
6545
6546      As an example, assume a :term:`Source Directory`
6547      top-level folder named ``poky`` and a default Build Directory at
6548      ``poky/build``. In this case, the work directory the build system
6549      uses to keep the unpacked recipe for ``db`` is the following::
6550
6551         poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
6552
6553      The unpacked source code resides in the ``db-5.1.19`` folder.
6554
6555      This next example assumes a Git repository. By default, Git
6556      repositories are cloned to ``${WORKDIR}/git`` during
6557      :ref:`ref-tasks-fetch`. Since this path is different
6558      from the default value of :term:`S`, you must set it specifically so the
6559      source can be located::
6560
6561         SRC_URI = "git://path/to/repo.git;branch=main"
6562         S = "${WORKDIR}/git"
6563
6564   :term:`SANITY_REQUIRED_UTILITIES`
6565      Specifies a list of command-line utilities that should be checked for
6566      during the initial sanity checking process when running BitBake. If
6567      any of the utilities are not installed on the build host, then
6568      BitBake immediately exits with an error.
6569
6570   :term:`SANITY_TESTED_DISTROS`
6571      A list of the host distribution identifiers that the build system has
6572      been tested against. Identifiers consist of the host distributor ID
6573      followed by the release, as reported by the ``lsb_release`` tool or
6574      as read from ``/etc/lsb-release``. Separate the list items with
6575      explicit newline characters (``\n``). If :term:`SANITY_TESTED_DISTROS` is
6576      not empty and the current value of
6577      :term:`NATIVELSBSTRING` does not appear in the
6578      list, then the build system reports a warning that indicates the
6579      current host distribution has not been tested as a build host.
6580
6581   :term:`SDK_ARCH`
6582      The target architecture for the SDK. Typically, you do not directly
6583      set this variable. Instead, use :term:`SDKMACHINE`.
6584
6585   :term:`SDK_CUSTOM_TEMPLATECONF`
6586      When building the extensible SDK, if :term:`SDK_CUSTOM_TEMPLATECONF` is set to
6587      "1" and a ``conf/templateconf.conf`` file exists in the build directory
6588      (:term:`TOPDIR`) then this will be copied into the SDK.
6589
6590   :term:`SDK_DEPLOY`
6591      The directory set up and used by the
6592      :ref:`populate_sdk_base <ref-classes-populate-sdk>` class to which
6593      the SDK is deployed. The ``populate_sdk_base`` class defines
6594      :term:`SDK_DEPLOY` as follows::
6595
6596         SDK_DEPLOY = "${TMPDIR}/deploy/sdk"
6597
6598   :term:`SDK_DIR`
6599      The parent directory used by the OpenEmbedded build system when
6600      creating SDK output. The
6601      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class defines
6602      the variable as follows::
6603
6604         SDK_DIR = "${WORKDIR}/sdk"
6605
6606      .. note::
6607
6608         The :term:`SDK_DIR` directory is a temporary directory as it is part of
6609         :term:`WORKDIR`. The final output directory is :term:`SDK_DEPLOY`.
6610
6611   :term:`SDK_EXT_TYPE`
6612      Controls whether or not shared state artifacts are copied into the
6613      extensible SDK. The default value of "full" copies all of the
6614      required shared state artifacts into the extensible SDK. The value
6615      "minimal" leaves these artifacts out of the SDK.
6616
6617      .. note::
6618
6619         If you set the variable to "minimal", you need to ensure
6620         :term:`SSTATE_MIRRORS` is set in the SDK's configuration to enable the
6621         artifacts to be fetched as needed.
6622
6623   :term:`SDK_HOST_MANIFEST`
6624      The manifest file for the host part of the SDK. This file lists all
6625      the installed packages that make up the host part of the SDK. The
6626      file contains package information on a line-per-package basis as
6627      follows::
6628
6629         packagename packagearch version
6630
6631      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
6632      defines the manifest file as follows::
6633
6634         SDK_HOST_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.host.manifest"
6635
6636      The location is derived using the :term:`SDK_DEPLOY` and
6637      :term:`TOOLCHAIN_OUTPUTNAME` variables.
6638
6639   :term:`SDK_INCLUDE_PKGDATA`
6640      When set to "1", specifies to include the packagedata for all recipes
6641      in the "world" target in the extensible SDK. Including this data
6642      allows the ``devtool search`` command to find these recipes in search
6643      results, as well as allows the ``devtool add`` command to map
6644      dependencies more effectively.
6645
6646      .. note::
6647
6648         Enabling the :term:`SDK_INCLUDE_PKGDATA`
6649         variable significantly increases build time because all of world
6650         needs to be built. Enabling the variable also slightly increases
6651         the size of the extensible SDK.
6652
6653   :term:`SDK_INCLUDE_TOOLCHAIN`
6654      When set to "1", specifies to include the toolchain in the extensible
6655      SDK. Including the toolchain is useful particularly when
6656      :term:`SDK_EXT_TYPE` is set to "minimal" to keep
6657      the SDK reasonably small but you still want to provide a usable
6658      toolchain. For example, suppose you want to use the toolchain from an
6659      IDE or from other tools and you do not want to perform additional
6660      steps to install the toolchain.
6661
6662      The :term:`SDK_INCLUDE_TOOLCHAIN` variable defaults to "0" if
6663      :term:`SDK_EXT_TYPE` is set to "minimal", and defaults to "1" if
6664      :term:`SDK_EXT_TYPE` is set to "full".
6665
6666   :term:`SDK_NAME`
6667      The base name for SDK output files. The name is derived from the
6668      :term:`DISTRO`, :term:`TCLIBC`,
6669      :term:`SDK_ARCH`,
6670      :term:`IMAGE_BASENAME`, and
6671      :term:`TUNE_PKGARCH` variables::
6672
6673         SDK_NAME = "${DISTRO}-${TCLIBC}-${SDK_ARCH}-${IMAGE_BASENAME}-${TUNE_PKGARCH}"
6674
6675   :term:`SDK_OS`
6676      Specifies the operating system for which the SDK will be built. The
6677      default value is the value of :term:`BUILD_OS`.
6678
6679   :term:`SDK_OUTPUT`
6680      The location used by the OpenEmbedded build system when creating SDK
6681      output. The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>`
6682      class defines the variable as follows::
6683
6684         SDK_DIR = "${WORKDIR}/sdk"
6685         SDK_OUTPUT = "${SDK_DIR}/image"
6686         SDK_DEPLOY = "${DEPLOY_DIR}/sdk"
6687
6688      .. note::
6689
6690         The :term:`SDK_OUTPUT` directory is a temporary directory as it is part of
6691         :term:`WORKDIR` by way of :term:`SDK_DIR`. The final output directory is
6692         :term:`SDK_DEPLOY`.
6693
6694   :term:`SDK_PACKAGE_ARCHS`
6695      Specifies a list of architectures compatible with the SDK machine.
6696      This variable is set automatically and should not normally be
6697      hand-edited. Entries are separated using spaces and listed in order
6698      of priority. The default value for :term:`SDK_PACKAGE_ARCHS` is "all any
6699      noarch ${SDK_ARCH}-${SDKPKGSUFFIX}".
6700
6701   :term:`SDK_POSTPROCESS_COMMAND`
6702      Specifies a list of functions to call once the OpenEmbedded build
6703      system creates the SDK. You can specify functions separated by
6704      semicolons: SDK_POSTPROCESS_COMMAND += "function; ... "
6705
6706      If you need to pass an SDK path to a command within a function, you
6707      can use ``${SDK_DIR}``, which points to the parent directory used by
6708      the OpenEmbedded build system when creating SDK output. See the
6709      :term:`SDK_DIR` variable for more information.
6710
6711   :term:`SDK_PREFIX`
6712      The toolchain binary prefix used for ``nativesdk`` recipes. The
6713      OpenEmbedded build system uses the :term:`SDK_PREFIX` value to set the
6714      :term:`TARGET_PREFIX` when building
6715      ``nativesdk`` recipes. The default value is "${SDK_SYS}-".
6716
6717   :term:`SDK_RECRDEP_TASKS`
6718      A list of shared state tasks added to the extensible SDK. By default,
6719      the following tasks are added:
6720
6721      - do_populate_lic
6722      - do_package_qa
6723      - do_populate_sysroot
6724      - do_deploy
6725
6726      Despite the default value of "" for the
6727      :term:`SDK_RECRDEP_TASKS` variable, the above four tasks are always added
6728      to the SDK. To specify tasks beyond these four, you need to use the
6729      :term:`SDK_RECRDEP_TASKS` variable (e.g. you are defining additional
6730      tasks that are needed in order to build
6731      :term:`SDK_TARGETS`).
6732
6733   :term:`SDK_SYS`
6734      Specifies the system, including the architecture and the operating
6735      system, for which the SDK will be built.
6736
6737      The OpenEmbedded build system automatically sets this variable based
6738      on :term:`SDK_ARCH`,
6739      :term:`SDK_VENDOR`, and
6740      :term:`SDK_OS`. You do not need to set the :term:`SDK_SYS`
6741      variable yourself.
6742
6743   :term:`SDK_TARGET_MANIFEST`
6744      The manifest file for the target part of the SDK. This file lists all
6745      the installed packages that make up the target part of the SDK. The
6746      file contains package information on a line-per-package basis as
6747      follows::
6748
6749         packagename packagearch version
6750
6751      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
6752      defines the manifest file as follows::
6753
6754         SDK_TARGET_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.target.manifest"
6755
6756      The location is derived using the :term:`SDK_DEPLOY` and
6757      :term:`TOOLCHAIN_OUTPUTNAME` variables.
6758
6759   :term:`SDK_TARGETS`
6760      A list of targets to install from shared state as part of the
6761      standard or extensible SDK installation. The default value is "${PN}"
6762      (i.e. the image from which the SDK is built).
6763
6764      The :term:`SDK_TARGETS` variable is an internal variable and typically
6765      would not be changed.
6766
6767   :term:`SDK_TITLE`
6768      The title to be printed when running the SDK installer. By default,
6769      this title is based on the :term:`DISTRO_NAME` or
6770      :term:`DISTRO` variable and is set in the
6771      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
6772      follows::
6773
6774         SDK_TITLE ??= "${@d.getVar('DISTRO_NAME') or d.getVar('DISTRO')} SDK"
6775
6776      For the default distribution "poky",
6777      :term:`SDK_TITLE` is set to "Poky (Yocto Project Reference Distro)".
6778
6779      For information on how to change this default title, see the
6780      ":ref:`sdk-manual/appendix-customizing:changing the extensible sdk installer title`"
6781      section in the Yocto Project Application Development and the
6782      Extensible Software Development Kit (eSDK) manual.
6783
6784   :term:`SDK_UPDATE_URL`
6785      An optional URL for an update server for the extensible SDK. If set,
6786      the value is used as the default update server when running
6787      ``devtool sdk-update`` within the extensible SDK.
6788
6789   :term:`SDK_VENDOR`
6790      Specifies the name of the SDK vendor.
6791
6792   :term:`SDK_VERSION`
6793      Specifies the version of the SDK. The Poky distribution configuration file
6794      (``/meta-poky/conf/distro/poky.conf``) sets the default
6795      :term:`SDK_VERSION` as follows::
6796
6797         SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"
6798
6799      For additional information, see the
6800      :term:`DISTRO_VERSION` and
6801      :term:`METADATA_REVISION` variables.
6802
6803   :term:`SDKEXTPATH`
6804      The default installation directory for the Extensible SDK. By
6805      default, this directory is based on the :term:`DISTRO`
6806      variable and is set in the
6807      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
6808      follows::
6809
6810         SDKEXTPATH ??= "~/${@d.getVar('DISTRO')}_sdk"
6811
6812      For the
6813      default distribution "poky", the :term:`SDKEXTPATH` is set to "poky_sdk".
6814
6815      For information on how to change this default directory, see the
6816      ":ref:`sdk-manual/appendix-customizing:changing the default sdk installation directory`"
6817      section in the Yocto Project Application Development and the
6818      Extensible Software Development Kit (eSDK) manual.
6819
6820   :term:`SDKIMAGE_FEATURES`
6821      Equivalent to :term:`IMAGE_FEATURES`. However, this variable applies to
6822      the SDK generated from an image using the following command::
6823
6824         $ bitbake -c populate_sdk imagename
6825
6826   :term:`SDKMACHINE`
6827      The machine for which the SDK is built. In other words, the SDK is built
6828      such that it runs on the target you specify with the :term:`SDKMACHINE`
6829      value. The value points to a corresponding ``.conf`` file under
6830      ``conf/machine-sdk/`` in the enabled layers, for example ``aarch64``,
6831      ``i586``, ``i686``, ``ppc64``, ``ppc64le``, and ``x86_64`` are
6832      :oe_git:`available in OpenEmbedded-Core </openembedded-core/tree/meta/conf/machine-sdk>`.
6833
6834      The variable defaults to :term:`BUILD_ARCH` so that SDKs are built for the
6835      architecture of the build machine.
