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
722      use must reside in the :term:`Build Directory`
723      ``conf/multiconfig`` directory (e.g.
724      ``build_directory/conf/multiconfig/configA.conf``).
725
726      For information on how to use :term:`BBMULTICONFIG` in an environment
727      that supports building targets with multiple configurations, see the
728      ":ref:`dev-manual/common-tasks:building images for multiple targets using multiple configurations`"
729      section in the Yocto Project Development Tasks Manual.
730
731   :term:`BBPATH`
732      Used by BitBake to locate ``.bbclass`` and configuration files. This
733      variable is analogous to the ``PATH`` variable.
734
735      .. note::
736
737         If you run BitBake from a directory outside of the
738         :term:`Build Directory`, you must be sure to set :term:`BBPATH`
739         to point to the Build Directory. Set the variable as you would any
740         environment variable and then run BitBake::
741
742                 $ BBPATH = "build_directory"
743                 $ export BBPATH
744                 $ bitbake target
745
746
747   :term:`BBSERVER`
748      If defined in the BitBake environment, :term:`BBSERVER` points to the
749      BitBake remote server.
750
751      Use the following format to export the variable to the BitBake
752      environment::
753
754         export BBSERVER=localhost:$port
755
756      By default, :term:`BBSERVER` also appears in :term:`BB_BASEHASH_IGNORE_VARS`.
757      Consequently, :term:`BBSERVER` is excluded from checksum and dependency
758      data.
759
760   :term:`BINCONFIG`
761      When inheriting the
762      :ref:`binconfig-disabled <ref-classes-binconfig-disabled>` class,
763      this variable specifies binary configuration scripts to disable in
764      favor of using ``pkg-config`` to query the information. The
765      :ref:`binconfig-disabled <ref-classes-binconfig-disabled>` class will modify the specified scripts to
766      return an error so that calls to them can be easily found and
767      replaced.
768
769      To add multiple scripts, separate them by spaces. Here is an example
770      from the ``libpng`` recipe::
771
772         BINCONFIG = "${bindir}/libpng-config ${bindir}/libpng16-config"
773
774   :term:`BINCONFIG_GLOB`
775      When inheriting the :ref:`binconfig <ref-classes-binconfig>` class,
776      this variable specifies a wildcard for configuration scripts that
777      need editing. The scripts are edited to correct any paths that have
778      been set up during compilation so that they are correct for use when
779      installed into the sysroot and called by the build processes of other
780      recipes.
781
782      .. note::
783
784         The :term:`BINCONFIG_GLOB` variable uses
785         `shell globbing <https://tldp.org/LDP/abs/html/globbingref.html>`__,
786         which is recognition and expansion of wildcards during pattern
787         matching. Shell globbing is very similar to
788         `fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__
789         and `glob <https://docs.python.org/3/library/glob.html>`__.
790
791      For more information on how this variable works, see
792      ``meta/classes/binconfig.bbclass`` in the :term:`Source Directory`.
793      You can also find general
794      information on the class in the
795      ":ref:`ref-classes-binconfig`" section.
796
797   :term:`BP`
798      The base recipe name and version but without any special recipe name
799      suffix (i.e. ``-native``, ``lib64-``, and so forth). :term:`BP` is
800      comprised of the following::
801
802         ${BPN}-${PV}
803
804   :term:`BPN`
805      This variable is a version of the :term:`PN` variable with
806      common prefixes and suffixes removed, such as ``nativesdk-``,
807      ``-cross``, ``-native``, and multilib's ``lib64-`` and ``lib32-``.
808      The exact lists of prefixes and suffixes removed are specified by the
809      :term:`MLPREFIX` and
810      :term:`SPECIAL_PKGSUFFIX` variables,
811      respectively.
812
813   :term:`BUGTRACKER`
814      Specifies a URL for an upstream bug tracking website for a recipe.
815      The OpenEmbedded build system does not use this variable. Rather, the
816      variable is a useful pointer in case a bug in the software being
817      built needs to be manually reported.
818
819   :term:`BUILD_ARCH`
820      Specifies the architecture of the build host (e.g. ``i686``). The
821      OpenEmbedded build system sets the value of :term:`BUILD_ARCH` from the
822      machine name reported by the ``uname`` command.
823
824   :term:`BUILD_AS_ARCH`
825      Specifies the architecture-specific assembler flags for the build
826      host. By default, the value of :term:`BUILD_AS_ARCH` is empty.
827
828   :term:`BUILD_CC_ARCH`
829      Specifies the architecture-specific C compiler flags for the build
830      host. By default, the value of :term:`BUILD_CC_ARCH` is empty.
831
832   :term:`BUILD_CCLD`
833      Specifies the linker command to be used for the build host when the C
834      compiler is being used as the linker. By default, :term:`BUILD_CCLD`
835      points to GCC and passes as arguments the value of
836      :term:`BUILD_CC_ARCH`, assuming
837      :term:`BUILD_CC_ARCH` is set.
838
839   :term:`BUILD_CFLAGS`
840      Specifies the flags to pass to the C compiler when building for the
841      build host. When building in the ``-native`` context,
842      :term:`CFLAGS` is set to the value of this variable by
843      default.
844
845   :term:`BUILD_CPPFLAGS`
846      Specifies the flags to pass to the C preprocessor (i.e. to both the C
847      and the C++ compilers) when building for the build host. When
848      building in the ``-native`` context, :term:`CPPFLAGS`
849      is set to the value of this variable by default.
850
851   :term:`BUILD_CXXFLAGS`
852      Specifies the flags to pass to the C++ compiler when building for the
853      build host. When building in the ``-native`` context,
854      :term:`CXXFLAGS` is set to the value of this variable
855      by default.
856
857   :term:`BUILD_FC`
858      Specifies the Fortran compiler command for the build host. By
859      default, :term:`BUILD_FC` points to Gfortran and passes as arguments the
860      value of :term:`BUILD_CC_ARCH`, assuming
861      :term:`BUILD_CC_ARCH` is set.
862
863   :term:`BUILD_LD`
864      Specifies the linker command for the build host. By default,
865      :term:`BUILD_LD` points to the GNU linker (ld) and passes as arguments
866      the value of :term:`BUILD_LD_ARCH`, assuming
867      :term:`BUILD_LD_ARCH` is set.
868
869   :term:`BUILD_LD_ARCH`
870      Specifies architecture-specific linker flags for the build host. By
871      default, the value of :term:`BUILD_LD_ARCH` is empty.
872
873   :term:`BUILD_LDFLAGS`
874      Specifies the flags to pass to the linker when building for the build
875      host. When building in the ``-native`` context,
876      :term:`LDFLAGS` is set to the value of this variable
877      by default.
878
879   :term:`BUILD_OPTIMIZATION`
880      Specifies the optimization flags passed to the C compiler when
881      building for the build host or the SDK. The flags are passed through
882      the :term:`BUILD_CFLAGS` and
883      :term:`BUILDSDK_CFLAGS` default values.
884
885      The default value of the :term:`BUILD_OPTIMIZATION` variable is "-O2
886      -pipe".
887
888   :term:`BUILD_OS`
889      Specifies the operating system in use on the build host (e.g.
890      "linux"). The OpenEmbedded build system sets the value of
891      :term:`BUILD_OS` from the OS reported by the ``uname`` command - the
892      first word, converted to lower-case characters.
893
894   :term:`BUILD_PREFIX`
895      The toolchain binary prefix used for native recipes. The OpenEmbedded
896      build system uses the :term:`BUILD_PREFIX` value to set the
897      :term:`TARGET_PREFIX` when building for
898      ``native`` recipes.
899
900   :term:`BUILD_STRIP`
901      Specifies the command to be used to strip debugging symbols from
902      binaries produced for the build host. By default, :term:`BUILD_STRIP`
903      points to
904      ``${``\ :term:`BUILD_PREFIX`\ ``}strip``.
905
906   :term:`BUILD_SYS`
907      Specifies the system, including the architecture and the operating
908      system, to use when building for the build host (i.e. when building
909      ``native`` recipes).
910
911      The OpenEmbedded build system automatically sets this variable based
912      on :term:`BUILD_ARCH`,
913      :term:`BUILD_VENDOR`, and
914      :term:`BUILD_OS`. You do not need to set the
915      :term:`BUILD_SYS` variable yourself.
916
917   :term:`BUILD_VENDOR`
918      Specifies the vendor name to use when building for the build host.
919      The default value is an empty string ("").
920
921   :term:`BUILDDIR`
922      Points to the location of the :term:`Build Directory`.
923      You can define this directory indirectly through the
924      :ref:`structure-core-script` script by passing in a Build
925      Directory path when you run the script. If you run the script and do
926      not provide a Build Directory path, the :term:`BUILDDIR` defaults to
927      ``build`` in the current directory.
928
929   :term:`BUILDHISTORY_COMMIT`
930      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
931      class, this variable specifies whether or not to commit the build
932      history output in a local Git repository. If set to "1", this local
933      repository will be maintained automatically by the :ref:`buildhistory <ref-classes-buildhistory>`
934      class and a commit will be created on every build for changes to each
935      top-level subdirectory of the build history output (images, packages,
936      and sdk). If you want to track changes to build history over time,
937      you should set this value to "1".
938
939      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class does not commit the build
940      history output in a local Git repository::
941
942         BUILDHISTORY_COMMIT ?= "0"
943
944   :term:`BUILDHISTORY_COMMIT_AUTHOR`
945      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
946      class, this variable specifies the author to use for each Git commit.
947      In order for the :term:`BUILDHISTORY_COMMIT_AUTHOR` variable to work, the
948      :term:`BUILDHISTORY_COMMIT` variable must
949      be set to "1".
950
951      Git requires that the value you provide for the
952      :term:`BUILDHISTORY_COMMIT_AUTHOR` variable takes the form of "name
953      email@host". Providing an email address or host that is not valid
954      does not produce an error.
955
956      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the variable as follows::
957
958         BUILDHISTORY_COMMIT_AUTHOR ?= "buildhistory <buildhistory@${DISTRO}>"
959
960   :term:`BUILDHISTORY_DIR`
961      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
962      class, this variable specifies the directory in which build history
963      information is kept. For more information on how the variable works,
964      see the :ref:`ref-classes-buildhistory` class.
965
966      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the directory as follows::
967
968         BUILDHISTORY_DIR ?= "${TOPDIR}/buildhistory"
969
970   :term:`BUILDHISTORY_FEATURES`
971      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
972      class, this variable specifies the build history features to be
973      enabled. For more information on how build history works, see the
974      ":ref:`dev-manual/common-tasks:maintaining build output quality`"
975      section in the Yocto Project Development Tasks Manual.
976
977      You can specify these features in the form of a space-separated list:
978
979      -  *image:* Analysis of the contents of images, which includes the
980         list of installed packages among other things.
981
982      -  *package:* Analysis of the contents of individual packages.
983
984      -  *sdk:* Analysis of the contents of the software development kit
985         (SDK).
986
987      -  *task:* Save output file signatures for
988         :ref:`shared state <overview-manual/concepts:shared state cache>`
989         (sstate) tasks.
990         This saves one file per task and lists the SHA-256 checksums for
991         each file staged (i.e. the output of the task).
992
993      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class enables the following
994      features::
995
996         BUILDHISTORY_FEATURES ?= "image package sdk"
997
998   :term:`BUILDHISTORY_IMAGE_FILES`
999      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1000      class, this variable specifies a list of paths to files copied from
1001      the image contents into the build history directory under an
1002      "image-files" directory in the directory for the image, so that you
1003      can track the contents of each file. The default is to copy
1004      ``/etc/passwd`` and ``/etc/group``, which allows you to monitor for
1005      changes in user and group entries. You can modify the list to include
1006      any file. Specifying an invalid path does not produce an error.
1007      Consequently, you can include files that might not always be present.
1008
1009      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class provides paths to the
1010      following files::
1011
1012         BUILDHISTORY_IMAGE_FILES ?= "/etc/passwd /etc/group"
1013
1014   :term:`BUILDHISTORY_PATH_PREFIX_STRIP`
1015      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1016      class, this variable specifies a common path prefix that should be
1017      stripped off the beginning of paths in the task signature list when the
1018      ``task`` feature is active in :term:`BUILDHISTORY_FEATURES`. This can be
1019      useful when build history is populated from multiple sources that may not
1020      all use the same top level directory.
1021
1022      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the variable as follows::
1023
1024         BUILDHISTORY_PATH_PREFIX_STRIP ?= ""
1025
1026      In this case, no prefixes will be stripped.
1027
1028   :term:`BUILDHISTORY_PUSH_REPO`
1029      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1030      class, this variable optionally specifies a remote repository to
1031      which build history pushes Git changes. In order for
1032      :term:`BUILDHISTORY_PUSH_REPO` to work,
1033      :term:`BUILDHISTORY_COMMIT` must be set to
1034      "1".
1035
1036      The repository should correspond to a remote address that specifies a
1037      repository as understood by Git, or alternatively to a remote name
1038      that you have set up manually using ``git remote`` within the local
1039      repository.
1040
1041      By default, the :ref:`buildhistory <ref-classes-buildhistory>` class sets the variable as follows::
1042
1043         BUILDHISTORY_PUSH_REPO ?= ""
1044
1045   :term:`BUILDSDK_CFLAGS`
1046      Specifies the flags to pass to the C compiler when building for the
1047      SDK. When building in the ``nativesdk-`` context,
1048      :term:`CFLAGS` is set to the value of this variable by
1049      default.
1050
1051   :term:`BUILDSDK_CPPFLAGS`
1052      Specifies the flags to pass to the C pre-processor (i.e. to both the
1053      C and the C++ compilers) when building for the SDK. When building in
1054      the ``nativesdk-`` context, :term:`CPPFLAGS` is set
1055      to the value of this variable by default.
1056
1057   :term:`BUILDSDK_CXXFLAGS`
1058      Specifies the flags to pass to the C++ compiler when building for the
1059      SDK. When building in the ``nativesdk-`` context,
1060      :term:`CXXFLAGS` is set to the value of this variable
1061      by default.
1062
1063   :term:`BUILDSDK_LDFLAGS`
1064      Specifies the flags to pass to the linker when building for the SDK.
1065      When building in the ``nativesdk-`` context,
1066      :term:`LDFLAGS` is set to the value of this variable
1067      by default.
1068
1069   :term:`BUILDSTATS_BASE`
1070      Points to the location of the directory that holds build statistics
1071      when you use and enable the
1072      :ref:`buildstats <ref-classes-buildstats>` class. The
1073      :term:`BUILDSTATS_BASE` directory defaults to
1074      ``${``\ :term:`TMPDIR`\ ``}/buildstats/``.
1075
1076   :term:`BUSYBOX_SPLIT_SUID`
1077      For the BusyBox recipe, specifies whether to split the output
1078      executable file into two parts: one for features that require
1079      ``setuid root``, and one for the remaining features (i.e. those that
1080      do not require ``setuid root``).
1081
1082      The :term:`BUSYBOX_SPLIT_SUID` variable defaults to "1", which results in
1083      splitting the output executable file. Set the variable to "0" to get
1084      a single output executable file.
1085
1086   :term:`CACHE`
1087      Specifies the directory BitBake uses to store a cache of the
1088      :term:`Metadata` so it does not need to be parsed every time
1089      BitBake is started.
1090
1091   :term:`CC`
1092      The minimal command and arguments used to run the C compiler.
1093
1094   :term:`CFLAGS`
1095      Specifies the flags to pass to the C compiler. This variable is
1096      exported to an environment variable and thus made visible to the
1097      software being built during the compilation step.
1098
1099      Default initialization for :term:`CFLAGS` varies depending on what is
1100      being built:
1101
1102      -  :term:`TARGET_CFLAGS` when building for the
1103         target
1104
1105      -  :term:`BUILD_CFLAGS` when building for the
1106         build host (i.e. ``-native``)
1107
1108      -  :term:`BUILDSDK_CFLAGS` when building for
1109         an SDK (i.e. ``nativesdk-``)
1110
1111   :term:`CLASSOVERRIDE`
1112      An internal variable specifying the special class override that
1113      should currently apply (e.g. "class-target", "class-native", and so
1114      forth). The classes that use this variable (e.g.
1115      :ref:`native <ref-classes-native>`,
1116      :ref:`nativesdk <ref-classes-nativesdk>`, and so forth) set the
1117      variable to appropriate values.
1118
1119      .. note::
1120
1121         :term:`CLASSOVERRIDE` gets its default "class-target" value from the
1122         ``bitbake.conf`` file.
1123
1124      As an example, the following override allows you to install extra
1125      files, but only when building for the target::
1126
1127         do_install:append:class-target() {
1128             install my-extra-file ${D}${sysconfdir}
1129         }
1130
1131      Here is an example where ``FOO`` is set to
1132      "native" when building for the build host, and to "other" when not
1133      building for the build host::
1134
1135         FOO:class-native = "native"
1136         FOO = "other"
1137
1138      The underlying mechanism behind :term:`CLASSOVERRIDE` is simply
1139      that it is included in the default value of
1140      :term:`OVERRIDES`.
1141
1142   :term:`CLEANBROKEN`
1143      If set to "1" within a recipe, :term:`CLEANBROKEN` specifies that the
1144      ``make clean`` command does not work for the software being built.
1145      Consequently, the OpenEmbedded build system will not try to run
1146      ``make clean`` during the :ref:`ref-tasks-configure`
1147      task, which is the default behavior.
1148
1149   :term:`COMBINED_FEATURES`
1150      Provides a list of hardware features that are enabled in both
1151      :term:`MACHINE_FEATURES` and
1152      :term:`DISTRO_FEATURES`. This select list of
1153      features contains features that make sense to be controlled both at
1154      the machine and distribution configuration level. For example, the
1155      "bluetooth" feature requires hardware support but should also be
1156      optional at the distribution level, in case the hardware supports
1157      Bluetooth but you do not ever intend to use it.
1158
1159   :term:`COMMON_LICENSE_DIR`
1160      Points to ``meta/files/common-licenses`` in the
1161      :term:`Source Directory`, which is where generic license
1162      files reside.
1163
1164   :term:`COMPATIBLE_HOST`
1165      A regular expression that resolves to one or more hosts (when the
1166      recipe is native) or one or more targets (when the recipe is
1167      non-native) with which a recipe is compatible. The regular expression
1168      is matched against :term:`HOST_SYS`. You can use the
1169      variable to stop recipes from being built for classes of systems with
1170      which the recipes are not compatible. Stopping these builds is
1171      particularly useful with kernels. The variable also helps to increase
1172      parsing speed since the build system skips parsing recipes not
1173      compatible with the current system.
1174
1175   :term:`COMPATIBLE_MACHINE`
1176      A regular expression that resolves to one or more target machines
1177      with which a recipe is compatible. The regular expression is matched
1178      against :term:`MACHINEOVERRIDES`. You can use
1179      the variable to stop recipes from being built for machines with which
1180      the recipes are not compatible. Stopping these builds is particularly
1181      useful with kernels. The variable also helps to increase parsing
1182      speed since the build system skips parsing recipes not compatible
1183      with the current machine.
1184
1185   :term:`COMPLEMENTARY_GLOB`
1186      Defines wildcards to match when installing a list of complementary
1187      packages for all the packages explicitly (or implicitly) installed in
1188      an image.
1189
1190      .. note::
1191
1192         The :term:`COMPLEMENTARY_GLOB` variable uses Unix filename pattern matching
1193         (`fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__),
1194         which is similar to the Unix style pathname pattern expansion
1195         (`glob <https://docs.python.org/3/library/glob.html>`__).
1196
1197      The resulting list of complementary packages is associated with an
1198      item that can be added to
1199      :term:`IMAGE_FEATURES`. An example usage of
1200      this is the "dev-pkgs" item that when added to :term:`IMAGE_FEATURES`
1201      will install -dev packages (containing headers and other development
1202      files) for every package in the image.
1203
1204      To add a new feature item pointing to a wildcard, use a variable flag
1205      to specify the feature item name and use the value to specify the
1206      wildcard. Here is an example::
1207
1208         COMPLEMENTARY_GLOB[dev-pkgs] = '*-dev'
1209
1210   :term:`COMPONENTS_DIR`
1211      Stores sysroot components for each recipe. The OpenEmbedded build
1212      system uses :term:`COMPONENTS_DIR` when constructing recipe-specific
1213      sysroots for other recipes.
1214
1215      The default is
1216      "``${``\ :term:`STAGING_DIR`\ ``}-components``."
1217      (i.e.
1218      "``${``\ :term:`TMPDIR`\ ``}/sysroots-components``").
1219
1220   :term:`CONF_VERSION`
1221      Tracks the version of the local configuration file (i.e.
1222      ``local.conf``). The value for :term:`CONF_VERSION` increments each time
1223      ``build/conf/`` compatibility changes.
1224
1225   :term:`CONFFILES`
1226      Identifies editable or configurable files that are part of a package.
1227      If the Package Management System (PMS) is being used to update
1228      packages on the target system, it is possible that configuration
1229      files you have changed after the original installation and that you
1230      now want to remain unchanged are overwritten. In other words,
1231      editable files might exist in the package that you do not want reset
1232      as part of the package update process. You can use the :term:`CONFFILES`
1233      variable to list the files in the package that you wish to prevent
1234      the PMS from overwriting during this update process.
1235
1236      To use the :term:`CONFFILES` variable, provide a package name override
1237      that identifies the resulting package. Then, provide a
1238      space-separated list of files. Here is an example::
1239
1240         CONFFILES:${PN} += "${sysconfdir}/file1 \
1241             ${sysconfdir}/file2 ${sysconfdir}/file3"
1242
1243      There is a relationship between the :term:`CONFFILES` and :term:`FILES`
1244      variables. The files listed within :term:`CONFFILES` must be a subset of
1245      the files listed within :term:`FILES`. Because the configuration files
1246      you provide with :term:`CONFFILES` are simply being identified so that
1247      the PMS will not overwrite them, it makes sense that the files must
1248      already be included as part of the package through the :term:`FILES`
1249      variable.
1250
1251      .. note::
1252
1253         When specifying paths as part of the :term:`CONFFILES` variable, it is
1254         good practice to use appropriate path variables.
1255         For example, ``${sysconfdir}`` rather than ``/etc`` or ``${bindir}``
1256         rather than ``/usr/bin``. You can find a list of these variables at
1257         the top of the ``meta/conf/bitbake.conf`` file in the
1258         :term:`Source Directory`.
1259
1260   :term:`CONFIG_INITRAMFS_SOURCE`
1261      Identifies the initial RAM filesystem (initramfs) source files. The
1262      OpenEmbedded build system receives and uses this kernel Kconfig
1263      variable as an environment variable. By default, the variable is set
1264      to null ("").
1265
1266      The :term:`CONFIG_INITRAMFS_SOURCE` can be either a single cpio archive
1267      with a ``.cpio`` suffix or a space-separated list of directories and
1268      files for building the initramfs image. A cpio archive should contain
1269      a filesystem archive to be used as an initramfs image. Directories
1270      should contain a filesystem layout to be included in the initramfs
1271      image. Files should contain entries according to the format described
1272      by the ``usr/gen_init_cpio`` program in the kernel tree.
1273
1274      If you specify multiple directories and files, the initramfs image
1275      will be the aggregate of all of them.
1276
1277      For information on creating an initramfs, see the
1278      ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
1279      in the Yocto Project Development Tasks Manual.
1280
1281   :term:`CONFIG_SITE`
1282      A list of files that contains ``autoconf`` test results relevant to
1283      the current build. This variable is used by the Autotools utilities
1284      when running ``configure``.
1285
1286   :term:`CONFIGURE_FLAGS`
1287      The minimal arguments for GNU configure.
1288
1289   :term:`CONFLICT_DISTRO_FEATURES`
1290      When inheriting the
1291      :ref:`features_check <ref-classes-features_check>`
1292      class, this variable identifies distribution features that would be
1293      in conflict should the recipe be built. In other words, if the
1294      :term:`CONFLICT_DISTRO_FEATURES` variable lists a feature that also
1295      appears in :term:`DISTRO_FEATURES` within the current configuration, then
1296      the recipe will be skipped, and if the build system attempts to build
1297      the recipe then an error will be triggered.
1298
1299   :term:`COPY_LIC_DIRS`
1300      If set to "1" along with the
1301      :term:`COPY_LIC_MANIFEST` variable, the
1302      OpenEmbedded build system copies into the image the license files,
1303      which are located in ``/usr/share/common-licenses``, for each
1304      package. The license files are placed in directories within the image
1305      itself during build time.
1306
1307      .. note::
1308
1309         The :term:`COPY_LIC_DIRS` does not offer a path for adding licenses for
1310         newly installed packages to an image, which might be most suitable for
1311         read-only filesystems that cannot be upgraded. See the
1312         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1313         You can also reference the ":ref:`dev-manual/common-tasks:providing license text`"
1314         section in the Yocto Project Development Tasks Manual for
1315         information on providing license text.
1316
1317   :term:`COPY_LIC_MANIFEST`
1318      If set to "1", the OpenEmbedded build system copies the license
1319      manifest for the image to
1320      ``/usr/share/common-licenses/license.manifest`` within the image
1321      itself during build time.
1322
1323      .. note::
1324
1325         The :term:`COPY_LIC_MANIFEST` does not offer a path for adding licenses for
1326         newly installed packages to an image, which might be most suitable for
1327         read-only filesystems that cannot be upgraded. See the
1328         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1329         You can also reference the ":ref:`dev-manual/common-tasks:providing license text`"
1330         section in the Yocto Project Development Tasks Manual for
1331         information on providing license text.
1332
1333   :term:`COPYLEFT_LICENSE_EXCLUDE`
1334      A space-separated list of licenses to exclude from the source
1335      archived by the :ref:`archiver <ref-classes-archiver>` class. In
1336      other words, if a license in a recipe's
1337      :term:`LICENSE` value is in the value of
1338      :term:`COPYLEFT_LICENSE_EXCLUDE`, then its source is not archived by the
1339      class.
1340
1341      .. note::
1342
1343         The :term:`COPYLEFT_LICENSE_EXCLUDE` variable takes precedence over the
1344         :term:`COPYLEFT_LICENSE_INCLUDE` variable.
1345
1346      The default value, which is "CLOSED Proprietary", for
1347      :term:`COPYLEFT_LICENSE_EXCLUDE` is set by the
1348      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1349      is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1350
1351   :term:`COPYLEFT_LICENSE_INCLUDE`
1352      A space-separated list of licenses to include in the source archived
1353      by the :ref:`archiver <ref-classes-archiver>` class. In other
1354      words, if a license in a recipe's :term:`LICENSE`
1355      value is in the value of :term:`COPYLEFT_LICENSE_INCLUDE`, then its
1356      source is archived by the class.
1357
1358      The default value is set by the
1359      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1360      is inherited by the :ref:`archiver <ref-classes-archiver>` class. The default value includes
1361      "GPL*", "LGPL*", and "AGPL*".
1362
1363   :term:`COPYLEFT_PN_EXCLUDE`
1364      A list of recipes to exclude in the source archived by the
1365      :ref:`archiver <ref-classes-archiver>` class. The
1366      :term:`COPYLEFT_PN_EXCLUDE` variable overrides the license inclusion and
1367      exclusion caused through the
1368      :term:`COPYLEFT_LICENSE_INCLUDE` and
1369      :term:`COPYLEFT_LICENSE_EXCLUDE`
1370      variables, respectively.
1371
1372      The default value, which is "" indicating to not explicitly exclude
1373      any recipes by name, for :term:`COPYLEFT_PN_EXCLUDE` is set by the
1374      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1375      is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1376
1377   :term:`COPYLEFT_PN_INCLUDE`
1378      A list of recipes to include in the source archived by the
1379      :ref:`archiver <ref-classes-archiver>` class. The
1380      :term:`COPYLEFT_PN_INCLUDE` 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 include
1387      any recipes by name, for :term:`COPYLEFT_PN_INCLUDE` 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_RECIPE_TYPES`
1392      A space-separated list of recipe types to include in the source
1393      archived by the :ref:`archiver <ref-classes-archiver>` class.
1394      Recipe types are ``target``, ``native``, ``nativesdk``, ``cross``,
1395      ``crosssdk``, and ``cross-canadian``.
1396
1397      The default value, which is "target*", for :term:`COPYLEFT_RECIPE_TYPES`
1398      is set by the :ref:`copyleft_filter <ref-classes-copyleft_filter>`
1399      class, which is inherited by the :ref:`archiver <ref-classes-archiver>` class.
1400
1401   :term:`CORE_IMAGE_EXTRA_INSTALL`
1402      Specifies the list of packages to be added to the image. You should
1403      only set this variable in the ``local.conf`` configuration file found
1404      in the :term:`Build Directory`.
1405
1406      This variable replaces ``POKY_EXTRA_INSTALL``, which is no longer
1407      supported.
1408
1409   :term:`COREBASE`
1410      Specifies the parent directory of the OpenEmbedded-Core Metadata
1411      layer (i.e. ``meta``).
1412
1413      It is an important distinction that :term:`COREBASE` points to the parent
1414      of this layer and not the layer itself. Consider an example where you
1415      have cloned the Poky Git repository and retained the ``poky`` name
1416      for your local copy of the repository. In this case, :term:`COREBASE`
1417      points to the ``poky`` folder because it is the parent directory of
1418      the ``poky/meta`` layer.
1419
1420   :term:`COREBASE_FILES`
1421      Lists files from the :term:`COREBASE` directory that
1422      should be copied other than the layers listed in the
1423      ``bblayers.conf`` file. The :term:`COREBASE_FILES` variable allows
1424      to copy metadata from the OpenEmbedded build system
1425      into the extensible SDK.
1426
1427      Explicitly listing files in :term:`COREBASE` is needed because it
1428      typically contains build directories and other files that should not
1429      normally be copied into the extensible SDK. Consequently, the value
1430      of :term:`COREBASE_FILES` is used in order to only copy the files that
1431      are actually needed.
1432
1433   :term:`CPP`
1434      The minimal command and arguments used to run the C preprocessor.
1435
1436   :term:`CPPFLAGS`
1437      Specifies the flags to pass to the C pre-processor (i.e. to both the
1438      C and the C++ compilers). This variable is exported to an environment
1439      variable and thus made visible to the software being built during the
1440      compilation step.
1441
1442      Default initialization for :term:`CPPFLAGS` varies depending on what is
1443      being built:
1444
1445      -  :term:`TARGET_CPPFLAGS` when building for
1446         the target
1447
1448      -  :term:`BUILD_CPPFLAGS` when building for the
1449         build host (i.e. ``-native``)
1450
1451      -  :term:`BUILDSDK_CPPFLAGS` when building
1452         for an SDK (i.e. ``nativesdk-``)
1453
1454   :term:`CROSS_COMPILE`
1455      The toolchain binary prefix for the target tools. The
1456      :term:`CROSS_COMPILE` variable is the same as the
1457      :term:`TARGET_PREFIX` variable.
1458
1459      .. note::
1460
1461         The OpenEmbedded build system sets the :term:`CROSS_COMPILE`
1462         variable only in certain contexts (e.g. when building for kernel
1463         and kernel module recipes).
1464
1465   :term:`CVE_CHECK_IGNORE`
1466      The list of CVE IDs which are ignored. Here is
1467      an example from the :oe_layerindex:`Python3 recipe</layerindex/recipe/23823>`::
1468
1469         # This is windows only issue.
1470         CVE_CHECK_IGNORE += "CVE-2020-15523"
1471
1472   :term:`CVE_CHECK_SKIP_RECIPE`
1473      The list of package names (:term:`PN`) for which
1474      CVEs (Common Vulnerabilities and Exposures) are ignored.
1475
1476   :term:`CVE_PRODUCT`
1477      In a recipe, defines the name used to match the recipe name
1478      against the name in the upstream `NIST CVE database <https://nvd.nist.gov/>`__.
1479
1480      The default is ${:term:`BPN`}. If it does not match the name in the NIST CVE
1481      database or matches with multiple entries in the database, the default
1482      value needs to be changed.
1483
1484      Here is an example from the :oe_layerindex:`Berkeley DB recipe </layerindex/recipe/544>`::
1485
1486         CVE_PRODUCT = "oracle_berkeley_db berkeley_db"
1487
1488      Sometimes the product name is not specific enough, for example
1489      "tar" has been matching CVEs for the GNU ``tar`` package and also
1490      the ``node-tar`` node.js extension. To avoid this problem, use the
1491      vendor name as a prefix. The syntax for this is::
1492
1493         CVE_PRODUCT = "vendor:package"
1494
1495   :term:`CVSDIR`
1496      The directory in which files checked out under the CVS system are
1497      stored.
1498
1499   :term:`CXX`
1500      The minimal command and arguments used to run the C++ compiler.
1501
1502   :term:`CXXFLAGS`
1503      Specifies the flags to pass to the C++ compiler. This variable is
1504      exported to an environment variable and thus made visible to the
1505      software being built during the compilation step.
1506
1507      Default initialization for :term:`CXXFLAGS` varies depending on what is
1508      being built:
1509
1510      -  :term:`TARGET_CXXFLAGS` when building for
1511         the target
1512
1513      -  :term:`BUILD_CXXFLAGS` when building for the
1514         build host (i.e. ``-native``)
1515
1516      -  :term:`BUILDSDK_CXXFLAGS` when building
1517         for an SDK (i.e. ``nativesdk-``)
1518
1519   :term:`D`
1520      The destination directory. The location in the :term:`Build Directory`
1521      where components are installed by the
1522      :ref:`ref-tasks-install` task. This location defaults
1523      to::
1524
1525         ${WORKDIR}/image
1526
1527      .. note::
1528
1529         Tasks that read from or write to this directory should run under
1530         :ref:`fakeroot <overview-manual/concepts:fakeroot and pseudo>`.
1531
1532   :term:`DATE`
1533      The date the build was started. Dates appear using the year, month,
1534      and day (YMD) format (e.g. "20150209" for February 9th, 2015).
1535
1536   :term:`DATETIME`
1537      The date and time on which the current build started. The format is
1538      suitable for timestamps.
1539
1540   :term:`DEBIAN_NOAUTONAME`
1541      When the :ref:`debian <ref-classes-debian>` class is inherited,
1542      which is the default behavior, :term:`DEBIAN_NOAUTONAME` specifies a
1543      particular package should not be renamed according to Debian library
1544      package naming. You must use the package name as an override when you
1545      set this variable. Here is an example from the ``fontconfig`` recipe::
1546
1547         DEBIAN_NOAUTONAME:fontconfig-utils = "1"
1548
1549   :term:`DEBIANNAME`
1550      When the :ref:`debian <ref-classes-debian>` class is inherited,
1551      which is the default behavior, :term:`DEBIANNAME` allows you to override
1552      the library name for an individual package. Overriding the library
1553      name in these cases is rare. You must use the package name as an
1554      override when you set this variable. Here is an example from the
1555      ``dbus`` recipe::
1556
1557         DEBIANNAME:${PN} = "dbus-1"
1558
1559   :term:`DEBUG_BUILD`
1560      Specifies to build packages with debugging information. This
1561      influences the value of the :term:`SELECTED_OPTIMIZATION` variable.
1562
1563   :term:`DEBUG_OPTIMIZATION`
1564      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
1565      compiling a system for debugging. This variable defaults to "-O
1566      -fno-omit-frame-pointer ${DEBUG_FLAGS} -pipe".
1567
1568   :term:`DEBUG_PREFIX_MAP`
1569      Allows to set C compiler options, such as ``-fdebug-prefix-map``,
1570      ``-fmacro-prefix-map``, and ``-ffile-prefix-map``, which allow to
1571      replace build-time paths by install-time ones in the debugging sections
1572      of binaries.  This makes compiler output files location independent,
1573      at the cost of having to pass an extra command to tell the debugger
1574      where source files are.
1575
1576      This is used by the Yocto Project to guarantee
1577      :doc:`/test-manual/reproducible-builds` even when the source code of
1578      a package uses the ``__FILE__`` or ``assert()`` macros. See the
1579      `reproducible-builds.org <https://reproducible-builds.org/docs/build-path/>`__
1580      website for details.
1581
1582      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1583      not intended to be user-configurable.
1584
1585   :term:`DEFAULT_PREFERENCE`
1586      Specifies a weak bias for recipe selection priority.
1587
1588      The most common usage of this is variable is to set it to "-1" within
1589      a recipe for a development version of a piece of software. Using the
1590      variable in this way causes the stable version of the recipe to build
1591      by default in the absence of :term:`PREFERRED_VERSION` being used to
1592      build the development version.
1593
1594      .. note::
1595
1596         The bias provided by :term:`DEFAULT_PREFERENCE` is weak and is overridden
1597         by :term:`BBFILE_PRIORITY` if that variable is different between two
1598         layers that contain different versions of the same recipe.
1599
1600   :term:`DEFAULTTUNE`
1601      The default CPU and Application Binary Interface (ABI) tunings (i.e.
1602      the "tune") used by the OpenEmbedded build system. The
1603      :term:`DEFAULTTUNE` helps define
1604      :term:`TUNE_FEATURES`.
1605
1606      The default tune is either implicitly or explicitly set by the
1607      machine (:term:`MACHINE`). However, you can override
1608      the setting using available tunes as defined with
1609      :term:`AVAILTUNES`.
1610
1611   :term:`DEPENDS`
1612      Lists a recipe's build-time dependencies. These are dependencies on
1613      other recipes whose contents (e.g. headers and shared libraries) are
1614      needed by the recipe at build time.
1615
1616      As an example, consider a recipe ``foo`` that contains the following
1617      assignment::
1618
1619          DEPENDS = "bar"
1620
1621      The practical effect of the previous
1622      assignment is that all files installed by bar will be available in
1623      the appropriate staging sysroot, given by the
1624      :term:`STAGING_DIR* <STAGING_DIR>` variables, by the time the
1625      :ref:`ref-tasks-configure` task for ``foo`` runs.
1626      This mechanism is implemented by having ``do_configure`` depend on
1627      the :ref:`ref-tasks-populate_sysroot` task of
1628      each recipe listed in :term:`DEPENDS`, through a
1629      ``[``\ :ref:`deptask <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]``
1630      declaration in the :ref:`base <ref-classes-base>` class.
1631
1632      .. note::
1633
1634         It seldom is necessary to reference, for example, :term:`STAGING_DIR_HOST`
1635         explicitly. The standard classes and build-related variables are
1636         configured to automatically use the appropriate staging sysroots.
1637
1638      As another example, :term:`DEPENDS` can also be used to add utilities
1639      that run on the build machine during the build. For example, a recipe
1640      that makes use of a code generator built by the recipe ``codegen``
1641      might have the following::
1642
1643         DEPENDS = "codegen-native"
1644
1645      For more
1646      information, see the :ref:`native <ref-classes-native>` class and
1647      the :term:`EXTRANATIVEPATH` variable.
1648
1649      .. note::
1650
1651         -  :term:`DEPENDS` is a list of recipe names. Or, to be more precise,
1652            it is a list of :term:`PROVIDES` names, which
1653            usually match recipe names. Putting a package name such as
1654            "foo-dev" in :term:`DEPENDS` does not make sense. Use "foo"
1655            instead, as this will put files from all the packages that make
1656            up ``foo``, which includes those from ``foo-dev``, into the
1657            sysroot.
1658
1659         -  One recipe having another recipe in :term:`DEPENDS` does not by
1660            itself add any runtime dependencies between the packages
1661            produced by the two recipes. However, as explained in the
1662            ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
1663            section in the Yocto Project Overview and Concepts Manual,
1664            runtime dependencies will often be added automatically, meaning
1665            :term:`DEPENDS` alone is sufficient for most recipes.
1666
1667         -  Counterintuitively, :term:`DEPENDS` is often necessary even for
1668            recipes that install precompiled components. For example, if
1669            ``libfoo`` is a precompiled library that links against
1670            ``libbar``, then linking against ``libfoo`` requires both
1671            ``libfoo`` and ``libbar`` to be available in the sysroot.
1672            Without a :term:`DEPENDS` from the recipe that installs ``libfoo``
1673            to the recipe that installs ``libbar``, other recipes might
1674            fail to link against ``libfoo``.
1675
1676      For information on runtime dependencies, see the
1677      :term:`RDEPENDS` variable. You can also see the
1678      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
1679      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
1680      BitBake User Manual for additional information on tasks and
1681      dependencies.
1682
1683   :term:`DEPLOY_DIR`
1684      Points to the general area that the OpenEmbedded build system uses to
1685      place images, packages, SDKs, and other output files that are ready
1686      to be used outside of the build system. By default, this directory
1687      resides within the :term:`Build Directory` as
1688      ``${TMPDIR}/deploy``.
1689
1690      For more information on the structure of the Build Directory, see
1691      ":ref:`ref-manual/structure:the build directory - \`\`build/\`\``" section.
1692      For more detail on the contents of the ``deploy`` directory, see the
1693      ":ref:`overview-manual/concepts:images`",
1694      ":ref:`overview-manual/concepts:package feeds`", and
1695      ":ref:`overview-manual/concepts:application development sdk`" sections all in the
1696      Yocto Project Overview and Concepts Manual.
1697
1698   :term:`DEPLOY_DIR_DEB`
1699      Points to the area that the OpenEmbedded build system uses to place
1700      Debian packages that are ready to be used outside of the build
1701      system. This variable applies only when
1702      :term:`PACKAGE_CLASSES` contains
1703      "package_deb".
1704
1705      The BitBake configuration file initially defines the
1706      :term:`DEPLOY_DIR_DEB` variable as a sub-folder of
1707      :term:`DEPLOY_DIR`::
1708
1709         DEPLOY_DIR_DEB = "${DEPLOY_DIR}/deb"
1710
1711      The :ref:`package_deb <ref-classes-package_deb>` class uses the
1712      :term:`DEPLOY_DIR_DEB` variable to make sure the
1713      :ref:`ref-tasks-package_write_deb` task
1714      writes Debian packages into the appropriate folder. For more
1715      information on how packaging works, see the
1716      ":ref:`overview-manual/concepts:package feeds`" section
1717      in the Yocto Project Overview and Concepts Manual.
1718
1719   :term:`DEPLOY_DIR_IMAGE`
1720      Points to the area that the OpenEmbedded build system uses to place
1721      images and other associated output files that are ready to be
1722      deployed onto the target machine. The directory is machine-specific
1723      as it contains the ``${MACHINE}`` name. By default, this directory
1724      resides within the :term:`Build Directory` as
1725      ``${DEPLOY_DIR}/images/${MACHINE}/``.
1726
1727      It must not be used directly in recipes when deploying files. Instead,
1728      it's only useful when a recipe needs to "read" a file already deployed
1729      by a dependency. So, it should be filled with the contents of
1730      :term:`DEPLOYDIR` by the :ref:`deploy <ref-classes-deploy>` class or
1731      with the contents of :term:`IMGDEPLOYDIR` by the :ref:`image
1732      <ref-classes-image>` class.
1733
1734      For more information on the structure of the Build Directory, see
1735      ":ref:`ref-manual/structure:the build directory - \`\`build/\`\``" section.
1736      For more detail on the contents of the ``deploy`` directory, see the
1737      ":ref:`overview-manual/concepts:images`" and
1738      ":ref:`overview-manual/concepts:application development sdk`" sections both in
1739      the Yocto Project Overview and Concepts Manual.
1740
1741   :term:`DEPLOY_DIR_IPK`
1742      Points to the area that the OpenEmbedded build system uses to place
1743      IPK packages that are ready to be used outside of the build system.
1744      This variable applies only when
1745      :term:`PACKAGE_CLASSES` contains
1746      "package_ipk".
1747
1748      The BitBake configuration file initially defines this variable as a
1749      sub-folder of :term:`DEPLOY_DIR`::
1750
1751         DEPLOY_DIR_IPK = "${DEPLOY_DIR}/ipk"
1752
1753      The :ref:`package_ipk <ref-classes-package_ipk>` class uses the
1754      :term:`DEPLOY_DIR_IPK` variable to make sure the
1755      :ref:`ref-tasks-package_write_ipk` task
1756      writes IPK packages into the appropriate folder. For more information
1757      on how packaging works, see the
1758      ":ref:`overview-manual/concepts:package feeds`" section
1759      in the Yocto Project Overview and Concepts Manual.
1760
1761   :term:`DEPLOY_DIR_RPM`
1762      Points to the area that the OpenEmbedded build system uses to place
1763      RPM packages that are ready to be used outside of the build system.
1764      This variable applies only when
1765      :term:`PACKAGE_CLASSES` contains
1766      "package_rpm".
1767
1768      The BitBake configuration file initially defines this variable as a
1769      sub-folder of :term:`DEPLOY_DIR`::
1770
1771         DEPLOY_DIR_RPM = "${DEPLOY_DIR}/rpm"
1772
1773      The :ref:`package_rpm <ref-classes-package_rpm>` class uses the
1774      :term:`DEPLOY_DIR_RPM` variable to make sure the
1775      :ref:`ref-tasks-package_write_rpm` task
1776      writes RPM packages into the appropriate folder. For more information
1777      on how packaging works, see the
1778      ":ref:`overview-manual/concepts:package feeds`" section
1779      in the Yocto Project Overview and Concepts Manual.
1780
1781   :term:`DEPLOY_DIR_TAR`
1782      Points to the area that the OpenEmbedded build system uses to place
1783      tarballs that are ready to be used outside of the build system. This
1784      variable applies only when
1785      :term:`PACKAGE_CLASSES` contains
1786      "package_tar".
1787
1788      The BitBake configuration file initially defines this variable as a
1789      sub-folder of :term:`DEPLOY_DIR`::
1790
1791         DEPLOY_DIR_TAR = "${DEPLOY_DIR}/tar"
1792
1793      The :ref:`package_tar <ref-classes-package_tar>` class uses the
1794      :term:`DEPLOY_DIR_TAR` variable to make sure the
1795      :ref:`ref-tasks-package_write_tar` task
1796      writes TAR packages into the appropriate folder. For more information
1797      on how packaging works, see the
1798      ":ref:`overview-manual/concepts:package feeds`" section
1799      in the Yocto Project Overview and Concepts Manual.
1800
1801   :term:`DEPLOYDIR`
1802      When inheriting the :ref:`deploy <ref-classes-deploy>` class, the
1803      :term:`DEPLOYDIR` points to a temporary work area for deployed files that
1804      is set in the :ref:`deploy <ref-classes-deploy>` class as follows::
1805
1806         DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
1807
1808      Recipes inheriting the :ref:`deploy <ref-classes-deploy>` class should copy files to be
1809      deployed into :term:`DEPLOYDIR`, and the class will take care of copying
1810      them into :term:`DEPLOY_DIR_IMAGE`
1811      afterwards.
1812
1813   :term:`DESCRIPTION`
1814      The package description used by package managers. If not set,
1815      :term:`DESCRIPTION` takes the value of the :term:`SUMMARY`
1816      variable.
1817
1818   :term:`DISTRO`
1819      The short name of the distribution. For information on the long name
1820      of the distribution, see the :term:`DISTRO_NAME`
1821      variable.
1822
1823      The :term:`DISTRO` variable corresponds to a distribution configuration
1824      file whose root name is the same as the variable's argument and whose
1825      filename extension is ``.conf``. For example, the distribution
1826      configuration file for the Poky distribution is named ``poky.conf``
1827      and resides in the ``meta-poky/conf/distro`` directory of the
1828      :term:`Source Directory`.
1829
1830      Within that ``poky.conf`` file, the :term:`DISTRO` variable is set as
1831      follows::
1832
1833         DISTRO = "poky"
1834
1835      Distribution configuration files are located in a ``conf/distro``
1836      directory within the :term:`Metadata` that contains the
1837      distribution configuration. The value for :term:`DISTRO` must not contain
1838      spaces, and is typically all lower-case.
1839
1840      .. note::
1841
1842         If the :term:`DISTRO` variable is blank, a set of default configurations
1843         are used, which are specified within
1844         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
1845
1846   :term:`DISTRO_CODENAME`
1847      Specifies a codename for the distribution being built.
1848
1849   :term:`DISTRO_EXTRA_RDEPENDS`
1850      Specifies a list of distro-specific packages to add to all images.
1851      This variable takes effect through ``packagegroup-base`` so the
1852      variable only really applies to the more full-featured images that
1853      include ``packagegroup-base``. You can use this variable to keep
1854      distro policy out of generic images. As with all other distro
1855      variables, you set this variable in the distro ``.conf`` file.
1856
1857   :term:`DISTRO_EXTRA_RRECOMMENDS`
1858      Specifies a list of distro-specific packages to add to all images if
1859      the packages exist. The packages might not exist or be empty (e.g.
1860      kernel modules). The list of packages are automatically installed but
1861      you can remove them.
1862
1863   :term:`DISTRO_FEATURES`
1864      The software support you want in your distribution for various
1865      features. You define your distribution features in the distribution
1866      configuration file.
1867
1868      In most cases, the presence or absence of a feature in
1869      :term:`DISTRO_FEATURES` is translated to the appropriate option supplied
1870      to the configure script during the
1871      :ref:`ref-tasks-configure` task for recipes that
1872      optionally support the feature. For example, specifying "x11" in
1873      :term:`DISTRO_FEATURES`, causes every piece of software built for the
1874      target that can optionally support X11 to have its X11 support
1875      enabled.
1876
1877      Two more examples are Bluetooth and NFS support. For a more complete
1878      list of features that ships with the Yocto Project and that you can
1879      provide with this variable, see the ":ref:`ref-features-distro`" section.
1880
1881   :term:`DISTRO_FEATURES_BACKFILL`
1882      Features to be added to :term:`DISTRO_FEATURES` if not also present in
1883      :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`.
1884
1885      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1886      not intended to be user-configurable. It is best to just reference
1887      the variable to see which distro features are being backfilled for
1888      all distro configurations. See the ":ref:`ref-features-backfill`" section
1889      for more information.
1890
1891   :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`
1892      Features from :term:`DISTRO_FEATURES_BACKFILL` that should not be
1893      backfilled (i.e. added to :term:`DISTRO_FEATURES`) during the build. See
1894      the ":ref:`ref-features-backfill`" section for more information.
1895
1896   :term:`DISTRO_FEATURES_DEFAULT`
1897      A convenience variable that gives you the default list of distro
1898      features with the exception of any features specific to the C library
1899      (``libc``).
1900
1901      When creating a custom distribution, you might find it useful to be
1902      able to reuse the default
1903      :term:`DISTRO_FEATURES` options without the
1904      need to write out the full set. Here is an example that uses
1905      :term:`DISTRO_FEATURES_DEFAULT` from a custom distro configuration file::
1906
1907         DISTRO_FEATURES ?= "${DISTRO_FEATURES_DEFAULT} myfeature"
1908
1909   :term:`DISTRO_FEATURES_FILTER_NATIVE`
1910      Specifies a list of features that if present in the target
1911      :term:`DISTRO_FEATURES` value should be
1912      included in :term:`DISTRO_FEATURES` when building native recipes. This
1913      variable is used in addition to the features filtered using the
1914      :term:`DISTRO_FEATURES_NATIVE`
1915      variable.
1916
1917   :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
1918      Specifies a list of features that if present in the target
1919      :term:`DISTRO_FEATURES` value should be
1920      included in :term:`DISTRO_FEATURES` when building nativesdk recipes. This
1921      variable is used in addition to the features filtered using the
1922      :term:`DISTRO_FEATURES_NATIVESDK`
1923      variable.
1924
1925   :term:`DISTRO_FEATURES_NATIVE`
1926      Specifies a list of features that should be included in
1927      :term:`DISTRO_FEATURES` when building native
1928      recipes. This variable is used in addition to the features filtered
1929      using the
1930      :term:`DISTRO_FEATURES_FILTER_NATIVE`
1931      variable.
1932
1933   :term:`DISTRO_FEATURES_NATIVESDK`
1934      Specifies a list of features that should be included in
1935      :term:`DISTRO_FEATURES` when building
1936      nativesdk recipes. This variable is used in addition to the features
1937      filtered using the
1938      :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
1939      variable.
1940
1941   :term:`DISTRO_NAME`
1942      The long name of the distribution. For information on the short name
1943      of the distribution, see the :term:`DISTRO` variable.
1944
1945      The :term:`DISTRO_NAME` variable corresponds to a distribution
1946      configuration file whose root name is the same as the variable's
1947      argument and whose filename extension is ``.conf``. For example, the
1948      distribution configuration file for the Poky distribution is named
1949      ``poky.conf`` and resides in the ``meta-poky/conf/distro`` directory
1950      of the :term:`Source Directory`.
1951
1952      Within that ``poky.conf`` file, the :term:`DISTRO_NAME` variable is set
1953      as follows::
1954
1955         DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
1956
1957      Distribution configuration files are located in a ``conf/distro``
1958      directory within the :term:`Metadata` that contains the
1959      distribution configuration.
1960
1961      .. note::
1962
1963         If the :term:`DISTRO_NAME` variable is blank, a set of default
1964         configurations are used, which are specified within
1965         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
1966
1967   :term:`DISTRO_VERSION`
1968      The version of the distribution.
1969
1970   :term:`DISTROOVERRIDES`
1971      A colon-separated list of overrides specific to the current
1972      distribution. By default, this list includes the value of
1973      :term:`DISTRO`.
1974
1975      You can extend :term:`DISTROOVERRIDES` to add extra overrides that should
1976      apply to the distribution.
1977
1978      The underlying mechanism behind :term:`DISTROOVERRIDES` is simply that it
1979      is included in the default value of
1980      :term:`OVERRIDES`.
1981
1982   :term:`DL_DIR`
1983      The central download directory used by the build process to store
1984      downloads. By default, :term:`DL_DIR` gets files suitable for mirroring
1985      for everything except Git repositories. If you want tarballs of Git
1986      repositories, use the
1987      :term:`BB_GENERATE_MIRROR_TARBALLS`
1988      variable.
1989
1990      You can set this directory by defining the :term:`DL_DIR` variable in the
1991      ``conf/local.conf`` file. This directory is self-maintaining and you
1992      should not have to touch it. By default, the directory is
1993      ``downloads`` in the :term:`Build Directory`.
1994      ::
1995
1996         #DL_DIR ?= "${TOPDIR}/downloads"
1997
1998      To specify a different download directory,
1999      simply remove the comment from the line and provide your directory.
2000
2001      During a first build, the system downloads many different source code
2002      tarballs from various upstream projects. Downloading can take a
2003      while, particularly if your network connection is slow. Tarballs are
2004      all stored in the directory defined by :term:`DL_DIR` and the build
2005      system looks there first to find source tarballs.
2006
2007      .. note::
2008
2009         When wiping and rebuilding, you can preserve this directory to
2010         speed up this part of subsequent builds.
2011
2012      You can safely share this directory between multiple builds on the
2013      same development machine. For additional information on how the build
2014      process gets source files when working behind a firewall or proxy
2015      server, see this specific question in the ":doc:`faq`"
2016      chapter. You can also refer to the
2017      ":yocto_wiki:`Working Behind a Network Proxy </Working_Behind_a_Network_Proxy>`"
2018      Wiki page.
2019
2020   :term:`DOC_COMPRESS`
2021      When inheriting the :ref:`compress_doc <ref-classes-compress_doc>`
2022      class, this variable sets the compression policy used when the
2023      OpenEmbedded build system compresses man pages and info pages. By
2024      default, the compression method used is gz (gzip). Other policies
2025      available are xz and bz2.
2026
2027      For information on policies and on how to use this variable, see the
2028      comments in the ``meta/classes/compress_doc.bbclass`` file.
2029
2030   :term:`EFI_PROVIDER`
2031      When building bootable images (i.e. where ``hddimg``, ``iso``, or
2032      ``wic.vmdk`` is in :term:`IMAGE_FSTYPES`), the
2033      :term:`EFI_PROVIDER` variable specifies the EFI bootloader to use. The
2034      default is "grub-efi", but "systemd-boot" can be used instead.
2035
2036      See the :ref:`systemd-boot <ref-classes-systemd-boot>` and
2037      :ref:`image-live <ref-classes-image-live>` classes for more
2038      information.
2039
2040   :term:`ENABLE_BINARY_LOCALE_GENERATION`
2041      Variable that controls which locales for ``glibc`` are generated
2042      during the build (useful if the target device has 64Mbytes of RAM or
2043      less).
2044
2045   :term:`ERR_REPORT_DIR`
2046      When used with the :ref:`report-error <ref-classes-report-error>`
2047      class, specifies the path used for storing the debug files created by
2048      the :ref:`error reporting
2049      tool <dev-manual/common-tasks:using the error reporting tool>`, which
2050      allows you to submit build errors you encounter to a central
2051      database. By default, the value of this variable is
2052      ``${``\ :term:`LOG_DIR`\ ``}/error-report``.
2053
2054      You can set :term:`ERR_REPORT_DIR` to the path you want the error
2055      reporting tool to store the debug files as follows in your
2056      ``local.conf`` file::
2057
2058         ERR_REPORT_DIR = "path"
2059
2060   :term:`ERROR_QA`
2061      Specifies the quality assurance checks whose failures are reported as
2062      errors by the OpenEmbedded build system. You set this variable in
2063      your distribution configuration file. For a list of the checks you
2064      can control with this variable, see the
2065      ":ref:`ref-classes-insane`" section.
2066
2067   :term:`ESDK_CLASS_INHERIT_DISABLE`
2068      A list of classes to remove from the :term:`INHERIT`
2069      value globally within the extensible SDK configuration. The
2070      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class sets the
2071      default value::
2072
2073         ESDK_CLASS_INHERIT_DISABLE ?= "buildhistory icecc"
2074
2075      Some classes are not generally applicable within the extensible SDK
2076      context. You can use this variable to disable those classes.
2077
2078      For additional information on how to customize the extensible SDK's
2079      configuration, see the
2080      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2081      section in the Yocto Project Application Development and the
2082      Extensible Software Development Kit (eSDK) manual.
2083
2084   :term:`ESDK_LOCALCONF_ALLOW`
2085      A list of variables allowed through from the OpenEmbedded build
2086      system configuration into the extensible SDK configuration. By
2087      default, the list of variables is empty and is set in the
2088      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class.
2089
2090      This list overrides the variables specified using the
2091      :term:`ESDK_LOCALCONF_REMOVE` variable as well as
2092      other variables automatically added due to the "/" character
2093      being found at the start of the
2094      value, which is usually indicative of being a path and thus might not
2095      be valid on the system where the SDK is installed.
2096
2097      For additional information on how to customize the extensible SDK's
2098      configuration, see the
2099      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2100      section in the Yocto Project Application Development and the
2101      Extensible Software Development Kit (eSDK) manual.
2102
2103   :term:`ESDK_LOCALCONF_REMOVE`
2104      A list of variables not allowed through from the OpenEmbedded build
2105      system configuration into the extensible SDK configuration. Usually,
2106      these are variables that are specific to the machine on which the
2107      build system is running and thus would be potentially problematic
2108      within the extensible SDK.
2109
2110      By default, :term:`ESDK_LOCALCONF_REMOVE` is set in the
2111      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class and
2112      excludes the following variables:
2113
2114      - :term:`CONF_VERSION`
2115      - :term:`BB_NUMBER_THREADS`
2116      - :term:`BB_NUMBER_PARSE_THREADS`
2117      - :term:`PARALLEL_MAKE`
2118      - :term:`PRSERV_HOST`
2119      - :term:`SSTATE_MIRRORS` :term:`DL_DIR`
2120      - :term:`SSTATE_DIR` :term:`TMPDIR`
2121      - :term:`BB_SERVER_TIMEOUT`
2122
2123      For additional information on how to customize the extensible SDK's
2124      configuration, see the
2125      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
2126      section in the Yocto Project Application Development and the
2127      Extensible Software Development Kit (eSDK) manual.
2128
2129   :term:`EXCLUDE_FROM_SHLIBS`
2130      Triggers the OpenEmbedded build system's shared libraries resolver to
2131      exclude an entire package when scanning for shared libraries.
2132
2133      .. note::
2134
2135         The shared libraries resolver's functionality results in part from
2136         the internal function ``package_do_shlibs``, which is part of the
2137         :ref:`ref-tasks-package` task. You should be aware that the shared
2138         libraries resolver might implicitly define some dependencies between
2139         packages.
2140
2141      The :term:`EXCLUDE_FROM_SHLIBS` variable is similar to the
2142      :term:`PRIVATE_LIBS` variable, which excludes a
2143      package's particular libraries only and not the whole package.
2144
2145      Use the :term:`EXCLUDE_FROM_SHLIBS` variable by setting it to "1" for a
2146      particular package::
2147
2148         EXCLUDE_FROM_SHLIBS = "1"
2149
2150   :term:`EXCLUDE_FROM_WORLD`
2151      Directs BitBake to exclude a recipe from world builds (i.e.
2152      ``bitbake world``). During world builds, BitBake locates, parses and
2153      builds all recipes found in every layer exposed in the
2154      ``bblayers.conf`` configuration file.
2155
2156      To exclude a recipe from a world build using this variable, set the
2157      variable to "1" in the recipe.
2158
2159      .. note::
2160
2161         Recipes added to :term:`EXCLUDE_FROM_WORLD` may still be built during a
2162         world build in order to satisfy dependencies of other recipes. Adding
2163         a recipe to :term:`EXCLUDE_FROM_WORLD` only ensures that the recipe is not
2164         explicitly added to the list of build targets in a world build.
2165
2166   :term:`EXTENDPE`
2167      Used with file and pathnames to create a prefix for a recipe's
2168      version based on the recipe's :term:`PE` value. If :term:`PE`
2169      is set and greater than zero for a recipe, :term:`EXTENDPE` becomes that
2170      value (e.g if :term:`PE` is equal to "1" then :term:`EXTENDPE` becomes "1").
2171      If a recipe's :term:`PE` is not set (the default) or is equal to zero,
2172      :term:`EXTENDPE` becomes "".
2173
2174      See the :term:`STAMP` variable for an example.
2175
2176   :term:`EXTENDPKGV`
2177      The full package version specification as it appears on the final
2178      packages produced by a recipe. The variable's value is normally used
2179      to fix a runtime dependency to the exact same version of another
2180      package in the same recipe::
2181
2182         RDEPENDS:${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
2183
2184      The dependency relationships are intended to force the package
2185      manager to upgrade these types of packages in lock-step.
2186
2187   :term:`EXTERNAL_KERNEL_TOOLS`
2188      When set, the :term:`EXTERNAL_KERNEL_TOOLS` variable indicates that these
2189      tools are not in the source tree.
2190
2191      When kernel tools are available in the tree, they are preferred over
2192      any externally installed tools. Setting the :term:`EXTERNAL_KERNEL_TOOLS`
2193      variable tells the OpenEmbedded build system to prefer the installed
2194      external tools. See the
2195      :ref:`kernel-yocto <ref-classes-kernel-yocto>` class in
2196      ``meta/classes`` to see how the variable is used.
2197
2198   :term:`EXTERNALSRC`
2199      When inheriting the :ref:`externalsrc <ref-classes-externalsrc>`
2200      class, this variable points to the source tree, which is outside of
2201      the OpenEmbedded build system. When set, this variable sets the
2202      :term:`S` variable, which is what the OpenEmbedded build
2203      system uses to locate unpacked recipe source code.
2204
2205      See the ":ref:`ref-classes-externalsrc`" section for details. You
2206      can also find information on how to use this variable in the
2207      ":ref:`dev-manual/common-tasks:building software from an external source`"
2208      section in the Yocto Project Development Tasks Manual.
2209
2210   :term:`EXTERNALSRC_BUILD`
2211      When inheriting the :ref:`externalsrc <ref-classes-externalsrc>`
2212      class, this variable points to the directory in which the recipe's
2213      source code is built, which is outside of the OpenEmbedded build
2214      system. When set, this variable sets the :term:`B` variable,
2215      which is what the OpenEmbedded build system uses to locate the Build
2216      Directory.
2217
2218      See the ":ref:`ref-classes-externalsrc`" section for details. You
2219      can also find information on how to use this variable in the
2220      ":ref:`dev-manual/common-tasks:building software from an external source`"
2221      section in the Yocto Project Development Tasks Manual.
2222
2223   :term:`EXTRA_AUTORECONF`
2224      For recipes inheriting the :ref:`autotools <ref-classes-autotools>`
2225      class, you can use :term:`EXTRA_AUTORECONF` to specify extra options to
2226      pass to the ``autoreconf`` command that is executed during the
2227      :ref:`ref-tasks-configure` task.
2228
2229      The default value is "--exclude=autopoint".
2230
2231   :term:`EXTRA_IMAGE_FEATURES`
2232      A list of additional features to include in an image. When listing
2233      more than one feature, separate them with a space.
2234
2235      Typically, you configure this variable in your ``local.conf`` file,
2236      which is found in the :term:`Build Directory`.
2237      Although you can use this variable from within a recipe, best
2238      practices dictate that you do not.
2239
2240      .. note::
2241
2242         To enable primary features from within the image recipe, use the
2243         :term:`IMAGE_FEATURES` variable.
2244
2245      Here are some examples of features you can add:
2246
2247        - "dbg-pkgs" - Adds -dbg packages for all installed packages including
2248          symbol information for debugging and profiling.
2249
2250        - "debug-tweaks" - Makes an image suitable for debugging. For example, allows root logins without passwords and
2251          enables post-installation logging. See the 'allow-empty-password' and
2252          'post-install-logging' features in the ":ref:`ref-features-image`"
2253          section for more information.
2254        - "dev-pkgs" - Adds -dev packages for all installed packages. This is
2255          useful if you want to develop against the libraries in the image.
2256        - "read-only-rootfs" - Creates an image whose root filesystem is
2257          read-only. See the
2258          ":ref:`dev-manual/common-tasks:creating a read-only root filesystem`"
2259          section in the Yocto Project Development Tasks Manual for more
2260          information
2261        - "tools-debug" - Adds debugging tools such as gdb and strace.
2262        - "tools-sdk" - Adds development tools such as gcc, make,
2263          pkgconfig and so forth.
2264        - "tools-testapps" - Adds useful testing tools
2265          such as ts_print, aplay, arecord and so forth.
2266
2267      For a complete list of image features that ships with the Yocto
2268      Project, see the ":ref:`ref-features-image`" section.
2269
2270      For an example that shows how to customize your image by using this
2271      variable, see the ":ref:`dev-manual/common-tasks:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
2272      section in the Yocto Project Development Tasks Manual.
2273
2274   :term:`EXTRA_IMAGECMD`
2275      Specifies additional options for the image creation command that has
2276      been specified in :term:`IMAGE_CMD`. When setting
2277      this variable, use an override for the associated image type. Here is
2278      an example::
2279
2280         EXTRA_IMAGECMD:ext3 ?= "-i 4096"
2281
2282   :term:`EXTRA_IMAGEDEPENDS`
2283      A list of recipes to build that do not provide packages for
2284      installing into the root filesystem.
2285
2286      Sometimes a recipe is required to build the final image but is not
2287      needed in the root filesystem. You can use the :term:`EXTRA_IMAGEDEPENDS`
2288      variable to list these recipes and thus specify the dependencies. A
2289      typical example is a required bootloader in a machine configuration.
2290
2291      .. note::
2292
2293         To add packages to the root filesystem, see the various
2294         :term:`RDEPENDS` and :term:`RRECOMMENDS` variables.
2295
2296   :term:`EXTRA_OECMAKE`
2297      Additional `CMake <https://cmake.org/overview/>`__ options. See the
2298      :ref:`cmake <ref-classes-cmake>` class for additional information.