6836
6837      .. note::
6838
6839         You cannot set the :term:`SDKMACHINE`
6840         variable in your distribution configuration file. If you do, the
6841         configuration will not take effect.
6842
6843   :term:`SDKPATH`
6844      Defines the path offered to the user for installation of the SDK that
6845      is generated by the OpenEmbedded build system. The path appears as
6846      the default location for installing the SDK when you run the SDK's
6847      installation script. You can override the offered path when you run
6848      the script.
6849
6850   :term:`SDKTARGETSYSROOT`
6851      The full path to the sysroot used for cross-compilation within an SDK
6852      as it will be when installed into the default
6853      :term:`SDKPATH`.
6854
6855   :term:`SECTION`
6856      The section in which packages should be categorized. Package
6857      management utilities can make use of this variable.
6858
6859   :term:`SELECTED_OPTIMIZATION`
6860      Specifies the optimization flags passed to the C compiler when
6861      building for the target. The flags are passed through the default
6862      value of the :term:`TARGET_CFLAGS` variable.
6863
6864      The :term:`SELECTED_OPTIMIZATION` variable takes the value of
6865      :term:`FULL_OPTIMIZATION` unless :term:`DEBUG_BUILD` = "1", in which
6866      case the value of :term:`DEBUG_OPTIMIZATION` is used.
6867
6868   :term:`SERIAL_CONSOLE`
6869      Defines a serial console (TTY) to enable using
6870      `getty <https://en.wikipedia.org/wiki/Getty_(Unix)>`__. Provide a
6871      value that specifies the baud rate followed by the TTY device name
6872      separated by a space. You cannot specify more than one TTY device::
6873
6874         SERIAL_CONSOLE = "115200 ttyS0"
6875
6876      .. note::
6877
6878         The :term:`SERIAL_CONSOLE` variable is deprecated. Please use the
6879         :term:`SERIAL_CONSOLES` variable.
6880
6881   :term:`SERIAL_CONSOLES`
6882      Defines a serial console (TTY) to enable using
6883      `getty <https://en.wikipedia.org/wiki/Getty_(Unix)>`__. Provide a
6884      value that specifies the baud rate followed by the TTY device name
6885      separated by a semicolon. Use spaces to separate multiple devices::
6886
6887         SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
6888
6889   :term:`SERIAL_CONSOLES_CHECK`
6890      Specifies serial consoles, which must be listed in
6891      :term:`SERIAL_CONSOLES`, to check against
6892      ``/proc/console`` before enabling them using getty. This variable
6893      allows aliasing in the format: <device>:<alias>. If a device was
6894      listed as "sclp_line0" in ``/dev/`` and "ttyS0" was listed in
6895      ``/proc/console``, you would do the following::
6896
6897         SERIAL_CONSOLES_CHECK = "slcp_line0:ttyS0"
6898
6899      This variable is currently only supported with SysVinit (i.e. not
6900      with systemd). Note that :term:`SERIAL_CONSOLES_CHECK` also requires
6901      ``/etc/inittab`` to be writable when used with SysVinit. This makes it
6902      incompatible with customizations such as the following::
6903
6904         EXTRA_IMAGE_FEATURES += "read-only-rootfs"
6905
6906   :term:`SETUPTOOLS_BUILD_ARGS`
6907      When used by recipes that inherit the
6908      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable can
6909      be used to specify additional arguments to be passed to ``setup.py build``
6910      in the ``setuptools3_do_compile()`` task.
6911
6912   :term:`SETUPTOOLS_INSTALL_ARGS`
6913      When used by recipes that inherit the
6914      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable can
6915      be used to specify additional arguments to be passed to ``setup.py install``
6916      in the ``setuptools3_do_install()`` task.
6917
6918   :term:`SETUPTOOLS_SETUP_PATH`
6919      When used by recipes that inherit the
6920      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable should
6921      be used to specify the directory in which the ``setup.py`` file is
6922      located if it is not at the root of the source tree (as specified by
6923      :term:`S`). For example, in a recipe where the sources are fetched from
6924      a Git repository and ``setup.py`` is in a ``python/pythonmodule``
6925      subdirectory, you would have this::
6926
6927         S = "${WORKDIR}/git"
6928         SETUPTOOLS_SETUP_PATH = "${S}/python/pythonmodule"
6929
6930   :term:`SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS`
6931      A list of recipe dependencies that should not be used to determine
6932      signatures of tasks from one recipe when they depend on tasks from
6933      another recipe. For example::
6934
6935         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
6936
6937      In the previous example, ``intone`` depends on ``mplayer2``.
6938
6939      You can use the special token ``"*"`` on the left-hand side of the
6940      dependency to match all recipes except the one on the right-hand
6941      side. Here is an example::
6942
6943         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "*->quilt-native"
6944
6945      In the previous example, all recipes except ``quilt-native`` ignore
6946      task signatures from the ``quilt-native`` recipe when determining
6947      their task signatures.
6948
6949      Use of this variable is one mechanism to remove dependencies that
6950      affect task signatures and thus force rebuilds when a recipe changes.
6951
6952      .. note::
6953
6954         If you add an inappropriate dependency for a recipe relationship,
6955         the software might break during runtime if the interface of the
6956         second recipe was changed after the first recipe had been built.
6957
6958   :term:`SIGGEN_EXCLUDERECIPES_ABISAFE`
6959      A list of recipes that are completely stable and will never change.
6960      The ABI for the recipes in the list are presented by output from the
6961      tasks run to build the recipe. Use of this variable is one way to
6962      remove dependencies from one recipe on another that affect task
6963      signatures and thus force rebuilds when the recipe changes.
6964
6965      .. note::
6966
6967         If you add an inappropriate variable to this list, the software
6968         might break at runtime if the interface of the recipe was changed
6969         after the other had been built.
6970
6971   :term:`SITEINFO_BITS`
6972      Specifies the number of bits for the target system CPU. The value
6973      should be either "32" or "64".
6974
6975   :term:`SITEINFO_ENDIANNESS`
6976      Specifies the endian byte order of the target system. The value
6977      should be either "le" for little-endian or "be" for big-endian.
6978
6979   :term:`SKIP_FILEDEPS`
6980      Enables removal of all files from the "Provides" section of an RPM
6981      package. Removal of these files is required for packages containing
6982      prebuilt binaries and libraries such as ``libstdc++`` and ``glibc``.
6983
6984      To enable file removal, set the variable to "1" in your
6985      ``conf/local.conf`` configuration file in your:
6986      :term:`Build Directory`.
6987      ::
6988
6989         SKIP_FILEDEPS = "1"
6990
6991   :term:`SKIP_RECIPE`
6992      Used to prevent the OpenEmbedded build system from building a given
6993      recipe. Specify the :term:`PN` value as a variable flag (``varflag``)
6994      and provide a reason, which will be reported when attempting to
6995      build the recipe.
6996
6997      To prevent a recipe from being built, use the :term:`SKIP_RECIPE`
6998      variable in your ``local.conf`` file or distribution configuration.
6999      Here is an example which prevents ``myrecipe`` from being built::
7000
7001         SKIP_RECIPE[myrecipe] = "Not supported by our organization."
7002
7003   :term:`SOC_FAMILY`
7004      Groups together machines based upon the same family of SOC (System On
7005      Chip). You typically set this variable in a common ``.inc`` file that
7006      you include in the configuration files of all the machines.
7007
7008      .. note::
7009
7010         You must include ``conf/machine/include/soc-family.inc`` for this
7011         variable to appear in :term:`MACHINEOVERRIDES`.
7012
7013   :term:`SOLIBS`
7014      Defines the suffix for shared libraries used on the target platform.
7015      By default, this suffix is ".so.*" for all Linux-based systems and is
7016      defined in the ``meta/conf/bitbake.conf`` configuration file.
7017
7018      You will see this variable referenced in the default values of
7019      ``FILES:${PN}``.
7020
7021   :term:`SOLIBSDEV`
7022      Defines the suffix for the development symbolic link (symlink) for
7023      shared libraries on the target platform. By default, this suffix is
7024      ".so" for Linux-based systems and is defined in the
7025      ``meta/conf/bitbake.conf`` configuration file.
7026
7027      You will see this variable referenced in the default values of
7028      ``FILES:${PN}-dev``.
7029
7030   :term:`SOURCE_DATE_EPOCH`
7031      This defines a date expressed in number of seconds since
7032      the UNIX EPOCH (01 Jan 1970 00:00:00 UTC), which is used by
7033      multiple build systems to force a timestamp in built binaries.
7034      Many upstream projects already support this variable.
7035
7036      You will find more details in the `official specifications
7037      <https://reproducible-builds.org/specs/source-date-epoch/>`__.
7038
7039      A value for each recipe is computed from the sources by
7040      :oe_git:`meta/lib/oe/reproducible.py </openembedded-core/tree/meta/lib/oe/reproducible.py>`.
7041
7042      If a recipe wishes to override the default behavior, it should set its
7043      own :term:`SOURCE_DATE_EPOCH` value::
7044
7045          SOURCE_DATE_EPOCH = "1613559011"
7046
7047   :term:`SOURCE_MIRROR_FETCH`
7048      When you are fetching files to create a mirror of sources (i.e.
7049      creating a source mirror), setting :term:`SOURCE_MIRROR_FETCH` to "1" in
7050      your ``local.conf`` configuration file ensures the source for all
7051      recipes are fetched regardless of whether or not a recipe is
7052      compatible with the configuration. A recipe is considered
7053      incompatible with the currently configured machine when either or
7054      both the :term:`COMPATIBLE_MACHINE`
7055      variable and :term:`COMPATIBLE_HOST` variables
7056      specify compatibility with a machine other than that of the current
7057      machine or host.
7058
7059      .. note::
7060
7061         Do not set the :term:`SOURCE_MIRROR_FETCH`
7062         variable unless you are creating a source mirror. In other words,
7063         do not set the variable during a normal build.
7064
7065   :term:`SOURCE_MIRROR_URL`
7066      Defines your own :term:`PREMIRRORS` from which to
7067      first fetch source before attempting to fetch from the upstream
7068      specified in :term:`SRC_URI`.
7069
7070      To use this variable, you must globally inherit the
7071      :ref:`own-mirrors <ref-classes-own-mirrors>` class and then provide
7072      the URL to your mirrors. Here is the general syntax::
7073
7074         INHERIT += "own-mirrors"
7075         SOURCE_MIRROR_URL = "http://example.com/my_source_mirror"
7076
7077      .. note::
7078
7079         You can specify only a single URL in :term:`SOURCE_MIRROR_URL`.
7080
7081   :term:`SPDXLICENSEMAP`
7082      Maps commonly used license names to their SPDX counterparts found in
7083      ``meta/files/common-licenses/``. For the default :term:`SPDXLICENSEMAP`
7084      mappings, see the ``meta/conf/licenses.conf`` file.
7085
7086      For additional information, see the :term:`LICENSE`
7087      variable.
7088
7089   :term:`SPECIAL_PKGSUFFIX`
7090      A list of prefixes for :term:`PN` used by the OpenEmbedded
7091      build system to create variants of recipes or packages. The list
7092      specifies the prefixes to strip off during certain circumstances such
7093      as the generation of the :term:`BPN` variable.
7094
7095   :term:`SPL_BINARY`
7096      The file type for the Secondary Program Loader (SPL). Some devices
7097      use an SPL from which to boot (e.g. the BeagleBone development
7098      board). For such cases, you can declare the file type of the SPL
7099      binary in the ``u-boot.inc`` include file, which is used in the
7100      U-Boot recipe.
7101
7102      The SPL file type is set to "null" by default in the ``u-boot.inc``
7103      file as follows::
7104
7105         # Some versions of u-boot build an SPL (Second Program Loader) image that
7106         # should be packaged along with the u-boot binary as well as placed in the
7107         # deploy directory. For those versions they can set the following variables
7108         # to allow packaging the SPL.
7109         SPL_BINARY ?= ""
7110         SPL_BINARYNAME ?= "${@os.path.basename(d.getVar("SPL_BINARY"))}"
7111         SPL_IMAGE ?= "${SPL_BINARYNAME}-${MACHINE}-${PV}-${PR}"
7112         SPL_SYMLINK ?= "${SPL_BINARYNAME}-${MACHINE}"
7113
7114      The :term:`SPL_BINARY` variable helps form
7115      various ``SPL_*`` variables used by the OpenEmbedded build system.
7116
7117      See the BeagleBone machine configuration example in the
7118      ":ref:`dev-manual/common-tasks:adding a layer using the \`\`bitbake-layers\`\` script`"
7119      section in the Yocto Project Board Support Package Developer's Guide
7120      for additional information.
7121
7122   :term:`SRC_URI`
7123
7124      See the BitBake manual for the initial description for this variable:
7125      :term:`bitbake:SRC_URI`.
7126
7127      The following features are added by OpenEmbedded and the Yocto Project.
7128
7129      There are standard and recipe-specific options. Here are standard ones:
7130
7131      -  ``apply`` --- whether to apply the patch or not. The default
7132         action is to apply the patch.
7133
7134      -  ``striplevel`` --- which striplevel to use when applying the
7135         patch. The default level is 1.
7136
7137      -  ``patchdir`` --- specifies the directory in which the patch should
7138         be applied. The default is ``${``\ :term:`S`\ ``}``.
7139
7140      Here are options specific to recipes building code from a revision
7141      control system:
7142
7143      -  ``mindate`` --- apply the patch only if
7144         :term:`SRCDATE` is equal to or greater than
7145         ``mindate``.
7146
7147      -  ``maxdate`` --- apply the patch only if :term:`SRCDATE` is not later
7148         than ``maxdate``.
7149
7150      -  ``minrev`` --- apply the patch only if :term:`SRCREV` is equal to or
7151         greater than ``minrev``.
7152
7153      -  ``maxrev`` --- apply the patch only if :term:`SRCREV` is not later
7154         than ``maxrev``.
7155
7156      -  ``rev`` --- apply the patch only if :term:`SRCREV` is equal to
7157         ``rev``.
7158
7159      -  ``notrev`` --- apply the patch only if :term:`SRCREV` is not equal to
7160         ``rev``.
7161
7162      .. note::
7163
7164         If you want the build system to pick up files specified through
7165         a :term:`SRC_URI` statement from your append file, you need to be
7166         sure to extend the :term:`FILESPATH` variable by also using the
7167         :term:`FILESEXTRAPATHS` variable from within your append file.
7168
7169   :term:`SRC_URI_OVERRIDES_PACKAGE_ARCH`
7170      By default, the OpenEmbedded build system automatically detects
7171      whether :term:`SRC_URI` contains files that are machine-specific. If so,
7172      the build system automatically changes :term:`PACKAGE_ARCH`. Setting this
7173      variable to "0" disables this behavior.
7174
7175   :term:`SRCDATE`
7176      The date of the source code used to build the package. This variable
7177      applies only if the source was fetched from a Source Code Manager
7178      (SCM).
7179
7180   :term:`SRCPV`
7181      Returns the version string of the current package. This string is
7182      used to help define the value of :term:`PV`.
7183
7184      The :term:`SRCPV` variable is defined in the ``meta/conf/bitbake.conf``
7185      configuration file in the :term:`Source Directory` as
7186      follows::
7187
7188         SRCPV = "${@bb.fetch2.get_srcrev(d)}"
7189
7190      Recipes that need to define :term:`PV` do so with the help of the
7191      :term:`SRCPV`. For example, the ``ofono`` recipe (``ofono_git.bb``)
7192      located in ``meta/recipes-connectivity`` in the Source Directory
7193      defines :term:`PV` as follows::
7194
7195         PV = "0.12-git${SRCPV}"
7196
7197   :term:`SRCREV`
7198      The revision of the source code used to build the package. This
7199      variable applies to Subversion, Git, Mercurial, and Bazaar only. Note
7200      that if you want to build a fixed revision and you want to avoid
7201      performing a query on the remote repository every time BitBake parses
7202      your recipe, you should specify a :term:`SRCREV` that is a full revision
7203      identifier and not just a tag.
7204
7205      .. note::
7206
7207         For information on limitations when inheriting the latest revision
7208         of software using :term:`SRCREV`, see the :term:`AUTOREV` variable
7209         description and the
7210         ":ref:`dev-manual/common-tasks:automatically incrementing a package version number`"
7211         section, which is in the Yocto Project Development Tasks Manual.
7212
7213   :term:`SRCTREECOVEREDTASKS`
7214      A list of tasks that are typically not relevant (and therefore skipped)
7215      when building using the :ref:`externalsrc <ref-classes-externalsrc>`
7216      class. The default value as set in that class file is the set of tasks
7217      that are rarely needed when using external source::
7218
7219         SRCTREECOVEREDTASKS ?= "do_patch do_unpack do_fetch"
7220
7221      The notable exception is when processing external kernel source as
7222      defined in the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
7223      class file (formatted for aesthetics)::
7224
7225         SRCTREECOVEREDTASKS += "\
7226           do_validate_branches \
7227           do_kernel_configcheck \
7228           do_kernel_checkout \
7229           do_fetch \
7230           do_unpack \
7231           do_patch \
7232         "
7233
7234      See the associated :term:`EXTERNALSRC` and :term:`EXTERNALSRC_BUILD`
7235      variables for more information.
7236
7237   :term:`SSTATE_DIR`
7238      The directory for the shared state cache.
7239
7240   :term:`SSTATE_EXCLUDEDEPS_SYSROOT`
7241      This variable allows to specify indirect dependencies to exclude
7242      from sysroots, for example to avoid the situations when a dependency on
7243      any ``-native`` recipe will pull in all dependencies of that recipe
7244      in the recipe sysroot. This behaviour might not always be wanted,
7245      for example when that ``-native`` recipe depends on build tools
7246      that are not relevant for the current recipe.
7247
7248      This way, irrelevant dependencies are ignored, which could have
7249      prevented the reuse of prebuilt artifacts stored in the Shared
7250      State Cache.
7251
7252      ``SSTATE_EXCLUDEDEPS_SYSROOT`` is evaluated as two regular
7253      expressions of recipe and dependency to ignore. An example
7254      is the rule in :oe_git:`meta/conf/layer.conf </meta/conf/layer.conf>`::
7255
7256         # Nothing needs to depend on libc-initial
7257         # base-passwd/shadow-sysroot don't need their dependencies
7258         SSTATE_EXCLUDEDEPS_SYSROOT += "\
7259             .*->.*-initial.* \
7260             .*(base-passwd|shadow-sysroot)->.* \
7261         "
7262
7263      The ``->`` substring represents the dependency between
7264      the two regular expressions.
7265
7266   :term:`SSTATE_MIRROR_ALLOW_NETWORK`
7267      If set to "1", allows fetches from mirrors that are specified in
7268      :term:`SSTATE_MIRRORS` to work even when
7269      fetching from the network is disabled by setting :term:`BB_NO_NETWORK` to
7270      "1". Using the :term:`SSTATE_MIRROR_ALLOW_NETWORK` variable is useful if
7271      you have set :term:`SSTATE_MIRRORS` to point to an internal server for
7272      your shared state cache, but you want to disable any other fetching
7273      from the network.
7274
7275   :term:`SSTATE_MIRRORS`
7276      Configures the OpenEmbedded build system to search other mirror
7277      locations for prebuilt cache data objects before building out the
7278      data. This variable works like fetcher :term:`MIRRORS`
7279      and :term:`PREMIRRORS` and points to the cache
7280      locations to check for the shared state (sstate) objects.
7281
7282      You can specify a filesystem directory or a remote URL such as HTTP
7283      or FTP. The locations you specify need to contain the shared state
7284      cache (sstate-cache) results from previous builds. The sstate-cache
7285      you point to can also be from builds on other machines.
7286
7287      When pointing to sstate build artifacts on another machine that uses
7288      a different GCC version for native builds, you must configure
7289      :term:`SSTATE_MIRRORS` with a regular expression that maps local search
7290      paths to server paths. The paths need to take into account
7291      :term:`NATIVELSBSTRING` set by the
7292      :ref:`uninative <ref-classes-uninative>` class. For example, the
7293      following maps the local search path ``universal-4.9`` to the
7294      server-provided path server_url_sstate_path::
7295
7296         SSTATE_MIRRORS ?= "file://universal-4.9/(.*) https://server_url_sstate_path/universal-4.8/\1"
7297
7298      If a mirror uses the same structure as
7299      :term:`SSTATE_DIR`, you need to add "PATH" at the
7300      end as shown in the examples below. The build system substitutes the
7301      correct path within the directory structure.
7302      ::
7303
7304         SSTATE_MIRRORS ?= "\
7305             file://.* https://someserver.tld/share/sstate/PATH;downloadfilename=PATH \
7306             file://.* file:///some-local-dir/sstate/PATH"
7307
7308   :term:`SSTATE_SCAN_FILES`
7309      Controls the list of files the OpenEmbedded build system scans for
7310      hardcoded installation paths. The variable uses a space-separated
7311      list of filenames (not paths) with standard wildcard characters
7312      allowed.
7313
7314      During a build, the OpenEmbedded build system creates a shared state
7315      (sstate) object during the first stage of preparing the sysroots.
7316      That object is scanned for hardcoded paths for original installation
7317      locations. The list of files that are scanned for paths is controlled
7318      by the :term:`SSTATE_SCAN_FILES` variable. Typically, recipes add files
7319      they want to be scanned to the value of :term:`SSTATE_SCAN_FILES` rather
7320      than the variable being comprehensively set. The
7321      :ref:`sstate <ref-classes-sstate>` class specifies the default list
7322      of files.
7323
7324      For details on the process, see the
7325      :ref:`staging <ref-classes-staging>` class.
7326
7327   :term:`STAGING_BASE_LIBDIR_NATIVE`
7328      Specifies the path to the ``/lib`` subdirectory of the sysroot
7329      directory for the build host.
7330
7331   :term:`STAGING_BASELIBDIR`
7332      Specifies the path to the ``/lib`` subdirectory of the sysroot
7333      directory for the target for which the current recipe is being built
7334      (:term:`STAGING_DIR_HOST`).
7335
7336   :term:`STAGING_BINDIR`
7337      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7338      directory for the target for which the current recipe is being built
7339      (:term:`STAGING_DIR_HOST`).
7340
7341   :term:`STAGING_BINDIR_CROSS`
7342      Specifies the path to the directory containing binary configuration
7343      scripts. These scripts provide configuration information for other
7344      software that wants to make use of libraries or include files
7345      provided by the software associated with the script.
7346
7347      .. note::
7348
7349         This style of build configuration has been largely replaced by
7350         ``pkg-config``. Consequently, if ``pkg-config`` is supported by the
7351         library to which you are linking, it is recommended you use
7352         ``pkg-config`` instead of a provided configuration script.
7353
7354   :term:`STAGING_BINDIR_NATIVE`
7355      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7356      directory for the build host.
7357
7358   :term:`STAGING_DATADIR`
7359      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7360      directory for the target for which the current recipe is being built
7361      (:term:`STAGING_DIR_HOST`).
7362
7363   :term:`STAGING_DATADIR_NATIVE`
7364      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7365      directory for the build host.
7366
7367   :term:`STAGING_DIR`
7368      Helps construct the ``recipe-sysroots`` directory, which is used
7369      during packaging.
7370
7371      For information on how staging for recipe-specific sysroots occurs,
7372      see the :ref:`ref-tasks-populate_sysroot`
7373      task, the ":ref:`sdk-manual/extensible:sharing files between recipes`"
7374      section in the Yocto Project Development Tasks Manual, the
7375      ":ref:`overview-manual/concepts:configuration, compilation, and staging`"
7376      section in the Yocto Project Overview and Concepts Manual, and the
7377      :term:`SYSROOT_DIRS` variable.
7378
7379      .. note::
7380
7381         Recipes should never write files directly under the :term:`STAGING_DIR`
7382         directory because the OpenEmbedded build system manages the
7383         directory automatically. Instead, files should be installed to
7384         ``${``\ :term:`D`\ ``}`` within your recipe's :ref:`ref-tasks-install`
7385         task and then the OpenEmbedded build system will stage a subset of
7386         those files into the sysroot.
7387
7388   :term:`STAGING_DIR_HOST`
7389      Specifies the path to the sysroot directory for the system on which
7390      the component is built to run (the system that hosts the component).
7391      For most recipes, this sysroot is the one in which that recipe's
7392      :ref:`ref-tasks-populate_sysroot` task copies
7393      files. Exceptions include ``-native`` recipes, where the
7394      ``do_populate_sysroot`` task instead uses
7395      :term:`STAGING_DIR_NATIVE`. Depending on
7396      the type of recipe and the build target, :term:`STAGING_DIR_HOST` can
7397      have the following values:
7398
7399      -  For recipes building for the target machine, the value is
7400         "${:term:`STAGING_DIR`}/${:term:`MACHINE`}".
7401
7402      -  For native recipes building for the build host, the value is empty
7403         given the assumption that when building for the build host, the
7404         build host's own directories should be used.
7405
7406         .. note::
7407
7408            ``-native`` recipes are not installed into host paths like such
7409            as ``/usr``. Rather, these recipes are installed into
7410            :term:`STAGING_DIR_NATIVE`. When compiling ``-native`` recipes,
7411            standard build environment variables such as
7412            :term:`CPPFLAGS` and
7413            :term:`CFLAGS` are set up so that both host paths
7414            and :term:`STAGING_DIR_NATIVE` are searched for libraries and
7415            headers using, for example, GCC's ``-isystem`` option.