2299
2300   :term:`EXTRA_OECONF`
2301      Additional ``configure`` script options. See
2302      :term:`PACKAGECONFIG_CONFARGS` for
2303      additional information on passing configure script options.
2304
2305   :term:`EXTRA_OEMAKE`
2306      Additional GNU ``make`` options.
2307
2308      Because the :term:`EXTRA_OEMAKE` defaults to "", you need to set the
2309      variable to specify any required GNU options.
2310
2311      :term:`PARALLEL_MAKE` and
2312      :term:`PARALLEL_MAKEINST` also make use of
2313      :term:`EXTRA_OEMAKE` to pass the required flags.
2314
2315   :term:`EXTRA_OESCONS`
2316      When inheriting the :ref:`scons <ref-classes-scons>` class, this
2317      variable specifies additional configuration options you want to pass
2318      to the ``scons`` command line.
2319
2320   :term:`EXTRA_USERS_PARAMS`
2321      When inheriting the :ref:`extrausers <ref-classes-extrausers>`
2322      class, this variable provides image level user and group operations.
2323      This is a more global method of providing user and group
2324      configuration as compared to using the
2325      :ref:`useradd <ref-classes-useradd>` class, which ties user and
2326      group configurations to a specific recipe.
2327
2328      The set list of commands you can configure using the
2329      :term:`EXTRA_USERS_PARAMS` is shown in the :ref:`extrausers <ref-classes-extrausers>` class. These
2330      commands map to the normal Unix commands of the same names::
2331
2332         # EXTRA_USERS_PARAMS = "\
2333         # useradd -p '' tester; \
2334         # groupadd developers; \
2335         # userdel nobody; \
2336         # groupdel -g video; \
2337         # groupmod -g 1020 developers; \
2338         # usermod -s /bin/sh tester; \
2339         # "
2340
2341      Hardcoded passwords are supported via the ``-p`` parameters for
2342      ``useradd`` or ``usermod``, but only hashed.
2343
2344      Here is an example that adds two users named "tester-jim" and "tester-sue" and assigns
2345      passwords. First on host, create the (escaped) password hash::
2346
2347         printf "%q" $(mkpasswd -m sha256crypt tester01)
2348
2349      The resulting hash is set to a variable and used in ``useradd`` command parameters::
2350
2351         inherit extrausers
2352         PASSWD = "\$X\$ABC123\$A-Long-Hash"
2353         EXTRA_USERS_PARAMS = "\
2354             useradd -p '${PASSWD}' tester-jim; \
2355             useradd -p '${PASSWD}' tester-sue; \
2356             "
2357
2358      Finally, here is an example that sets the root password::
2359
2360         inherit extrausers
2361         EXTRA_USERS_PARAMS = "\
2362             usermod -p '${PASSWD}' root; \
2363             "
2364
2365      .. note::
2366
2367         From a security perspective, hardcoding a default password is not
2368         generally a good idea or even legal in some jurisdictions. It is
2369         recommended that you do not do this if you are building a production
2370         image.
2371
2372      Additionally there is a special ``passwd-expire`` command that will
2373      cause the password for a user to be expired and thus force changing it
2374      on first login, for example::
2375
2376         EXTRA_USERS_PARAMS += " useradd myuser; passwd-expire myuser;"
2377
2378      .. note::
2379
2380         At present, ``passwd-expire`` may only work for remote logins when
2381         using OpenSSH and not dropbear as an SSH server.
2382
2383   :term:`EXTRANATIVEPATH`
2384      A list of subdirectories of
2385      ``${``\ :term:`STAGING_BINDIR_NATIVE`\ ``}``
2386      added to the beginning of the environment variable ``PATH``. As an
2387      example, the following prepends
2388      "${STAGING_BINDIR_NATIVE}/foo:${STAGING_BINDIR_NATIVE}/bar:" to
2389      ``PATH``::
2390
2391         EXTRANATIVEPATH = "foo bar"
2392
2393   :term:`FEATURE_PACKAGES`
2394      Defines one or more packages to include in an image when a specific
2395      item is included in :term:`IMAGE_FEATURES`.
2396      When setting the value, :term:`FEATURE_PACKAGES` should have the name of
2397      the feature item as an override. Here is an example::
2398
2399         FEATURE_PACKAGES_widget = "package1 package2"
2400
2401      In this example, if "widget" were added to :term:`IMAGE_FEATURES`,
2402      package1 and package2 would be included in the image.
2403
2404      .. note::
2405
2406         Packages installed by features defined through :term:`FEATURE_PACKAGES`
2407         are often package groups. While similarly named, you should not
2408         confuse the :term:`FEATURE_PACKAGES` variable with package groups, which
2409         are discussed elsewhere in the documentation.
2410
2411   :term:`FEED_DEPLOYDIR_BASE_URI`
2412      Points to the base URL of the server and location within the
2413      document-root that provides the metadata and packages required by
2414      OPKG to support runtime package management of IPK packages. You set
2415      this variable in your ``local.conf`` file.
2416
2417      Consider the following example::
2418
2419         FEED_DEPLOYDIR_BASE_URI = "http://192.168.7.1/BOARD-dir"
2420
2421      This example assumes you are serving
2422      your packages over HTTP and your databases are located in a directory
2423      named ``BOARD-dir``, which is underneath your HTTP server's
2424      document-root. In this case, the OpenEmbedded build system generates
2425      a set of configuration files for you in your target that work with
2426      the feed.
2427
2428   :term:`FILES`
2429      The list of files and directories that are placed in a package. The
2430      :term:`PACKAGES` variable lists the packages
2431      generated by a recipe.
2432
2433      To use the :term:`FILES` variable, provide a package name override that
2434      identifies the resulting package. Then, provide a space-separated
2435      list of files or paths that identify the files you want included as
2436      part of the resulting package. Here is an example::
2437
2438         FILES:${PN} += "${bindir}/mydir1 ${bindir}/mydir2/myfile"
2439
2440      .. note::
2441
2442         -  When specifying files or paths, you can pattern match using
2443            Python's
2444            `glob <https://docs.python.org/3/library/glob.html>`_
2445            syntax. For details on the syntax, see the documentation by
2446            following the previous link.
2447
2448         -  When specifying paths as part of the :term:`FILES` variable, it is
2449            good practice to use appropriate path variables. For example,
2450            use ``${sysconfdir}`` rather than ``/etc``, or ``${bindir}``
2451            rather than ``/usr/bin``. You can find a list of these
2452            variables at the top of the ``meta/conf/bitbake.conf`` file in
2453            the :term:`Source Directory`. You will also
2454            find the default values of the various ``FILES:*`` variables in
2455            this file.
2456
2457      If some of the files you provide with the :term:`FILES` variable are
2458      editable and you know they should not be overwritten during the
2459      package update process by the Package Management System (PMS), you
2460      can identify these files so that the PMS will not overwrite them. See
2461      the :term:`CONFFILES` variable for information on
2462      how to identify these files to the PMS.
2463
2464   :term:`FILES_SOLIBSDEV`
2465      Defines the file specification to match
2466      :term:`SOLIBSDEV`. In other words,
2467      :term:`FILES_SOLIBSDEV` defines the full path name of the development
2468      symbolic link (symlink) for shared libraries on the target platform.
2469
2470      The following statement from the ``bitbake.conf`` shows how it is
2471      set::
2472
2473         FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}"
2474
2475   :term:`FILESEXTRAPATHS`
2476      Extends the search path the OpenEmbedded build system uses when
2477      looking for files and patches as it processes recipes and append
2478      files. The default directories BitBake uses when it processes recipes
2479      are initially defined by the :term:`FILESPATH`
2480      variable. You can extend :term:`FILESPATH` variable by using
2481      :term:`FILESEXTRAPATHS`.
2482
2483      Best practices dictate that you accomplish this by using
2484      :term:`FILESEXTRAPATHS` from within a ``.bbappend`` file and that you
2485      prepend paths as follows::
2486
2487         FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
2488
2489      In the above example, the build system first
2490      looks for files in a directory that has the same name as the
2491      corresponding append file.
2492
2493      .. note::
2494
2495         When extending :term:`FILESEXTRAPATHS`, be sure to use the immediate
2496         expansion (``:=``) operator. Immediate expansion makes sure that
2497         BitBake evaluates :term:`THISDIR` at the time the
2498         directive is encountered rather than at some later time when
2499         expansion might result in a directory that does not contain the
2500         files you need.
2501
2502         Also, include the trailing separating colon character if you are
2503         prepending. The trailing colon character is necessary because you
2504         are directing BitBake to extend the path by prepending directories
2505         to the search path.
2506
2507      Here is another common use::
2508
2509         FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
2510
2511      In this example, the build system extends the
2512      :term:`FILESPATH` variable to include a directory named ``files`` that is
2513      in the same directory as the corresponding append file.
2514
2515      This next example specifically adds three paths::
2516
2517         FILESEXTRAPATHS:prepend := "path_1:path_2:path_3:"
2518
2519      A final example shows how you can extend the search path and include
2520      a :term:`MACHINE`-specific override, which is useful
2521      in a BSP layer::
2522
2523          FILESEXTRAPATHS:prepend:intel-x86-common := "${THISDIR}/${PN}:"
2524
2525      The previous statement appears in the
2526      ``linux-yocto-dev.bbappend`` file, which is found in the
2527      :ref:`overview-manual/development-environment:yocto project source repositories` in
2528      ``meta-intel/common/recipes-kernel/linux``. Here, the machine
2529      override is a special :term:`PACKAGE_ARCH`
2530      definition for multiple ``meta-intel`` machines.
2531
2532      .. note::
2533
2534         For a layer that supports a single BSP, the override could just be
2535         the value of :term:`MACHINE`.
2536
2537      By prepending paths in ``.bbappend`` files, you allow multiple append
2538      files that reside in different layers but are used for the same
2539      recipe to correctly extend the path.
2540
2541   :term:`FILESOVERRIDES`
2542      A subset of :term:`OVERRIDES` used by the
2543      OpenEmbedded build system for creating
2544      :term:`FILESPATH`. The :term:`FILESOVERRIDES` variable
2545      uses overrides to automatically extend the
2546      :term:`FILESPATH` variable. For an example of how
2547      that works, see the :term:`FILESPATH` variable
2548      description. Additionally, you find more information on how overrides
2549      are handled in the
2550      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
2551      section of the BitBake User Manual.
2552
2553      By default, the :term:`FILESOVERRIDES` variable is defined as::
2554
2555         FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
2556
2557      .. note::
2558
2559         Do not hand-edit the :term:`FILESOVERRIDES` variable. The values match up
2560         with expected overrides and are used in an expected manner by the
2561         build system.
2562
2563   :term:`FILESPATH`
2564      The default set of directories the OpenEmbedded build system uses
2565      when searching for patches and files.
2566
2567      During the build process, BitBake searches each directory in
2568      :term:`FILESPATH` in the specified order when looking for files and
2569      patches specified by each ``file://`` URI in a recipe's
2570      :term:`SRC_URI` statements.
2571
2572      The default value for the :term:`FILESPATH` variable is defined in the
2573      :ref:`ref-classes-base` class found in ``meta/classes`` in the
2574      :term:`Source Directory`::
2575
2576         FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
2577             "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
2578
2579      The
2580      :term:`FILESPATH` variable is automatically extended using the overrides
2581      from the :term:`FILESOVERRIDES` variable.
2582
2583      .. note::
2584
2585         -  Do not hand-edit the :term:`FILESPATH` variable. If you want the
2586            build system to look in directories other than the defaults,
2587            extend the :term:`FILESPATH` variable by using the
2588            :term:`FILESEXTRAPATHS` variable.
2589
2590         -  Be aware that the default :term:`FILESPATH` directories do not map
2591            to directories in custom layers where append files
2592            (``.bbappend``) are used. If you want the build system to find
2593            patches or files that reside with your append files, you need
2594            to extend the :term:`FILESPATH` variable by using the
2595            :term:`FILESEXTRAPATHS` variable.
2596
2597      You can take advantage of this searching behavior in useful ways. For
2598      example, consider a case where there is the following directory structure
2599      for general and machine-specific configurations::
2600
2601         files/defconfig
2602         files/MACHINEA/defconfig
2603         files/MACHINEB/defconfig
2604
2605      Also in the example, the :term:`SRC_URI` statement contains
2606      "file://defconfig". Given this scenario, you can set
2607      :term:`MACHINE` to "MACHINEA" and cause the build
2608      system to use files from ``files/MACHINEA``. Set :term:`MACHINE` to
2609      "MACHINEB" and the build system uses files from ``files/MACHINEB``.
2610      Finally, for any machine other than "MACHINEA" and "MACHINEB", the
2611      build system uses files from ``files/defconfig``.
2612
2613      You can find out more about the patching process in the
2614      ":ref:`overview-manual/concepts:patching`" section
2615      in the Yocto Project Overview and Concepts Manual and the
2616      ":ref:`dev-manual/common-tasks:patching code`" section in
2617      the Yocto Project Development Tasks Manual. See the
2618      :ref:`ref-tasks-patch` task as well.
2619
2620   :term:`FILESYSTEM_PERMS_TABLES`
2621      Allows you to define your own file permissions settings table as part
2622      of your configuration for the packaging process. For example, suppose
2623      you need a consistent set of custom permissions for a set of groups
2624      and users across an entire work project. It is best to do this in the
2625      packages themselves but this is not always possible.
2626
2627      By default, the OpenEmbedded build system uses the ``fs-perms.txt``,
2628      which is located in the ``meta/files`` folder in the :term:`Source Directory`.
2629      If you create your own file
2630      permissions setting table, you should place it in your layer or the
2631      distro's layer.
2632
2633      You define the :term:`FILESYSTEM_PERMS_TABLES` variable in the
2634      ``conf/local.conf`` file, which is found in the :term:`Build Directory`,
2635      to point to your custom
2636      ``fs-perms.txt``. You can specify more than a single file permissions
2637      setting table. The paths you specify to these files must be defined
2638      within the :term:`BBPATH` variable.
2639
2640      For guidance on how to create your own file permissions settings
2641      table file, examine the existing ``fs-perms.txt``.
2642
2643   :term:`FIT_DESC`
2644      Specifies the description string encoded into a fitImage. The default
2645      value is set by the :ref:`kernel-fitimage <ref-classes-kernel-fitimage>`
2646      class as follows::
2647
2648         FIT_DESC ?= "U-Boot fitImage for ${DISTRO_NAME}/${PV}/${MACHINE}"
2649
2650   :term:`FIT_GENERATE_KEYS`
2651      Decides whether to generate the keys for signing fitImage if they
2652      don't already exist. The keys are created in :term:`UBOOT_SIGN_KEYDIR`.
2653      The default value is 0.
2654
2655   :term:`FIT_HASH_ALG`
2656      Specifies the hash algorithm used in creating the FIT Image. For e.g. sha256.
2657
2658   :term:`FIT_KERNEL_COMP_ALG`
2659      Compression algorithm to use for the kernel image inside the FIT Image.
2660      At present, the only supported values are "gzip" (default) or "none"
2661      If you set this variable to anything other than "none" you may also need
2662      to set :term:`FIT_KERNEL_COMP_ALG_EXTENSION`.
2663
2664   :term:`FIT_KERNEL_COMP_ALG_EXTENSION`
2665      File extension corresponding to :term:`FIT_KERNEL_COMP_ALG`. The default
2666      value is ".gz".
2667
2668   :term:`FIT_KEY_GENRSA_ARGS`
2669      Arguments to openssl genrsa for generating RSA private key for signing
2670      fitImage. The default value is "-F4". i.e. the public exponent 65537 to
2671      use.
2672
2673   :term:`FIT_KEY_REQ_ARGS`
2674      Arguments to openssl req for generating certificate for signing fitImage.
2675      The default value is "-batch -new". batch for non interactive mode
2676      and new for generating new keys.
2677
2678   :term:`FIT_KEY_SIGN_PKCS`
2679      Format for public key certificate used in signing fitImage.
2680      The default value is "x509".
2681
2682   :term:`FIT_SIGN_ALG`
2683      Specifies the signature algorithm used in creating the FIT Image.
2684      For e.g. rsa2048.
2685
2686   :term:`FIT_SIGN_INDIVIDUAL`
2687      If set to "1", then the :ref:`kernel-fitimage <ref-classes-kernel-fitimage>`
2688      class will sign the kernel, dtb and ramdisk images individually in addition
2689      to signing the fitImage itself. This could be useful if you are
2690      intending to verify signatures in another context than booting via
2691      U-Boot.
2692
2693   :term:`FIT_SIGN_NUMBITS`
2694      Size of private key in number of bits used in fitImage. The default
2695      value is "2048".
2696
2697   :term:`FONT_EXTRA_RDEPENDS`
2698      When inheriting the :ref:`fontcache <ref-classes-fontcache>` class,
2699      this variable specifies the runtime dependencies for font packages.
2700      By default, the :term:`FONT_EXTRA_RDEPENDS` is set to "fontconfig-utils".
2701
2702   :term:`FONT_PACKAGES`
2703      When inheriting the :ref:`fontcache <ref-classes-fontcache>` class,
2704      this variable identifies packages containing font files that need to
2705      be cached by Fontconfig. By default, the :ref:`fontcache <ref-classes-fontcache>` class assumes
2706      that fonts are in the recipe's main package (i.e.
2707      ``${``\ :term:`PN`\ ``}``). Use this variable if fonts you
2708      need are in a package other than that main package.
2709
2710   :term:`FORCE_RO_REMOVE`
2711      Forces the removal of the packages listed in ``ROOTFS_RO_UNNEEDED``
2712      during the generation of the root filesystem.
2713
2714      Set the variable to "1" to force the removal of these packages.
2715
2716   :term:`FULL_OPTIMIZATION`
2717      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
2718      compiling an optimized system. This variable defaults to "-O2 -pipe
2719      ${DEBUG_FLAGS}".
2720
2721   :term:`GCCPIE`
2722      Enables Position Independent Executables (PIE) within the GNU C
2723      Compiler (GCC). Enabling PIE in the GCC makes Return Oriented
2724      Programming (ROP) attacks much more difficult to execute.
2725
2726      By default the ``security_flags.inc`` file enables PIE by setting the
2727      variable as follows::
2728
2729         GCCPIE ?= "--enable-default-pie"
2730
2731   :term:`GCCVERSION`
2732      Specifies the default version of the GNU C Compiler (GCC) used for
2733      compilation. By default, :term:`GCCVERSION` is set to "8.x" in the
2734      ``meta/conf/distro/include/tcmode-default.inc`` include file::
2735
2736         GCCVERSION ?= "8.%"
2737
2738      You can override this value by setting it in a
2739      configuration file such as the ``local.conf``.
2740
2741   :term:`GDB`
2742      The minimal command and arguments to run the GNU Debugger.
2743
2744   :term:`GIR_EXTRA_LIBS_PATH`
2745      Allows to specify an extra search path for ``.so`` files
2746      in GLib related recipes using GObject introspection,
2747      and which do not compile without this setting.
2748      See the ":ref:`dev-manual/common-tasks:enabling gobject introspection support`"
2749      section for details.
2750
2751   :term:`GITDIR`
2752      The directory in which a local copy of a Git repository is stored
2753      when it is cloned.
2754
2755   :term:`GLIBC_GENERATE_LOCALES`
2756      Specifies the list of GLIBC locales to generate should you not wish
2757      to generate all LIBC locals, which can be time consuming.
2758
2759      .. note::
2760
2761         If you specifically remove the locale ``en_US.UTF-8``, you must set
2762         :term:`IMAGE_LINGUAS` appropriately.
2763
2764      You can set :term:`GLIBC_GENERATE_LOCALES` in your ``local.conf`` file.
2765      By default, all locales are generated.
2766      ::
2767
2768         GLIBC_GENERATE_LOCALES = "en_GB.UTF-8 en_US.UTF-8"
2769
2770   :term:`GROUPADD_PARAM`
2771      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
2772      this variable specifies for a package what parameters should be
2773      passed to the ``groupadd`` command if you wish to add a group to the
2774      system when the package is installed.
2775
2776      Here is an example from the ``dbus`` recipe::
2777
2778         GROUPADD_PARAM:${PN} = "-r netdev"
2779
2780      For information on the standard Linux shell command
2781      ``groupadd``, see https://linux.die.net/man/8/groupadd.
2782
2783   :term:`GROUPMEMS_PARAM`
2784      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
2785      this variable specifies for a package what parameters should be
2786      passed to the ``groupmems`` command if you wish to modify the members
2787      of a group when the package is installed.
2788
2789      For information on the standard Linux shell command ``groupmems``,
2790      see https://linux.die.net/man/8/groupmems.
2791
2792   :term:`GRUB_GFXSERIAL`
2793      Configures the GNU GRand Unified Bootloader (GRUB) to have graphics
2794      and serial in the boot menu. Set this variable to "1" in your
2795      ``local.conf`` or distribution configuration file to enable graphics
2796      and serial in the menu.
2797
2798      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
2799      information on how this variable is used.
2800
2801   :term:`GRUB_OPTS`
2802      Additional options to add to the GNU GRand Unified Bootloader (GRUB)
2803      configuration. Use a semi-colon character (``;``) to separate
2804      multiple options.
2805
2806      The :term:`GRUB_OPTS` variable is optional. See the
2807      :ref:`grub-efi <ref-classes-grub-efi>` class for more information
2808      on how this variable is used.
2809
2810   :term:`GRUB_TIMEOUT`
2811      Specifies the timeout before executing the default ``LABEL`` in the
2812      GNU GRand Unified Bootloader (GRUB).
2813
2814      The :term:`GRUB_TIMEOUT` variable is optional. See the
2815      :ref:`grub-efi <ref-classes-grub-efi>` class for more information
2816      on how this variable is used.
2817
2818   :term:`GTKIMMODULES_PACKAGES`
2819      When inheriting the
2820      :ref:`gtk-immodules-cache <ref-classes-gtk-immodules-cache>` class,
2821      this variable specifies the packages that contain the GTK+ input
2822      method modules being installed when the modules are in packages other
2823      than the main package.
2824
2825   :term:`HOMEPAGE`
2826      Website where more information about the software the recipe is
2827      building can be found.
2828
2829   :term:`HOST_ARCH`
2830      The name of the target architecture, which is normally the same as
2831      :term:`TARGET_ARCH`. The OpenEmbedded build system
2832      supports many architectures. Here is an example list of architectures
2833      supported. This list is by no means complete as the architecture is
2834      configurable:
2835
2836      - arm
2837      - i586
2838      - x86_64
2839      - powerpc
2840      - powerpc64
2841      - mips
2842      - mipsel
2843
2844   :term:`HOST_CC_ARCH`
2845      Specifies architecture-specific compiler flags that are passed to the
2846      C compiler.
2847
2848      Default initialization for :term:`HOST_CC_ARCH` varies depending on what
2849      is being built:
2850
2851      -  :term:`TARGET_CC_ARCH` when building for the
2852         target
2853
2854      -  :term:`BUILD_CC_ARCH` when building for the build host (i.e.
2855         ``-native``)
2856
2857      -  ``BUILDSDK_CC_ARCH`` when building for an SDK (i.e.
2858         ``nativesdk-``)
2859
2860   :term:`HOST_OS`
2861      Specifies the name of the target operating system, which is normally
2862      the same as the :term:`TARGET_OS`. The variable can
2863      be set to "linux" for ``glibc``-based systems and to "linux-musl" for
2864      ``musl``. For ARM/EABI targets, there are also "linux-gnueabi" and
2865      "linux-musleabi" values possible.
2866
2867   :term:`HOST_PREFIX`
2868      Specifies the prefix for the cross-compile toolchain. :term:`HOST_PREFIX`
2869      is normally the same as :term:`TARGET_PREFIX`.
2870
2871   :term:`HOST_SYS`
2872      Specifies the system, including the architecture and the operating
2873      system, for which the build is occurring in the context of the
2874      current recipe.
2875
2876      The OpenEmbedded build system automatically sets this variable based
2877      on :term:`HOST_ARCH`,
2878      :term:`HOST_VENDOR`, and
2879      :term:`HOST_OS` variables.
2880
2881      .. note::
2882
2883         You do not need to set the variable yourself.
2884
2885      Consider these two examples:
2886
2887      -  Given a native recipe on a 32-bit x86 machine running Linux, the
2888         value is "i686-linux".
2889
2890      -  Given a recipe being built for a little-endian MIPS target running
2891         Linux, the value might be "mipsel-linux".
2892
2893   :term:`HOST_VENDOR`
2894      Specifies the name of the vendor. :term:`HOST_VENDOR` is normally the
2895      same as :term:`TARGET_VENDOR`.
2896
2897   :term:`HOSTTOOLS`
2898      A space-separated list (filter) of tools on the build host that
2899      should be allowed to be called from within build tasks. Using this
2900      filter helps reduce the possibility of host contamination. If a tool
2901      specified in the value of :term:`HOSTTOOLS` is not found on the build
2902      host, the OpenEmbedded build system produces an error and the build
2903      is not started.
2904
2905      For additional information, see
2906      :term:`HOSTTOOLS_NONFATAL`.
2907
2908   :term:`HOSTTOOLS_NONFATAL`
2909      A space-separated list (filter) of tools on the build host that
2910      should be allowed to be called from within build tasks. Using this
2911      filter helps reduce the possibility of host contamination. Unlike
2912      :term:`HOSTTOOLS`, the OpenEmbedded build system
2913      does not produce an error if a tool specified in the value of
2914      :term:`HOSTTOOLS_NONFATAL` is not found on the build host. Thus, you can
2915      use :term:`HOSTTOOLS_NONFATAL` to filter optional host tools.
2916
2917   :term:`ICECC_CLASS_DISABLE`
2918      Identifies user classes that you do not want the Icecream distributed
2919      compile support to consider. This variable is used by the
2920      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2921      your ``local.conf`` file.
2922
2923      When you list classes using this variable, the recipes inheriting
2924      those classes will not benefit from distributed compilation across
2925      remote hosts. Instead they will be built locally.
2926
2927   :term:`ICECC_DISABLED`
2928      Disables or enables the ``icecc`` (Icecream) function. For more
2929      information on this function and best practices for using this
2930      variable, see the ":ref:`ref-classes-icecc`"
2931      section.
2932
2933      Setting this variable to "1" in your ``local.conf`` disables the
2934      function::
2935
2936         ICECC_DISABLED ??= "1"
2937
2938      To enable the function, set the variable as follows::
2939
2940         ICECC_DISABLED = ""
2941
2942   :term:`ICECC_ENV_EXEC`
2943      Points to the ``icecc-create-env`` script that you provide. This
2944      variable is used by the :ref:`icecc <ref-classes-icecc>` class. You
2945      set this variable in your ``local.conf`` file.
2946
2947      If you do not point to a script that you provide, the OpenEmbedded
2948      build system uses the default script provided by the
2949      ``icecc-create-env.bb`` recipe, which is a modified version and not
2950      the one that comes with ``icecc``.
2951
2952   :term:`ICECC_PARALLEL_MAKE`
2953      Extra options passed to the ``make`` command during the
2954      :ref:`ref-tasks-compile` task that specify parallel
2955      compilation. This variable usually takes the form of "-j x", where x
2956      represents the maximum number of parallel threads ``make`` can run.
2957
2958      .. note::
2959
2960         The options passed affect builds on all enabled machines on the
2961         network, which are machines running the ``iceccd`` daemon.
2962
2963      If your enabled machines support multiple cores, coming up with the
2964      maximum number of parallel threads that gives you the best
2965      performance could take some experimentation since machine speed,
2966      network lag, available memory, and existing machine loads can all
2967      affect build time. Consequently, unlike the
2968      :term:`PARALLEL_MAKE` variable, there is no
2969      rule-of-thumb for setting :term:`ICECC_PARALLEL_MAKE` to achieve optimal
2970      performance.
2971
2972      If you do not set :term:`ICECC_PARALLEL_MAKE`, the build system does not
2973      use it (i.e. the system does not detect and assign the number of
2974      cores as is done with :term:`PARALLEL_MAKE`).
2975
2976   :term:`ICECC_PATH`
2977      The location of the ``icecc`` binary. You can set this variable in
2978      your ``local.conf`` file. If your ``local.conf`` file does not define
2979      this variable, the :ref:`icecc <ref-classes-icecc>` class attempts
2980      to define it by locating ``icecc`` using ``which``.
2981
2982   :term:`ICECC_RECIPE_DISABLE`
2983      Identifies user recipes that you do not want the Icecream distributed
2984      compile support to consider. This variable is used by the
2985      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2986      your ``local.conf`` file.
2987
2988      When you list recipes using this variable, you are excluding them
2989      from distributed compilation across remote hosts. Instead they will
2990      be built locally.
2991
2992   :term:`ICECC_RECIPE_ENABLE`
2993      Identifies user recipes that use an empty
2994      :term:`PARALLEL_MAKE` variable that you want to
2995      force remote distributed compilation on using the Icecream
2996      distributed compile support. This variable is used by the
2997      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2998      your ``local.conf`` file.
2999
3000   :term:`IMAGE_BASENAME`
3001      The base name of image output files. This variable defaults to the
3002      recipe name (``${``\ :term:`PN`\ ``}``).
3003
3004   :term:`IMAGE_BOOT_FILES`
3005      A space-separated list of files installed into the boot partition
3006      when preparing an image using the Wic tool with the
3007      ``bootimg-partition`` source plugin. By default,
3008      the files are
3009      installed under the same name as the source files. To change the
3010      installed name, separate it from the original name with a semi-colon
3011      (;). Source files need to be located in
3012      :term:`DEPLOY_DIR_IMAGE`. Here are two
3013      examples::
3014
3015         IMAGE_BOOT_FILES = "u-boot.img uImage;kernel"
3016         IMAGE_BOOT_FILES = "u-boot.${UBOOT_SUFFIX} ${KERNEL_IMAGETYPE}"
3017
3018      Alternatively, source files can be picked up using a glob pattern. In
3019      this case, the destination file must have the same name as the base
3020      name of the source file path. To install files into a directory
3021      within the target location, pass its name after a semi-colon (;).
3022      Here are two examples::
3023
3024         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*"
3025         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*;boot/"
3026
3027      The first example
3028      installs all files from ``${DEPLOY_DIR_IMAGE}/bcm2835-bootfiles``
3029      into the root of the target partition. The second example installs
3030      the same files into a ``boot`` directory within the target partition.
3031
3032      You can find information on how to use the Wic tool in the
3033      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
3034      section of the Yocto Project Development Tasks Manual. Reference
3035      material for Wic is located in the
3036      ":doc:`/ref-manual/kickstart`" chapter.
3037
3038   :term:`IMAGE_CLASSES`
3039      A list of classes that all images should inherit. You typically use
3040      this variable to specify the list of classes that register the
3041      different types of images the OpenEmbedded build system creates.
3042
3043      The default value for :term:`IMAGE_CLASSES` is ``image_types``. You can
3044      set this variable in your ``local.conf`` or in a distribution
3045      configuration file.
3046
3047      For more information, see ``meta/classes/image_types.bbclass`` in the
3048      :term:`Source Directory`.
3049
3050   :term:`IMAGE_CMD`
3051      Specifies the command to create the image file for a specific image
3052      type, which corresponds to the value set in
3053      :term:`IMAGE_FSTYPES`, (e.g. ``ext3``,
3054      ``btrfs``, and so forth). When setting this variable, you should use
3055      an override for the associated type. Here is an example::
3056
3057         IMAGE_CMD:jffs2 = "mkfs.jffs2 --root=${IMAGE_ROOTFS} --faketime \
3058             --output=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.jffs2 \
3059             ${EXTRA_IMAGECMD}"
3060
3061      You typically do not need to set this variable unless you are adding
3062      support for a new image type. For more examples on how to set this
3063      variable, see the :ref:`image_types <ref-classes-image_types>`
3064      class file, which is ``meta/classes/image_types.bbclass``.
3065
3066   :term:`IMAGE_DEVICE_TABLES`
3067      Specifies one or more files that contain custom device tables that
3068      are passed to the ``makedevs`` command as part of creating an image.
3069      These files list basic device nodes that should be created under
3070      ``/dev`` within the image. If :term:`IMAGE_DEVICE_TABLES` is not set,
3071      ``files/device_table-minimal.txt`` is used, which is located by
3072      :term:`BBPATH`. For details on how you should write
3073      device table files, see ``meta/files/device_table-minimal.txt`` as an
3074      example.
3075
3076   :term:`IMAGE_EFI_BOOT_FILES`
3077      A space-separated list of files installed into the boot partition
3078      when preparing an image using the Wic tool with the
3079      ``bootimg-efi`` source plugin. By default,
3080      the files are
3081      installed under the same name as the source files. To change the
3082      installed name, separate it from the original name with a semi-colon
3083      (;). Source files need to be located in
3084      :term:`DEPLOY_DIR_IMAGE`. Here are two
3085      examples::
3086
3087         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE};bz2"
3088         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE} microcode.cpio"
3089
3090      Alternatively, source files can be picked up using a glob pattern. In
3091      this case, the destination file must have the same name as the base
3092      name of the source file path. To install files into a directory
3093      within the target location, pass its name after a semi-colon (;).
3094      Here are two examples::
3095
3096         IMAGE_EFI_BOOT_FILES = "boot/loader/*"
3097         IMAGE_EFI_BOOT_FILES = "boot/loader/*;boot/"
3098
3099      The first example
3100      installs all files from ``${DEPLOY_DIR_IMAGE}/boot/loader/``
3101      into the root of the target partition. The second example installs
3102      the same files into a ``boot`` directory within the target partition.
3103
3104      You can find information on how to use the Wic tool in the
3105      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
3106      section of the Yocto Project Development Tasks Manual. Reference
3107      material for Wic is located in the
3108      ":doc:`/ref-manual/kickstart`" chapter.