7416
7417            Thus, the emphasis is that the ``STAGING_DIR*`` variables
7418            should be viewed as input variables by tasks such as
7419            :ref:`ref-tasks-configure`,
7420            :ref:`ref-tasks-compile`, and
7421            :ref:`ref-tasks-install`. Having the real system
7422            root correspond to :term:`STAGING_DIR_HOST` makes conceptual sense
7423            for ``-native`` recipes, as they make use of host headers and
7424            libraries.
7425
7426   :term:`STAGING_DIR_NATIVE`
7427      Specifies the path to the sysroot directory used when building
7428      components that run on the build host itself.
7429
7430   :term:`STAGING_DIR_TARGET`
7431      Specifies the path to the sysroot used for the system for which the
7432      component generates code. For components that do not generate code,
7433      which is the majority, :term:`STAGING_DIR_TARGET` is set to match
7434      :term:`STAGING_DIR_HOST`.
7435
7436      Some recipes build binaries that can run on the target system but
7437      those binaries in turn generate code for another different system
7438      (e.g. cross-canadian recipes). Using terminology from GNU, the
7439      primary system is referred to as the "HOST" and the secondary, or
7440      different, system is referred to as the "TARGET". Thus, the binaries
7441      run on the "HOST" system and generate binaries for the "TARGET"
7442      system. The :term:`STAGING_DIR_HOST` variable points to the sysroot used
7443      for the "HOST" system, while :term:`STAGING_DIR_TARGET` points to the
7444      sysroot used for the "TARGET" system.
7445
7446   :term:`STAGING_ETCDIR_NATIVE`
7447      Specifies the path to the ``/etc`` subdirectory of the sysroot
7448      directory for the build host.
7449
7450   :term:`STAGING_EXECPREFIXDIR`
7451      Specifies the path to the ``/usr`` subdirectory of the sysroot
7452      directory for the target for which the current recipe is being built
7453      (:term:`STAGING_DIR_HOST`).
7454
7455   :term:`STAGING_INCDIR`
7456      Specifies the path to the ``/usr/include`` subdirectory of the
7457      sysroot directory for the target for which the current recipe being
7458      built (:term:`STAGING_DIR_HOST`).
7459
7460   :term:`STAGING_INCDIR_NATIVE`
7461      Specifies the path to the ``/usr/include`` subdirectory of the
7462      sysroot directory for the build host.
7463
7464   :term:`STAGING_KERNEL_BUILDDIR`
7465      Points to the directory containing the kernel build artifacts.
7466      Recipes building software that needs to access kernel build artifacts
7467      (e.g. ``systemtap-uprobes``) can look in the directory specified with
7468      the :term:`STAGING_KERNEL_BUILDDIR` variable to find these artifacts
7469      after the kernel has been built.
7470
7471   :term:`STAGING_KERNEL_DIR`
7472      The directory with kernel headers that are required to build
7473      out-of-tree modules.
7474
7475   :term:`STAGING_LIBDIR`
7476      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
7477      directory for the target for which the current recipe is being built
7478      (:term:`STAGING_DIR_HOST`).
7479
7480   :term:`STAGING_LIBDIR_NATIVE`
7481      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
7482      directory for the build host.
7483
7484   :term:`STAMP`
7485      Specifies the base path used to create recipe stamp files. The path
7486      to an actual stamp file is constructed by evaluating this string and
7487      then appending additional information. Currently, the default
7488      assignment for :term:`STAMP` as set in the ``meta/conf/bitbake.conf``
7489      file is::
7490
7491         STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
7492
7493      For information on how BitBake uses stamp files to determine if a
7494      task should be rerun, see the
7495      ":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`"
7496      section in the Yocto Project Overview and Concepts Manual.
7497
7498      See :term:`STAMPS_DIR`,
7499      :term:`MULTIMACH_TARGET_SYS`,
7500      :term:`PN`, :term:`EXTENDPE`,
7501      :term:`PV`, and :term:`PR` for related variable
7502      information.
7503
7504   :term:`STAMPS_DIR`
7505      Specifies the base directory in which the OpenEmbedded build system
7506      places stamps. The default directory is ``${TMPDIR}/stamps``.
7507
7508   :term:`STRIP`
7509      The minimal command and arguments to run ``strip``, which is used to
7510      strip symbols.
7511
7512   :term:`SUMMARY`
7513      The short (72 characters or less) summary of the binary package for
7514      packaging systems such as ``opkg``, ``rpm``, or ``dpkg``. By default,
7515      :term:`SUMMARY` is used to define the
7516      :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
7517      not set in the recipe.
7518
7519   :term:`SVNDIR`
7520      The directory in which files checked out of a Subversion system are
7521      stored.
7522
7523   :term:`SYSLINUX_DEFAULT_CONSOLE`
7524      Specifies the kernel boot default console. If you want to use a
7525      console other than the default, set this variable in your recipe as
7526      follows where "X" is the console number you want to use::
7527
7528         SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
7529
7530      The :ref:`syslinux <ref-classes-syslinux>` class initially sets
7531      this variable to null but then checks for a value later.
7532
7533   :term:`SYSLINUX_OPTS`
7534      Lists additional options to add to the syslinux file. You need to set
7535      this variable in your recipe. If you want to list multiple options,
7536      separate the options with a semicolon character (``;``).
7537
7538      The :ref:`syslinux <ref-classes-syslinux>` class uses this variable
7539      to create a set of options.
7540
7541   :term:`SYSLINUX_SERIAL`
7542      Specifies the alternate serial port or turns it off. To turn off
7543      serial, set this variable to an empty string in your recipe. The
7544      variable's default value is set in the
7545      :ref:`syslinux <ref-classes-syslinux>` class as follows::
7546
7547         SYSLINUX_SERIAL ?= "0 115200"
7548
7549      The class checks for and uses the variable as needed.
7550
7551   :term:`SYSLINUX_SERIAL_TTY`
7552      Specifies the alternate console=tty... kernel boot argument. The
7553      variable's default value is set in the
7554      :ref:`syslinux <ref-classes-syslinux>` class as follows::
7555
7556         SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
7557
7558      The class checks for and uses the variable as needed.
7559
7560   :term:`SYSLINUX_SPLASH`
7561      An ``.LSS`` file used as the background for the VGA boot menu when
7562      you use the boot menu. You need to set this variable in your recipe.
7563
7564      The :ref:`syslinux <ref-classes-syslinux>` class checks for this
7565      variable and if found, the OpenEmbedded build system installs the
7566      splash screen.
7567
7568   :term:`SYSROOT_DESTDIR`
7569      Points to the temporary directory under the work directory (default
7570      "``${``\ :term:`WORKDIR`\ ``}/sysroot-destdir``")
7571      where the files populated into the sysroot are assembled during the
7572      :ref:`ref-tasks-populate_sysroot` task.
7573
7574   :term:`SYSROOT_DIRS`
7575      Directories that are staged into the sysroot by the
7576      :ref:`ref-tasks-populate_sysroot` task. By
7577      default, the following directories are staged::
7578
7579         SYSROOT_DIRS = " \
7580             ${includedir} \
7581             ${libdir} \
7582             ${base_libdir} \
7583             ${nonarch_base_libdir} \
7584             ${datadir} \
7585             /sysroot-only \
7586             "
7587
7588   :term:`SYSROOT_DIRS_IGNORE`
7589      Directories that are not staged into the sysroot by the
7590      :ref:`ref-tasks-populate_sysroot` task. You
7591      can use this variable to exclude certain subdirectories of
7592      directories listed in :term:`SYSROOT_DIRS` from
7593      staging. By default, the following directories are not staged::
7594
7595         SYSROOT_DIRS_IGNORE = " \
7596             ${mandir} \
7597             ${docdir} \
7598             ${infodir} \
7599             ${datadir}/X11/locale \
7600             ${datadir}/applications \
7601             ${datadir}/bash-completion \
7602             ${datadir}/fonts \
7603             ${datadir}/gtk-doc/html \
7604             ${datadir}/installed-tests \
7605             ${datadir}/locale \
7606             ${datadir}/pixmaps \
7607             ${datadir}/terminfo \
7608             ${libdir}/${BPN}/ptest \
7609             "
7610
7611   :term:`SYSROOT_DIRS_NATIVE`
7612      Extra directories staged into the sysroot by the
7613      :ref:`ref-tasks-populate_sysroot` task for
7614      ``-native`` recipes, in addition to those specified in
7615      :term:`SYSROOT_DIRS`. By default, the following
7616      extra directories are staged::
7617
7618         SYSROOT_DIRS_NATIVE = " \
7619             ${bindir} \
7620             ${sbindir} \
7621             ${base_bindir} \
7622             ${base_sbindir} \
7623             ${libexecdir} \
7624             ${sysconfdir} \
7625             ${localstatedir} \
7626             "
7627
7628      .. note::
7629
7630         Programs built by ``-native`` recipes run directly from the sysroot
7631         (:term:`STAGING_DIR_NATIVE`), which is why additional directories
7632         containing program executables and supporting files need to be staged.
7633
7634   :term:`SYSROOT_PREPROCESS_FUNCS`
7635      A list of functions to execute after files are staged into the
7636      sysroot. These functions are usually used to apply additional
7637      processing on the staged files, or to stage additional files.
7638
7639   :term:`SYSTEMD_AUTO_ENABLE`
7640      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7641      this variable specifies whether the specified service in
7642      :term:`SYSTEMD_SERVICE` should start
7643      automatically or not. By default, the service is enabled to
7644      automatically start at boot time. The default setting is in the
7645      :ref:`systemd <ref-classes-systemd>` class as follows::
7646
7647         SYSTEMD_AUTO_ENABLE ??= "enable"
7648
7649      You can disable the service by setting the variable to "disable".
7650
7651   :term:`SYSTEMD_BOOT_CFG`
7652      When :term:`EFI_PROVIDER` is set to
7653      "systemd-boot", the :term:`SYSTEMD_BOOT_CFG` variable specifies the
7654      configuration file that should be used. By default, the
7655      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7656      :term:`SYSTEMD_BOOT_CFG` as follows::
7657
7658         SYSTEMD_BOOT_CFG ?= "${:term:`S`}/loader.conf"
7659
7660      For information on Systemd-boot, see the `Systemd-boot
7661      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7662
7663   :term:`SYSTEMD_BOOT_ENTRIES`
7664      When :term:`EFI_PROVIDER` is set to
7665      "systemd-boot", the :term:`SYSTEMD_BOOT_ENTRIES` variable specifies a
7666      list of entry files (``*.conf``) to install that contain one boot
7667      entry per file. By default, the
7668      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7669      :term:`SYSTEMD_BOOT_ENTRIES` as follows::
7670
7671          SYSTEMD_BOOT_ENTRIES ?= ""
7672
7673      For information on Systemd-boot, see the `Systemd-boot
7674      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7675
7676   :term:`SYSTEMD_BOOT_TIMEOUT`
7677      When :term:`EFI_PROVIDER` is set to
7678      "systemd-boot", the :term:`SYSTEMD_BOOT_TIMEOUT` variable specifies the
7679      boot menu timeout in seconds. By default, the
7680      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7681      :term:`SYSTEMD_BOOT_TIMEOUT` as follows::
7682
7683         SYSTEMD_BOOT_TIMEOUT ?= "10"
7684
7685      For information on Systemd-boot, see the `Systemd-boot
7686      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7687
7688   :term:`SYSTEMD_DEFAULT_TARGET`
7689
7690      This variable allows to set the default unit that systemd starts at bootup.
7691      Usually, this is either ``multi-user.target`` or ``graphical.target``.
7692      This works by creating a ``default.target`` symbolic link to the chosen systemd
7693      target file.
7694
7695      See `systemd's documentation
7696      <https://www.freedesktop.org/software/systemd/man/systemd.special.html>`__
7697      for details.
7698
7699      For example, this variable is used in the
7700      `core-image-minimal-xfce.bb
7701      <https://git.openembedded.org/meta-openembedded/tree/meta-xfce/recipes-core/images/core-image-minimal-xfce.bb>`__
7702      recipe::
7703
7704          SYSTEMD_DEFAULT_TARGET = "graphical.target"
7705
7706   :term:`SYSTEMD_PACKAGES`
7707      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7708      this variable locates the systemd unit files when they are not found
7709      in the main recipe's package. By default, the :term:`SYSTEMD_PACKAGES`
7710      variable is set such that the systemd unit files are assumed to
7711      reside in the recipes main package::
7712
7713         SYSTEMD_PACKAGES ?= "${PN}"
7714
7715      If these unit files are not in this recipe's main package, you need
7716      to use :term:`SYSTEMD_PACKAGES` to list the package or packages in which
7717      the build system can find the systemd unit files.
7718
7719   :term:`SYSTEMD_SERVICE`
7720      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7721      this variable specifies the systemd service name for a package.
7722
7723      Multiple services can be specified, each one separated by a space.
7724
7725      When you specify this file in your recipe, use a package name
7726      override to indicate the package to which the value applies. Here is
7727      an example from the connman recipe::
7728
7729         SYSTEMD_SERVICE:${PN} = "connman.service"
7730
7731      The package overrides that can be specified are directly related to the value of
7732      term:`SYSTEMD_PACKAGES`. Overrides not included in term:`SYSTEMD_PACKAGES`
7733      will be silently ignored.
7734
7735   :term:`SYSVINIT_ENABLED_GETTYS`
7736      When using
7737      :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,
7738      specifies a space-separated list of the virtual terminals that should
7739      run a `getty <https://en.wikipedia.org/wiki/Getty_%28Unix%29>`__
7740      (allowing login), assuming :term:`USE_VT` is not set to
7741      "0".
7742
7743      The default value for :term:`SYSVINIT_ENABLED_GETTYS` is "1" (i.e. only
7744      run a getty on the first virtual terminal).
7745
7746   :term:`T`
7747      This variable points to a directory were BitBake places temporary
7748      files, which consist mostly of task logs and scripts, when building a
7749      particular recipe. The variable is typically set as follows::
7750
7751         T = "${WORKDIR}/temp"
7752
7753      The :term:`WORKDIR` is the directory into which
7754      BitBake unpacks and builds the recipe. The default ``bitbake.conf``
7755      file sets this variable.
7756
7757      The :term:`T` variable is not to be confused with the
7758      :term:`TMPDIR` variable, which points to the root of
7759      the directory tree where BitBake places the output of an entire
7760      build.
7761
7762   :term:`TARGET_ARCH`
7763      The target machine's architecture. The OpenEmbedded build system
7764      supports many architectures. Here is an example list of architectures
7765      supported. This list is by no means complete as the architecture is
7766      configurable:
7767
7768      - arm
7769      - i586
7770      - x86_64
7771      - powerpc
7772      - powerpc64
7773      - mips
7774      - mipsel
7775
7776      For additional information on machine architectures, see the
7777      :term:`TUNE_ARCH` variable.
7778
7779   :term:`TARGET_AS_ARCH`
7780      Specifies architecture-specific assembler flags for the target
7781      system. :term:`TARGET_AS_ARCH` is initialized from
7782      :term:`TUNE_ASARGS` by default in the BitBake
7783      configuration file (``meta/conf/bitbake.conf``)::
7784
7785         TARGET_AS_ARCH = "${TUNE_ASARGS}"
7786
7787   :term:`TARGET_CC_ARCH`
7788      Specifies architecture-specific C compiler flags for the target
7789      system. :term:`TARGET_CC_ARCH` is initialized from
7790      :term:`TUNE_CCARGS` by default.
7791
7792      .. note::
7793
7794         It is a common workaround to append :term:`LDFLAGS` to
7795         :term:`TARGET_CC_ARCH` in recipes that build software for the target that
7796         would not otherwise respect the exported :term:`LDFLAGS` variable.
7797
7798   :term:`TARGET_CC_KERNEL_ARCH`
7799      This is a specific kernel compiler flag for a CPU or Application
7800      Binary Interface (ABI) tune. The flag is used rarely and only for
7801      cases where a userspace :term:`TUNE_CCARGS` is not
7802      compatible with the kernel compilation. The :term:`TARGET_CC_KERNEL_ARCH`
7803      variable allows the kernel (and associated modules) to use a
7804      different configuration. See the
7805      ``meta/conf/machine/include/arm/feature-arm-thumb.inc`` file in the
7806      :term:`Source Directory` for an example.
7807
7808   :term:`TARGET_CFLAGS`
7809      Specifies the flags to pass to the C compiler when building for the
7810      target. When building in the target context,
7811      :term:`CFLAGS` is set to the value of this variable by
7812      default.
7813
7814      Additionally, the SDK's environment setup script sets the :term:`CFLAGS`
7815      variable in the environment to the :term:`TARGET_CFLAGS` value so that
7816      executables built using the SDK also have the flags applied.
7817
7818   :term:`TARGET_CPPFLAGS`
7819      Specifies the flags to pass to the C pre-processor (i.e. to both the
7820      C and the C++ compilers) when building for the target. When building
7821      in the target context, :term:`CPPFLAGS` is set to the
7822      value of this variable by default.
7823
7824      Additionally, the SDK's environment setup script sets the
7825      :term:`CPPFLAGS` variable in the environment to the :term:`TARGET_CPPFLAGS`
7826      value so that executables built using the SDK also have the flags
7827      applied.
7828
7829   :term:`TARGET_CXXFLAGS`
7830      Specifies the flags to pass to the C++ compiler when building for the
7831      target. When building in the target context,
7832      :term:`CXXFLAGS` is set to the value of this variable
7833      by default.
7834
7835      Additionally, the SDK's environment setup script sets the
7836      :term:`CXXFLAGS` variable in the environment to the :term:`TARGET_CXXFLAGS`
7837      value so that executables built using the SDK also have the flags
7838      applied.
7839
7840   :term:`TARGET_FPU`
7841      Specifies the method for handling FPU code. For FPU-less targets,
7842      which include most ARM CPUs, the variable must be set to "soft". If
7843      not, the kernel emulation gets used, which results in a performance
7844      penalty.
7845
7846   :term:`TARGET_LD_ARCH`
7847      Specifies architecture-specific linker flags for the target system.
7848      :term:`TARGET_LD_ARCH` is initialized from
7849      :term:`TUNE_LDARGS` by default in the BitBake
7850      configuration file (``meta/conf/bitbake.conf``)::
7851
7852         TARGET_LD_ARCH = "${TUNE_LDARGS}"
7853
7854   :term:`TARGET_LDFLAGS`
7855      Specifies the flags to pass to the linker when building for the
7856      target. When building in the target context,
7857      :term:`LDFLAGS` is set to the value of this variable
7858      by default.
7859
7860      Additionally, the SDK's environment setup script sets the
7861      :term:`LDFLAGS` variable in the environment to the
7862      :term:`TARGET_LDFLAGS` value so that executables built using the SDK also
7863      have the flags applied.
7864
7865   :term:`TARGET_OS`
7866      Specifies the target's operating system. The variable can be set to
7867      "linux" for glibc-based systems (GNU C Library) and to "linux-musl"
7868      for musl libc. For ARM/EABI targets, the possible values are
7869      "linux-gnueabi" and "linux-musleabi".
7870
7871   :term:`TARGET_PREFIX`
7872      Specifies the prefix used for the toolchain binary target tools.
7873
7874      Depending on the type of recipe and the build target,
7875      :term:`TARGET_PREFIX` is set as follows:
7876
7877      -  For recipes building for the target machine, the value is
7878         "${:term:`TARGET_SYS`}-".
7879
7880      -  For native recipes, the build system sets the variable to the
7881         value of :term:`BUILD_PREFIX`.
7882
7883      -  For native SDK recipes (``nativesdk``), the build system sets the
7884         variable to the value of :term:`SDK_PREFIX`.
7885
7886   :term:`TARGET_SYS`
7887      Specifies the system, including the architecture and the operating
7888      system, for which the build is occurring in the context of the
7889      current recipe.
7890
7891      The OpenEmbedded build system automatically sets this variable based
7892      on :term:`TARGET_ARCH`,
7893      :term:`TARGET_VENDOR`, and
7894      :term:`TARGET_OS` variables.
7895
7896      .. note::
7897
7898         You do not need to set the :term:`TARGET_SYS` variable yourself.
7899
7900      Consider these two examples:
7901
7902      -  Given a native recipe on a 32-bit, x86 machine running Linux, the
7903         value is "i686-linux".
7904
7905      -  Given a recipe being built for a little-endian, MIPS target
7906         running Linux, the value might be "mipsel-linux".
7907
7908   :term:`TARGET_VENDOR`
7909      Specifies the name of the target vendor.
7910
7911   :term:`TCLIBC`
7912      Specifies the GNU standard C library (``libc``) variant to use during
7913      the build process.
7914
7915      You can select "glibc", "musl", "newlib", or "baremetal".
7916
7917   :term:`TCLIBCAPPEND`
7918      Specifies a suffix to be appended onto the
7919      :term:`TMPDIR` value. The suffix identifies the
7920      ``libc`` variant for building. When you are building for multiple
7921      variants with the same :term:`Build Directory`, this
7922      mechanism ensures that output for different ``libc`` variants is kept
7923      separate to avoid potential conflicts.
7924
7925      In the ``defaultsetup.conf`` file, the default value of
7926      :term:`TCLIBCAPPEND` is "-${TCLIBC}". However, distros such as poky,
7927      which normally only support one ``libc`` variant, set
7928      :term:`TCLIBCAPPEND` to "" in their distro configuration file resulting
7929      in no suffix being applied.
7930
7931   :term:`TCMODE`
7932      Specifies the toolchain selector. :term:`TCMODE` controls the
7933      characteristics of the generated packages and images by telling the
7934      OpenEmbedded build system which toolchain profile to use. By default,
7935      the OpenEmbedded build system builds its own internal toolchain. The
7936      variable's default value is "default", which uses that internal
7937      toolchain.
7938
7939      .. note::
7940
7941         If :term:`TCMODE` is set to a value other than "default", then it is your
7942         responsibility to ensure that the toolchain is compatible with the
7943         default toolchain. Using older or newer versions of these
7944         components might cause build problems. See the Release Notes for
7945         the Yocto Project release for the specific components with which
7946         the toolchain must be compatible. To access the Release Notes, go
7947         to the :yocto_home:`Downloads </software-overview/downloads>`
7948         page on the Yocto Project website and click on the "RELEASE
7949         INFORMATION" link for the appropriate release.
7950
7951      The :term:`TCMODE` variable is similar to :term:`TCLIBC`,
7952      which controls the variant of the GNU standard C library (``libc``)
7953      used during the build process: ``glibc`` or ``musl``.
7954
7955      With additional layers, it is possible to use a pre-compiled external
7956      toolchain. One example is the Sourcery G++ Toolchain. The support for
7957      this toolchain resides in the separate Mentor Graphics
7958      ``meta-sourcery`` layer at
7959      https://github.com/MentorEmbedded/meta-sourcery/.
7960
7961      The layer's ``README`` file contains information on how to use the
7962      Sourcery G++ Toolchain as an external toolchain. In summary, you must
7963      be sure to add the layer to your ``bblayers.conf`` file in front of
7964      the ``meta`` layer and then set the ``EXTERNAL_TOOLCHAIN`` variable
7965      in your ``local.conf`` file to the location in which you installed
7966      the toolchain.
7967
7968      The fundamentals used for this example apply to any external
7969      toolchain. You can use ``meta-sourcery`` as a template for adding
7970      support for other external toolchains.
7971
7972   :term:`TEMPLATECONF`
7973      Specifies the directory used by the build system to find templates
7974      from which to build the ``bblayers.conf`` and ``local.conf`` files.
7975      Use this variable if you wish to customize such files, and the default
7976      BitBake targets shown when sourcing the ``oe-init-build-env`` script.
7977
7978      For details, see the
7979      :ref:`dev-manual/common-tasks:creating a custom template configuration directory`
7980      section in the Yocto Project Development Tasks manual.
7981
7982      .. note::
7983
7984         You must set this variable in the external environment in order
7985         for it to work.
7986
7987   :term:`TEST_EXPORT_DIR`
7988      The location the OpenEmbedded build system uses to export tests when
7989      the :term:`TEST_EXPORT_ONLY` variable is set
7990      to "1".
7991
7992      The :term:`TEST_EXPORT_DIR` variable defaults to
7993      ``"${TMPDIR}/testimage/${PN}"``.
7994
7995   :term:`TEST_EXPORT_ONLY`
7996      Specifies to export the tests only. Set this variable to "1" if you
7997      do not want to run the tests but you want them to be exported in a
7998      manner that you to run them outside of the build system.
7999
8000   :term:`TEST_LOG_DIR`
8001      Holds the SSH log and the boot log for QEMU machines. The
8002      :term:`TEST_LOG_DIR` variable defaults to ``"${WORKDIR}/testimage"``.
8003
8004      .. note::
8005
8006         Actual test results reside in the task log (``log.do_testimage``),
8007         which is in the ``${WORKDIR}/temp/`` directory.
8008
8009   :term:`TEST_POWERCONTROL_CMD`
8010      For automated hardware testing, specifies the command to use to
8011      control the power of the target machine under test. Typically, this
8012      command would point to a script that performs the appropriate action
8013      (e.g. interacting with a web-enabled power strip). The specified
8014      command should expect to receive as the last argument "off", "on" or
8015      "cycle" specifying to power off, on, or cycle (power off and then
8016      power on) the device, respectively.
8017
8018   :term:`TEST_POWERCONTROL_EXTRA_ARGS`
8019      For automated hardware testing, specifies additional arguments to
8020      pass through to the command specified in
8021      :term:`TEST_POWERCONTROL_CMD`. Setting
8022      :term:`TEST_POWERCONTROL_EXTRA_ARGS` is optional. You can use it if you
8023      wish, for example, to separate the machine-specific and
8024      non-machine-specific parts of the arguments.