3109
3110   :term:`IMAGE_FEATURES`
3111      The primary list of features to include in an image. Typically, you
3112      configure this variable in an image recipe. Although you can use this
3113      variable from your ``local.conf`` file, which is found in the
3114      :term:`Build Directory`, best practices dictate that you do
3115      not.
3116
3117      .. note::
3118
3119         To enable extra features from outside the image recipe, use the
3120         :term:`EXTRA_IMAGE_FEATURES` variable.
3121
3122      For a list of image features that ships with the Yocto Project, see
3123      the ":ref:`ref-features-image`" section.
3124
3125      For an example that shows how to customize your image by using this
3126      variable, see the ":ref:`dev-manual/common-tasks:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
3127      section in the Yocto Project Development Tasks Manual.
3128
3129   :term:`IMAGE_FSTYPES`
3130      Specifies the formats the OpenEmbedded build system uses during the
3131      build when creating the root filesystem. For example, setting
3132      :term:`IMAGE_FSTYPES` as follows causes the build system to create root
3133      filesystems using two formats: ``.ext3`` and ``.tar.bz2``::
3134
3135         IMAGE_FSTYPES = "ext3 tar.bz2"
3136
3137      For the complete list of supported image formats from which you can
3138      choose, see :term:`IMAGE_TYPES`.
3139
3140      .. note::
3141
3142         -  If an image recipe uses the "inherit image" line and you are
3143            setting :term:`IMAGE_FSTYPES` inside the recipe, you must set
3144            :term:`IMAGE_FSTYPES` prior to using the "inherit image" line.
3145
3146         -  Due to the way the OpenEmbedded build system processes this
3147            variable, you cannot update its contents by using ``:append``
3148            or ``:prepend``. You must use the ``+=`` operator to add one or
3149            more options to the :term:`IMAGE_FSTYPES` variable.
3150
3151   :term:`IMAGE_INSTALL`
3152      Used by recipes to specify the packages to install into an image
3153      through the :ref:`image <ref-classes-image>` class. Use the
3154      :term:`IMAGE_INSTALL` variable with care to avoid ordering issues.
3155
3156      Image recipes set :term:`IMAGE_INSTALL` to specify the packages to
3157      install into an image through :ref:`ref-classes-image`. Additionally,
3158      there are "helper" classes such as the
3159      :ref:`core-image <ref-classes-core-image>` class which can
3160      take lists used with :term:`IMAGE_FEATURES` and turn them into
3161      auto-generated entries in :term:`IMAGE_INSTALL` in addition to its
3162      default contents.
3163
3164      When you use this variable, it is best to use it as follows::
3165
3166         IMAGE_INSTALL:append = " package-name"
3167
3168      Be sure to include the space
3169      between the quotation character and the start of the package name or
3170      names.
3171
3172      .. note::
3173
3174         -  When working with a
3175            :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
3176            image, do not use the :term:`IMAGE_INSTALL` variable to specify
3177            packages for installation. Instead, use the
3178            :term:`PACKAGE_INSTALL` variable, which
3179            allows the initial RAM filesystem (initramfs) recipe to use a
3180            fixed set of packages and not be affected by :term:`IMAGE_INSTALL`.
3181            For information on creating an initramfs, see the
3182            ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`"
3183            section in the Yocto Project Development Tasks Manual.
3184
3185         -  Using :term:`IMAGE_INSTALL` with the
3186            :ref:`+= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:appending (+=) and prepending (=+) with spaces>`
3187            BitBake operator within the ``/conf/local.conf`` file or from
3188            within an image recipe is not recommended. Use of this operator
3189            in these ways can cause ordering issues. Since
3190            :ref:`ref-classes-core-image` sets :term:`IMAGE_INSTALL` to a default
3191            value using the
3192            :ref:`?= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:setting a default value (?=)>`
3193            operator, using a ``+=`` operation against :term:`IMAGE_INSTALL`
3194            results in unexpected behavior when used within
3195            ``conf/local.conf``. Furthermore, the same operation from
3196            within an image recipe may or may not succeed depending on the
3197            specific situation. In both these cases, the behavior is
3198            contrary to how most users expect the ``+=`` operator to work.
3199
3200   :term:`IMAGE_LINGUAS`
3201      Specifies the list of locales to install into the image during the
3202      root filesystem construction process. The OpenEmbedded build system
3203      automatically splits locale files, which are used for localization,
3204      into separate packages. Setting the :term:`IMAGE_LINGUAS` variable
3205      ensures that any locale packages that correspond to packages already
3206      selected for installation into the image are also installed. Here is
3207      an example::
3208
3209         IMAGE_LINGUAS = "pt-br de-de"
3210
3211      In this example, the build system ensures any Brazilian Portuguese
3212      and German locale files that correspond to packages in the image are
3213      installed (i.e. ``*-locale-pt-br`` and ``*-locale-de-de`` as well as
3214      ``*-locale-pt`` and ``*-locale-de``, since some software packages
3215      only provide locale files by language and not by country-specific
3216      language).
3217
3218      See the :term:`GLIBC_GENERATE_LOCALES`
3219      variable for information on generating GLIBC locales.
3220
3221
3222   :term:`IMAGE_LINK_NAME`
3223      The name of the output image symlink (which does not include
3224      the version part as :term:`IMAGE_NAME` does). The default value
3225      is derived using the :term:`IMAGE_BASENAME` and :term:`MACHINE`
3226      variables::
3227
3228         IMAGE_LINK_NAME ?= "${IMAGE_BASENAME}-${MACHINE}"
3229
3230
3231   :term:`IMAGE_MANIFEST`
3232      The manifest file for the image. This file lists all the installed
3233      packages that make up the image. The file contains package
3234      information on a line-per-package basis as follows::
3235
3236          packagename packagearch version
3237
3238      The :ref:`rootfs-postcommands <ref-classes-rootfs*>` class defines the manifest
3239      file as follows::
3240
3241         IMAGE_MANIFEST ="${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.manifest"
3242
3243      The location is
3244      derived using the :term:`IMGDEPLOYDIR`
3245      and :term:`IMAGE_NAME` variables. You can find
3246      information on how the image is created in the ":ref:`overview-manual/concepts:image generation`"
3247      section in the Yocto Project Overview and Concepts Manual.
3248
3249   :term:`IMAGE_NAME`
3250      The name of the output image files minus the extension. This variable
3251      is derived using the :term:`IMAGE_BASENAME`,
3252      :term:`MACHINE`, and :term:`IMAGE_VERSION_SUFFIX`
3253      variables::
3254
3255         IMAGE_NAME ?= "${IMAGE_BASENAME}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3256
3257   :term:`IMAGE_NAME_SUFFIX`
3258      Suffix used for the image output filename - defaults to ``".rootfs"``
3259      to distinguish the image file from other files created during image
3260      building; however if this suffix is redundant or not desired you can
3261      clear the value of this variable (set the value to ""). For example,
3262      this is typically cleared in initramfs image recipes.
3263
3264   :term:`IMAGE_OVERHEAD_FACTOR`
3265      Defines a multiplier that the build system applies to the initial
3266      image size for cases when the multiplier times the returned disk
3267      usage value for the image is greater than the sum of
3268      :term:`IMAGE_ROOTFS_SIZE` and :term:`IMAGE_ROOTFS_EXTRA_SPACE`. The result of
3269      the multiplier applied to the initial image size creates free disk
3270      space in the image as overhead. By default, the build process uses a
3271      multiplier of 1.3 for this variable. This default value results in
3272      30% free disk space added to the image when this method is used to
3273      determine the final generated image size. You should be aware that
3274      post install scripts and the package management system uses disk
3275      space inside this overhead area. Consequently, the multiplier does
3276      not produce an image with all the theoretical free disk space. See
3277      :term:`IMAGE_ROOTFS_SIZE` for information on how the build system
3278      determines the overall image size.
3279
3280      The default 30% free disk space typically gives the image enough room
3281      to boot and allows for basic post installs while still leaving a
3282      small amount of free disk space. If 30% free space is inadequate, you
3283      can increase the default value. For example, the following setting
3284      gives you 50% free space added to the image::
3285
3286         IMAGE_OVERHEAD_FACTOR = "1.5"
3287
3288      Alternatively, you can ensure a specific amount of free disk space is
3289      added to the image by using the :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3290      variable.
3291
3292   :term:`IMAGE_PKGTYPE`
3293      Defines the package type (i.e. DEB, RPM, IPK, or TAR) used by the
3294      OpenEmbedded build system. The variable is defined appropriately by
3295      the :ref:`package_deb <ref-classes-package_deb>`,
3296      :ref:`package_rpm <ref-classes-package_rpm>`,
3297      :ref:`package_ipk <ref-classes-package_ipk>`, or
3298      :ref:`package_tar <ref-classes-package_tar>` class.
3299
3300      .. note::
3301
3302         The ``package_tar`` class is broken and is not supported. It is
3303         recommended that you do not use it.
3304
3305      The :ref:`populate_sdk_* <ref-classes-populate-sdk-*>` and
3306      :ref:`image <ref-classes-image>` classes use the :term:`IMAGE_PKGTYPE`
3307      for packaging up images and SDKs.
3308
3309      You should not set the :term:`IMAGE_PKGTYPE` manually. Rather, the
3310      variable is set indirectly through the appropriate
3311      :ref:`package_* <ref-classes-package>` class using the
3312      :term:`PACKAGE_CLASSES` variable. The
3313      OpenEmbedded build system uses the first package type (e.g. DEB, RPM,
3314      or IPK) that appears with the variable
3315
3316      .. note::
3317
3318         Files using the ``.tar`` format are never used as a substitute
3319         packaging format for DEB, RPM, and IPK formatted files for your image
3320         or SDK.
3321
3322   :term:`IMAGE_POSTPROCESS_COMMAND`
3323      Specifies a list of functions to call once the OpenEmbedded build
3324      system creates the final image output files. You can specify
3325      functions separated by semicolons::
3326
3327         IMAGE_POSTPROCESS_COMMAND += "function; ... "
3328
3329      If you need to pass the root filesystem path to a command within the
3330      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3331      directory that becomes the root filesystem image. See the
3332      :term:`IMAGE_ROOTFS` variable for more
3333      information.
3334
3335   :term:`IMAGE_PREPROCESS_COMMAND`
3336      Specifies a list of functions to call before the OpenEmbedded build
3337      system creates the final image output files. You can specify
3338      functions separated by semicolons::
3339
3340         IMAGE_PREPROCESS_COMMAND += "function; ... "
3341
3342      If you need to pass the root filesystem path to a command within the
3343      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3344      directory that becomes the root filesystem image. See the
3345      :term:`IMAGE_ROOTFS` variable for more
3346      information.
3347
3348   :term:`IMAGE_ROOTFS`
3349      The location of the root filesystem while it is under construction
3350      (i.e. during the :ref:`ref-tasks-rootfs` task). This
3351      variable is not configurable. Do not change it.
3352
3353   :term:`IMAGE_ROOTFS_ALIGNMENT`
3354      Specifies the alignment for the output image file in Kbytes. If the
3355      size of the image is not a multiple of this value, then the size is
3356      rounded up to the nearest multiple of the value. The default value is
3357      "1". See :term:`IMAGE_ROOTFS_SIZE` for
3358      additional information.
3359
3360   :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3361      Defines additional free disk space created in the image in Kbytes. By
3362      default, this variable is set to "0". This free disk space is added
3363      to the image after the build system determines the image size as
3364      described in :term:`IMAGE_ROOTFS_SIZE`.
3365
3366      This variable is particularly useful when you want to ensure that a
3367      specific amount of free disk space is available on a device after an
3368      image is installed and running. For example, to be sure 5 Gbytes of
3369      free disk space is available, set the variable as follows::
3370
3371         IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
3372
3373      For example, the Yocto Project Build Appliance specifically requests
3374      40 Gbytes of extra space with the line::
3375
3376         IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
3377
3378   :term:`IMAGE_ROOTFS_SIZE`
3379      Defines the size in Kbytes for the generated image. The OpenEmbedded
3380      build system determines the final size for the generated image using
3381      an algorithm that takes into account the initial disk space used for
3382      the generated image, a requested size for the image, and requested
3383      additional free disk space to be added to the image. Programatically,
3384      the build system determines the final size of the generated image as
3385      follows::
3386
3387         if (image-du * overhead) < rootfs-size:
3388             internal-rootfs-size = rootfs-size + xspace
3389         else:
3390             internal-rootfs-size = (image-du * overhead) + xspace
3391         where:
3392             image-du = Returned value of the du command on the image.
3393             overhead = IMAGE_OVERHEAD_FACTOR
3394             rootfs-size = IMAGE_ROOTFS_SIZE
3395             internal-rootfs-size = Initial root filesystem size before any modifications.
3396             xspace = IMAGE_ROOTFS_EXTRA_SPACE
3397
3398      See the :term:`IMAGE_OVERHEAD_FACTOR`
3399      and :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3400      variables for related information.
3401
3402   :term:`IMAGE_TYPEDEP`
3403      Specifies a dependency from one image type on another. Here is an
3404      example from the :ref:`image-live <ref-classes-image-live>` class::
3405
3406         IMAGE_TYPEDEP:live = "ext3"
3407
3408      In the previous example, the variable ensures that when "live" is
3409      listed with the :term:`IMAGE_FSTYPES` variable,
3410      the OpenEmbedded build system produces an ``ext3`` image first since
3411      one of the components of the live image is an ``ext3`` formatted
3412      partition containing the root filesystem.
3413
3414   :term:`IMAGE_TYPES`
3415      Specifies the complete list of supported image types by default:
3416
3417      - btrfs
3418      - container
3419      - cpio
3420      - cpio.gz
3421      - cpio.lz4
3422      - cpio.lzma
3423      - cpio.xz
3424      - cramfs
3425      - erofs
3426      - erofs-lz4
3427      - erofs-lz4hc
3428      - ext2
3429      - ext2.bz2
3430      - ext2.gz
3431      - ext2.lzma
3432      - ext3
3433      - ext3.gz
3434      - ext4
3435      - ext4.gz
3436      - f2fs
3437      - hddimg
3438      - iso
3439      - jffs2
3440      - jffs2.sum
3441      - multiubi
3442      - squashfs
3443      - squashfs-lz4
3444      - squashfs-lzo
3445      - squashfs-xz
3446      - tar
3447      - tar.bz2
3448      - tar.gz
3449      - tar.lz4
3450      - tar.xz
3451      - tar.zst
3452      - ubi
3453      - ubifs
3454      - wic
3455      - wic.bz2
3456      - wic.gz
3457      - wic.lzma
3458
3459      For more information about these types of images, see
3460      ``meta/classes/image_types*.bbclass`` in the :term:`Source Directory`.
3461
3462   :term:`IMAGE_VERSION_SUFFIX`
3463      Version suffix that is part of the default :term:`IMAGE_NAME` and
3464      :term:`KERNEL_ARTIFACT_NAME` values.
3465      Defaults to ``"-${DATETIME}"``, however you could set this to a
3466      version string that comes from your external build environment if
3467      desired, and this suffix would then be used consistently across
3468      the build artifacts.
3469
3470   :term:`IMGDEPLOYDIR`
3471      When inheriting the :ref:`image <ref-classes-image>` class directly or
3472      through the :ref:`core-image <ref-classes-core-image>` class, the
3473      :term:`IMGDEPLOYDIR` points to a temporary work area for deployed files
3474      that is set in the ``image`` class as follows::
3475
3476         IMGDEPLOYDIR = "${WORKDIR}/deploy-${PN}-image-complete"
3477
3478      Recipes inheriting the ``image`` class should copy files to be
3479      deployed into :term:`IMGDEPLOYDIR`, and the class will take care of
3480      copying them into :term:`DEPLOY_DIR_IMAGE` afterwards.
3481
3482   :term:`INC_PR`
3483      Helps define the recipe revision for recipes that share a common
3484      ``include`` file. You can think of this variable as part of the
3485      recipe revision as set from within an include file.
3486
3487      Suppose, for example, you have a set of recipes that are used across
3488      several projects. And, within each of those recipes the revision (its
3489      :term:`PR` value) is set accordingly. In this case, when
3490      the revision of those recipes changes, the burden is on you to find
3491      all those recipes and be sure that they get changed to reflect the
3492      updated version of the recipe. In this scenario, it can get
3493      complicated when recipes that are used in many places and provide
3494      common functionality are upgraded to a new revision.
3495
3496      A more efficient way of dealing with this situation is to set the
3497      :term:`INC_PR` variable inside the ``include`` files that the recipes
3498      share and then expand the :term:`INC_PR` variable within the recipes to
3499      help define the recipe revision.
3500
3501      The following provides an example that shows how to use the
3502      :term:`INC_PR` variable given a common ``include`` file that defines the
3503      variable. Once the variable is defined in the ``include`` file, you
3504      can use the variable to set the :term:`PR` values in each recipe. You
3505      will notice that when you set a recipe's :term:`PR` you can provide more
3506      granular revisioning by appending values to the :term:`INC_PR` variable::
3507
3508         recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2"
3509         recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1"
3510         recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0"
3511         recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
3512
3513      The
3514      first line of the example establishes the baseline revision to be
3515      used for all recipes that use the ``include`` file. The remaining
3516      lines in the example are from individual recipes and show how the
3517      :term:`PR` value is set.
3518
3519   :term:`INCOMPATIBLE_LICENSE`
3520      Specifies a space-separated list of license names (as they would
3521      appear in :term:`LICENSE`) that should be excluded
3522      from the build. Recipes that provide no alternatives to listed
3523      incompatible licenses are not built. Packages that are individually
3524      licensed with the specified incompatible licenses will be deleted.
3525
3526      There is some support for wildcards in this variable's value,
3527      however it is restricted to specific licenses. Currently only
3528      these wildcards are allowed and expand as follows:
3529
3530      - ``AGPL-3.0*"``: ``AGPL-3.0-only``, ``AGPL-3.0-or-later``
3531      - ``GPL-3.0*``: ``GPL-3.0-only``, ``GPL-3.0-or-later``
3532      - ``LGPL-3.0*``: ``LGPL-3.0-only``, ``LGPL-3.0-or-later``
3533
3534      .. note::
3535
3536         This functionality is only regularly tested using the following
3537         setting::
3538
3539                 INCOMPATIBLE_LICENSE = "GPL-3.0* LGPL-3.0* AGPL-3.0*"
3540
3541
3542         Although you can use other settings, you might be required to
3543         remove dependencies on or provide alternatives to components that
3544         are required to produce a functional system image.
3545
3546   :term:`INHERIT`
3547      Causes the named class or classes to be inherited globally. Anonymous
3548      functions in the class or classes are not executed for the base
3549      configuration and in each individual recipe. The OpenEmbedded build
3550      system ignores changes to :term:`INHERIT` in individual recipes.
3551
3552      For more information on :term:`INHERIT`, see the
3553      :ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:\`\`inherit\`\` configuration directive`"
3554      section in the Bitbake User Manual.
3555
3556   :term:`INHERIT_DISTRO`
3557      Lists classes that will be inherited at the distribution level. It is
3558      unlikely that you want to edit this variable.
3559
3560      The default value of the variable is set as follows in the
3561      ``meta/conf/distro/defaultsetup.conf`` file::
3562
3563         INHERIT_DISTRO ?= "debian devshell sstate license"
3564
3565   :term:`INHIBIT_DEFAULT_DEPS`
3566      Prevents the default dependencies, namely the C compiler and standard
3567      C library (libc), from being added to :term:`DEPENDS`.
3568      This variable is usually used within recipes that do not require any
3569      compilation using the C compiler.
3570
3571      Set the variable to "1" to prevent the default dependencies from
3572      being added.
3573
3574   :term:`INHIBIT_PACKAGE_DEBUG_SPLIT`
3575      Prevents the OpenEmbedded build system from splitting out debug
3576      information during packaging. By default, the build system splits out
3577      debugging information during the
3578      :ref:`ref-tasks-package` task. For more information on
3579      how debug information is split out, see the
3580      :term:`PACKAGE_DEBUG_SPLIT_STYLE`
3581      variable.
3582
3583      To prevent the build system from splitting out debug information
3584      during packaging, set the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable as
3585      follows::
3586
3587         INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
3588
3589   :term:`INHIBIT_PACKAGE_STRIP`
3590      If set to "1", causes the build to not strip binaries in resulting
3591      packages and prevents the ``-dbg`` package from containing the source
3592      files.
3593
3594      By default, the OpenEmbedded build system strips binaries and puts
3595      the debugging symbols into ``${``\ :term:`PN`\ ``}-dbg``.
3596      Consequently, you should not set :term:`INHIBIT_PACKAGE_STRIP` when you
3597      plan to debug in general.
3598
3599   :term:`INHIBIT_SYSROOT_STRIP`
3600      If set to "1", causes the build to not strip binaries in the
3601      resulting sysroot.
3602
3603      By default, the OpenEmbedded build system strips binaries in the
3604      resulting sysroot. When you specifically set the
3605      :term:`INHIBIT_SYSROOT_STRIP` variable to "1" in your recipe, you inhibit
3606      this stripping.
3607
3608      If you want to use this variable, include the
3609      :ref:`staging <ref-classes-staging>` class. This class uses a
3610      ``sys_strip()`` function to test for the variable and acts
3611      accordingly.
3612
3613      .. note::
3614
3615         Use of the :term:`INHIBIT_SYSROOT_STRIP` variable occurs in rare and
3616         special circumstances. For example, suppose you are building
3617         bare-metal firmware by using an external GCC toolchain. Furthermore,
3618         even if the toolchain's binaries are strippable, there are other files
3619         needed for the build that are not strippable.
3620
3621   :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
3622      Indicates the deploy directory used by ``do_bundle_initramfs`` where the
3623      :term:`INITRAMFS_IMAGE` will be fetched from.
3624      This variable is set by default to ``${DEPLOY_DIR_IMAGE}`` in the
3625      :ref:`kernel <ref-classes-kernel>` class and it's only meant to be changed
3626      when building an initramfs image from a separate multiconfig via :term:`INITRAMFS_MULTICONFIG`.
3627
3628   :term:`INITRAMFS_FSTYPES`
3629      Defines the format for the output image of an initial RAM filesystem
3630      (initramfs), which is used during boot. Supported formats are the
3631      same as those supported by the
3632      :term:`IMAGE_FSTYPES` variable.
3633
3634      The default value of this variable, which is set in the
3635      ``meta/conf/bitbake.conf`` configuration file in the
3636      :term:`Source Directory`, is "cpio.gz". The Linux kernel's
3637      initramfs mechanism, as opposed to the initial RAM filesystem
3638      `initrd <https://en.wikipedia.org/wiki/Initrd>`__ mechanism, expects
3639      an optionally compressed cpio archive.
3640
3641   :term:`INITRAMFS_IMAGE`
3642      Specifies the :term:`PROVIDES` name of an image
3643      recipe that is used to build an initial RAM filesystem (initramfs)
3644      image. In other words, the :term:`INITRAMFS_IMAGE` variable causes an
3645      additional recipe to be built as a dependency to whatever root
3646      filesystem recipe you might be using (e.g. ``core-image-sato``). The
3647      initramfs image recipe you provide should set
3648      :term:`IMAGE_FSTYPES` to
3649      :term:`INITRAMFS_FSTYPES`.
3650
3651      An initramfs image provides a temporary root filesystem used for
3652      early system initialization (e.g. loading of modules needed to locate
3653      and mount the "real" root filesystem).
3654
3655      .. note::
3656
3657         See the ``meta/recipes-core/images/core-image-minimal-initramfs.bb``
3658         recipe in the :term:`Source Directory`
3659         for an example initramfs recipe. To select this sample recipe as
3660         the one built to provide the initramfs image, set :term:`INITRAMFS_IMAGE`
3661         to "core-image-minimal-initramfs".
3662
3663      You can also find more information by referencing the
3664      ``meta-poky/conf/local.conf.sample.extended`` configuration file in
3665      the Source Directory, the :ref:`image <ref-classes-image>` class,
3666      and the :ref:`kernel <ref-classes-kernel>` class to see how to use
3667      the :term:`INITRAMFS_IMAGE` variable.
3668
3669      If :term:`INITRAMFS_IMAGE` is empty, which is the default, then no
3670      initramfs image is built.
3671
3672      For more information, you can also see the
3673      :term:`INITRAMFS_IMAGE_BUNDLE`
3674      variable, which allows the generated image to be bundled inside the
3675      kernel image. Additionally, for information on creating an initramfs
3676      image, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
3677      in the Yocto Project Development Tasks Manual.
3678
3679   :term:`INITRAMFS_IMAGE_BUNDLE`
3680      Controls whether or not the image recipe specified by
3681      :term:`INITRAMFS_IMAGE` is run through an
3682      extra pass
3683      (:ref:`ref-tasks-bundle_initramfs`) during
3684      kernel compilation in order to build a single binary that contains
3685      both the kernel image and the initial RAM filesystem (initramfs)
3686      image. This makes use of the
3687      :term:`CONFIG_INITRAMFS_SOURCE` kernel
3688      feature.
3689
3690      .. note::
3691
3692         Bundling the initramfs with the kernel conflates the code in the
3693         initramfs with the GPLv2 licensed Linux kernel binary. Thus only GPLv2
3694         compatible software may be part of a bundled initramfs.
3695
3696      .. note::
3697
3698         Using an extra compilation pass to bundle the initramfs avoids a
3699         circular dependency between the kernel recipe and the initramfs
3700         recipe should the initramfs include kernel modules. Should that be
3701         the case, the initramfs recipe depends on the kernel for the
3702         kernel modules, and the kernel depends on the initramfs recipe
3703         since the initramfs is bundled inside the kernel image.
3704
3705      The combined binary is deposited into the ``tmp/deploy`` directory,
3706      which is part of the :term:`Build Directory`.
3707
3708      Setting the variable to "1" in a configuration file causes the
3709      OpenEmbedded build system to generate a kernel image with the
3710      initramfs specified in :term:`INITRAMFS_IMAGE` bundled within::
3711
3712         INITRAMFS_IMAGE_BUNDLE = "1"
3713
3714      By default, the
3715      :ref:`kernel <ref-classes-kernel>` class sets this variable to a
3716      null string as follows::
3717
3718         INITRAMFS_IMAGE_BUNDLE ?= ""
3719
3720      .. note::
3721
3722         You must set the :term:`INITRAMFS_IMAGE_BUNDLE` variable in a
3723         configuration file. You cannot set the variable in a recipe file.
3724
3725      See the
3726      :yocto_git:`local.conf.sample.extended </poky/tree/meta-poky/conf/local.conf.sample.extended>`
3727      file for additional information. Also, for information on creating an
3728      initramfs, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
3729      in the Yocto Project Development Tasks Manual.
3730
3731   :term:`INITRAMFS_LINK_NAME`
3732      The link name of the initial RAM filesystem image. This variable is
3733      set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3734      follows::
3735
3736         INITRAMFS_LINK_NAME ?= "initramfs-${KERNEL_ARTIFACT_LINK_NAME}"
3737
3738      The value of the
3739      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
3740      file, has the following value::
3741
3742         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
3743
3744      See the :term:`MACHINE` variable for additional
3745      information.
3746
3747   :term:`INITRAMFS_MULTICONFIG`
3748      Defines the multiconfig to create a multiconfig dependency to be used by the :ref:`kernel <ref-classes-kernel>` class.
3749
3750      This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
3751      a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
3752
3753      For more information on how to bundle an initramfs image from a separate
3754      multiconfig see the ":ref:`dev-manual/common-tasks:Bundling an Initramfs Image From a Separate Multiconfig`"
3755      section in the Yocto Project Development Tasks Manual.
3756
3757   :term:`INITRAMFS_NAME`
3758      The base name of the initial RAM filesystem image. This variable is
3759      set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3760      follows::
3761
3762         INITRAMFS_NAME ?= "initramfs-${KERNEL_ARTIFACT_NAME}"
3763
3764      The value of the :term:`KERNEL_ARTIFACT_NAME`
3765      variable, which is set in the same file, has the following value::
3766
3767         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3768
3769   :term:`INITRD`
3770      Indicates list of filesystem images to concatenate and use as an
3771      initial RAM disk (``initrd``).
3772
3773      The :term:`INITRD` variable is an optional variable used with the
3774      :ref:`image-live <ref-classes-image-live>` class.
3775
3776   :term:`INITRD_IMAGE`
3777      When building a "live" bootable image (i.e. when
3778      :term:`IMAGE_FSTYPES` contains "live"),
3779      :term:`INITRD_IMAGE` specifies the image recipe that should be built to
3780      provide the initial RAM disk image. The default value is
3781      "core-image-minimal-initramfs".
3782
3783      See the :ref:`image-live <ref-classes-image-live>` class for more
3784      information.
3785
3786   :term:`INITSCRIPT_NAME`
3787      The filename of the initialization script as installed to
3788      ``${sysconfdir}/init.d``.
3789
3790      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
3791      The variable is mandatory.
3792
3793   :term:`INITSCRIPT_PACKAGES`
3794      A list of the packages that contain initscripts. If multiple packages
3795      are specified, you need to append the package name to the other
3796      ``INITSCRIPT_*`` as an override.
3797
3798      This variable is used in recipes when using :ref:`ref-classes-update-rc.d`.
3799      The variable is optional and defaults to the :term:`PN`
3800      variable.
3801
3802   :term:`INITSCRIPT_PARAMS`
3803      Specifies the options to pass to ``update-rc.d``. Here is an example::
3804
3805         INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
3806
3807      In this example, the script has a runlevel of 99, starts the script
3808      in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
3809
3810      The variable's default value is "defaults", which is set in the
3811      :ref:`update-rc.d <ref-classes-update-rc.d>` class.
3812
3813      The value in :term:`INITSCRIPT_PARAMS` is passed through to the
3814      ``update-rc.d`` command. For more information on valid parameters,
3815      please see the ``update-rc.d`` manual page at
3816      https://manpages.debian.org/buster/init-system-helpers/update-rc.d.8.en.html
3817
3818   :term:`INSANE_SKIP`
3819      Specifies the QA checks to skip for a specific package within a
3820      recipe. For example, to skip the check for symbolic link ``.so``
3821      files in the main package of a recipe, add the following to the
3822      recipe. The package name override must be used, which in this example
3823      is ``${PN}``::
3824
3825         INSANE_SKIP:${PN} += "dev-so"
3826
3827      See the ":ref:`ref-classes-insane`" section for a
3828      list of the valid QA checks you can specify using this variable.
3829
3830   :term:`INSTALL_TIMEZONE_FILE`
3831      By default, the ``tzdata`` recipe packages an ``/etc/timezone`` file.
3832      Set the :term:`INSTALL_TIMEZONE_FILE` variable to "0" at the
3833      configuration level to disable this behavior.
3834
3835   :term:`IPK_FEED_URIS`
3836      When the IPK backend is in use and package management is enabled on
3837      the target, you can use this variable to set up ``opkg`` in the
3838      target image to point to package feeds on a nominated server. Once
3839      the feed is established, you can perform installations or upgrades
3840      using the package manager at runtime.
3841
3842   :term:`KARCH`
3843      Defines the kernel architecture used when assembling the
3844      configuration. Architectures supported for this release are:
3845
3846      - powerpc
3847      - i386
3848      - x86_64
3849      - arm
3850      - qemu
3851      - mips
3852
3853      You define the :term:`KARCH` variable in the :ref:`kernel-dev/advanced:bsp descriptions`.
3854
3855   :term:`KBRANCH`
3856      A regular expression used by the build process to explicitly identify
3857      the kernel branch that is validated, patched, and configured during a
3858      build. You must set this variable to ensure the exact kernel branch
3859      you want is being used by the build process.
3860
3861      Values for this variable are set in the kernel's recipe file and the
3862      kernel's append file. For example, if you are using the
3863      ``linux-yocto_4.12`` kernel, the kernel recipe file is the
3864      ``meta/recipes-kernel/linux/linux-yocto_4.12.bb`` file. :term:`KBRANCH`
3865      is set as follows in that kernel recipe file::
3866
3867         KBRANCH ?= "standard/base"
3868
3869      This variable is also used from the kernel's append file to identify
3870      the kernel branch specific to a particular machine or target
3871      hardware. Continuing with the previous kernel example, the kernel's
3872      append file (i.e. ``linux-yocto_4.12.bbappend``) is located in the
3873      BSP layer for a given machine. For example, the append file for the
3874      Beaglebone, EdgeRouter, and generic versions of both 32 and 64-bit IA
3875      machines (``meta-yocto-bsp``) is named
3876      ``meta-yocto-bsp/recipes-kernel/linux/linux-yocto_4.12.bbappend``.
3877      Here are the related statements from that append file::
3878
3879         KBRANCH:genericx86 = "standard/base"
3880         KBRANCH:genericx86-64 = "standard/base"
3881         KBRANCH:edgerouter = "standard/edgerouter"
3882         KBRANCH:beaglebone = "standard/beaglebone"
3883
3884      The :term:`KBRANCH` statements
3885      identify the kernel branch to use when building for each supported
3886      BSP.
3887
3888   :term:`KBUILD_DEFCONFIG`
3889      When used with the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
3890      class, specifies an "in-tree" kernel configuration file for use
3891      during a kernel build.
3892
3893      Typically, when using a ``defconfig`` to configure a kernel during a
3894      build, you place the file in your layer in the same manner as you
3895      would place patch files and configuration fragment files (i.e.
3896      "out-of-tree"). However, if you want to use a ``defconfig`` file that
3897      is part of the kernel tree (i.e. "in-tree"), you can use the
3898      :term:`KBUILD_DEFCONFIG` variable and append the
3899      :term:`KMACHINE` variable to point to the
3900      ``defconfig`` file.