8025
8026   :term:`TEST_QEMUBOOT_TIMEOUT`
8027      The time in seconds allowed for an image to boot before automated
8028      runtime tests begin to run against an image. The default timeout
8029      period to allow the boot process to reach the login prompt is 500
8030      seconds. You can specify a different value in the ``local.conf``
8031      file.
8032
8033      For more information on testing images, see the
8034      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
8035      section in the Yocto Project Development Tasks Manual.
8036
8037   :term:`TEST_SERIALCONTROL_CMD`
8038      For automated hardware testing, specifies the command to use to
8039      connect to the serial console of the target machine under test. This
8040      command simply needs to connect to the serial console and forward
8041      that connection to standard input and output as any normal terminal
8042      program does.
8043
8044      For example, to use the Picocom terminal program on serial device
8045      ``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows::
8046
8047         TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
8048
8049   :term:`TEST_SERIALCONTROL_EXTRA_ARGS`
8050      For automated hardware testing, specifies additional arguments to
8051      pass through to the command specified in
8052      :term:`TEST_SERIALCONTROL_CMD`. Setting
8053      :term:`TEST_SERIALCONTROL_EXTRA_ARGS` is optional. You can use it if you
8054      wish, for example, to separate the machine-specific and
8055      non-machine-specific parts of the command.
8056
8057   :term:`TEST_SERVER_IP`
8058      The IP address of the build machine (host machine). This IP address
8059      is usually automatically detected. However, if detection fails, this
8060      variable needs to be set to the IP address of the build machine (i.e.
8061      where the build is taking place).
8062
8063      .. note::
8064
8065         The :term:`TEST_SERVER_IP` variable is only used for a small number of
8066         tests such as the "dnf" test suite, which needs to download packages
8067         from ``WORKDIR/oe-rootfs-repo``.
8068
8069   :term:`TEST_SUITES`
8070      An ordered list of tests (modules) to run against an image when
8071      performing automated runtime testing.
8072
8073      The OpenEmbedded build system provides a core set of tests that can
8074      be used against images.
8075
8076      .. note::
8077
8078         Currently, there is only support for running these tests under
8079         QEMU.
8080
8081      Tests include ``ping``, ``ssh``, ``df`` among others. You can add
8082      your own tests to the list of tests by appending :term:`TEST_SUITES` as
8083      follows::
8084
8085         TEST_SUITES:append = " mytest"
8086
8087      Alternatively, you can
8088      provide the "auto" option to have all applicable tests run against
8089      the image.
8090      ::
8091
8092         TEST_SUITES:append = " auto"
8093
8094      Using this option causes the
8095      build system to automatically run tests that are applicable to the
8096      image. Tests that are not applicable are skipped.
8097
8098      The order in which tests are run is important. Tests that depend on
8099      another test must appear later in the list than the test on which
8100      they depend. For example, if you append the list of tests with two
8101      tests (``test_A`` and ``test_B``) where ``test_B`` is dependent on
8102      ``test_A``, then you must order the tests as follows::
8103
8104         TEST_SUITES = "test_A test_B"
8105
8106      For more information on testing images, see the
8107      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
8108      section in the Yocto Project Development Tasks Manual.
8109
8110   :term:`TEST_TARGET`
8111      Specifies the target controller to use when running tests against a
8112      test image. The default controller to use is "qemu"::
8113
8114         TEST_TARGET = "qemu"
8115
8116      A target controller is a class that defines how an image gets
8117      deployed on a target and how a target is started. A layer can extend
8118      the controllers by adding a module in the layer's
8119      ``/lib/oeqa/controllers`` directory and by inheriting the
8120      ``BaseTarget`` class, which is an abstract class that cannot be used
8121      as a value of :term:`TEST_TARGET`.
8122
8123      You can provide the following arguments with :term:`TEST_TARGET`:
8124
8125      -  *"qemu":* Boots a QEMU image and runs the tests. See the
8126         ":ref:`dev-manual/common-tasks:enabling runtime tests on qemu`" section
8127         in the Yocto Project Development Tasks Manual for more
8128         information.
8129
8130      -  *"simpleremote":* Runs the tests on target hardware that is
8131         already up and running. The hardware can be on the network or it
8132         can be a device running an image on QEMU. You must also set
8133         :term:`TEST_TARGET_IP` when you use
8134         "simpleremote".
8135
8136         .. note::
8137
8138            This argument is defined in
8139            ``meta/lib/oeqa/controllers/simpleremote.py``.
8140
8141      For information on running tests on hardware, see the
8142      ":ref:`dev-manual/common-tasks:enabling runtime tests on hardware`"
8143      section in the Yocto Project Development Tasks Manual.
8144
8145   :term:`TEST_TARGET_IP`
8146      The IP address of your hardware under test. The :term:`TEST_TARGET_IP`
8147      variable has no effect when :term:`TEST_TARGET` is
8148      set to "qemu".
8149
8150      When you specify the IP address, you can also include a port. Here is
8151      an example::
8152
8153         TEST_TARGET_IP = "192.168.1.4:2201"
8154
8155      Specifying a port is
8156      useful when SSH is started on a non-standard port or in cases when
8157      your hardware under test is behind a firewall or network that is not
8158      directly accessible from your host and you need to do port address
8159      translation.
8160
8161   :term:`TESTIMAGE_AUTO`
8162      Automatically runs the series of automated tests for images when an
8163      image is successfully built. Setting :term:`TESTIMAGE_AUTO` to "1" causes
8164      any image that successfully builds to automatically boot under QEMU.
8165      Using the variable also adds in dependencies so that any SDK for
8166      which testing is requested is automatically built first.
8167
8168      These tests are written in Python making use of the ``unittest``
8169      module, and the majority of them run commands on the target system
8170      over ``ssh``. You can set this variable to "1" in your ``local.conf``
8171      file in the :term:`Build Directory` to have the
8172      OpenEmbedded build system automatically run these tests after an
8173      image successfully builds:
8174
8175         TESTIMAGE_AUTO = "1"
8176
8177      For more information
8178      on enabling, running, and writing these tests, see the
8179      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
8180      section in the Yocto Project Development Tasks Manual and the
8181      ":ref:`ref-classes-testimage*`" section.
8182
8183   :term:`THISDIR`
8184      The directory in which the file BitBake is currently parsing is
8185      located. Do not manually set this variable.
8186
8187   :term:`TIME`
8188      The time the build was started. Times appear using the hour, minute,
8189      and second (HMS) format (e.g. "140159" for one minute and fifty-nine
8190      seconds past 1400 hours).
8191
8192   :term:`TMPDIR`
8193      This variable is the base directory the OpenEmbedded build system
8194      uses for all build output and intermediate files (other than the
8195      shared state cache). By default, the :term:`TMPDIR` variable points to
8196      ``tmp`` within the :term:`Build Directory`.
8197
8198      If you want to establish this directory in a location other than the
8199      default, you can uncomment and edit the following statement in the
8200      ``conf/local.conf`` file in the :term:`Source Directory`::
8201
8202         #TMPDIR = "${TOPDIR}/tmp"
8203
8204      An example use for this scenario is to set :term:`TMPDIR` to a local disk,
8205      which does not use NFS, while having the Build Directory use NFS.
8206
8207      The filesystem used by :term:`TMPDIR` must have standard filesystem
8208      semantics (i.e. mixed-case files are unique, POSIX file locking, and
8209      persistent inodes). Due to various issues with NFS and bugs in some
8210      implementations, NFS does not meet this minimum requirement.
8211      Consequently, :term:`TMPDIR` cannot be on NFS.
8212
8213   :term:`TOOLCHAIN_HOST_TASK`
8214      This variable lists packages the OpenEmbedded build system uses when
8215      building an SDK, which contains a cross-development environment. The
8216      packages specified by this variable are part of the toolchain set
8217      that runs on the :term:`SDKMACHINE`, and each
8218      package should usually have the prefix ``nativesdk-``. For example,
8219      consider the following command when building an SDK::
8220
8221         $ bitbake -c populate_sdk imagename
8222
8223      In this case, a default list of packages is
8224      set in this variable, but you can add additional packages to the
8225      list. See the
8226      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8227      in the Yocto Project Application Development and the Extensible
8228      Software Development Kit (eSDK) manual for more information.
8229
8230      For background information on cross-development toolchains in the
8231      Yocto Project development environment, see the
8232      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8233      section in the Yocto Project Overview and Concepts Manual. For
8234      information on setting up a cross-development environment, see the
8235      :doc:`/sdk-manual/index` manual.
8236
8237      Note that this variable applies to building an SDK, not an eSDK,
8238      in which case the term:`TOOLCHAIN_HOST_TASK_ESDK` setting should be
8239      used instead.
8240
8241   :term:`TOOLCHAIN_HOST_TASK_ESDK`
8242      This variable allows to extend what is installed in the host
8243      portion of an eSDK. This is similar to :term:`TOOLCHAIN_HOST_TASK`
8244      applying to SDKs.
8245
8246   :term:`TOOLCHAIN_OUTPUTNAME`
8247      This variable defines the name used for the toolchain output. The
8248      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class sets
8249      the :term:`TOOLCHAIN_OUTPUTNAME` variable as follows::
8250
8251         TOOLCHAIN_OUTPUTNAME ?= "${SDK_NAME}-toolchain-${SDK_VERSION}"
8252
8253      See
8254      the :term:`SDK_NAME` and
8255      :term:`SDK_VERSION` variables for additional
8256      information.
8257
8258   :term:`TOOLCHAIN_TARGET_TASK`
8259      This variable lists packages the OpenEmbedded build system uses when
8260      it creates the target part of an SDK (i.e. the part built for the
8261      target hardware), which includes libraries and headers. Use this
8262      variable to add individual packages to the part of the SDK that runs
8263      on the target. See the
8264      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8265      in the Yocto Project Application Development and the Extensible
8266      Software Development Kit (eSDK) manual for more information.
8267
8268      For background information on cross-development toolchains in the
8269      Yocto Project development environment, see the
8270      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8271      section in the Yocto Project Overview and Concepts Manual. For
8272      information on setting up a cross-development environment, see the
8273      :doc:`/sdk-manual/index` manual.
8274
8275   :term:`TRANSLATED_TARGET_ARCH`
8276      A sanitized version of :term:`TARGET_ARCH`. This
8277      variable is used where the architecture is needed in a value where
8278      underscores are not allowed, for example within package filenames. In
8279      this case, dash characters replace any underscore characters used in
8280      :term:`TARGET_ARCH`.
8281
8282      Do not edit this variable.
8283
8284   :term:`TUNE_ARCH`
8285      The GNU canonical architecture for a specific architecture (i.e.
8286      ``arm``, ``armeb``, ``mips``, ``mips64``, and so forth). BitBake uses
8287      this value to setup configuration.
8288
8289      :term:`TUNE_ARCH` definitions are specific to a given architecture. The
8290      definitions can be a single static definition, or can be dynamically
8291      adjusted. You can see details for a given CPU family by looking at
8292      the architecture's ``README`` file. For example, the
8293      ``meta/conf/machine/include/mips/README`` file in the
8294      :term:`Source Directory` provides information for
8295      :term:`TUNE_ARCH` specific to the ``mips`` architecture.
8296
8297      :term:`TUNE_ARCH` is tied closely to
8298      :term:`TARGET_ARCH`, which defines the target
8299      machine's architecture. The BitBake configuration file
8300      (``meta/conf/bitbake.conf``) sets :term:`TARGET_ARCH` as follows::
8301
8302         TARGET_ARCH = "${TUNE_ARCH}"
8303
8304      The following list, which is by no means complete since architectures
8305      are configurable, shows supported machine architectures:
8306
8307      - arm
8308      - i586
8309      - x86_64
8310      - powerpc
8311      - powerpc64
8312      - mips
8313      - mipsel
8314
8315   :term:`TUNE_ASARGS`
8316      Specifies architecture-specific assembler flags for the target
8317      system. The set of flags is based on the selected tune features.
8318      :term:`TUNE_ASARGS` is set using the tune include files, which are
8319      typically under ``meta/conf/machine/include/`` and are influenced
8320      through :term:`TUNE_FEATURES`. For example, the
8321      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8322      for the x86 architecture as follows::
8323
8324         TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
8325
8326      .. note::
8327
8328         Board Support Packages (BSPs) select the tune. The selected tune,
8329         in turn, affects the tune variables themselves (i.e. the tune can
8330         supply its own set of flags).
8331
8332   :term:`TUNE_CCARGS`
8333      Specifies architecture-specific C compiler flags for the target
8334      system. The set of flags is based on the selected tune features.
8335      :term:`TUNE_CCARGS` is set using the tune include files, which are
8336      typically under ``meta/conf/machine/include/`` and are influenced
8337      through :term:`TUNE_FEATURES`.
8338
8339      .. note::
8340
8341         Board Support Packages (BSPs) select the tune. The selected tune,
8342         in turn, affects the tune variables themselves (i.e. the tune can
8343         supply its own set of flags).
8344
8345   :term:`TUNE_FEATURES`
8346      Features used to "tune" a compiler for optimal use given a specific
8347      processor. The features are defined within the tune files and allow
8348      arguments (i.e. ``TUNE_*ARGS``) to be dynamically generated based on
8349      the features.
8350
8351      The OpenEmbedded build system verifies the features to be sure they
8352      are not conflicting and that they are supported.
8353
8354      The BitBake configuration file (``meta/conf/bitbake.conf``) defines
8355      :term:`TUNE_FEATURES` as follows::
8356
8357         TUNE_FEATURES ??= "${TUNE_FEATURES:tune-${DEFAULTTUNE}}"
8358
8359      See the :term:`DEFAULTTUNE` variable for more information.
8360
8361   :term:`TUNE_LDARGS`
8362      Specifies architecture-specific linker flags for the target system.
8363      The set of flags is based on the selected tune features.
8364      :term:`TUNE_LDARGS` is set using the tune include files, which are
8365      typically under ``meta/conf/machine/include/`` and are influenced
8366      through :term:`TUNE_FEATURES`. For example, the
8367      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8368      for the x86 architecture as follows::
8369
8370         TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
8371
8372      .. note::
8373
8374         Board Support Packages (BSPs) select the tune. The selected tune,
8375         in turn, affects the tune variables themselves (i.e. the tune can
8376         supply its own set of flags).
8377
8378   :term:`TUNE_PKGARCH`
8379      The package architecture understood by the packaging system to define
8380      the architecture, ABI, and tuning of output packages. The specific
8381      tune is defined using the "_tune" override as follows::
8382
8383         TUNE_PKGARCH:tune-tune = "tune"
8384
8385      These tune-specific package architectures are defined in the machine
8386      include files. Here is an example of the "core2-32" tuning as used in
8387      the ``meta/conf/machine/include/x86/tune-core2.inc`` file::
8388
8389         TUNE_PKGARCH:tune-core2-32 = "core2-32"
8390
8391   :term:`TUNECONFLICTS[feature]`
8392      Specifies CPU or Application Binary Interface (ABI) tuning features
8393      that conflict with feature.
8394
8395      Known tuning conflicts are specified in the machine include files in
8396      the :term:`Source Directory`. Here is an example from
8397      the ``meta/conf/machine/include/mips/arch-mips.inc`` include file
8398      that lists the "o32" and "n64" features as conflicting with the "n32"
8399      feature::
8400
8401         TUNECONFLICTS[n32] = "o32 n64"
8402
8403   :term:`TUNEVALID[feature]`
8404      Specifies a valid CPU or Application Binary Interface (ABI) tuning
8405      feature. The specified feature is stored as a flag. Valid features
8406      are specified in the machine include files (e.g.
8407      ``meta/conf/machine/include/arm/arch-arm.inc``). Here is an example
8408      from that file::
8409
8410         TUNEVALID[bigendian] = "Enable big-endian mode."
8411
8412      See the machine include files in the :term:`Source Directory`
8413      for these features.
8414
8415   :term:`UBOOT_CONFIG`
8416      Configures the :term:`UBOOT_MACHINE` and can
8417      also define :term:`IMAGE_FSTYPES` for individual
8418      cases.
8419
8420      Following is an example from the ``meta-fsl-arm`` layer. ::
8421
8422         UBOOT_CONFIG ??= "sd"
8423         UBOOT_CONFIG[sd] = "mx6qsabreauto_config,sdcard"
8424         UBOOT_CONFIG[eimnor] = "mx6qsabreauto_eimnor_config"
8425         UBOOT_CONFIG[nand] = "mx6qsabreauto_nand_config,ubifs"
8426         UBOOT_CONFIG[spinor] = "mx6qsabreauto_spinor_config"
8427
8428      In this example, "sd" is selected as the configuration of the possible four for the
8429      :term:`UBOOT_MACHINE`. The "sd" configuration defines
8430      "mx6qsabreauto_config" as the value for :term:`UBOOT_MACHINE`, while the
8431      "sdcard" specifies the :term:`IMAGE_FSTYPES` to use for the U-Boot image.
8432
8433      For more information on how the :term:`UBOOT_CONFIG` is handled, see the
8434      :ref:`uboot-config <ref-classes-uboot-config>`
8435      class.
8436
8437   :term:`UBOOT_DTB_LOADADDRESS`
8438      Specifies the load address for the dtb image used by U-Boot. During FIT
8439      image creation, the :term:`UBOOT_DTB_LOADADDRESS` variable is used in
8440      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify
8441      the load address to be used in
8442      creating the dtb sections of Image Tree Source for the FIT image.
8443
8444   :term:`UBOOT_DTBO_LOADADDRESS`
8445      Specifies the load address for the dtbo image used by U-Boot.  During FIT
8446      image creation, the :term:`UBOOT_DTBO_LOADADDRESS` variable is used in
8447      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the load address to be used in
8448      creating the dtbo sections of Image Tree Source for the FIT image.
8449
8450   :term:`UBOOT_ENTRYPOINT`
8451      Specifies the entry point for the U-Boot image. During U-Boot image
8452      creation, the :term:`UBOOT_ENTRYPOINT` variable is passed as a
8453      command-line parameter to the ``uboot-mkimage`` utility.
8454
8455   :term:`UBOOT_LOADADDRESS`
8456      Specifies the load address for the U-Boot image. During U-Boot image
8457      creation, the :term:`UBOOT_LOADADDRESS` variable is passed as a
8458      command-line parameter to the ``uboot-mkimage`` utility.
8459
8460   :term:`UBOOT_LOCALVERSION`
8461      Appends a string to the name of the local version of the U-Boot
8462      image. For example, assuming the version of the U-Boot image built
8463      was "2013.10", the full version string reported by U-Boot would be
8464      "2013.10-yocto" given the following statement::
8465
8466         UBOOT_LOCALVERSION = "-yocto"
8467
8468   :term:`UBOOT_MACHINE`
8469      Specifies the value passed on the ``make`` command line when building
8470      a U-Boot image. The value indicates the target platform
8471      configuration. You typically set this variable from the machine
8472      configuration file (i.e. ``conf/machine/machine_name.conf``).
8473
8474      Please see the "Selection of Processor Architecture and Board Type"
8475      section in the U-Boot README for valid values for this variable.
8476
8477   :term:`UBOOT_MAKE_TARGET`
8478      Specifies the target called in the ``Makefile``. The default target
8479      is "all".
8480
8481   :term:`UBOOT_MKIMAGE`
8482      Specifies the name of the mkimage command as used by the
8483      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to assemble
8484      the FIT image. This can be used to substitute an alternative command, wrapper
8485      script or function if desired. The default is "uboot-mkimage".
8486
8487   :term:`UBOOT_MKIMAGE_DTCOPTS`
8488      Options for the device tree compiler passed to mkimage '-D'
8489      feature while creating FIT image in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class.
8490      If :term:`UBOOT_MKIMAGE_DTCOPTS` is not set then kernel-fitimage will not
8491      pass the ``-D`` option to mkimage.
8492
8493   :term:`UBOOT_MKIMAGE_SIGN`
8494      Specifies the name of the mkimage command as used by the
8495      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to sign
8496      the FIT image after it has been assembled (if enabled). This can be used
8497      to substitute an alternative command, wrapper script or function if
8498      desired. The default is "${:term:`UBOOT_MKIMAGE`}".
8499
8500   :term:`UBOOT_MKIMAGE_SIGN_ARGS`
8501      Optionally specifies additional arguments for the
8502      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to pass to the
8503      mkimage command when signing the FIT image.
8504
8505   :term:`UBOOT_RD_ENTRYPOINT`
8506      Specifies the entrypoint for the RAM disk image.
8507      During FIT image creation, the
8508      :term:`UBOOT_RD_ENTRYPOINT` variable is used
8509      in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the
8510      entrypoint to be used in creating the Image Tree Source for
8511      the FIT image.
8512
8513   :term:`UBOOT_RD_LOADADDRESS`
8514      Specifies the load address for the RAM disk image.
8515      During FIT image creation, the
8516      :term:`UBOOT_RD_LOADADDRESS` variable is used
8517      in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the
8518      load address to be used in creating the Image Tree Source for
8519      the FIT image.
8520
8521   :term:`UBOOT_SIGN_ENABLE`
8522      Enable signing of FIT image. The default value is "0".
8523
8524   :term:`UBOOT_SIGN_KEYDIR`
8525      Location of the directory containing the RSA key and
8526      certificate used for signing FIT image.
8527
8528   :term:`UBOOT_SIGN_KEYNAME`
8529      The name of keys used for signing U-Boot FIT image stored in
8530      :term:`UBOOT_SIGN_KEYDIR` directory. For e.g. dev.key key and dev.crt
8531      certificate stored in :term:`UBOOT_SIGN_KEYDIR` directory will have
8532      :term:`UBOOT_SIGN_KEYNAME` set to "dev".
8533
8534   :term:`UBOOT_SUFFIX`
8535      Points to the generated U-Boot extension. For example, ``u-boot.sb``
8536      has a ``.sb`` extension.
8537
8538      The default U-Boot extension is ``.bin``
8539
8540   :term:`UBOOT_TARGET`
8541      Specifies the target used for building U-Boot. The target is passed
8542      directly as part of the "make" command (e.g. SPL and AIS). If you do
8543      not specifically set this variable, the OpenEmbedded build process
8544      passes and uses "all" for the target during the U-Boot building
8545      process.
8546
8547   :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`
8548      Specifies a list of options that, if reported by the configure script
8549      as being invalid, should not generate a warning during the
8550      :ref:`ref-tasks-configure` task. Normally, invalid
8551      configure options are simply not passed to the configure script (e.g.
8552      should be removed from :term:`EXTRA_OECONF` or
8553      :term:`PACKAGECONFIG_CONFARGS`).
8554      However, there are common options that are passed to all
8555      configure scripts at a class level, but might not be valid for some
8556      configure scripts. Therefore warnings about these options are useless.
8557      For these cases, the options are added to :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`.
8558
8559      The configure arguments check that uses
8560      :term:`UNKNOWN_CONFIGURE_OPT_IGNORE` is part of the
8561      :ref:`insane <ref-classes-insane>` class and is only enabled if the
8562      recipe inherits the :ref:`autotools <ref-classes-autotools>` class.
8563
8564   :term:`UPDATERCPN`
8565      For recipes inheriting the
8566      :ref:`update-rc.d <ref-classes-update-rc.d>` class, :term:`UPDATERCPN`
8567      specifies the package that contains the initscript that is enabled.
8568
8569      The default value is "${PN}". Given that almost all recipes that
8570      install initscripts package them in the main package for the recipe,
8571      you rarely need to set this variable in individual recipes.
8572
8573   :term:`UPSTREAM_CHECK_COMMITS`
8574      You can perform a per-recipe check for what the latest upstream
8575      source code version is by calling ``devtool latest-version recipe``. If
8576      the recipe source code is provided from Git repositories, but
8577      releases are not identified by Git tags, set :term:`UPSTREAM_CHECK_COMMITS`
8578      to ``1`` in the recipe, and the OpenEmbedded build system
8579      will compare the latest commit with the one currently specified
8580      by the recipe (:term:`SRCREV`).
8581      ::
8582
8583         UPSTREAM_CHECK_COMMITS = "1"
8584
8585   :term:`UPSTREAM_CHECK_GITTAGREGEX`
8586      You can perform a per-recipe check for what the latest upstream
8587      source code version is by calling ``devtool latest-version recipe``. If
8588      the recipe source code is provided from Git repositories, the
8589      OpenEmbedded build system determines the latest upstream version by
8590      picking the latest tag from the list of all repository tags.
8591
8592      You can use the :term:`UPSTREAM_CHECK_GITTAGREGEX` variable to provide a
8593      regular expression to filter only the relevant tags should the
8594      default filter not work correctly.
8595      ::
8596
8597         UPSTREAM_CHECK_GITTAGREGEX = "git_tag_regex"
8598
8599   :term:`UPSTREAM_CHECK_REGEX`
8600      Use the :term:`UPSTREAM_CHECK_REGEX` variable to specify a different
8601      regular expression instead of the default one when the package
8602      checking system is parsing the page found using
8603      :term:`UPSTREAM_CHECK_URI`.
8604      ::
8605
8606         UPSTREAM_CHECK_REGEX = "package_regex"
8607
8608   :term:`UPSTREAM_CHECK_URI`
8609      You can perform a per-recipe check for what the latest upstream
8610      source code version is by calling ``devtool latest-version recipe``. If
8611      the source code is provided from tarballs, the latest version is
8612      determined by fetching the directory listing where the tarball is and
8613      attempting to find a later tarball. When this approach does not work,
8614      you can use :term:`UPSTREAM_CHECK_URI` to provide a different URI that
8615      contains the link to the latest tarball.
8616      ::
8617
8618         UPSTREAM_CHECK_URI = "recipe_url"
8619
8620   :term:`UPSTREAM_VERSION_UNKNOWN`
8621      You can perform a per-recipe check for what the latest upstream
8622      source code version is by calling ``devtool latest-version recipe``.