3901
3902      To use the variable, set it in the append file for your kernel recipe
3903      using the following form::
3904
3905         KBUILD_DEFCONFIG_KMACHINE ?= defconfig_file
3906
3907      Here is an example from a "raspberrypi2" :term:`KMACHINE` build that uses
3908      a ``defconfig`` file named "bcm2709_defconfig"::
3909
3910         KBUILD_DEFCONFIG:raspberrypi2 = "bcm2709_defconfig"
3911
3912      As an alternative, you can use the following within your append file::
3913
3914         KBUILD_DEFCONFIG:pn-linux-yocto ?= "defconfig_file"
3915
3916      For more
3917      information on how to use the :term:`KBUILD_DEFCONFIG` variable, see the
3918      ":ref:`kernel-dev/common:using an "in-tree" \`\`defconfig\`\` file`"
3919      section in the Yocto Project Linux Kernel Development Manual.
3920
3921   :term:`KCONFIG_MODE`
3922      When used with the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
3923      class, specifies the kernel configuration values to use for options
3924      not specified in the provided ``defconfig`` file. Valid options are::
3925
3926         KCONFIG_MODE = "alldefconfig"
3927         KCONFIG_MODE = "allnoconfig"
3928
3929      In ``alldefconfig`` mode the options not explicitly specified will be
3930      assigned their Kconfig default value. In ``allnoconfig`` mode the
3931      options not explicitly specified will be disabled in the kernel
3932      config.
3933
3934      In case :term:`KCONFIG_MODE` is not set the behaviour will depend on where
3935      the ``defconfig`` file is coming from. An "in-tree" ``defconfig`` file
3936      will be handled in ``alldefconfig`` mode, a ``defconfig`` file placed
3937      in ``${WORKDIR}`` through a meta-layer will be handled in
3938      ``allnoconfig`` mode.
3939
3940      An "in-tree" ``defconfig`` file can be selected via the
3941      :term:`KBUILD_DEFCONFIG` variable. :term:`KCONFIG_MODE` does not need to
3942      be explicitly set.
3943
3944      A ``defconfig`` file compatible with ``allnoconfig`` mode can be
3945      generated by copying the ``.config`` file from a working Linux kernel
3946      build, renaming it to ``defconfig`` and placing it into the Linux
3947      kernel ``${WORKDIR}`` through your meta-layer. :term:`KCONFIG_MODE` does
3948      not need to be explicitly set.
3949
3950      A ``defconfig`` file compatible with ``alldefconfig`` mode can be
3951      generated using the
3952      :ref:`ref-tasks-savedefconfig`
3953      task and placed into the Linux kernel ``${WORKDIR}`` through your
3954      meta-layer. Explicitely set :term:`KCONFIG_MODE`::
3955
3956         KCONFIG_MODE = "alldefconfig"
3957
3958
3959   :term:`KERNEL_ALT_IMAGETYPE`
3960      Specifies an alternate kernel image type for creation in addition to
3961      the kernel image type specified using the
3962      :term:`KERNEL_IMAGETYPE` variable.
3963
3964   :term:`KERNEL_ARTIFACT_NAME`
3965      Specifies the name of all of the build artifacts. You can change the
3966      name of the artifacts by changing the :term:`KERNEL_ARTIFACT_NAME`
3967      variable.
3968
3969      The value of :term:`KERNEL_ARTIFACT_NAME`, which is set in the
3970      ``meta/classes/kernel-artifact-names.bbclass`` file, has the
3971      following default value::
3972
3973         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3974
3975      See the :term:`PKGE`, :term:`PKGV`, :term:`PKGR`, :term:`MACHINE`
3976      and :term:`IMAGE_VERSION_SUFFIX` variables for additional information.
3977
3978   :term:`KERNEL_CLASSES`
3979      A list of classes defining kernel image types that the
3980      :ref:`kernel <ref-classes-kernel>` class should inherit. You
3981      typically append this variable to enable extended image types. An
3982      example is the "kernel-fitimage", which enables fitImage support and
3983      resides in ``meta/classes/kernel-fitimage.bbclass``. You can register
3984      custom kernel image types with the :ref:`kernel <ref-classes-kernel>` class using this
3985      variable.
3986
3987   :term:`KERNEL_DEBUG_TIMESTAMPS`
3988      If set to "1", enables timestamping functionality during building
3989      the kernel. The default is "0" to disable this for reproducibility
3990      reasons.
3991
3992   :term:`KERNEL_DEVICETREE`
3993      Specifies the name of the generated Linux kernel device tree (i.e.
3994      the ``.dtb``) file.
3995
3996      .. note::
3997
3998         There is legacy support for specifying the full path to the device
3999         tree. However, providing just the ``.dtb`` file is preferred.
4000
4001      In order to use this variable, the
4002      :ref:`kernel-devicetree <ref-classes-kernel-devicetree>` class must
4003      be inherited.
4004
4005   :term:`KERNEL_DTB_LINK_NAME`
4006      The link name of the kernel device tree binary (DTB). This variable
4007      is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
4008      follows::
4009
4010         KERNEL_DTB_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4011
4012      The
4013      value of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in
4014      the same file, has the following value::
4015
4016         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4017
4018      See the :term:`MACHINE` variable for additional
4019      information.
4020
4021   :term:`KERNEL_DTB_NAME`
4022      The base name of the kernel device tree binary (DTB). This variable
4023      is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
4024      follows::
4025
4026         KERNEL_DTB_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4027
4028      The value of the :term:`KERNEL_ARTIFACT_NAME`
4029      variable, which is set in the same file, has the following value::
4030
4031         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4032
4033   :term:`KERNEL_DTC_FLAGS`
4034      Specifies the ``dtc`` flags that are passed to the Linux kernel build
4035      system when generating the device trees (via ``DTC_FLAGS`` environment
4036      variable).
4037
4038      In order to use this variable, the
4039      :ref:`kernel-devicetree <ref-classes-kernel-devicetree>` class must
4040      be inherited.
4041
4042   :term:`KERNEL_EXTRA_ARGS`
4043      Specifies additional ``make`` command-line arguments the OpenEmbedded
4044      build system passes on when compiling the kernel.
4045
4046   :term:`KERNEL_FEATURES`
4047      Includes additional kernel metadata. In the OpenEmbedded build
4048      system, the default Board Support Packages (BSPs)
4049      :term:`Metadata` is provided through the
4050      :term:`KMACHINE` and :term:`KBRANCH`
4051      variables. You can use the :term:`KERNEL_FEATURES` variable from within
4052      the kernel recipe or kernel append file to further add metadata for
4053      all BSPs or specific BSPs.
4054
4055      The metadata you add through this variable includes config fragments
4056      and features descriptions, which usually includes patches as well as
4057      config fragments. You typically override the :term:`KERNEL_FEATURES`
4058      variable for a specific machine. In this way, you can provide
4059      validated, but optional, sets of kernel configurations and features.
4060
4061      For example, the following example from the ``linux-yocto-rt_4.12``
4062      kernel recipe adds "netfilter" and "taskstats" features to all BSPs
4063      as well as "virtio" configurations to all QEMU machines. The last two
4064      statements add specific configurations to targeted machine types::
4065
4066         KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc features/taskstats/taskstats.scc"
4067         KERNEL_FEATURES:append = "${KERNEL_EXTRA_FEATURES}"
4068         KERNEL_FEATURES:append:qemuall = "cfg/virtio.scc"
4069         KERNEL_FEATURES:append:qemux86 = " cfg/sound.scc cfg/paravirt_kvm.scc"
4070         KERNEL_FEATURES:append:qemux86-64 = "cfg/sound.scc"
4071
4072   :term:`KERNEL_FIT_LINK_NAME`
4073      The link name of the kernel flattened image tree (FIT) image. This
4074      variable is set in the ``meta/classes/kernel-artifact-names.bbclass``
4075      file as follows::
4076
4077         KERNEL_FIT_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4078
4079      The value of the
4080      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4081      file, has the following value::
4082
4083         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4084
4085      See the :term:`MACHINE` variable for additional
4086      information.
4087
4088   :term:`KERNEL_FIT_NAME`
4089      The base name of the kernel flattened image tree (FIT) image. This
4090      variable is set in the ``meta/classes/kernel-artifact-names.bbclass``
4091      file as follows::
4092
4093         KERNEL_FIT_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4094
4095      The value of the :term:`KERNEL_ARTIFACT_NAME`
4096      variable, which is set in the same file, has the following value::
4097
4098         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4099
4100   :term:`KERNEL_IMAGE_LINK_NAME`
4101      The link name for the kernel image. This variable is set in the
4102      ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4103
4104         KERNEL_IMAGE_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4105
4106      The value of
4107      the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
4108      file, has the following value::
4109
4110         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4111
4112      See the :term:`MACHINE` variable for additional
4113      information.
4114
4115   :term:`KERNEL_IMAGE_MAXSIZE`
4116      Specifies the maximum size of the kernel image file in kilobytes. If
4117      :term:`KERNEL_IMAGE_MAXSIZE` is set, the size of the kernel image file is
4118      checked against the set value during the
4119      :ref:`ref-tasks-sizecheck` task. The task fails if
4120      the kernel image file is larger than the setting.
4121
4122      :term:`KERNEL_IMAGE_MAXSIZE` is useful for target devices that have a
4123      limited amount of space in which the kernel image must be stored.
4124
4125      By default, this variable is not set, which means the size of the
4126      kernel image is not checked.
4127
4128   :term:`KERNEL_IMAGE_NAME`
4129      The base name of the kernel image. This variable is set in the
4130      ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4131
4132         KERNEL_IMAGE_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4133
4134      The value of the
4135      :term:`KERNEL_ARTIFACT_NAME` variable,
4136      which is set in the same file, has the following value::
4137
4138         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4139
4140   :term:`KERNEL_IMAGETYPE`
4141      The type of kernel to build for a device, usually set by the machine
4142      configuration files and defaults to "zImage". This variable is used
4143      when building the kernel and is passed to ``make`` as the target to
4144      build.
4145
4146      If you want to build an alternate kernel image type in addition to that
4147      specified by :term:`KERNEL_IMAGETYPE`, use the :term:`KERNEL_ALT_IMAGETYPE`
4148      variable.
4149
4150   :term:`KERNEL_MODULE_AUTOLOAD`
4151      Lists kernel modules that need to be auto-loaded during boot.
4152
4153      .. note::
4154
4155         This variable replaces the deprecated :term:`module_autoload`
4156         variable.
4157
4158      You can use the :term:`KERNEL_MODULE_AUTOLOAD` variable anywhere that it
4159      can be recognized by the kernel recipe or by an out-of-tree kernel
4160      module recipe (e.g. a machine configuration file, a distribution
4161      configuration file, an append file for the recipe, or the recipe
4162      itself).
4163
4164      Specify it as follows::
4165
4166         KERNEL_MODULE_AUTOLOAD += "module_name1 module_name2 module_name3"
4167
4168      Including :term:`KERNEL_MODULE_AUTOLOAD` causes the OpenEmbedded build
4169      system to populate the ``/etc/modules-load.d/modname.conf`` file with
4170      the list of modules to be auto-loaded on boot. The modules appear
4171      one-per-line in the file. Here is an example of the most common use
4172      case::
4173
4174         KERNEL_MODULE_AUTOLOAD += "module_name"
4175
4176      For information on how to populate the ``modname.conf`` file with
4177      ``modprobe.d`` syntax lines, see the :term:`KERNEL_MODULE_PROBECONF` variable.
4178
4179   :term:`KERNEL_MODULE_PROBECONF`
4180      Provides a list of modules for which the OpenEmbedded build system
4181      expects to find ``module_conf_``\ modname values that specify
4182      configuration for each of the modules. For information on how to
4183      provide those module configurations, see the
4184      :term:`module_conf_* <module_conf>` variable.
4185
4186   :term:`KERNEL_PATH`
4187      The location of the kernel sources. This variable is set to the value
4188      of the :term:`STAGING_KERNEL_DIR` within
4189      the :ref:`module <ref-classes-module>` class. For information on
4190      how this variable is used, see the
4191      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4192      section in the Yocto Project Linux Kernel Development Manual.
4193
4194      To help maximize compatibility with out-of-tree drivers used to build
4195      modules, the OpenEmbedded build system also recognizes and uses the
4196      :term:`KERNEL_SRC` variable, which is identical to
4197      the :term:`KERNEL_PATH` variable. Both variables are common variables
4198      used by external Makefiles to point to the kernel source directory.
4199
4200   :term:`KERNEL_SRC`
4201      The location of the kernel sources. This variable is set to the value
4202      of the :term:`STAGING_KERNEL_DIR` within
4203      the :ref:`module <ref-classes-module>` class. For information on
4204      how this variable is used, see the
4205      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4206      section in the Yocto Project Linux Kernel Development Manual.
4207
4208      To help maximize compatibility with out-of-tree drivers used to build
4209      modules, the OpenEmbedded build system also recognizes and uses the
4210      :term:`KERNEL_PATH` variable, which is identical
4211      to the :term:`KERNEL_SRC` variable. Both variables are common variables
4212      used by external Makefiles to point to the kernel source directory.
4213
4214   :term:`KERNEL_VERSION`
4215      Specifies the version of the kernel as extracted from ``version.h``
4216      or ``utsrelease.h`` within the kernel sources. Effects of setting
4217      this variable do not take effect until the kernel has been
4218      configured. Consequently, attempting to refer to this variable in
4219      contexts prior to configuration will not work.
4220
4221   :term:`KERNELDEPMODDEPEND`
4222      Specifies whether the data referenced through
4223      :term:`PKGDATA_DIR` is needed or not.
4224      :term:`KERNELDEPMODDEPEND` does not control whether or not that data
4225      exists, but simply whether or not it is used. If you do not need to
4226      use the data, set the :term:`KERNELDEPMODDEPEND` variable in your
4227      ``initramfs`` recipe. Setting the variable there when the data is not
4228      needed avoids a potential dependency loop.
4229
4230   :term:`KFEATURE_DESCRIPTION`
4231      Provides a short description of a configuration fragment. You use
4232      this variable in the ``.scc`` file that describes a configuration
4233      fragment file. Here is the variable used in a file named ``smp.scc``
4234      to describe SMP being enabled::
4235
4236          define KFEATURE_DESCRIPTION "Enable SMP"
4237
4238   :term:`KMACHINE`
4239      The machine as known by the kernel. Sometimes the machine name used
4240      by the kernel does not match the machine name used by the
4241      OpenEmbedded build system. For example, the machine name that the
4242      OpenEmbedded build system understands as ``core2-32-intel-common``
4243      goes by a different name in the Linux Yocto kernel. The kernel
4244      understands that machine as ``intel-core2-32``. For cases like these,
4245      the :term:`KMACHINE` variable maps the kernel machine name to the
4246      OpenEmbedded build system machine name.
4247
4248      These mappings between different names occur in the Yocto Linux
4249      Kernel's ``meta`` branch. As an example take a look in the
4250      ``common/recipes-kernel/linux/linux-yocto_3.19.bbappend`` file::
4251
4252         LINUX_VERSION:core2-32-intel-common = "3.19.0"
4253         COMPATIBLE_MACHINE:core2-32-intel-common = "${MACHINE}"
4254         SRCREV_meta:core2-32-intel-common = "8897ef68b30e7426bc1d39895e71fb155d694974"
4255         SRCREV_machine:core2-32-intel-common = "43b9eced9ba8a57add36af07736344dcc383f711"
4256         KMACHINE:core2-32-intel-common = "intel-core2-32"
4257         KBRANCH:core2-32-intel-common = "standard/base"
4258         KERNEL_FEATURES:append:core2-32-intel-common = "${KERNEL_FEATURES_INTEL_COMMON}"
4259
4260      The :term:`KMACHINE` statement says
4261      that the kernel understands the machine name as "intel-core2-32".
4262      However, the OpenEmbedded build system understands the machine as
4263      "core2-32-intel-common".
4264
4265   :term:`KTYPE`
4266      Defines the kernel type to be used in assembling the configuration.
4267      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4268      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4269      section in the
4270      Yocto Project Linux Kernel Development Manual for more information on
4271      kernel types.
4272
4273      You define the :term:`KTYPE` variable in the
4274      :ref:`kernel-dev/advanced:bsp descriptions`. The
4275      value you use must match the value used for the
4276      :term:`LINUX_KERNEL_TYPE` value used by the
4277      kernel recipe.
4278
4279   :term:`LABELS`
4280      Provides a list of targets for automatic configuration.
4281
4282      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
4283      information on how this variable is used.
4284
4285   :term:`LAYERDEPENDS`
4286      Lists the layers, separated by spaces, on which this recipe depends.
4287      Optionally, you can specify a specific layer version for a dependency
4288      by adding it to the end of the layer name. Here is an example::
4289
4290         LAYERDEPENDS_mylayer = "anotherlayer (=3)"
4291
4292      In this previous example,
4293      version 3 of "anotherlayer" is compared against
4294      :term:`LAYERVERSION`\ ``_anotherlayer``.
4295
4296      An error is produced if any dependency is missing or the version
4297      numbers (if specified) do not match exactly. This variable is used in
4298      the ``conf/layer.conf`` file and must be suffixed with the name of
4299      the specific layer (e.g. ``LAYERDEPENDS_mylayer``).
4300
4301   :term:`LAYERDIR`
4302      When used inside the ``layer.conf`` configuration file, this variable
4303      provides the path of the current layer. This variable is not
4304      available outside of ``layer.conf`` and references are expanded
4305      immediately when parsing of the file completes.
4306
4307   :term:`LAYERRECOMMENDS`
4308      Lists the layers, separated by spaces, recommended for use with this
4309      layer.
4310
4311      Optionally, you can specify a specific layer version for a
4312      recommendation by adding the version to the end of the layer name.
4313      Here is an example::
4314
4315         LAYERRECOMMENDS_mylayer = "anotherlayer (=3)"
4316
4317      In this previous example, version 3 of "anotherlayer" is compared
4318      against ``LAYERVERSION_anotherlayer``.
4319
4320      This variable is used in the ``conf/layer.conf`` file and must be
4321      suffixed with the name of the specific layer (e.g.
4322      ``LAYERRECOMMENDS_mylayer``).
4323
4324   :term:`LAYERSERIES_COMPAT`
4325      Lists the versions of the :term:`OpenEmbedded-Core (OE-Core)` for which
4326      a layer is compatible. Using the :term:`LAYERSERIES_COMPAT` variable
4327      allows the layer maintainer to indicate which combinations of the
4328      layer and OE-Core can be expected to work. The variable gives the
4329      system a way to detect when a layer has not been tested with new
4330      releases of OE-Core (e.g. the layer is not maintained).
4331
4332      To specify the OE-Core versions for which a layer is compatible, use
4333      this variable in your layer's ``conf/layer.conf`` configuration file.
4334      For the list, use the Yocto Project
4335      :yocto_wiki:`Release Name </Releases>` (e.g.
4336      &DISTRO_NAME_NO_CAP;). To specify multiple OE-Core versions for the
4337      layer, use a space-separated list::
4338
4339         LAYERSERIES_COMPAT_layer_root_name = "&DISTRO_NAME_NO_CAP; &DISTRO_NAME_NO_CAP_MINUS_ONE;"
4340
4341      .. note::
4342
4343         Setting :term:`LAYERSERIES_COMPAT` is required by the Yocto Project
4344         Compatible version 2 standard.
4345         The OpenEmbedded build system produces a warning if the variable
4346         is not set for any given layer.
4347
4348      See the ":ref:`dev-manual/common-tasks:creating your own layer`"
4349      section in the Yocto Project Development Tasks Manual.
4350
4351   :term:`LAYERVERSION`
4352      Optionally specifies the version of a layer as a single number. You
4353      can use this within :term:`LAYERDEPENDS` for
4354      another layer in order to depend on a specific version of the layer.
4355      This variable is used in the ``conf/layer.conf`` file and must be
4356      suffixed with the name of the specific layer (e.g.
4357      ``LAYERVERSION_mylayer``).
4358
4359   :term:`LD`
4360      The minimal command and arguments used to run the linker.
4361
4362   :term:`LDFLAGS`
4363      Specifies the flags to pass to the linker. This variable is exported
4364      to an environment variable and thus made visible to the software
4365      being built during the compilation step.
4366
4367      Default initialization for :term:`LDFLAGS` varies depending on what is
4368      being built:
4369
4370      -  :term:`TARGET_LDFLAGS` when building for the
4371         target
4372
4373      -  :term:`BUILD_LDFLAGS` when building for the
4374         build host (i.e. ``-native``)
4375
4376      -  :term:`BUILDSDK_LDFLAGS` when building for
4377         an SDK (i.e. ``nativesdk-``)
4378
4379   :term:`LEAD_SONAME`
4380      Specifies the lead (or primary) compiled library file (i.e. ``.so``)
4381      that the :ref:`debian <ref-classes-debian>` class applies its
4382      naming policy to given a recipe that packages multiple libraries.
4383
4384      This variable works in conjunction with the :ref:`debian <ref-classes-debian>` class.
4385
4386   :term:`LIC_FILES_CHKSUM`
4387      Checksums of the license text in the recipe source code.
4388
4389      This variable tracks changes in license text of the source code
4390      files. If the license text is changed, it will trigger a build
4391      failure, which gives the developer an opportunity to review any
4392      license change.
4393
4394      This variable must be defined for all recipes (unless
4395      :term:`LICENSE` is set to "CLOSED").
4396
4397      For more information, see the ":ref:`dev-manual/common-tasks:tracking license changes`"
4398      section in the Yocto Project Development Tasks Manual.
4399
4400   :term:`LICENSE`
4401      The list of source licenses for the recipe. Follow these rules:
4402
4403      -  Do not use spaces within individual license names.
4404
4405      -  Separate license names using \| (pipe) when there is a choice
4406         between licenses.
4407
4408      -  Separate license names using & (ampersand) when there are
4409         multiple licenses for different parts of the source.
4410
4411      -  You can use spaces between license names.
4412
4413      -  For standard licenses, use the names of the files in
4414         ``meta/files/common-licenses/`` or the
4415         :term:`SPDXLICENSEMAP` flag names defined in
4416         ``meta/conf/licenses.conf``.
4417
4418      Here are some examples::
4419
4420         LICENSE = "LGPL-2.1-only | GPL-3.0-only"
4421         LICENSE = "MPL-1.0 & LGPL-2.1-only"
4422         LICENSE = "GPL-2.0-or-later"
4423
4424      The first example is from the
4425      recipes for Qt, which the user may choose to distribute under either
4426      the LGPL version 2.1 or GPL version 3. The second example is from
4427      Cairo where two licenses cover different parts of the source code.
4428      The final example is from ``sysstat``, which presents a single
4429      license.
4430
4431      You can also specify licenses on a per-package basis to handle
4432      situations where components of the output have different licenses.
4433      For example, a piece of software whose code is licensed under GPLv2
4434      but has accompanying documentation licensed under the GNU Free
4435      Documentation License 1.2 could be specified as follows::
4436
4437         LICENSE = "GFDL-1.2 & GPL-2.0-only"
4438         LICENSE:${PN} = "GPL-2.0.only"
4439         LICENSE:${PN}-doc = "GFDL-1.2"
4440
4441   :term:`LICENSE_CREATE_PACKAGE`
4442      Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
4443      build system to create an extra package (i.e.
4444      ``${``\ :term:`PN`\ ``}-lic``) for each recipe and to add
4445      those packages to the
4446      :term:`RRECOMMENDS`\ ``:${PN}``.
4447
4448      The ``${PN}-lic`` package installs a directory in
4449      ``/usr/share/licenses`` named ``${PN}``, which is the recipe's base
4450      name, and installs files in that directory that contain license and
4451      copyright information (i.e. copies of the appropriate license files
4452      from ``meta/common-licenses`` that match the licenses specified in
4453      the :term:`LICENSE` variable of the recipe metadata
4454      and copies of files marked in
4455      :term:`LIC_FILES_CHKSUM` as containing
4456      license text).
4457
4458      For related information on providing license text, see the
4459      :term:`COPY_LIC_DIRS` variable, the
4460      :term:`COPY_LIC_MANIFEST` variable, and the
4461      ":ref:`dev-manual/common-tasks:providing license text`"
4462      section in the Yocto Project Development Tasks Manual.
4463
4464   :term:`LICENSE_FLAGS`
4465      Specifies additional flags for a recipe you must allow through
4466      :term:`LICENSE_FLAGS_ACCEPTED` in
4467      order for the recipe to be built. When providing multiple flags,
4468      separate them with spaces.
4469
4470      This value is independent of :term:`LICENSE` and is
4471      typically used to mark recipes that might require additional licenses
4472      in order to be used in a commercial product. For more information,
4473      see the
4474      ":ref:`dev-manual/common-tasks:enabling commercially licensed recipes`"
4475      section in the Yocto Project Development Tasks Manual.
4476
4477   :term:`LICENSE_FLAGS_ACCEPTED`
4478      Lists license flags that when specified in
4479      :term:`LICENSE_FLAGS` within a recipe should not
4480      prevent that recipe from being built.  For more information, see the
4481      ":ref:`dev-manual/common-tasks:enabling commercially licensed recipes`"
4482      section in the Yocto Project Development Tasks Manual.
4483
4484   :term:`LICENSE_PATH`
4485      Path to additional licenses used during the build. By default, the
4486      OpenEmbedded build system uses :term:`COMMON_LICENSE_DIR` to define the
4487      directory that holds common license text used during the build. The
4488      :term:`LICENSE_PATH` variable allows you to extend that location to other
4489      areas that have additional licenses::
4490
4491         LICENSE_PATH += "path-to-additional-common-licenses"
4492
4493   :term:`LINUX_KERNEL_TYPE`
4494      Defines the kernel type to be used in assembling the configuration.
4495      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4496      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4497      section in the
4498      Yocto Project Linux Kernel Development Manual for more information on
4499      kernel types.
4500
4501      If you do not specify a :term:`LINUX_KERNEL_TYPE`, it defaults to
4502      "standard". Together with :term:`KMACHINE`, the
4503      :term:`LINUX_KERNEL_TYPE` variable defines the search arguments used by
4504      the kernel tools to find the appropriate description within the
4505      kernel :term:`Metadata` with which to build out the sources
4506      and configuration.
4507
4508   :term:`LINUX_VERSION`
4509      The Linux version from ``kernel.org`` on which the Linux kernel image
4510      being built using the OpenEmbedded build system is based. You define
4511      this variable in the kernel recipe. For example, the
4512      ``linux-yocto-3.4.bb`` kernel recipe found in
4513      ``meta/recipes-kernel/linux`` defines the variables as follows::
4514
4515         LINUX_VERSION ?= "3.4.24"
4516
4517      The :term:`LINUX_VERSION` variable is used to define :term:`PV`
4518      for the recipe::
4519
4520         PV = "${LINUX_VERSION}+git${SRCPV}"
4521
4522   :term:`LINUX_VERSION_EXTENSION`
4523      A string extension compiled into the version string of the Linux
4524      kernel built with the OpenEmbedded build system. You define this
4525      variable in the kernel recipe. For example, the linux-yocto kernel
4526      recipes all define the variable as follows::
4527
4528         LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
4529
4530      Defining this variable essentially sets the Linux kernel
4531      configuration item ``CONFIG_LOCALVERSION``, which is visible through
4532      the ``uname`` command. Here is an example that shows the extension
4533      assuming it was set as previously shown::
4534
4535         $ uname -r
4536         3.7.0-rc8-custom
4537
4538   :term:`LOG_DIR`
4539      Specifies the directory to which the OpenEmbedded build system writes
4540      overall log files. The default directory is ``${TMPDIR}/log``.
4541
4542      For the directory containing logs specific to each task, see the
4543      :term:`T` variable.
4544
4545   :term:`MACHINE`
4546      Specifies the target device for which the image is built. You define
4547      :term:`MACHINE` in the ``local.conf`` file found in the
4548      :term:`Build Directory`. By default, :term:`MACHINE` is set to
4549      "qemux86", which is an x86-based architecture machine to be emulated
4550      using QEMU::
4551
4552         MACHINE ?= "qemux86"
4553
4554      The variable corresponds to a machine configuration file of the same
4555      name, through which machine-specific configurations are set. Thus,
4556      when :term:`MACHINE` is set to "qemux86", the corresponding
4557      ``qemux86.conf`` machine configuration file can be found in
4558      the :term:`Source Directory` in
4559      ``meta/conf/machine``.
4560
4561      The list of machines supported by the Yocto Project as shipped
4562      include the following::
4563
4564         MACHINE ?= "qemuarm"
4565         MACHINE ?= "qemuarm64"
4566         MACHINE ?= "qemumips"
4567         MACHINE ?= "qemumips64"
4568         MACHINE ?= "qemuppc"
4569         MACHINE ?= "qemux86"
4570         MACHINE ?= "qemux86-64"
4571         MACHINE ?= "genericx86"
4572         MACHINE ?= "genericx86-64"
4573         MACHINE ?= "beaglebone"
4574         MACHINE ?= "edgerouter"
4575
4576      The last five are Yocto Project reference hardware
4577      boards, which are provided in the ``meta-yocto-bsp`` layer.
4578
4579      .. note::
4580
4581         Adding additional Board Support Package (BSP) layers to your
4582         configuration adds new possible settings for :term:`MACHINE`.
4583
4584   :term:`MACHINE_ARCH`
4585      Specifies the name of the machine-specific architecture. This
4586      variable is set automatically from :term:`MACHINE` or
4587      :term:`TUNE_PKGARCH`. You should not hand-edit
4588      the :term:`MACHINE_ARCH` variable.
4589
4590   :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4591      A list of required machine-specific packages to install as part of
4592      the image being built. The build process depends on these packages
4593      being present. Furthermore, because this is a "machine-essential"
4594      variable, the list of packages are essential for the machine to boot.
4595      The impact of this variable affects images based on
4596      ``packagegroup-core-boot``, including the ``core-image-minimal``
4597      image.
4598
4599      This variable is similar to the
4600      :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` variable with the exception
4601      that the image being built has a build dependency on the variable's
4602      list of packages. In other words, the image will not build if a file
4603      in this list is not found.
4604
4605      As an example, suppose the machine for which you are building
4606      requires ``example-init`` to be run during boot to initialize the
4607      hardware. In this case, you would use the following in the machine's
4608      ``.conf`` configuration file::
4609
4610         MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
4611
4612   :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS`
4613      A list of recommended machine-specific packages to install as part of
4614      the image being built. The build process does not depend on these
4615      packages being present. However, because this is a
4616      "machine-essential" variable, the list of packages are essential for
4617      the machine to boot. The impact of this variable affects images based
4618      on ``packagegroup-core-boot``, including the ``core-image-minimal``
4619      image.
4620
4621      This variable is similar to the :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4622      variable with the exception that the image being built does not have
4623      a build dependency on the variable's list of packages. In other
4624      words, the image will still build if a package in this list is not
4625      found. Typically, this variable is used to handle essential kernel
4626      modules, whose functionality may be selected to be built into the
4627      kernel rather than as a module, in which case a package will not be
4628      produced.
4629
4630      Consider an example where you have a custom kernel where a specific
4631      touchscreen driver is required for the machine to be usable. However,
4632      the driver can be built as a module or into the kernel depending on
4633      the kernel configuration. If the driver is built as a module, you
4634      want it to be installed. But, when the driver is built into the
4635      kernel, you still want the build to succeed. This variable sets up a
4636      "recommends" relationship so that in the latter case, the build will
4637      not fail due to the missing package. To accomplish this, assuming the
4638      package for the module was called ``kernel-module-ab123``, you would
4639      use the following in the machine's ``.conf`` configuration file::
4640
4641         MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
4642
4643      .. note::
4644
4645         In this example, the ``kernel-module-ab123`` recipe needs to
4646         explicitly set its :term:`PACKAGES` variable to ensure that BitBake
4647         does not use the kernel recipe's :term:`PACKAGES_DYNAMIC` variable to
4648         satisfy the dependency.
4649
4650      Some examples of these machine essentials are flash, screen,
4651      keyboard, mouse, or touchscreen drivers (depending on the machine).
4652
4653   :term:`MACHINE_EXTRA_RDEPENDS`
4654      A list of machine-specific packages to install as part of the image
4655      being built that are not essential for the machine to boot. However,
4656      the build process for more fully-featured images depends on the
4657      packages being present.
4658
4659      This variable affects all images based on ``packagegroup-base``,
4660      which does not include the ``core-image-minimal`` or
4661      ``core-image-full-cmdline`` images.
4662
4663      The variable is similar to the :term:`MACHINE_EXTRA_RRECOMMENDS` variable
4664      with the exception that the image being built has a build dependency
4665      on the variable's list of packages. In other words, the image will
4666      not build if a file in this list is not found.
4667
4668      An example is a machine that has WiFi capability but is not essential
4669      for the machine to boot the image. However, if you are building a
4670      more fully-featured image, you want to enable the WiFi. The package
4671      containing the firmware for the WiFi hardware is always expected to
4672      exist, so it is acceptable for the build process to depend upon
4673      finding the package. In this case, assuming the package for the
4674      firmware was called ``wifidriver-firmware``, you would use the
4675      following in the ``.conf`` file for the machine::
4676
4677         MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
4678
4679   :term:`MACHINE_EXTRA_RRECOMMENDS`
4680      A list of machine-specific packages to install as part of the image
4681      being built that are not essential for booting the machine. The image
4682      being built has no build dependency on this list of packages.
4683
4684      This variable affects only images based on ``packagegroup-base``,
4685      which does not include the ``core-image-minimal`` or
4686      ``core-image-full-cmdline`` images.