8623      If no combination of the :term:`UPSTREAM_CHECK_URI`, :term:`UPSTREAM_CHECK_REGEX`,
8624      :term:`UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
8625      the recipe allows to determine what the latest upstream version is,
8626      you can set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1`` in the recipe
8627      to acknowledge that the check cannot be performed.
8628      ::
8629
8630         UPSTREAM_VERSION_UNKNOWN = "1"
8631
8632   :term:`USE_DEVFS`
8633      Determines if ``devtmpfs`` is used for ``/dev`` population. The
8634      default value used for :term:`USE_DEVFS` is "1" when no value is
8635      specifically set. Typically, you would set :term:`USE_DEVFS` to "0" for a
8636      statically populated ``/dev`` directory.
8637
8638      See the ":ref:`dev-manual/common-tasks:selecting a device manager`" section in
8639      the Yocto Project Development Tasks Manual for information on how to
8640      use this variable.
8641
8642   :term:`USE_VT`
8643      When using
8644      :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,
8645      determines whether or not to run a
8646      `getty <https://en.wikipedia.org/wiki/Getty_%28Unix%29>`__ on any
8647      virtual terminals in order to enable logging in through those
8648      terminals.
8649
8650      The default value used for :term:`USE_VT` is "1" when no default value is
8651      specifically set. Typically, you would set :term:`USE_VT` to "0" in the
8652      machine configuration file for machines that do not have a graphical
8653      display attached and therefore do not need virtual terminal
8654      functionality.
8655
8656   :term:`USER_CLASSES`
8657      A list of classes to globally inherit. These classes are used by the
8658      OpenEmbedded build system to enable extra features.
8659
8660      The default list is set in your ``local.conf`` file::
8661
8662         USER_CLASSES ?= "buildstats"
8663
8664      For more information, see
8665      ``meta-poky/conf/local.conf.sample`` in the :term:`Source Directory`.
8666
8667   :term:`USERADD_ERROR_DYNAMIC`
8668      If set to ``error``, forces the OpenEmbedded build system to produce
8669      an error if the user identification (``uid``) and group
8670      identification (``gid``) values are not defined in any of the files
8671      listed in :term:`USERADD_UID_TABLES` and
8672      :term:`USERADD_GID_TABLES`. If set to
8673      ``warn``, a warning will be issued instead.
8674
8675      The default behavior for the build system is to dynamically apply
8676      ``uid`` and ``gid`` values. Consequently, the
8677      :term:`USERADD_ERROR_DYNAMIC` variable is by default not set. If you plan
8678      on using statically assigned ``gid`` and ``uid`` values, you should
8679      set the :term:`USERADD_ERROR_DYNAMIC` variable in your ``local.conf``
8680      file as follows::
8681
8682         USERADD_ERROR_DYNAMIC = "error"
8683
8684      Overriding the
8685      default behavior implies you are going to also take steps to set
8686      static ``uid`` and ``gid`` values through use of the
8687      :term:`USERADDEXTENSION`,
8688      :term:`USERADD_UID_TABLES`, and
8689      :term:`USERADD_GID_TABLES` variables.
8690
8691      .. note::
8692
8693         There is a difference in behavior between setting
8694         :term:`USERADD_ERROR_DYNAMIC` to ``error`` and setting it to ``warn``.
8695         When it is set to ``warn``, the build system will report a warning for
8696         every undefined ``uid`` and ``gid`` in any recipe. But when it is set
8697         to ``error``, it will only report errors for recipes that are actually
8698         built.
8699         This saves you from having to add static IDs for recipes that you
8700         know will never be built.
8701
8702   :term:`USERADD_GID_TABLES`
8703      Specifies a password file to use for obtaining static group
8704      identification (``gid``) values when the OpenEmbedded build system
8705      adds a group to the system during package installation.
8706
8707      When applying static group identification (``gid``) values, the
8708      OpenEmbedded build system looks in :term:`BBPATH` for a
8709      ``files/group`` file and then applies those ``uid`` values. Set the
8710      variable as follows in your ``local.conf`` file::
8711
8712
8713         USERADD_GID_TABLES = "files/group"
8714
8715      .. note::
8716
8717         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
8718         causes the build system to use static ``gid`` values.
8719
8720   :term:`USERADD_PACKAGES`
8721      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
8722      this variable specifies the individual packages within the recipe
8723      that require users and/or groups to be added.
8724
8725      You must set this variable if the recipe inherits the class. For
8726      example, the following enables adding a user for the main package in
8727      a recipe::
8728
8729         USERADD_PACKAGES = "${PN}"
8730
8731      .. note::
8732
8733         It follows that if you are going to use the :term:`USERADD_PACKAGES`
8734         variable, you need to set one or more of the :term:`USERADD_PARAM`,
8735         :term:`GROUPADD_PARAM`, or :term:`GROUPMEMS_PARAM` variables.
8736
8737   :term:`USERADD_PARAM`
8738      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
8739      this variable specifies for a package what parameters should pass to
8740      the ``useradd`` command if you add a user to the system when the
8741      package is installed.
8742
8743      Here is an example from the ``dbus`` recipe::
8744
8745         USERADD_PARAM:${PN} = "--system --home ${localstatedir}/lib/dbus \
8746                                --no-create-home --shell /bin/false \
8747                                --user-group messagebus"
8748
8749      For information on the
8750      standard Linux shell command ``useradd``, see
8751      https://linux.die.net/man/8/useradd.
8752
8753   :term:`USERADD_UID_TABLES`
8754      Specifies a password file to use for obtaining static user
8755      identification (``uid``) values when the OpenEmbedded build system
8756      adds a user to the system during package installation.
8757
8758      When applying static user identification (``uid``) values, the
8759      OpenEmbedded build system looks in :term:`BBPATH` for a
8760      ``files/passwd`` file and then applies those ``uid`` values. Set the
8761      variable as follows in your ``local.conf`` file::
8762
8763         USERADD_UID_TABLES = "files/passwd"
8764
8765      .. note::
8766
8767         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
8768         causes the build system to use static ``uid`` values.
8769
8770   :term:`USERADDEXTENSION`
8771      When set to "useradd-staticids", causes the OpenEmbedded build system
8772      to base all user and group additions on a static ``passwd`` and
8773      ``group`` files found in :term:`BBPATH`.
8774
8775      To use static user identification (``uid``) and group identification
8776      (``gid``) values, set the variable as follows in your ``local.conf``
8777      file: USERADDEXTENSION = "useradd-staticids"
8778
8779      .. note::
8780
8781         Setting this variable to use static ``uid`` and ``gid``
8782         values causes the OpenEmbedded build system to employ the
8783         :ref:`ref-classes-useradd` class.
8784
8785      If you use static ``uid`` and ``gid`` information, you must also
8786      specify the ``files/passwd`` and ``files/group`` files by setting the
8787      :term:`USERADD_UID_TABLES` and
8788      :term:`USERADD_GID_TABLES` variables.
8789      Additionally, you should also set the
8790      :term:`USERADD_ERROR_DYNAMIC` variable.
8791
8792   :term:`VOLATILE_LOG_DIR`
8793      Specifies the persistence of the target's ``/var/log`` directory,
8794      which is used to house postinstall target log files.
8795
8796      By default, :term:`VOLATILE_LOG_DIR` is set to "yes", which means the
8797      file is not persistent. You can override this setting by setting the
8798      variable to "no" to make the log directory persistent.
8799
8800   :term:`WARN_QA`
8801      Specifies the quality assurance checks whose failures are reported as
8802      warnings by the OpenEmbedded build system. You set this variable in
8803      your distribution configuration file. For a list of the checks you
8804      can control with this variable, see the
8805      ":ref:`ref-classes-insane`" section.
8806
8807   :term:`WKS_FILE`
8808      Specifies the location of the Wic kickstart file that is used by the
8809      OpenEmbedded build system to create a partitioned image
8810      (``image.wic``). For information on how to create a partitioned
8811      image, see the
8812      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
8813      section in the Yocto Project Development Tasks Manual. For details on
8814      the kickstart file format, see the ":doc:`/ref-manual/kickstart`" Chapter.
8815
8816   :term:`WKS_FILE_DEPENDS`
8817      When placed in the recipe that builds your image, this variable lists
8818      build-time dependencies. The :term:`WKS_FILE_DEPENDS` variable is only
8819      applicable when Wic images are active (i.e. when
8820      :term:`IMAGE_FSTYPES` contains entries related
8821      to Wic). If your recipe does not create Wic images, the variable has
8822      no effect.
8823
8824      The :term:`WKS_FILE_DEPENDS` variable is similar to the
8825      :term:`DEPENDS` variable. When you use the variable in
8826      your recipe that builds the Wic image, dependencies you list in the
8827      :term:`WKS_FILE_DEPENDS` variable are added to the :term:`DEPENDS` variable.
8828
8829      With the :term:`WKS_FILE_DEPENDS` variable, you have the possibility to
8830      specify a list of additional dependencies (e.g. native tools,
8831      bootloaders, and so forth), that are required to build Wic images.
8832      Following is an example::
8833
8834         WKS_FILE_DEPENDS = "some-native-tool"
8835
8836      In the
8837      previous example, some-native-tool would be replaced with an actual
8838      native tool on which the build would depend.
8839
8840   :term:`WKS_FILES`
8841      Specifies a list of candidate Wic kickstart files to be used by the
8842      OpenEmbedded build system to create a partitioned image. Only the
8843      first one that is found, from left to right, will be used.
8844
8845      This is only useful when there are multiple ``.wks`` files that can be
8846      used to produce an image. A typical case is when multiple layers are
8847      used for different hardware platforms, each supplying a different
8848      ``.wks`` file. In this case, you specify all possible ones through
8849      :term:`WKS_FILES`.
8850
8851      If only one ``.wks`` file is used, set :term:`WKS_FILE` instead.
8852
8853   :term:`WORKDIR`
8854      The pathname of the work directory in which the OpenEmbedded build
8855      system builds a recipe. This directory is located within the
8856      :term:`TMPDIR` directory structure and is specific to
8857      the recipe being built and the system for which it is being built.
8858
8859      The :term:`WORKDIR` directory is defined as follows::
8860
8861         ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
8862
8863      The actual directory depends on several things:
8864
8865      -  :term:`TMPDIR`: The top-level build output directory
8866      -  :term:`MULTIMACH_TARGET_SYS`: The target system identifier
8867      -  :term:`PN`: The recipe name
8868      -  :term:`EXTENDPE`: The epoch --- if :term:`PE` is not specified, which
8869         is usually the case for most recipes, then `EXTENDPE` is blank.
8870      -  :term:`PV`: The recipe version
8871      -  :term:`PR`: The recipe revision
8872
8873      As an example, assume a Source Directory top-level folder name
8874      ``poky``, a default Build Directory at ``poky/build``, and a
8875      ``qemux86-poky-linux`` machine target system. Furthermore, suppose
8876      your recipe is named ``foo_1.3.0-r0.bb``. In this case, the work
8877      directory the build system uses to build the package would be as
8878      follows::
8879
8880         poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
8881
8882   :term:`XSERVER`
8883      Specifies the packages that should be installed to provide an X
8884      server and drivers for the current machine, assuming your image
8885      directly includes ``packagegroup-core-x11-xserver`` or, perhaps
8886      indirectly, includes "x11-base" in
8887      :term:`IMAGE_FEATURES`.
8888
8889      The default value of :term:`XSERVER`, if not specified in the machine
8890      configuration, is "xserver-xorg xf86-video-fbdev xf86-input-evdev".
8891
8892   :term:`XZ_THREADS`
8893      Specifies the number of parallel threads that should be used when
8894      using xz compression.
8895
8896      By default this scales with core count, but is never set less than 2
8897      to ensure that multi-threaded mode is always used so that the output
8898      file contents are deterministic. Builds will work with a value of 1
8899      but the output will differ compared to the output from the compression
8900      generated when more than one thread is used.
8901
8902      On systems where many tasks run in parallel, setting a limit to this
8903      can be helpful in controlling system resource usage.
8904
8905    :term:`XZ_MEMLIMIT`
8906      Specifies the maximum memory the xz compression should use as a percentage
8907      of system memory. If unconstrained the xz compressor can use large amounts of
8908      memory and become problematic with parallelism elsewhere in the build.
8909      "50%" has been found to be a good value.
8910
8911   :term:`ZSTD_THREADS`
8912      Specifies the number of parallel threads that should be used when
8913      using ZStandard compression.
8914
8915      By default this scales with core count, but is never set less than 2
8916      to ensure that multi-threaded mode is always used so that the output
8917      file contents are deterministic. Builds will work with a value of 1
8918      but the output will differ compared to the output from the compression
8919      generated when more than one thread is used.
8920
8921      On systems where many tasks run in parallel, setting a limit to this
8922      can be helpful in controlling system resource usage.
8923
8924