4687
4688      This variable is similar to the :term:`MACHINE_EXTRA_RDEPENDS` variable
4689      with the exception that the image being built does not have a build
4690      dependency on the variable's list of packages. In other words, the
4691      image will 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 WiFi. In this case, the
4696      package containing the WiFi kernel module will not be produced if the
4697      WiFi driver is built into the kernel, in which case you still want
4698      the build to succeed instead of failing as a result of the package
4699      not being found. To accomplish this, assuming the package for the
4700      module was called ``kernel-module-examplewifi``, you would use the
4701      following in the ``.conf`` file for the machine::
4702
4703         MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
4704
4705   :term:`MACHINE_FEATURES`
4706      Specifies the list of hardware features the
4707      :term:`MACHINE` is capable of supporting. For related
4708      information on enabling features, see the
4709      :term:`DISTRO_FEATURES`,
4710      :term:`COMBINED_FEATURES`, and
4711      :term:`IMAGE_FEATURES` variables.
4712
4713      For a list of hardware features supported by the Yocto Project as
4714      shipped, see the ":ref:`ref-features-machine`" section.
4715
4716   :term:`MACHINE_FEATURES_BACKFILL`
4717      Features to be added to :term:`MACHINE_FEATURES` if not also present in
4718      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`.
4719
4720      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
4721      not intended to be user-configurable. It is best to just reference
4722      the variable to see which machine features are being backfilled for
4723      all machine configurations. See the ":ref:`ref-features-backfill`"
4724      section for more information.
4725
4726   :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`
4727      Features from :term:`MACHINE_FEATURES_BACKFILL` that should not be
4728      backfilled (i.e. added to :term:`MACHINE_FEATURES`) during the build. See
4729      the ":ref:`ref-features-backfill`" section for more information.
4730
4731   :term:`MACHINEOVERRIDES`
4732      A colon-separated list of overrides that apply to the current
4733      machine. By default, this list includes the value of
4734      :term:`MACHINE`.
4735
4736      You can extend :term:`MACHINEOVERRIDES` to add extra overrides that
4737      should apply to a machine. For example, all machines emulated in QEMU
4738      (e.g. ``qemuarm``, ``qemux86``, and so forth) include a file named
4739      ``meta/conf/machine/include/qemu.inc`` that prepends the following
4740      override to :term:`MACHINEOVERRIDES`::
4741
4742         MACHINEOVERRIDES =. "qemuall:"
4743
4744      This
4745      override allows variables to be overridden for all machines emulated
4746      in QEMU, like in the following example from the ``connman-conf``
4747      recipe::
4748
4749         SRC_URI:append:qemuall = " file://wired.config \
4750             file://wired-setup \
4751             "
4752
4753      The underlying mechanism behind
4754      :term:`MACHINEOVERRIDES` is simply that it is included in the default
4755      value of :term:`OVERRIDES`.
4756
4757   :term:`MAINTAINER`
4758      The email address of the distribution maintainer.
4759
4760   :term:`METADATA_BRANCH`
4761      The branch currently checked out for the OpenEmbedded-Core layer (path
4762      determined by :term:`COREBASE`).
4763
4764   :term:`METADATA_REVISION`
4765      The revision currently checked out for the OpenEmbedded-Core layer (path
4766      determined by :term:`COREBASE`).
4767
4768   :term:`MIRRORS`
4769      Specifies additional paths from which the OpenEmbedded build system
4770      gets source code. When the build system searches for source code, it
4771      first tries the local download directory. If that location fails, the
4772      build system tries locations defined by
4773      :term:`PREMIRRORS`, the upstream source, and then
4774      locations specified by :term:`MIRRORS` in that order.
4775
4776      Assuming your distribution (:term:`DISTRO`) is "poky",
4777      the default value for :term:`MIRRORS` is defined in the
4778      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
4779
4780   :term:`MLPREFIX`
4781      Specifies a prefix has been added to :term:`PN` to create a
4782      special version of a recipe or package (i.e. a Multilib version). The
4783      variable is used in places where the prefix needs to be added to or
4784      removed from a the name (e.g. the :term:`BPN` variable).
4785      :term:`MLPREFIX` gets set when a prefix has been added to :term:`PN`.
4786
4787      .. note::
4788
4789         The "ML" in :term:`MLPREFIX` stands for "MultiLib". This representation is
4790         historical and comes from a time when ``nativesdk`` was a suffix
4791         rather than a prefix on the recipe name. When ``nativesdk`` was turned
4792         into a prefix, it made sense to set :term:`MLPREFIX` for it as well.
4793
4794      To help understand when :term:`MLPREFIX` might be needed, consider when
4795      :term:`BBCLASSEXTEND` is used to provide a
4796      ``nativesdk`` version of a recipe in addition to the target version.
4797      If that recipe declares build-time dependencies on tasks in other
4798      recipes by using :term:`DEPENDS`, then a dependency on
4799      "foo" will automatically get rewritten to a dependency on
4800      "nativesdk-foo". However, dependencies like the following will not
4801      get rewritten automatically::
4802
4803         do_foo[depends] += "recipe:do_foo"
4804
4805      If you want such a dependency to also get transformed, you can do the
4806      following::
4807
4808         do_foo[depends] += "${MLPREFIX}recipe:do_foo"
4809
4810   :term:`module_autoload`
4811      This variable has been replaced by the :term:`KERNEL_MODULE_AUTOLOAD`
4812      variable. You should replace all occurrences of :term:`module_autoload`
4813      with additions to :term:`KERNEL_MODULE_AUTOLOAD`, for example::
4814
4815         module_autoload_rfcomm = "rfcomm"
4816
4817      should now be replaced with::
4818
4819         KERNEL_MODULE_AUTOLOAD += "rfcomm"
4820
4821      See the :term:`KERNEL_MODULE_AUTOLOAD` variable for more information.
4822
4823   :term:`module_conf`
4824      Specifies `modprobe.d <https://linux.die.net/man/5/modprobe.d>`_
4825      syntax lines for inclusion in the ``/etc/modprobe.d/modname.conf``
4826      file.
4827
4828      You can use this variable anywhere that it can be recognized by the
4829      kernel recipe or out-of-tree kernel module recipe (e.g. a machine
4830      configuration file, a distribution configuration file, an append file
4831      for the recipe, or the recipe itself). If you use this variable, you
4832      must also be sure to list the module name in the
4833      :term:`KERNEL_MODULE_PROBECONF`
4834      variable.
4835
4836      Here is the general syntax::
4837
4838         module_conf_module_name = "modprobe.d-syntax"
4839
4840      You must use the kernel module name override.
4841
4842      Run ``man modprobe.d`` in the shell to find out more information on
4843      the exact syntax you want to provide with :term:`module_conf`.
4844
4845      Including :term:`module_conf` causes the OpenEmbedded build system to
4846      populate the ``/etc/modprobe.d/modname.conf`` file with
4847      ``modprobe.d`` syntax lines. Here is an example that adds the options
4848      ``arg1`` and ``arg2`` to a module named ``mymodule``::
4849
4850         module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
4851
4852      For information on how to specify kernel modules to auto-load on
4853      boot, see the :term:`KERNEL_MODULE_AUTOLOAD` variable.
4854
4855   :term:`MODULE_TARBALL_DEPLOY`
4856      Controls creation of the ``modules-*.tgz`` file. Set this variable to
4857      "0" to disable creation of this file, which contains all of the
4858      kernel modules resulting from a kernel build.
4859
4860   :term:`MODULE_TARBALL_LINK_NAME`
4861      The link name of the kernel module tarball. This variable is set in
4862      the ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4863
4864         MODULE_TARBALL_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4865
4866      The value
4867      of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the
4868      same file, has the following value::
4869
4870         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4871
4872      See the :term:`MACHINE` variable for additional information.
4873
4874   :term:`MODULE_TARBALL_NAME`
4875      The base name of the kernel module tarball. This variable is set in
4876      the ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4877
4878         MODULE_TARBALL_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4879
4880      The value of the :term:`KERNEL_ARTIFACT_NAME` variable,
4881      which is set in the same file, has the following value::
4882
4883         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4884
4885   :term:`MULTIMACH_TARGET_SYS`
4886      Uniquely identifies the type of the target system for which packages
4887      are being built. This variable allows output for different types of
4888      target systems to be put into different subdirectories of the same
4889      output directory.
4890
4891      The default value of this variable is::
4892
4893         ${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}
4894
4895      Some classes (e.g.
4896      :ref:`cross-canadian <ref-classes-cross-canadian>`) modify the
4897      :term:`MULTIMACH_TARGET_SYS` value.
4898
4899      See the :term:`STAMP` variable for an example. See the
4900      :term:`STAGING_DIR_TARGET` variable for more information.
4901
4902   :term:`NATIVELSBSTRING`
4903      A string identifying the host distribution. Strings consist of the
4904      host distributor ID followed by the release, as reported by the
4905      ``lsb_release`` tool or as read from ``/etc/lsb-release``. For
4906      example, when running a build on Ubuntu 12.10, the value is
4907      "Ubuntu-12.10". If this information is unable to be determined, the
4908      value resolves to "Unknown".
4909
4910      This variable is used by default to isolate native shared state
4911      packages for different distributions (e.g. to avoid problems with
4912      ``glibc`` version incompatibilities). Additionally, the variable is
4913      checked against
4914      :term:`SANITY_TESTED_DISTROS` if that
4915      variable is set.
4916
4917   :term:`NM`
4918      The minimal command and arguments to run ``nm``.
4919
4920   :term:`NO_GENERIC_LICENSE`
4921      Avoids QA errors when you use a non-common, non-CLOSED license in a
4922      recipe. There are packages, such as the linux-firmware package, with many
4923      licenses that are not in any way common. Also, new licenses are added
4924      occasionally to avoid introducing a lot of common license files,
4925      which are only applicable to a specific package.
4926      :term:`NO_GENERIC_LICENSE` is used to allow copying a license that does
4927      not exist in common licenses.
4928
4929      The following example shows how to add :term:`NO_GENERIC_LICENSE` to a
4930      recipe::
4931
4932         NO_GENERIC_LICENSE[license_name] = "license_file_in_fetched_source"
4933
4934      Here is an example that
4935      uses the ``LICENSE.Abilis.txt`` file as the license from the fetched
4936      source::
4937
4938         NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt"
4939
4940   :term:`NO_RECOMMENDATIONS`
4941      Prevents installation of all "recommended-only" packages.
4942      Recommended-only packages are packages installed only through the
4943      :term:`RRECOMMENDS` variable). Setting the
4944      :term:`NO_RECOMMENDATIONS` variable to "1" turns this feature on::
4945
4946         NO_RECOMMENDATIONS = "1"
4947
4948      You can set this variable globally in your ``local.conf`` file or you
4949      can attach it to a specific image recipe by using the recipe name
4950      override::
4951
4952         NO_RECOMMENDATIONS:pn-target_image = "1"
4953
4954      It is important to realize that if you choose to not install packages
4955      using this variable and some other packages are dependent on them
4956      (i.e. listed in a recipe's :term:`RDEPENDS`
4957      variable), the OpenEmbedded build system ignores your request and
4958      will install the packages to avoid dependency errors.
4959
4960      .. note::
4961
4962         Some recommended packages might be required for certain system
4963         functionality, such as kernel modules. It is up to you to add
4964         packages with the :term:`IMAGE_INSTALL` variable.
4965
4966      This variable is only supported when using the IPK and RPM
4967      packaging backends. DEB is not supported.
4968
4969      See the :term:`BAD_RECOMMENDATIONS` and
4970      the :term:`PACKAGE_EXCLUDE` variables for
4971      related information.
4972
4973   :term:`NOAUTOPACKAGEDEBUG`
4974      Disables auto package from splitting ``.debug`` files. If a recipe
4975      requires ``FILES:${PN}-dbg`` to be set manually, the
4976      :term:`NOAUTOPACKAGEDEBUG` can be defined allowing you to define the
4977      content of the debug package. For example::
4978
4979         NOAUTOPACKAGEDEBUG = "1"
4980         FILES:${PN}-dev = "${includedir}/${QT_DIR_NAME}/Qt/*"
4981         FILES:${PN}-dbg = "/usr/src/debug/"
4982         FILES:${QT_BASE_NAME}-demos-doc = "${docdir}/${QT_DIR_NAME}/qch/qt.qch"
4983
4984   :term:`NON_MULTILIB_RECIPES`
4985      A list of recipes that should not be built for multilib. OE-Core's
4986      ``multilib.conf`` file defines a reasonable starting point for this
4987      list with::
4988
4989         NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot"
4990
4991   :term:`OBJCOPY`
4992      The minimal command and arguments to run ``objcopy``.
4993
4994   :term:`OBJDUMP`
4995      The minimal command and arguments to run ``objdump``.
4996
4997   :term:`OE_BINCONFIG_EXTRA_MANGLE`
4998      When inheriting the :ref:`binconfig <ref-classes-binconfig>` class,
4999      this variable specifies additional arguments passed to the "sed"
5000      command. The sed command alters any paths in configuration scripts
5001      that have been set up during compilation. Inheriting this class
5002      results in all paths in these scripts being changed to point into the
5003      ``sysroots/`` directory so that all builds that use the script will
5004      use the correct directories for the cross compiling layout.
5005
5006      See the ``meta/classes/binconfig.bbclass`` in the
5007      :term:`Source Directory` for details on how this class
5008      applies these additional sed command arguments.
5009
5010   :term:`OE_IMPORTS`
5011      An internal variable used to tell the OpenEmbedded build system what
5012      Python modules to import for every Python function run by the system.
5013
5014      .. note::
5015
5016         Do not set this variable. It is for internal use only.
5017
5018   :term:`OE_INIT_ENV_SCRIPT`
5019      The name of the build environment setup script for the purposes of
5020      setting up the environment within the extensible SDK. The default
5021      value is "oe-init-build-env".
5022
5023      If you use a custom script to set up your build environment, set the
5024      :term:`OE_INIT_ENV_SCRIPT` variable to its name.
5025
5026   :term:`OE_TERMINAL`
5027      Controls how the OpenEmbedded build system spawns interactive
5028      terminals on the host development system (e.g. using the BitBake
5029      command with the ``-c devshell`` command-line option). For more
5030      information, see the ":ref:`dev-manual/common-tasks:using a development shell`" section in
5031      the Yocto Project Development Tasks Manual.
5032
5033      You can use the following values for the :term:`OE_TERMINAL` variable:
5034
5035      - auto
5036      - gnome
5037      - xfce
5038      - rxvt
5039      - screen
5040      - konsole
5041      - none
5042
5043   :term:`OEROOT`
5044      The directory from which the top-level build environment setup script
5045      is sourced. The Yocto Project provides a top-level build environment
5046      setup script: :ref:`structure-core-script`. When you run this
5047      script, the :term:`OEROOT` variable resolves to the directory that
5048      contains the script.
5049
5050      For additional information on how this variable is used, see the
5051      initialization script.
5052
5053   :term:`OLDEST_KERNEL`
5054      Declares the oldest version of the Linux kernel that the produced
5055      binaries must support. This variable is passed into the build of the
5056      Embedded GNU C Library (``glibc``).
5057
5058      The default for this variable comes from the
5059      ``meta/conf/bitbake.conf`` configuration file. You can override this
5060      default by setting the variable in a custom distribution
5061      configuration file.
5062
5063   :term:`OVERRIDES`
5064      A colon-separated list of overrides that currently apply. Overrides
5065      are a BitBake mechanism that allows variables to be selectively
5066      overridden at the end of parsing. The set of overrides in
5067      :term:`OVERRIDES` represents the "state" during building, which includes
5068      the current recipe being built, the machine for which it is being
5069      built, and so forth.
5070
5071      As an example, if the string "an-override" appears as an element in
5072      the colon-separated list in :term:`OVERRIDES`, then the following
5073      assignment will override ``FOO`` with the value "overridden" at the
5074      end of parsing::
5075
5076         FOO:an-override = "overridden"
5077
5078      See the
5079      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
5080      section in the BitBake User Manual for more information on the
5081      overrides mechanism.
5082
5083      The default value of :term:`OVERRIDES` includes the values of the
5084      :term:`CLASSOVERRIDE`,
5085      :term:`MACHINEOVERRIDES`, and
5086      :term:`DISTROOVERRIDES` variables. Another
5087      important override included by default is ``pn-${PN}``. This override
5088      allows variables to be set for a single recipe within configuration
5089      (``.conf``) files. Here is an example::
5090
5091         FOO:pn-myrecipe = "myrecipe-specific value"
5092
5093      .. note::
5094
5095         An easy way to see what overrides apply is to search for :term:`OVERRIDES`
5096         in the output of the ``bitbake -e`` command. See the
5097         ":ref:`dev-manual/common-tasks:viewing variable values`" section in the Yocto
5098         Project Development Tasks Manual for more information.
5099
5100   :term:`P`
5101      The recipe name and version. :term:`P` is comprised of the following::
5102
5103         ${PN}-${PV}
5104
5105   :term:`PACKAGE_ADD_METADATA`
5106      This variable defines additional metadata to add to packages.
5107
5108      You may find you need to inject additional metadata into packages.
5109      This variable allows you to do that by setting the injected data as
5110      the value. Multiple fields can be added by splitting the content with
5111      the literal separator "\n".
5112
5113      The suffixes '_IPK', '_DEB', or '_RPM' can be applied to the variable
5114      to do package type specific settings. It can also be made package
5115      specific by using the package name as a suffix.
5116
5117      You can find out more about applying this variable in the
5118      ":ref:`dev-manual/common-tasks:adding custom metadata to packages`"
5119      section in the Yocto Project Development Tasks Manual.
5120
5121   :term:`PACKAGE_ARCH`
5122      The architecture of the resulting package or packages.
5123
5124      By default, the value of this variable is set to
5125      :term:`TUNE_PKGARCH` when building for the
5126      target, :term:`BUILD_ARCH` when building for the
5127      build host, and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building for the
5128      SDK.
5129
5130      .. note::
5131
5132         See :term:`SDK_ARCH` for more information.
5133
5134      However, if your recipe's output packages are built specific to the
5135      target machine rather than generally for the architecture of the
5136      machine, you should set :term:`PACKAGE_ARCH` to the value of
5137      :term:`MACHINE_ARCH` in the recipe as follows::
5138
5139         PACKAGE_ARCH = "${MACHINE_ARCH}"
5140
5141   :term:`PACKAGE_ARCHS`
5142      Specifies a list of architectures compatible with the target machine.
5143      This variable is set automatically and should not normally be
5144      hand-edited. Entries are separated using spaces and listed in order
5145      of priority. The default value for :term:`PACKAGE_ARCHS` is "all any
5146      noarch ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
5147
5148   :term:`PACKAGE_BEFORE_PN`
5149      Enables easily adding packages to :term:`PACKAGES` before ``${PN}`` so
5150      that those added packages can pick up files that would normally be
5151      included in the default package.
5152
5153   :term:`PACKAGE_CLASSES`
5154      This variable, which is set in the ``local.conf`` configuration file
5155      found in the ``conf`` folder of the
5156      :term:`Build Directory`, specifies the package manager the
5157      OpenEmbedded build system uses when packaging data.
5158
5159      You can provide one or more of the following arguments for the
5160      variable: PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk
5161      package_tar"
5162
5163      .. note::
5164
5165         While it is a legal option, the ``package_tar``
5166         class has limited functionality due to no support for package
5167         dependencies by that backend. Therefore, it is recommended that
5168         you do not use it.
5169
5170      The build system uses only the first argument in the list as the
5171      package manager when creating your image or SDK. However, packages
5172      will be created using any additional packaging classes you specify.
5173      For example, if you use the following in your ``local.conf`` file::
5174
5175         PACKAGE_CLASSES ?= "package_ipk"
5176
5177      The OpenEmbedded build system uses
5178      the IPK package manager to create your image or SDK.
5179
5180      For information on packaging and build performance effects as a
5181      result of the package manager in use, see the
5182      ":ref:`ref-classes-package`" section.
5183
5184   :term:`PACKAGE_DEBUG_SPLIT_STYLE`
5185      Determines how to split up and package debug and source information
5186      when creating debugging packages to be used with the GNU Project
5187      Debugger (GDB). In general, based on the value of this variable,
5188      you can combine the source and debug info in a single package,
5189      you can break out the source into a separate package that can be
5190      installed independently, or you can choose to not have the source
5191      packaged at all.
5192
5193      The possible values of :term:`PACKAGE_DEBUG_SPLIT_STYLE` variable:
5194
5195      -  "``.debug``": All debugging and source info is placed in a single
5196         ``*-dbg`` package; debug symbol files are placed next to the
5197         binary in a ``.debug`` directory so that, if a binary is installed
5198         into ``/bin``, the corresponding debug symbol file is installed
5199         in ``/bin/.debug``. Source files are installed in the same ``*-dbg``
5200         package under ``/usr/src/debug``.
5201
5202      -  "``debug-file-directory``": As above, all debugging and source info
5203         is placed in a single ``*-dbg`` package; debug symbol files are
5204         placed entirely under the directory ``/usr/lib/debug`` and separated
5205         by the path from where the binary is installed, so that if a binary
5206         is installed in ``/bin``, the corresponding debug symbols are installed
5207         in ``/usr/lib/debug/bin``, and so on. As above, source is installed
5208         in the same package under ``/usr/src/debug``.
5209
5210      -  "``debug-with-srcpkg``": Debugging info is placed in the standard
5211         ``*-dbg`` package as with the ``.debug`` value, while source is
5212         placed in a separate ``*-src`` package, which can be installed
5213         independently.  This is the default setting for this variable,
5214         as defined in Poky's ``bitbake.conf`` file.
5215
5216      -  "``debug-without-src``": The same behavior as with the ``.debug``
5217         setting, but no source is packaged at all.
5218
5219      .. note::
5220
5221         Much of the above package splitting can be overridden via
5222         use of the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable.
5223
5224      You can find out more about debugging using GDB by reading the
5225      ":ref:`dev-manual/common-tasks:debugging with the gnu project debugger (gdb) remotely`" section
5226      in the Yocto Project Development Tasks Manual.
5227
5228   :term:`PACKAGE_EXCLUDE`
5229      Lists packages that should not be installed into an image. For
5230      example::
5231
5232         PACKAGE_EXCLUDE = "package_name package_name package_name ..."
5233
5234      You can set this variable globally in your ``local.conf`` file or you
5235      can attach it to a specific image recipe by using the recipe name
5236      override::
5237
5238         PACKAGE_EXCLUDE:pn-target_image = "package_name"
5239
5240      If you choose to not install a package using this variable and some
5241      other package is dependent on it (i.e. listed in a recipe's
5242      :term:`RDEPENDS` variable), the OpenEmbedded build
5243      system generates a fatal installation error. Because the build system
5244      halts the process with a fatal error, you can use the variable with
5245      an iterative development process to remove specific components from a
5246      system.
5247
5248      This variable is supported only when using the IPK and RPM
5249      packaging backends. DEB is not supported.
5250
5251      See the :term:`NO_RECOMMENDATIONS` and the
5252      :term:`BAD_RECOMMENDATIONS` variables for
5253      related information.
5254
5255   :term:`PACKAGE_EXCLUDE_COMPLEMENTARY`
5256      Prevents specific packages from being installed when you are
5257      installing complementary packages.
5258
5259      You might find that you want to prevent installing certain packages
5260      when you are installing complementary packages. For example, if you
5261      are using :term:`IMAGE_FEATURES` to install
5262      ``dev-pkgs``, you might not want to install all packages from a
5263      particular multilib. If you find yourself in this situation, you can
5264      use the :term:`PACKAGE_EXCLUDE_COMPLEMENTARY` variable to specify regular
5265      expressions to match the packages you want to exclude.
5266
5267   :term:`PACKAGE_EXTRA_ARCHS`
5268      Specifies the list of architectures compatible with the device CPU.
5269      This variable is useful when you build for several different devices
5270      that use miscellaneous processors such as XScale and ARM926-EJS.
5271
5272   :term:`PACKAGE_FEED_ARCHS`
5273      Optionally specifies the package architectures used as part of the
5274      package feed URIs during the build. When used, the
5275      :term:`PACKAGE_FEED_ARCHS` variable is appended to the final package feed
5276      URI, which is constructed using the
5277      :term:`PACKAGE_FEED_URIS` and
5278      :term:`PACKAGE_FEED_BASE_PATHS`
5279      variables.
5280
5281      .. note::
5282
5283         You can use the :term:`PACKAGE_FEED_ARCHS`
5284         variable to allow specific package architectures. If you do
5285         not need to allow specific architectures, which is a common
5286         case, you can omit this variable. Omitting the variable results in
5287         all available architectures for the current machine being included
5288         into remote package feeds.
5289
5290      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5291      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5292      defined in your ``local.conf`` file::
5293
5294         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5295                              https://example.com/packagerepos/updates"
5296         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5297         PACKAGE_FEED_ARCHS = "all core2-64"
5298
5299      Given these settings, the resulting package feeds are as follows:
5300
5301      .. code-block:: none
5302
5303         https://example.com/packagerepos/release/rpm/all
5304         https://example.com/packagerepos/release/rpm/core2-64
5305         https://example.com/packagerepos/release/rpm-dev/all
5306         https://example.com/packagerepos/release/rpm-dev/core2-64
5307         https://example.com/packagerepos/updates/rpm/all
5308         https://example.com/packagerepos/updates/rpm/core2-64
5309         https://example.com/packagerepos/updates/rpm-dev/all
5310         https://example.com/packagerepos/updates/rpm-dev/core2-64
5311
5312   :term:`PACKAGE_FEED_BASE_PATHS`
5313      Specifies the base path used when constructing package feed URIs. The
5314      :term:`PACKAGE_FEED_BASE_PATHS` variable makes up the middle portion of a
5315      package feed URI used by the OpenEmbedded build system. The base path
5316      lies between the :term:`PACKAGE_FEED_URIS`
5317      and :term:`PACKAGE_FEED_ARCHS` variables.
5318
5319      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5320      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5321      defined in your ``local.conf`` file::
5322
5323         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5324                              https://example.com/packagerepos/updates"
5325         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5326         PACKAGE_FEED_ARCHS = "all core2-64"
5327
5328      Given these settings, the resulting package feeds are as follows:
5329
5330      .. code-block:: none
5331
5332         https://example.com/packagerepos/release/rpm/all
5333         https://example.com/packagerepos/release/rpm/core2-64
5334         https://example.com/packagerepos/release/rpm-dev/all
5335         https://example.com/packagerepos/release/rpm-dev/core2-64
5336         https://example.com/packagerepos/updates/rpm/all
5337         https://example.com/packagerepos/updates/rpm/core2-64
5338         https://example.com/packagerepos/updates/rpm-dev/all
5339         https://example.com/packagerepos/updates/rpm-dev/core2-64
5340
5341   :term:`PACKAGE_FEED_URIS`
5342      Specifies the front portion of the package feed URI used by the
5343      OpenEmbedded build system. Each final package feed URI is comprised
5344      of :term:`PACKAGE_FEED_URIS`,
5345      :term:`PACKAGE_FEED_BASE_PATHS`, and
5346      :term:`PACKAGE_FEED_ARCHS` variables.
5347
5348      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5349      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5350      defined in your ``local.conf`` file::
5351
5352         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5353                              https://example.com/packagerepos/updates"
5354         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5355         PACKAGE_FEED_ARCHS = "all core2-64"
5356
5357      Given these settings, the resulting package feeds are as follows:
5358
5359      .. code-block:: none
5360
5361         https://example.com/packagerepos/release/rpm/all
5362         https://example.com/packagerepos/release/rpm/core2-64
5363         https://example.com/packagerepos/release/rpm-dev/all
5364         https://example.com/packagerepos/release/rpm-dev/core2-64
5365         https://example.com/packagerepos/updates/rpm/all
5366         https://example.com/packagerepos/updates/rpm/core2-64
5367         https://example.com/packagerepos/updates/rpm-dev/all
5368         https://example.com/packagerepos/updates/rpm-dev/core2-64
5369
5370   :term:`PACKAGE_INSTALL`
5371      The final list of packages passed to the package manager for
5372      installation into the image.
5373
5374      Because the package manager controls actual installation of all
5375      packages, the list of packages passed using :term:`PACKAGE_INSTALL` is
5376      not the final list of packages that are actually installed. This
5377      variable is internal to the image construction code. Consequently, in
5378      general, you should use the
5379      :term:`IMAGE_INSTALL` variable to specify
5380      packages for installation. The exception to this is when working with
5381      the :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
5382      image. When working with an initial RAM filesystem (initramfs) image,
5383      use the :term:`PACKAGE_INSTALL` variable. For information on creating an
5384      initramfs, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
5385      in the Yocto Project Development Tasks Manual.
5386
5387   :term:`PACKAGE_INSTALL_ATTEMPTONLY`
5388      Specifies a list of packages the OpenEmbedded build system attempts
5389      to install when creating an image. If a listed package fails to
5390      install, the build system does not generate an error. This variable
5391      is generally not user-defined.
5392
5393   :term:`PACKAGE_PREPROCESS_FUNCS`
5394      Specifies a list of functions run to pre-process the
5395      :term:`PKGD` directory prior to splitting the files out
5396      to individual packages.
5397
5398   :term:`PACKAGE_WRITE_DEPS`
5399      Specifies a list of dependencies for post-installation and
5400      pre-installation scripts on native/cross tools. If your
5401      post-installation or pre-installation script can execute at root filesystem
5402      creation time rather than on the target but depends on a native tool
5403      in order to execute, you need to list the tools in
5404      :term:`PACKAGE_WRITE_DEPS`.
5405
5406      For information on running post-installation scripts, see the
5407      ":ref:`dev-manual/common-tasks:post-installation scripts`"
5408      section in the Yocto Project Development Tasks Manual.
5409
5410   :term:`PACKAGECONFIG`
5411      This variable provides a means of enabling or disabling features of a
5412      recipe on a per-recipe basis. :term:`PACKAGECONFIG` blocks are defined in
5413      recipes when you specify features and then arguments that define
5414      feature behaviors. Here is the basic block structure (broken over
5415      multiple lines for readability)::
5416
5417         PACKAGECONFIG ??= "f1 f2 f3 ..."
5418         PACKAGECONFIG[f1] = "\
5419             --with-f1, \
5420             --without-f1, \
5421             build-deps-for-f1, \
5422             runtime-deps-for-f1, \
5423             runtime-recommends-for-f1, \
5424             packageconfig-conflicts-for-f1"
5425         PACKAGECONFIG[f2] = "\
5426              ... and so on and so on ...
5427
5428      The :term:`PACKAGECONFIG` variable itself specifies a space-separated
5429      list of the features to enable. Following the features, you can
5430      determine the behavior of each feature by providing up to six
5431      order-dependent arguments, which are separated by commas. You can
5432      omit any argument you like but must retain the separating commas. The
5433      order is important and specifies the following:
5434
5435      1. Extra arguments that should be added to the configure script
5436         argument list (:term:`EXTRA_OECONF` or
5437         :term:`PACKAGECONFIG_CONFARGS`) if
5438         the feature is enabled.
5439
5440      2. Extra arguments that should be added to :term:`EXTRA_OECONF` or
5441         :term:`PACKAGECONFIG_CONFARGS` if the feature is disabled.
5442
5443      3. Additional build dependencies (:term:`DEPENDS`)
5444         that should be added if the feature is enabled.
5445
5446      4. Additional runtime dependencies (:term:`RDEPENDS`)
5447         that should be added if the feature is enabled.
5448
5449      5. Additional runtime recommendations
5450         (:term:`RRECOMMENDS`) that should be added if
5451         the feature is enabled.
5452
5453      6. Any conflicting (that is, mutually exclusive) :term:`PACKAGECONFIG`
5454         settings for this feature.
5455
5456      Consider the following :term:`PACKAGECONFIG` block taken from the
5457      ``librsvg`` recipe. In this example the feature is ``gtk``, which has
5458      three arguments that determine the feature's behavior.
5459      ::
5460
5461         PACKAGECONFIG[gtk] = "--with-gtk3,--without-gtk3,gtk+3"
5462
5463      The
5464      ``--with-gtk3`` and ``gtk+3`` arguments apply only if the feature is
5465      enabled. In this case, ``--with-gtk3`` is added to the configure
5466      script argument list and ``gtk+3`` is added to :term:`DEPENDS`. On the
5467      other hand, if the feature is disabled say through a ``.bbappend``
5468      file in another layer, then the second argument ``--without-gtk3`` is
5469      added to the configure script instead.
5470
5471      The basic :term:`PACKAGECONFIG` structure previously described holds true
5472      regardless of whether you are creating a block or changing a block.
5473      When creating a block, use the structure inside your recipe.
5474
5475      If you want to change an existing :term:`PACKAGECONFIG` block, you can do
5476      so one of two ways:
5477
5478      -  *Append file:* Create an append file named
5479         ``recipename.bbappend`` in your layer and override the value of
5480         :term:`PACKAGECONFIG`. You can either completely override the
5481         variable::
5482
5483            PACKAGECONFIG = "f4 f5"
5484
5485         Or, you can just append the variable::
5486
5487            PACKAGECONFIG:append = " f4"
5488
5489      -  *Configuration file:* This method is identical to changing the
5490         block through an append file except you edit your ``local.conf``
5491         or ``mydistro.conf`` file. As with append files previously
5492         described, you can either completely override the variable::
5493
5494            PACKAGECONFIG:pn-recipename = "f4 f5"
5495
5496         Or, you can just amend the variable::
5497
5498            PACKAGECONFIG:append:pn-recipename = " f4"
5499
5500   :term:`PACKAGECONFIG_CONFARGS`
5501      A space-separated list of configuration options generated from the
5502      :term:`PACKAGECONFIG` setting.
5503
5504      Classes such as :ref:`autotools <ref-classes-autotools>` and
5505      :ref:`cmake <ref-classes-cmake>` use :term:`PACKAGECONFIG_CONFARGS` to
5506      pass :term:`PACKAGECONFIG` options to ``configure`` and ``cmake``,
5507      respectively. If you are using :term:`PACKAGECONFIG` but not a class that
5508      handles the ``do_configure`` task, then you need to use
5509      :term:`PACKAGECONFIG_CONFARGS` appropriately.
5510
5511   :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY`
5512      For recipes inheriting the
5513      :ref:`packagegroup <ref-classes-packagegroup>` class, setting
5514      :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY` to "1" specifies that the
5515      normal complementary packages (i.e. ``-dev``, ``-dbg``, and so forth)
5516      should not be automatically created by the ``packagegroup`` recipe,
5517      which is the default behavior.
5518
5519   :term:`PACKAGES`
5520      The list of packages the recipe creates. The default value is the
5521      following::
5522
5523         ${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
5524
5525      During packaging, the :ref:`ref-tasks-package` task
5526      goes through :term:`PACKAGES` and uses the :term:`FILES`
5527      variable corresponding to each package to assign files to the
5528      package. If a file matches the :term:`FILES` variable for more than one
5529      package in :term:`PACKAGES`, it will be assigned to the earliest
5530      (leftmost) package.
5531
5532      Packages in the variable's list that are empty (i.e. where none of
5533      the patterns in ``FILES:``\ pkg match any files installed by the
5534      :ref:`ref-tasks-install` task) are not generated,
5535      unless generation is forced through the
5536      :term:`ALLOW_EMPTY` variable.
5537
5538   :term:`PACKAGES_DYNAMIC`
5539      A promise that your recipe satisfies runtime dependencies for
5540      optional modules that are found in other recipes.
5541      :term:`PACKAGES_DYNAMIC` does not actually satisfy the dependencies, it
5542      only states that they should be satisfied. For example, if a hard,
5543      runtime dependency (:term:`RDEPENDS`) of another
5544      package is satisfied at build time through the :term:`PACKAGES_DYNAMIC`
5545      variable, but a package with the module name is never actually
5546      produced, then the other package will be broken. Thus, if you attempt
5547      to include that package in an image, you will get a dependency
5548      failure from the packaging system during the
5549      :ref:`ref-tasks-rootfs` task.
5550
5551      Typically, if there is a chance that such a situation can occur and
5552      the package that is not created is valid without the dependency being
5553      satisfied, then you should use :term:`RRECOMMENDS`
5554      (a soft runtime dependency) instead of :term:`RDEPENDS`.
5555
5556      For an example of how to use the :term:`PACKAGES_DYNAMIC` variable when
5557      you are splitting packages, see the
5558      ":ref:`dev-manual/common-tasks:handling optional module packaging`"
5559      section in the Yocto Project Development Tasks Manual.
5560
5561   :term:`PACKAGESPLITFUNCS`
5562      Specifies a list of functions run to perform additional splitting of
5563      files into individual packages. Recipes can either prepend to this
5564      variable or prepend to the ``populate_packages`` function in order to
5565      perform additional package splitting. In either case, the function
5566      should set :term:`PACKAGES`,
5567      :term:`FILES`, :term:`RDEPENDS` and
5568      other packaging variables appropriately in order to perform the
5569      desired splitting.
5570
5571   :term:`PARALLEL_MAKE`
5572      Extra options passed to the ``make`` command during the
5573      :ref:`ref-tasks-compile` task in order to specify
5574      parallel compilation on the local build host. This variable is
5575      usually in the form "-j x", where x represents the maximum number of
5576      parallel threads ``make`` can run.
5577
5578      .. note::
5579
5580         In order for :term:`PARALLEL_MAKE` to be effective, ``make`` must be
5581         called with ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy way to ensure
5582         this is to use the ``oe_runmake`` function.
5583
5584      By default, the OpenEmbedded build system automatically sets this
5585      variable to be equal to the number of cores the build system uses.
5586
5587      .. note::
5588
5589         If the software being built experiences dependency issues during
5590         the ``do_compile`` task that result in race conditions, you can clear
5591         the :term:`PARALLEL_MAKE` variable within the recipe as a workaround. For
5592         information on addressing race conditions, see the
5593         ":ref:`dev-manual/common-tasks:debugging parallel make races`"
5594         section in the Yocto Project Development Tasks Manual.
5595
5596      For single socket systems (i.e. one CPU), you should not have to
5597      override this variable to gain optimal parallelism during builds.
5598      However, if you have very large systems that employ multiple physical
5599      CPUs, you might want to make sure the :term:`PARALLEL_MAKE` variable is
5600      not set higher than "-j 20".
5601
5602      For more information on speeding up builds, see the
5603      ":ref:`dev-manual/common-tasks:speeding up a build`"
5604      section in the Yocto Project Development Tasks Manual.
5605
5606   :term:`PARALLEL_MAKEINST`
5607      Extra options passed to the ``make install`` command during the
5608      :ref:`ref-tasks-install` task in order to specify
5609      parallel installation. This variable defaults to the value of
5610      :term:`PARALLEL_MAKE`.
5611
5612      .. note::
5613
5614         In order for :term:`PARALLEL_MAKEINST` to be effective, ``make`` must
5615         be called with
5616         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
5617         way to ensure this is to use the ``oe_runmake`` function.
5618
5619         If the software being built experiences dependency issues during
5620         the ``do_install`` task that result in race conditions, you can
5621         clear the :term:`PARALLEL_MAKEINST` variable within the recipe as a
5622         workaround. For information on addressing race conditions, see the
5623         ":ref:`dev-manual/common-tasks:debugging parallel make races`"
5624         section in the Yocto Project Development Tasks Manual.
5625
5626   :term:`PATCHRESOLVE`
5627      Determines the action to take when a patch fails. You can set this
5628      variable to one of two values: "noop" and "user".
5629
5630      The default value of "noop" causes the build to simply fail when the
5631      OpenEmbedded build system cannot successfully apply a patch. Setting
5632      the value to "user" causes the build system to launch a shell and
5633      places you in the right location so that you can manually resolve the
5634      conflicts.
5635
5636      Set this variable in your ``local.conf`` file.
5637
5638   :term:`PATCHTOOL`
5639      Specifies the utility used to apply patches for a recipe during the
5640      :ref:`ref-tasks-patch` task. You can specify one of
5641      three utilities: "patch", "quilt", or "git". The default utility used
5642      is "quilt" except for the quilt-native recipe itself. Because the
5643      quilt tool is not available at the time quilt-native is being
5644      patched, it uses "patch".
5645
5646      If you wish to use an alternative patching tool, set the variable in
5647      the recipe using one of the following::
5648
5649         PATCHTOOL = "patch"
5650         PATCHTOOL = "quilt"
5651         PATCHTOOL = "git"
5652
5653   :term:`PE`
5654      The epoch of the recipe. By default, this variable is unset. The
5655      variable is used to make upgrades possible when the versioning scheme
5656      changes in some backwards incompatible way.
5657
5658      :term:`PE` is the default value of the :term:`PKGE` variable.
5659
5660   :term:`PEP517_BUILD_API`
5661      When used by recipes that inherit the :ref:`python_pep517
5662      <ref-classes-python_pep517>` class, specifies the entry point to the
5663      PEP-517 compliant build API (such as ``flit_core.buildapi``).
5664
5665   :term:`PEP517_WHEEL_PATH`
5666      When used by recipes that inherit the
5667      :ref:`python_pep517 <ref-classes-python_pep517>` class,
5668      denotes the path to ``dist/`` (short for distribution) where the
5669      binary archive ``wheel`` is built.
5670
5671   :term:`PF`
5672      Specifies the recipe or package name and includes all version and
5673      revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
5674      ``bash-4.2-r1/``). This variable is comprised of the following:
5675      ${:term:`PN`}-${:term:`EXTENDPE`}${:term:`PV`}-${:term:`PR`}
5676
5677   :term:`PIXBUF_PACKAGES`
5678      When inheriting the :ref:`pixbufcache <ref-classes-pixbufcache>`
5679      class, this variable identifies packages that contain the pixbuf
5680      loaders used with ``gdk-pixbuf``. By default, the ``pixbufcache``
5681      class assumes that the loaders are in the recipe's main package (i.e.
5682      ``${``\ :term:`PN`\ ``}``). Use this variable if the
5683      loaders you need are in a package other than that main package.
5684
5685   :term:`PKG`
5686      The name of the resulting package created by the OpenEmbedded build
5687      system.
5688
5689      .. note::
5690
5691         When using the :term:`PKG` variable, you must use a package name override.
5692
5693      For example, when the :ref:`debian <ref-classes-debian>` class
5694      renames the output package, it does so by setting
5695      ``PKG:packagename``.
5696
5697   :term:`PKG_CONFIG_PATH`
5698      The path to ``pkg-config`` files for the current build context.
5699      ``pkg-config`` reads this variable from the environment.
5700
5701   :term:`PKGD`
5702      Points to the destination directory for files to be packaged before
5703      they are split into individual packages. This directory defaults to
5704      the following::
5705
5706         ${WORKDIR}/package
5707
5708      Do not change this default.
5709
5710   :term:`PKGDATA_DIR`
5711      Points to a shared, global-state directory that holds data generated
5712      during the packaging process. During the packaging process, the
5713      :ref:`ref-tasks-packagedata` task packages data
5714      for each recipe and installs it into this temporary, shared area.
5715      This directory defaults to the following, which you should not
5716      change::
5717
5718         ${STAGING_DIR_HOST}/pkgdata
5719
5720      For examples of how this data is used, see the
5721      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
5722      section in the Yocto Project Overview and Concepts Manual and the
5723      ":ref:`dev-manual/common-tasks:viewing package information with \`\`oe-pkgdata-util\`\``"
5724      section in the Yocto Project Development Tasks Manual. For more
5725      information on the shared, global-state directory, see
5726      :term:`STAGING_DIR_HOST`.
5727
5728   :term:`PKGDEST`
5729      Points to the parent directory for files to be packaged after they
5730      have been split into individual packages. This directory defaults to
5731      the following::
5732
5733         ${WORKDIR}/packages-split
5734
5735      Under this directory, the build system creates directories for each
5736      package specified in :term:`PACKAGES`. Do not change
5737      this default.
5738
5739   :term:`PKGDESTWORK`
5740      Points to a temporary work area where the
5741      :ref:`ref-tasks-package` task saves package metadata.
5742      The :term:`PKGDESTWORK` location defaults to the following::
5743
5744         ${WORKDIR}/pkgdata
5745
5746      Do not change this default.
5747
5748      The :ref:`ref-tasks-packagedata` task copies the
5749      package metadata from :term:`PKGDESTWORK` to
5750      :term:`PKGDATA_DIR` to make it available globally.
5751
5752   :term:`PKGE`
5753      The epoch of the package(s) built by the recipe. By default, :term:`PKGE`
5754      is set to :term:`PE`.
5755
5756   :term:`PKGR`
5757      The revision of the package(s) built by the recipe. By default,
5758      :term:`PKGR` is set to :term:`PR`.
5759
5760   :term:`PKGV`
5761      The version of the package(s) built by the recipe. By default,
5762      :term:`PKGV` is set to :term:`PV`.
5763
5764   :term:`PN`
5765      This variable can have two separate functions depending on the
5766      context: a recipe name or a resulting package name.
5767
5768      :term:`PN` refers to a recipe name in the context of a file used by the
5769      OpenEmbedded build system as input to create a package. The name is
5770      normally extracted from the recipe file name. For example, if the
5771      recipe is named ``expat_2.0.1.bb``, then the default value of :term:`PN`
5772      will be "expat".
5773
5774      The variable refers to a package name in the context of a file
5775      created or produced by the OpenEmbedded build system.
5776
5777      If applicable, the :term:`PN` variable also contains any special suffix
5778      or prefix. For example, using ``bash`` to build packages for the
5779      native machine, :term:`PN` is ``bash-native``. Using ``bash`` to build
5780      packages for the target and for Multilib, :term:`PN` would be ``bash``
5781      and ``lib64-bash``, respectively.
5782
5783   :term:`POPULATE_SDK_POST_HOST_COMMAND`
5784      Specifies a list of functions to call once the OpenEmbedded build
5785      system has created the host part of the SDK. You can specify
5786      functions separated by semicolons::
5787
5788          POPULATE_SDK_POST_HOST_COMMAND += "function; ... "
5789
5790      If you need to pass the SDK path to a command within a function, you
5791      can use ``${SDK_DIR}``, which points to the parent directory used by
5792      the OpenEmbedded build system when creating SDK output. See the
5793      :term:`SDK_DIR` variable for more information.
5794
5795   :term:`POPULATE_SDK_POST_TARGET_COMMAND`
5796      Specifies a list of functions to call once the OpenEmbedded build
5797      system has created the target part of the SDK. You can specify
5798      functions separated by semicolons::
5799
5800         POPULATE_SDK_POST_TARGET_COMMAND += "function; ... "
5801
5802      If you need to pass the SDK path to a command within a function, you
5803      can use ``${SDK_DIR}``, which points to the parent directory used by
5804      the OpenEmbedded build system when creating SDK output. See the
5805      :term:`SDK_DIR` variable for more information.
5806
5807   :term:`PR`
5808      The revision of the recipe. The default value for this variable is
5809      "r0". Subsequent revisions of the recipe conventionally have the
5810      values "r1", "r2", and so forth. When :term:`PV` increases,
5811      :term:`PR` is conventionally reset to "r0".
5812
5813      .. note::
5814
5815         The OpenEmbedded build system does not need the aid of :term:`PR`
5816         to know when to rebuild a recipe. The build system uses the task
5817         :ref:`input checksums <overview-manual/concepts:checksums (signatures)>` along with the
5818         :ref:`stamp <structure-build-tmp-stamps>` and
5819         :ref:`overview-manual/concepts:shared state cache`
5820         mechanisms.
5821
5822      The :term:`PR` variable primarily becomes significant when a package
5823      manager dynamically installs packages on an already built image. In
5824      this case, :term:`PR`, which is the default value of
5825      :term:`PKGR`, helps the package manager distinguish which
5826      package is the most recent one in cases where many packages have the
5827      same :term:`PV` (i.e. :term:`PKGV`). A component having many packages with
5828      the same :term:`PV` usually means that the packages all install the same
5829      upstream version, but with later (:term:`PR`) version packages including
5830      packaging fixes.
5831
5832      .. note::
5833
5834         :term:`PR` does not need to be increased for changes that do not change the
5835         package contents or metadata.
5836
5837      Because manually managing :term:`PR` can be cumbersome and error-prone,
5838      an automated solution exists. See the
5839      ":ref:`dev-manual/common-tasks:working with a pr service`" section
5840      in the Yocto Project Development Tasks Manual for more information.
5841
5842   :term:`PREFERRED_PROVIDER`
5843      If multiple recipes provide the same item, this variable determines
5844      which recipe is preferred and thus provides the item (i.e. the
5845      preferred provider). You should always suffix this variable with the
5846      name of the provided item. And, you should define the variable using
5847      the preferred recipe's name (:term:`PN`). Here is a common
5848      example::
5849
5850         PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
5851
5852      In the previous example, multiple recipes are providing "virtual/kernel".
5853      The :term:`PREFERRED_PROVIDER` variable is set with the name (:term:`PN`) of
5854      the recipe you prefer to provide "virtual/kernel".
5855
5856      Following are more examples::
5857
5858         PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
5859         PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
5860
5861      For more
5862      information, see the ":ref:`dev-manual/common-tasks:using virtual providers`"
5863      section in the Yocto Project Development Tasks Manual.
5864
5865      .. note::
5866
5867         If you use a ``virtual/\*`` item with :term:`PREFERRED_PROVIDER`, then any
5868         recipe that :term:`PROVIDES` that item but is not selected (defined)
5869         by :term:`PREFERRED_PROVIDER` is prevented from building, which is usually
5870         desirable since this mechanism is designed to select between mutually
5871         exclusive alternative providers.
5872
5873   :term:`PREFERRED_VERSION`
5874      If there are multiple versions of a recipe available, this variable
5875      determines which version should be given preference. You must always
5876      suffix the variable with the :term:`PN` you want to select (`python` in
5877      the first example below), and you should specify the :term:`PV`
5878      accordingly (`3.4.0` in the example).
5879
5880      The :term:`PREFERRED_VERSION` variable supports limited wildcard use
5881      through the "``%``" character. You can use the character to match any
5882      number of characters, which can be useful when specifying versions
5883      that contain long revision numbers that potentially change. Here are
5884      two examples::
5885
5886         PREFERRED_VERSION_python = "3.4.0"
5887         PREFERRED_VERSION_linux-yocto = "5.0%"
5888
5889      .. note::
5890
5891         The use of the "%" character is limited in that it only works at the end of the
5892         string. You cannot use the wildcard character in any other
5893         location of the string.
5894
5895      The specified version is matched against :term:`PV`, which
5896      does not necessarily match the version part of the recipe's filename.
5897      For example, consider two recipes ``foo_1.2.bb`` and ``foo_git.bb``
5898      where ``foo_git.bb`` contains the following assignment::
5899
5900         PV = "1.1+git${SRCPV}"
5901
5902      In this case, the correct way to select
5903      ``foo_git.bb`` is by using an assignment such as the following::
5904
5905         PREFERRED_VERSION_foo = "1.1+git%"
5906
5907      Compare that previous example
5908      against the following incorrect example, which does not work::
5909
5910         PREFERRED_VERSION_foo = "git"
5911
5912      Sometimes the :term:`PREFERRED_VERSION` variable can be set by
5913      configuration files in a way that is hard to change. You can use
5914      :term:`OVERRIDES` to set a machine-specific
5915      override. Here is an example::
5916
5917         PREFERRED_VERSION_linux-yocto:qemux86 = "5.0%"
5918
5919      Although not recommended, worst case, you can also use the
5920      "forcevariable" override, which is the strongest override possible.
5921      Here is an example::
5922
5923         PREFERRED_VERSION_linux-yocto:forcevariable = "5.0%"
5924
5925      .. note::
5926
5927         The ``:forcevariable`` override is not handled specially. This override
5928         only works because the default value of :term:`OVERRIDES` includes "forcevariable".
5929
5930      If a recipe with the specified version is not available, a warning
5931      message will be shown. See :term:`REQUIRED_VERSION` if you want this
5932      to be an error instead.
5933
5934   :term:`PREMIRRORS`
5935      Specifies additional paths from which the OpenEmbedded build system
5936      gets source code. When the build system searches for source code, it
5937      first tries the local download directory. If that location fails, the
5938      build system tries locations defined by :term:`PREMIRRORS`, the upstream
5939      source, and then locations specified by
5940      :term:`MIRRORS` in that order.
5941
5942      Assuming your distribution (:term:`DISTRO`) is "poky",
5943      the default value for :term:`PREMIRRORS` is defined in the
5944      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
5945
5946      Typically, you could add a specific server for the build system to
5947      attempt before any others by adding something like the following to
5948      the ``local.conf`` configuration file in the
5949      :term:`Build Directory`::
5950
5951         PREMIRRORS:prepend = "\
5952             git://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
5953             ftp://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
5954             http://.*/.* &YOCTO_DL_URL;/mirror/sources/ \
5955             https://.*/.* &YOCTO_DL_URL;/mirror/sources/"
5956
5957      These changes cause the
5958      build system to intercept Git, FTP, HTTP, and HTTPS requests and
5959      direct them to the ``http://`` sources mirror. You can use
5960      ``file://`` URLs to point to local directories or network shares as
5961      well.
5962
5963   :term:`PRIORITY`
5964      Indicates the importance of a package.
5965
5966      :term:`PRIORITY` is considered to be part of the distribution policy
5967      because the importance of any given recipe depends on the purpose for
5968      which the distribution is being produced. Thus, :term:`PRIORITY` is not
5969      normally set within recipes.
5970
5971      You can set :term:`PRIORITY` to "required", "standard", "extra", and
5972      "optional", which is the default.
5973
5974   :term:`PRIVATE_LIBS`
5975      Specifies libraries installed within a recipe that should be ignored
5976      by the OpenEmbedded build system's shared library resolver. This
5977      variable is typically used when software being built by a recipe has
5978      its own private versions of a library normally provided by another
5979      recipe. In this case, you would not want the package containing the
5980      private libraries to be set as a dependency on other unrelated
5981      packages that should instead depend on the package providing the
5982      standard version of the library.
5983
5984      Libraries specified in this variable should be specified by their
5985      file name. For example, from the Firefox recipe in meta-browser::
5986
5987         PRIVATE_LIBS = "libmozjs.so \
5988                         libxpcom.so \
5989                         libnspr4.so \
5990                         libxul.so \
5991                         libmozalloc.so \
5992                         libplc4.so \
5993                         libplds4.so"
5994
5995      For more information, see the
5996      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
5997      section in the Yocto Project Overview and Concepts Manual.
5998
5999   :term:`PROVIDES`
6000      A list of aliases by which a particular recipe can be known. By
6001      default, a recipe's own :term:`PN` is implicitly already in its
6002      :term:`PROVIDES` list and therefore does not need to mention that it
6003      provides itself. If a recipe uses :term:`PROVIDES`, the additional
6004      aliases are synonyms for the recipe and can be useful for satisfying
6005      dependencies of other recipes during the build as specified by
6006      :term:`DEPENDS`.
6007
6008      Consider the following example :term:`PROVIDES` statement from the recipe
6009      file ``eudev_3.2.9.bb``::
6010
6011         PROVIDES += "udev"
6012
6013      The :term:`PROVIDES` statement
6014      results in the "eudev" recipe also being available as simply "udev".
6015
6016      .. note::
6017
6018         A recipe's own recipe name (:term:`PN`) is always implicitly prepended
6019         to `PROVIDES`, so while using "+=" in the above example may not be
6020         strictly necessary it is recommended to avoid confusion.
6021
6022      In addition to providing recipes under alternate names, the
6023      :term:`PROVIDES` mechanism is also used to implement virtual targets. A
6024      virtual target is a name that corresponds to some particular
6025      functionality (e.g. a Linux kernel). Recipes that provide the
6026      functionality in question list the virtual target in :term:`PROVIDES`.
6027      Recipes that depend on the functionality in question can include the
6028      virtual target in :term:`DEPENDS` to leave the choice of provider open.
6029
6030      Conventionally, virtual targets have names on the form
6031      "virtual/function" (e.g. "virtual/kernel"). The slash is simply part
6032      of the name and has no syntactical significance.
6033
6034      The :term:`PREFERRED_PROVIDER` variable is
6035      used to select which particular recipe provides a virtual target.
6036
6037      .. note::
6038
6039         A corresponding mechanism for virtual runtime dependencies
6040         (packages) exists. However, the mechanism does not depend on any
6041         special functionality beyond ordinary variable assignments. For
6042         example, ``VIRTUAL-RUNTIME_dev_manager`` refers to the package of
6043         the component that manages the ``/dev`` directory.
6044
6045         Setting the "preferred provider" for runtime dependencies is as
6046         simple as using the following assignment in a configuration file::
6047
6048                 VIRTUAL-RUNTIME_dev_manager = "udev"
6049
6050
6051   :term:`PRSERV_HOST`
6052      The network based :term:`PR` service host and port.
6053
6054      The ``conf/local.conf.sample.extended`` configuration file in the
6055      :term:`Source Directory` shows how the
6056      :term:`PRSERV_HOST` variable is set::
6057
6058         PRSERV_HOST = "localhost:0"
6059
6060      You must
6061      set the variable if you want to automatically start a local :ref:`PR
6062      service <dev-manual/common-tasks:working with a pr service>`. You can
6063      set :term:`PRSERV_HOST` to other values to use a remote PR service.
6064
6065
6066   :term:`PSEUDO_IGNORE_PATHS`
6067      A comma-separated (without spaces) list of path prefixes that should be ignored
6068      by pseudo when monitoring and recording file operations, in order to avoid
6069      problems with files being written to outside of the pseudo context and
6070      reduce pseudo's overhead. A path is ignored if it matches any prefix in the list
6071      and can include partial directory (or file) names.
6072
6073
6074   :term:`PTEST_ENABLED`
6075      Specifies whether or not :ref:`Package
6076      Test <dev-manual/common-tasks:testing packages with ptest>` (ptest)
6077      functionality is enabled when building a recipe. You should not set
6078      this variable directly. Enabling and disabling building Package Tests
6079      at build time should be done by adding "ptest" to (or removing it
6080      from) :term:`DISTRO_FEATURES`.
6081
6082   :term:`PV`
6083      The version of the recipe. The version is normally extracted from the
6084      recipe filename. For example, if the recipe is named
6085      ``expat_2.0.1.bb``, then the default value of :term:`PV` will be "2.0.1".
6086      :term:`PV` is generally not overridden within a recipe unless it is
6087      building an unstable (i.e. development) version from a source code
6088      repository (e.g. Git or Subversion).
6089
6090      :term:`PV` is the default value of the :term:`PKGV` variable.
6091
6092   :term:`PYTHON_ABI`
6093      When used by recipes that inherit the
6094      :ref:`setuptools3 <ref-classes-setuptools3>` class, denotes the
6095      Application Binary Interface (ABI) currently in use for Python. By
6096      default, the ABI is "m". You do not have to set this variable as the
6097      OpenEmbedded build system sets it for you.
6098
6099      The OpenEmbedded build system uses the ABI to construct directory
6100      names used when installing the Python headers and libraries in
6101      sysroot (e.g. ``.../python3.3m/...``).
6102
6103   :term:`PYTHON_PN`
6104      When used by recipes that inherit the
6105      :ref:`setuptools3 <ref-classes-setuptools3>` classe, specifies the
6106      major Python version being built. For Python 3.x, :term:`PYTHON_PN` would
6107      be "python3". You do not have to set this variable as the
6108      OpenEmbedded build system automatically sets it for you.
6109
6110      The variable allows recipes to use common infrastructure such as the
6111      following::
6112
6113         DEPENDS += "${PYTHON_PN}-native"
6114
6115      In the previous example,
6116      the version of the dependency is :term:`PYTHON_PN`.
6117
6118   :term:`QA_EMPTY_DIRS`
6119      Specifies a list of directories that are expected to be empty when
6120      packaging; if ``empty-dirs`` appears in :term:`ERROR_QA` or
6121      :term:`WARN_QA` these will be checked and an error or warning
6122      (respectively) will be produced.
6123
6124      The default :term:`QA_EMPTY_DIRS` value is set in
6125      :ref:`insane.bbclass <ref-classes-insane>`.
6126
6127   :term:`QA_EMPTY_DIRS_RECOMMENDATION`
6128      Specifies a recommendation for why a directory must be empty,
6129      which will be included in the error message if a specific directory
6130      is found to contain files. Must be overridden with the directory
6131      path to match on.
6132
6133      If no recommendation is specified for a directory, then the default
6134      "but it is expected to be empty" will be used.
6135
6136      An example message shows if files were present in '/dev'::
6137
6138         QA_EMPTY_DIRS_RECOMMENDATION:/dev = "but all devices must be created at runtime"
6139
6140   :term:`RANLIB`
6141      The minimal command and arguments to run ``ranlib``.
6142
6143   :term:`RCONFLICTS`
6144      The list of packages that conflict with packages. Note that packages
6145      will not be installed if conflicting packages are not first removed.
6146
6147      Like all package-controlling variables, you must always use them in
6148      conjunction with a package name override. Here is an example::
6149
6150         RCONFLICTS:${PN} = "another_conflicting_package_name"
6151
6152      BitBake, which the OpenEmbedded build system uses, supports
6153      specifying versioned dependencies. Although the syntax varies
6154      depending on the packaging format, BitBake hides these differences
6155      from you. Here is the general syntax to specify versions with the
6156      :term:`RCONFLICTS` variable::
6157
6158         RCONFLICTS:${PN} = "package (operator version)"
6159
6160      For ``operator``, you can specify the following:
6161
6162      - =
6163      - <
6164      - >
6165      - <=
6166      - >=
6167
6168      For example, the following sets up a dependency on version 1.2 or
6169      greater of the package ``foo``::
6170
6171         RCONFLICTS:${PN} = "foo (>= 1.2)"
6172
6173   :term:`RDEPENDS`
6174      Lists runtime dependencies of a package. These dependencies are other
6175      packages that must be installed in order for the package to function
6176      correctly. As an example, the following assignment declares that the
6177      package ``foo`` needs the packages ``bar`` and ``baz`` to be
6178      installed::
6179
6180         RDEPENDS:foo = "bar baz"
6181
6182      The most common types of package
6183      runtime dependencies are automatically detected and added. Therefore,
6184      most recipes do not need to set :term:`RDEPENDS`. For more information,
6185      see the
6186      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6187      section in the Yocto Project Overview and Concepts Manual.
6188
6189      The practical effect of the above :term:`RDEPENDS` assignment is that
6190      ``bar`` and ``baz`` will be declared as dependencies inside the
6191      package ``foo`` when it is written out by one of the
6192      :ref:`do_package_write_\* <ref-tasks-package_write_deb>` tasks.
6193      Exactly how this is done depends on which package format is used,
6194      which is determined by
6195      :term:`PACKAGE_CLASSES`. When the
6196      corresponding package manager installs the package, it will know to
6197      also install the packages on which it depends.
6198
6199      To ensure that the packages ``bar`` and ``baz`` get built, the
6200      previous :term:`RDEPENDS` assignment also causes a task dependency to be
6201      added. This dependency is from the recipe's
6202      :ref:`ref-tasks-build` (not to be confused with
6203      :ref:`ref-tasks-compile`) task to the
6204      ``do_package_write_*`` task of the recipes that build ``bar`` and
6205      ``baz``.
6206
6207      The names of the packages you list within :term:`RDEPENDS` must be the
6208      names of other packages - they cannot be recipe names. Although
6209      package names and recipe names usually match, the important point
6210      here is that you are providing package names within the :term:`RDEPENDS`
6211      variable. For an example of the default list of packages created from
6212      a recipe, see the :term:`PACKAGES` variable.
6213
6214      Because the :term:`RDEPENDS` variable applies to packages being built,
6215      you should always use the variable in a form with an attached package
6216      name (remember that a single recipe can build multiple packages). For
6217      example, suppose you are building a development package that depends
6218      on the ``perl`` package. In this case, you would use the following
6219      :term:`RDEPENDS` statement::
6220
6221         RDEPENDS:${PN}-dev += "perl"
6222
6223      In the example,
6224      the development package depends on the ``perl`` package. Thus, the
6225      :term:`RDEPENDS` variable has the ``${PN}-dev`` package name as part of
6226      the variable.
6227
6228      .. note::
6229
6230         ``RDEPENDS:${PN}-dev`` includes ``${``\ :term:`PN`\ ``}``
6231         by default. This default is set in the BitBake configuration file
6232         (``meta/conf/bitbake.conf``). Be careful not to accidentally remove
6233         ``${PN}`` when modifying ``RDEPENDS:${PN}-dev``. Use the "+=" operator
6234         rather than the "=" operator.
6235
6236      The package names you use with :term:`RDEPENDS` must appear as they would
6237      in the :term:`PACKAGES` variable. The :term:`PKG` variable
6238      allows a different name to be used for the final package (e.g. the
6239      :ref:`debian <ref-classes-debian>` class uses this to rename
6240      packages), but this final package name cannot be used with
6241      :term:`RDEPENDS`, which makes sense as :term:`RDEPENDS` is meant to be
6242      independent of the package format used.
6243
6244      BitBake, which the OpenEmbedded build system uses, supports
6245      specifying versioned dependencies. Although the syntax varies
6246      depending on the packaging format, BitBake hides these differences
6247      from you. Here is the general syntax to specify versions with the
6248      :term:`RDEPENDS` variable::
6249
6250         RDEPENDS:${PN} = "package (operator version)"
6251
6252      For ``operator``, you can specify the following:
6253
6254      - =
6255      - <
6256      - >
6257      - <=
6258      - >=
6259
6260      For version, provide the version number.
6261
6262      .. note::
6263
6264         You can use :term:`EXTENDPKGV` to provide a full package version
6265         specification.
6266
6267      For example, the following sets up a dependency on version 1.2 or
6268      greater of the package ``foo``::
6269
6270         RDEPENDS:${PN} = "foo (>= 1.2)"
6271
6272      For information on build-time dependencies, see the
6273      :term:`DEPENDS` variable. You can also see the
6274      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
6275      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
6276      BitBake User Manual for additional information on tasks and
6277      dependencies.
6278
6279   :term:`RECIPE_NO_UPDATE_REASON`
6280      If a recipe should not be replaced by a more recent upstream version,
6281      putting the reason why in this variable in a recipe allows
6282      ``devtool check-upgrade-status`` command to display it, as explained
6283      in the ":ref:`ref-manual/devtool-reference:checking on the upgrade status of a recipe`"
6284      section.
6285
6286   :term:`REQUIRED_DISTRO_FEATURES`
6287      When inheriting the
6288      :ref:`features_check <ref-classes-features_check>`
6289      class, this variable identifies distribution features that must exist
6290      in the current configuration in order for the OpenEmbedded build
6291      system to build the recipe. In other words, if the
6292      :term:`REQUIRED_DISTRO_FEATURES` variable lists a feature that does not
6293      appear in :term:`DISTRO_FEATURES` within the current configuration, then
6294      the recipe will be skipped, and if the build system attempts to build
6295      the recipe then an error will be triggered.
6296
6297   :term:`REQUIRED_VERSION`
6298      If there are multiple versions of a recipe available, this variable
6299      determines which version should be given preference.
6300      :term:`REQUIRED_VERSION` works in exactly the same manner as
6301      :term:`PREFERRED_VERSION`, except that if the specified version is not
6302      available then an error message is shown and the build fails
6303      immediately.
6304
6305      If both :term:`REQUIRED_VERSION` and :term:`PREFERRED_VERSION` are set
6306      for the same recipe, the :term:`REQUIRED_VERSION` value applies.
6307
6308   :term:`RM_WORK_EXCLUDE`
6309      With ``rm_work`` enabled, this variable specifies a list of recipes
6310      whose work directories should not be removed. See the
6311      ":ref:`ref-classes-rm-work`" section for more
6312      details.
6313
6314   :term:`ROOT_HOME`
6315      Defines the root home directory. By default, this directory is set as
6316      follows in the BitBake configuration file::
6317
6318         ROOT_HOME ??= "/home/root"
6319
6320      .. note::
6321
6322         This default value is likely used because some embedded solutions
6323         prefer to have a read-only root filesystem and prefer to keep
6324         writeable data in one place.
6325
6326      You can override the default by setting the variable in any layer or
6327      in the ``local.conf`` file. Because the default is set using a "weak"
6328      assignment (i.e. "??="), you can use either of the following forms to
6329      define your override::
6330
6331         ROOT_HOME = "/root"
6332         ROOT_HOME ?= "/root"
6333
6334      These
6335      override examples use ``/root``, which is probably the most commonly
6336      used override.
6337
6338   :term:`ROOTFS`
6339      Indicates a filesystem image to include as the root filesystem.
6340
6341      The :term:`ROOTFS` variable is an optional variable used with the
6342      :ref:`image-live <ref-classes-image-live>` class.
6343
6344   :term:`ROOTFS_POSTINSTALL_COMMAND`
6345      Specifies a list of functions to call after the OpenEmbedded build
6346      system has installed packages. You can specify functions separated by
6347      semicolons::
6348
6349         ROOTFS_POSTINSTALL_COMMAND += "function; ... "
6350
6351      If you need to pass the root filesystem path to a command within a
6352      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6353      directory that becomes the root filesystem image. See the
6354      :term:`IMAGE_ROOTFS` variable for more
6355      information.
6356
6357   :term:`ROOTFS_POSTPROCESS_COMMAND`
6358      Specifies a list of functions to call once the OpenEmbedded build
6359      system has created the root filesystem. You can specify functions
6360      separated by semicolons::
6361
6362         ROOTFS_POSTPROCESS_COMMAND += "function; ... "
6363
6364      If you need to pass the root filesystem path to a command within a
6365      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6366      directory that becomes the root filesystem image. See the
6367      :term:`IMAGE_ROOTFS` variable for more
6368      information.
6369
6370   :term:`ROOTFS_POSTUNINSTALL_COMMAND`
6371      Specifies a list of functions to call after the OpenEmbedded build
6372      system has removed unnecessary packages. When runtime package
6373      management is disabled in the image, several packages are removed
6374      including ``base-passwd``, ``shadow``, and ``update-alternatives``.
6375      You can specify functions separated by semicolons::
6376
6377         ROOTFS_POSTUNINSTALL_COMMAND += "function; ... "
6378
6379      If you need to pass the root filesystem path to a command within a
6380      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6381      directory that becomes the root filesystem image. See the
6382      :term:`IMAGE_ROOTFS` variable for more
6383      information.
6384
6385   :term:`ROOTFS_PREPROCESS_COMMAND`
6386      Specifies a list of functions to call before the OpenEmbedded build
6387      system has created the root filesystem. You can specify functions
6388      separated by semicolons::
6389
6390         ROOTFS_PREPROCESS_COMMAND += "function; ... "
6391
6392      If you need to pass the root filesystem path to a command within a
6393      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6394      directory that becomes the root filesystem image. See the
6395      :term:`IMAGE_ROOTFS` variable for more
6396      information.
6397
6398   :term:`RPROVIDES`
6399      A list of package name aliases that a package also provides. These
6400      aliases are useful for satisfying runtime dependencies of other
6401      packages both during the build and on the target (as specified by
6402      :term:`RDEPENDS`).
6403
6404      .. note::
6405
6406         A package's own name is implicitly already in its :term:`RPROVIDES` list.
6407
6408      As with all package-controlling variables, you must always use the
6409      variable in conjunction with a package name override. Here is an
6410      example::
6411
6412         RPROVIDES:${PN} = "widget-abi-2"
6413
6414   :term:`RRECOMMENDS`
6415      A list of packages that extends the usability of a package being
6416      built. The package being built does not depend on this list of
6417      packages in order to successfully build, but rather uses them for
6418      extended usability. To specify runtime dependencies for packages, see
6419      the :term:`RDEPENDS` variable.
6420
6421      The package manager will automatically install the :term:`RRECOMMENDS`
6422      list of packages when installing the built package. However, you can
6423      prevent listed packages from being installed by using the
6424      :term:`BAD_RECOMMENDATIONS`,
6425      :term:`NO_RECOMMENDATIONS`, and
6426      :term:`PACKAGE_EXCLUDE` variables.
6427
6428      Packages specified in :term:`RRECOMMENDS` need not actually be produced.
6429      However, there must be a recipe providing each package, either
6430      through the :term:`PACKAGES` or
6431      :term:`PACKAGES_DYNAMIC` variables or the
6432      :term:`RPROVIDES` variable, or an error will occur
6433      during the build. If such a recipe does exist and the package is not
6434      produced, the build continues without error.
6435
6436      Because the :term:`RRECOMMENDS` variable applies to packages being built,
6437      you should always attach an override to the variable to specify the
6438      particular package whose usability is being extended. For example,
6439      suppose you are building a development package that is extended to
6440      support wireless functionality. In this case, you would use the
6441      following::
6442
6443         RRECOMMENDS:${PN}-dev += "wireless_package_name"
6444
6445      In the
6446      example, the package name (``${PN}-dev``) must appear as it would in
6447      the :term:`PACKAGES` namespace before any renaming of the output package
6448      by classes such as :ref:`ref-classes-debian`.
6449
6450      BitBake, which the OpenEmbedded build system uses, supports
6451      specifying versioned recommends. Although the syntax varies depending
6452      on the packaging format, BitBake hides these differences from you.
6453      Here is the general syntax to specify versions with the
6454      :term:`RRECOMMENDS` variable::
6455
6456         RRECOMMENDS:${PN} = "package (operator version)"
6457
6458      For ``operator``, you can specify the following:
6459
6460      - =
6461      - <
6462      - >
6463      - <=
6464      - >=
6465
6466      For example, the following sets up a recommend on version 1.2 or
6467      greater of the package ``foo``::
6468
6469         RRECOMMENDS:${PN} = "foo (>= 1.2)"
6470
6471   :term:`RREPLACES`
6472      A list of packages replaced by a package. The package manager uses
6473      this variable to determine which package should be installed to
6474      replace other package(s) during an upgrade. In order to also have the
6475      other package(s) removed at the same time, you must add the name of
6476      the other package to the :term:`RCONFLICTS` variable.
6477
6478      As with all package-controlling variables, you must use this variable
6479      in conjunction with a package name override. Here is an example::
6480
6481         RREPLACES:${PN} = "other_package_being_replaced"
6482
6483      BitBake, which the OpenEmbedded build system uses, supports
6484      specifying versioned replacements. Although the syntax varies
6485      depending on the packaging format, BitBake hides these differences
6486      from you. Here is the general syntax to specify versions with the
6487      :term:`RREPLACES` variable::
6488
6489         RREPLACES:${PN} = "package (operator version)"
6490
6491      For ``operator``, you can specify the following:
6492
6493      - =
6494      - <
6495      - >
6496      - <=
6497      - >=
6498
6499      For example, the following sets up a replacement using version 1.2
6500      or greater of the package ``foo``::
6501
6502          RREPLACES:${PN} = "foo (>= 1.2)"
6503
6504   :term:`RSUGGESTS`
6505      A list of additional packages that you can suggest for installation
6506      by the package manager at the time a package is installed. Not all
6507      package managers support this functionality.
6508
6509      As with all package-controlling variables, you must always use this
6510      variable in conjunction with a package name override. Here is an
6511      example::
6512
6513         RSUGGESTS:${PN} = "useful_package another_package"
6514
6515   :term:`S`
6516      The location in the :term:`Build Directory` where
6517      unpacked recipe source code resides. By default, this directory is
6518      ``${``\ :term:`WORKDIR`\ ``}/${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
6519      where ``${BPN}`` is the base recipe name and ``${PV}`` is the recipe
6520      version. If the source tarball extracts the code to a directory named
6521      anything other than ``${BPN}-${PV}``, or if the source code is
6522      fetched from an SCM such as Git or Subversion, then you must set
6523      :term:`S` in the recipe so that the OpenEmbedded build system knows where
6524      to find the unpacked source.
6525
6526      As an example, assume a :term:`Source Directory`
6527      top-level folder named ``poky`` and a default Build Directory at
6528      ``poky/build``. In this case, the work directory the build system
6529      uses to keep the unpacked recipe for ``db`` is the following::
6530
6531         poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
6532
6533      The unpacked source code resides in the ``db-5.1.19`` folder.
6534
6535      This next example assumes a Git repository. By default, Git
6536      repositories are cloned to ``${WORKDIR}/git`` during
6537      :ref:`ref-tasks-fetch`. Since this path is different
6538      from the default value of :term:`S`, you must set it specifically so the
6539      source can be located::
6540
6541         SRC_URI = "git://path/to/repo.git;branch=main"
6542         S = "${WORKDIR}/git"
6543
6544   :term:`SANITY_REQUIRED_UTILITIES`
6545      Specifies a list of command-line utilities that should be checked for
6546      during the initial sanity checking process when running BitBake. If
6547      any of the utilities are not installed on the build host, then
6548      BitBake immediately exits with an error.
6549
6550   :term:`SANITY_TESTED_DISTROS`
6551      A list of the host distribution identifiers that the build system has
6552      been tested against. Identifiers consist of the host distributor ID
6553      followed by the release, as reported by the ``lsb_release`` tool or
6554      as read from ``/etc/lsb-release``. Separate the list items with
6555      explicit newline characters (``\n``). If :term:`SANITY_TESTED_DISTROS` is
6556      not empty and the current value of
6557      :term:`NATIVELSBSTRING` does not appear in the
6558      list, then the build system reports a warning that indicates the
6559      current host distribution has not been tested as a build host.
6560
6561   :term:`SDK_ARCH`
6562      The target architecture for the SDK. Typically, you do not directly
6563      set this variable. Instead, use :term:`SDKMACHINE`.
6564
6565   :term:`SDK_CUSTOM_TEMPLATECONF`
6566      When building the extensible SDK, if :term:`SDK_CUSTOM_TEMPLATECONF` is set to
6567      "1" and a ``conf/templateconf.conf`` file exists in the build directory
6568      (:term:`TOPDIR`) then this will be copied into the SDK.
6569
6570   :term:`SDK_DEPLOY`
6571      The directory set up and used by the
6572      :ref:`populate_sdk_base <ref-classes-populate-sdk>` class to which
6573      the SDK is deployed. The ``populate_sdk_base`` class defines
6574      :term:`SDK_DEPLOY` as follows::
6575
6576         SDK_DEPLOY = "${TMPDIR}/deploy/sdk"
6577
6578   :term:`SDK_DIR`
6579      The parent directory used by the OpenEmbedded build system when
6580      creating SDK output. The
6581      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class defines
6582      the variable as follows::
6583
6584         SDK_DIR = "${WORKDIR}/sdk"
6585
6586      .. note::
6587
6588         The :term:`SDK_DIR` directory is a temporary directory as it is part of
6589         :term:`WORKDIR`. The final output directory is :term:`SDK_DEPLOY`.
6590
6591   :term:`SDK_EXT_TYPE`
6592      Controls whether or not shared state artifacts are copied into the
6593      extensible SDK. The default value of "full" copies all of the
6594      required shared state artifacts into the extensible SDK. The value
6595      "minimal" leaves these artifacts out of the SDK.
6596
6597      .. note::
6598
6599         If you set the variable to "minimal", you need to ensure
6600         :term:`SSTATE_MIRRORS` is set in the SDK's configuration to enable the
6601         artifacts to be fetched as needed.
6602
6603   :term:`SDK_HOST_MANIFEST`
6604      The manifest file for the host part of the SDK. This file lists all
6605      the installed packages that make up the host part of the SDK. The
6606      file contains package information on a line-per-package basis as
6607      follows::
6608
6609         packagename packagearch version
6610
6611      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
6612      defines the manifest file as follows::
6613
6614         SDK_HOST_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.host.manifest"
6615
6616      The location is derived using the :term:`SDK_DEPLOY` and
6617      :term:`TOOLCHAIN_OUTPUTNAME` variables.
6618
6619   :term:`SDK_INCLUDE_PKGDATA`
6620      When set to "1", specifies to include the packagedata for all recipes
6621      in the "world" target in the extensible SDK. Including this data
6622      allows the ``devtool search`` command to find these recipes in search
6623      results, as well as allows the ``devtool add`` command to map
6624      dependencies more effectively.
6625
6626      .. note::
6627
6628         Enabling the :term:`SDK_INCLUDE_PKGDATA`
6629         variable significantly increases build time because all of world
6630         needs to be built. Enabling the variable also slightly increases
6631         the size of the extensible SDK.
6632
6633   :term:`SDK_INCLUDE_TOOLCHAIN`
6634      When set to "1", specifies to include the toolchain in the extensible
6635      SDK. Including the toolchain is useful particularly when
6636      :term:`SDK_EXT_TYPE` is set to "minimal" to keep
6637      the SDK reasonably small but you still want to provide a usable
6638      toolchain. For example, suppose you want to use the toolchain from an
6639      IDE or from other tools and you do not want to perform additional
6640      steps to install the toolchain.
6641
6642      The :term:`SDK_INCLUDE_TOOLCHAIN` variable defaults to "0" if
6643      :term:`SDK_EXT_TYPE` is set to "minimal", and defaults to "1" if
6644      :term:`SDK_EXT_TYPE` is set to "full".
6645
6646   :term:`SDK_NAME`
6647      The base name for SDK output files. The name is derived from the
6648      :term:`DISTRO`, :term:`TCLIBC`,
6649      :term:`SDK_ARCH`,
6650      :term:`IMAGE_BASENAME`, and
6651      :term:`TUNE_PKGARCH` variables::
6652
6653         SDK_NAME = "${DISTRO}-${TCLIBC}-${SDK_ARCH}-${IMAGE_BASENAME}-${TUNE_PKGARCH}"
6654
6655   :term:`SDK_OS`
6656      Specifies the operating system for which the SDK will be built. The
6657      default value is the value of :term:`BUILD_OS`.
6658
6659   :term:`SDK_OUTPUT`
6660      The location used by the OpenEmbedded build system when creating SDK
6661      output. The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>`
6662      class defines the variable as follows::
6663
6664         SDK_DIR = "${WORKDIR}/sdk"
6665         SDK_OUTPUT = "${SDK_DIR}/image"
6666         SDK_DEPLOY = "${DEPLOY_DIR}/sdk"
6667
6668      .. note::
6669
6670         The :term:`SDK_OUTPUT` directory is a temporary directory as it is part of
6671         :term:`WORKDIR` by way of :term:`SDK_DIR`. The final output directory is
6672         :term:`SDK_DEPLOY`.
6673
6674   :term:`SDK_PACKAGE_ARCHS`
6675      Specifies a list of architectures compatible with the SDK machine.
6676      This variable is set automatically and should not normally be
6677      hand-edited. Entries are separated using spaces and listed in order
6678      of priority. The default value for :term:`SDK_PACKAGE_ARCHS` is "all any
6679      noarch ${SDK_ARCH}-${SDKPKGSUFFIX}".
6680
6681   :term:`SDK_POSTPROCESS_COMMAND`
6682      Specifies a list of functions to call once the OpenEmbedded build
6683      system creates the SDK. You can specify functions separated by
6684      semicolons: SDK_POSTPROCESS_COMMAND += "function; ... "
6685
6686      If you need to pass an SDK path to a command within a function, you
6687      can use ``${SDK_DIR}``, which points to the parent directory used by
6688      the OpenEmbedded build system when creating SDK output. See the
6689      :term:`SDK_DIR` variable for more information.
6690
6691   :term:`SDK_PREFIX`
6692      The toolchain binary prefix used for ``nativesdk`` recipes. The
6693      OpenEmbedded build system uses the :term:`SDK_PREFIX` value to set the
6694      :term:`TARGET_PREFIX` when building
6695      ``nativesdk`` recipes. The default value is "${SDK_SYS}-".
6696
6697   :term:`SDK_RECRDEP_TASKS`
6698      A list of shared state tasks added to the extensible SDK. By default,
6699      the following tasks are added:
6700
6701      - do_populate_lic
6702      - do_package_qa
6703      - do_populate_sysroot
6704      - do_deploy
6705
6706      Despite the default value of "" for the
6707      :term:`SDK_RECRDEP_TASKS` variable, the above four tasks are always added
6708      to the SDK. To specify tasks beyond these four, you need to use the
6709      :term:`SDK_RECRDEP_TASKS` variable (e.g. you are defining additional
6710      tasks that are needed in order to build
6711      :term:`SDK_TARGETS`).
6712
6713   :term:`SDK_SYS`
6714      Specifies the system, including the architecture and the operating
6715      system, for which the SDK will be built.
6716
6717      The OpenEmbedded build system automatically sets this variable based
6718      on :term:`SDK_ARCH`,
6719      :term:`SDK_VENDOR`, and
6720      :term:`SDK_OS`. You do not need to set the :term:`SDK_SYS`
6721      variable yourself.
6722
6723   :term:`SDK_TARGET_MANIFEST`
6724      The manifest file for the target part of the SDK. This file lists all
6725      the installed packages that make up the target part of the SDK. The
6726      file contains package information on a line-per-package basis as
6727      follows::
6728
6729         packagename packagearch version
6730
6731      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
6732      defines the manifest file as follows::
6733
6734         SDK_TARGET_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.target.manifest"
6735
6736      The location is derived using the :term:`SDK_DEPLOY` and
6737      :term:`TOOLCHAIN_OUTPUTNAME` variables.
6738
6739   :term:`SDK_TARGETS`
6740      A list of targets to install from shared state as part of the
6741      standard or extensible SDK installation. The default value is "${PN}"
6742      (i.e. the image from which the SDK is built).
6743
6744      The :term:`SDK_TARGETS` variable is an internal variable and typically
6745      would not be changed.
6746
6747   :term:`SDK_TITLE`
6748      The title to be printed when running the SDK installer. By default,
6749      this title is based on the :term:`DISTRO_NAME` or
6750      :term:`DISTRO` variable and is set in the
6751      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
6752      follows::
6753
6754         SDK_TITLE ??= "${@d.getVar('DISTRO_NAME') or d.getVar('DISTRO')} SDK"
6755
6756      For the default distribution "poky",
6757      :term:`SDK_TITLE` is set to "Poky (Yocto Project Reference Distro)".
6758
6759      For information on how to change this default title, see the
6760      ":ref:`sdk-manual/appendix-customizing:changing the extensible sdk installer title`"
6761      section in the Yocto Project Application Development and the
6762      Extensible Software Development Kit (eSDK) manual.
6763
6764   :term:`SDK_UPDATE_URL`
6765      An optional URL for an update server for the extensible SDK. If set,
6766      the value is used as the default update server when running
6767      ``devtool sdk-update`` within the extensible SDK.
6768
6769   :term:`SDK_VENDOR`
6770      Specifies the name of the SDK vendor.
6771
6772   :term:`SDK_VERSION`
6773      Specifies the version of the SDK. The Poky distribution configuration file
6774      (``/meta-poky/conf/distro/poky.conf``) sets the default
6775      :term:`SDK_VERSION` as follows::
6776
6777         SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"
6778
6779      For additional information, see the
6780      :term:`DISTRO_VERSION` and
6781      :term:`METADATA_REVISION` variables.
6782
6783   :term:`SDKEXTPATH`
6784      The default installation directory for the Extensible SDK. By
6785      default, this directory is based on the :term:`DISTRO`
6786      variable and is set in the
6787      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
6788      follows::
6789
6790         SDKEXTPATH ??= "~/${@d.getVar('DISTRO')}_sdk"
6791
6792      For the
6793      default distribution "poky", the :term:`SDKEXTPATH` is set to "poky_sdk".
6794
6795      For information on how to change this default directory, see the
6796      ":ref:`sdk-manual/appendix-customizing:changing the default sdk installation directory`"
6797      section in the Yocto Project Application Development and the
6798      Extensible Software Development Kit (eSDK) manual.
6799
6800   :term:`SDKIMAGE_FEATURES`
6801      Equivalent to :term:`IMAGE_FEATURES`. However, this variable applies to
6802      the SDK generated from an image using the following command::
6803
6804         $ bitbake -c populate_sdk imagename
6805
6806   :term:`SDKMACHINE`
6807      The machine for which the SDK is built. In other words, the SDK is built
6808      such that it runs on the target you specify with the :term:`SDKMACHINE`
6809      value. The value points to a corresponding ``.conf`` file under
6810      ``conf/machine-sdk/`` in the enabled layers, for example ``aarch64``,
6811      ``i586``, ``i686``, ``ppc64``, ``ppc64le``, and ``x86_64`` are
6812      :oe_git:`available in OpenEmbedded-Core </openembedded-core/tree/meta/conf/machine-sdk>`.
6813
6814      The variable defaults to :term:`BUILD_ARCH` so that SDKs are built for the
6815      architecture of the build machine.
6816
6817      .. note::
6818
6819         You cannot set the :term:`SDKMACHINE`
6820         variable in your distribution configuration file. If you do, the
6821         configuration will not take effect.
6822
6823   :term:`SDKPATH`
6824      Defines the path offered to the user for installation of the SDK that
6825      is generated by the OpenEmbedded build system. The path appears as
6826      the default location for installing the SDK when you run the SDK's
6827      installation script. You can override the offered path when you run
6828      the script.
6829
6830   :term:`SDKTARGETSYSROOT`
6831      The full path to the sysroot used for cross-compilation within an SDK
6832      as it will be when installed into the default
6833      :term:`SDKPATH`.
6834
6835   :term:`SECTION`
6836      The section in which packages should be categorized. Package
6837      management utilities can make use of this variable.
6838
6839   :term:`SELECTED_OPTIMIZATION`
6840      Specifies the optimization flags passed to the C compiler when
6841      building for the target. The flags are passed through the default
6842      value of the :term:`TARGET_CFLAGS` variable.
6843
6844      The :term:`SELECTED_OPTIMIZATION` variable takes the value of
6845      :term:`FULL_OPTIMIZATION` unless :term:`DEBUG_BUILD` = "1", in which
6846      case the value of :term:`DEBUG_OPTIMIZATION` is used.
6847
6848   :term:`SERIAL_CONSOLE`
6849      Defines a serial console (TTY) to enable using
6850      `getty <https://en.wikipedia.org/wiki/Getty_(Unix)>`__. Provide a
6851      value that specifies the baud rate followed by the TTY device name
6852      separated by a space. You cannot specify more than one TTY device::
6853
6854         SERIAL_CONSOLE = "115200 ttyS0"
6855
6856      .. note::
6857
6858         The :term:`SERIAL_CONSOLE` variable is deprecated. Please use the
6859         :term:`SERIAL_CONSOLES` variable.
6860
6861   :term:`SERIAL_CONSOLES`
6862      Defines a serial console (TTY) to enable using
6863      `getty <https://en.wikipedia.org/wiki/Getty_(Unix)>`__. Provide a
6864      value that specifies the baud rate followed by the TTY device name
6865      separated by a semicolon. Use spaces to separate multiple devices::
6866
6867         SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
6868
6869   :term:`SERIAL_CONSOLES_CHECK`
6870      Specifies serial consoles, which must be listed in
6871      :term:`SERIAL_CONSOLES`, to check against
6872      ``/proc/console`` before enabling them using getty. This variable
6873      allows aliasing in the format: <device>:<alias>. If a device was
6874      listed as "sclp_line0" in ``/dev/`` and "ttyS0" was listed in
6875      ``/proc/console``, you would do the following::
6876
6877         SERIAL_CONSOLES_CHECK = "slcp_line0:ttyS0"
6878
6879      This variable is currently only supported with SysVinit (i.e. not
6880      with systemd). Note that :term:`SERIAL_CONSOLES_CHECK` also requires
6881      ``/etc/inittab`` to be writable when used with SysVinit. This makes it
6882      incompatible with customizations such as the following::
6883
6884         EXTRA_IMAGE_FEATURES += "read-only-rootfs"
6885
6886   :term:`SETUPTOOLS_BUILD_ARGS`
6887      When used by recipes that inherit the
6888      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable can
6889      be used to specify additional arguments to be passed to ``setup.py build``
6890      in the ``setuptools3_do_compile()`` task.
6891
6892   :term:`SETUPTOOLS_INSTALL_ARGS`
6893      When used by recipes that inherit the
6894      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable can
6895      be used to specify additional arguments to be passed to ``setup.py install``
6896      in the ``setuptools3_do_install()`` task.
6897
6898   :term:`SETUPTOOLS_SETUP_PATH`
6899      When used by recipes that inherit the
6900      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable should
6901      be used to specify the directory in which the ``setup.py`` file is
6902      located if it is not at the root of the source tree (as specified by
6903      :term:`S`). For example, in a recipe where the sources are fetched from
6904      a Git repository and ``setup.py`` is in a ``python/pythonmodule``
6905      subdirectory, you would have this::
6906
6907         S = "${WORKDIR}/git"
6908         SETUPTOOLS_SETUP_PATH = "${S}/python/pythonmodule"
6909
6910   :term:`SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS`
6911      A list of recipe dependencies that should not be used to determine
6912      signatures of tasks from one recipe when they depend on tasks from
6913      another recipe. For example::
6914
6915         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
6916
6917      In the previous example, ``intone`` depends on ``mplayer2``.
6918
6919      You can use the special token ``"*"`` on the left-hand side of the
6920      dependency to match all recipes except the one on the right-hand
6921      side. Here is an example::
6922
6923         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "*->quilt-native"
6924
6925      In the previous example, all recipes except ``quilt-native`` ignore
6926      task signatures from the ``quilt-native`` recipe when determining
6927      their task signatures.
6928
6929      Use of this variable is one mechanism to remove dependencies that
6930      affect task signatures and thus force rebuilds when a recipe changes.
6931
6932      .. note::
6933
6934         If you add an inappropriate dependency for a recipe relationship,
6935         the software might break during runtime if the interface of the
6936         second recipe was changed after the first recipe had been built.
6937
6938   :term:`SIGGEN_EXCLUDERECIPES_ABISAFE`
6939      A list of recipes that are completely stable and will never change.
6940      The ABI for the recipes in the list are presented by output from the
6941      tasks run to build the recipe. Use of this variable is one way to
6942      remove dependencies from one recipe on another that affect task
6943      signatures and thus force rebuilds when the recipe changes.
6944
6945      .. note::
6946
6947         If you add an inappropriate variable to this list, the software
6948         might break at runtime if the interface of the recipe was changed
6949         after the other had been built.
6950
6951   :term:`SITEINFO_BITS`
6952      Specifies the number of bits for the target system CPU. The value
6953      should be either "32" or "64".
6954
6955   :term:`SITEINFO_ENDIANNESS`
6956      Specifies the endian byte order of the target system. The value
6957      should be either "le" for little-endian or "be" for big-endian.
6958
6959   :term:`SKIP_FILEDEPS`
6960      Enables removal of all files from the "Provides" section of an RPM
6961      package. Removal of these files is required for packages containing
6962      prebuilt binaries and libraries such as ``libstdc++`` and ``glibc``.
6963
6964      To enable file removal, set the variable to "1" in your
6965      ``conf/local.conf`` configuration file in your:
6966      :term:`Build Directory`.
6967      ::
6968
6969         SKIP_FILEDEPS = "1"
6970
6971   :term:`SKIP_RECIPE`
6972      Used to prevent the OpenEmbedded build system from building a given
6973      recipe. Specify the :term:`PN` value as a variable flag (``varflag``)
6974      and provide a reason, which will be reported when attempting to
6975      build the recipe.
6976
6977      To prevent a recipe from being built, use the :term:`SKIP_RECIPE`
6978      variable in your ``local.conf`` file or distribution configuration.
6979      Here is an example which prevents ``myrecipe`` from being built::
6980
6981         SKIP_RECIPE[myrecipe] = "Not supported by our organization."
6982
6983   :term:`SOC_FAMILY`
6984      Groups together machines based upon the same family of SOC (System On
6985      Chip). You typically set this variable in a common ``.inc`` file that
6986      you include in the configuration files of all the machines.
6987
6988      .. note::
6989
6990         You must include ``conf/machine/include/soc-family.inc`` for this
6991         variable to appear in :term:`MACHINEOVERRIDES`.
6992
6993   :term:`SOLIBS`
6994      Defines the suffix for shared libraries used on the target platform.
6995      By default, this suffix is ".so.*" for all Linux-based systems and is
6996      defined in the ``meta/conf/bitbake.conf`` configuration file.
6997
6998      You will see this variable referenced in the default values of
6999      ``FILES:${PN}``.
7000
7001   :term:`SOLIBSDEV`
7002      Defines the suffix for the development symbolic link (symlink) for
7003      shared libraries on the target platform. By default, this suffix is
7004      ".so" for Linux-based systems and is defined in the
7005      ``meta/conf/bitbake.conf`` configuration file.
7006
7007      You will see this variable referenced in the default values of
7008      ``FILES:${PN}-dev``.
7009
7010   :term:`SOURCE_DATE_EPOCH`
7011      This defines a date expressed in number of seconds since
7012      the UNIX EPOCH (01 Jan 1970 00:00:00 UTC), which is used by
7013      multiple build systems to force a timestamp in built binaries.
7014      Many upstream projects already support this variable.
7015
7016      You will find more details in the `official specifications
7017      <https://reproducible-builds.org/specs/source-date-epoch/>`__.
7018
7019      A value for each recipe is computed from the sources by
7020      :oe_git:`meta/lib/oe/reproducible.py </openembedded-core/tree/meta/lib/oe/reproducible.py>`.
7021
7022      If a recipe wishes to override the default behavior, it should set its
7023      own :term:`SOURCE_DATE_EPOCH` value::
7024
7025          SOURCE_DATE_EPOCH = "1613559011"
7026
7027   :term:`SOURCE_MIRROR_FETCH`
7028      When you are fetching files to create a mirror of sources (i.e.
7029      creating a source mirror), setting :term:`SOURCE_MIRROR_FETCH` to "1" in
7030      your ``local.conf`` configuration file ensures the source for all
7031      recipes are fetched regardless of whether or not a recipe is
7032      compatible with the configuration. A recipe is considered
7033      incompatible with the currently configured machine when either or
7034      both the :term:`COMPATIBLE_MACHINE`
7035      variable and :term:`COMPATIBLE_HOST` variables
7036      specify compatibility with a machine other than that of the current
7037      machine or host.
7038
7039      .. note::
7040
7041         Do not set the :term:`SOURCE_MIRROR_FETCH`
7042         variable unless you are creating a source mirror. In other words,
7043         do not set the variable during a normal build.
7044
7045   :term:`SOURCE_MIRROR_URL`
7046      Defines your own :term:`PREMIRRORS` from which to
7047      first fetch source before attempting to fetch from the upstream
7048      specified in :term:`SRC_URI`.
7049
7050      To use this variable, you must globally inherit the
7051      :ref:`own-mirrors <ref-classes-own-mirrors>` class and then provide
7052      the URL to your mirrors. Here is the general syntax::
7053
7054         INHERIT += "own-mirrors"
7055         SOURCE_MIRROR_URL = "http://example.com/my_source_mirror"
7056
7057      .. note::
7058
7059         You can specify only a single URL in :term:`SOURCE_MIRROR_URL`.
7060
7061   :term:`SPDXLICENSEMAP`
7062      Maps commonly used license names to their SPDX counterparts found in
7063      ``meta/files/common-licenses/``. For the default :term:`SPDXLICENSEMAP`
7064      mappings, see the ``meta/conf/licenses.conf`` file.
7065
7066      For additional information, see the :term:`LICENSE`
7067      variable.
7068
7069   :term:`SPECIAL_PKGSUFFIX`
7070      A list of prefixes for :term:`PN` used by the OpenEmbedded
7071      build system to create variants of recipes or packages. The list
7072      specifies the prefixes to strip off during certain circumstances such
7073      as the generation of the :term:`BPN` variable.
7074
7075   :term:`SPL_BINARY`
7076      The file type for the Secondary Program Loader (SPL). Some devices
7077      use an SPL from which to boot (e.g. the BeagleBone development
7078      board). For such cases, you can declare the file type of the SPL
7079      binary in the ``u-boot.inc`` include file, which is used in the
7080      U-Boot recipe.
7081
7082      The SPL file type is set to "null" by default in the ``u-boot.inc``
7083      file as follows::
7084
7085         # Some versions of u-boot build an SPL (Second Program Loader) image that
7086         # should be packaged along with the u-boot binary as well as placed in the
7087         # deploy directory. For those versions they can set the following variables
7088         # to allow packaging the SPL.
7089         SPL_BINARY ?= ""
7090         SPL_BINARYNAME ?= "${@os.path.basename(d.getVar("SPL_BINARY"))}"
7091         SPL_IMAGE ?= "${SPL_BINARYNAME}-${MACHINE}-${PV}-${PR}"
7092         SPL_SYMLINK ?= "${SPL_BINARYNAME}-${MACHINE}"
7093
7094      The :term:`SPL_BINARY` variable helps form
7095      various ``SPL_*`` variables used by the OpenEmbedded build system.
7096
7097      See the BeagleBone machine configuration example in the
7098      ":ref:`dev-manual/common-tasks:adding a layer using the \`\`bitbake-layers\`\` script`"
7099      section in the Yocto Project Board Support Package Developer's Guide
7100      for additional information.
7101
7102   :term:`SRC_URI`
7103
7104      See the BitBake manual for the initial description for this variable:
7105      :term:`bitbake:SRC_URI`.
7106
7107      The following features are added by OpenEmbedded and the Yocto Project.
7108
7109      There are standard and recipe-specific options. Here are standard ones:
7110
7111      -  ``apply`` - Whether to apply the patch or not. The default
7112         action is to apply the patch.
7113
7114      -  ``striplevel`` - Which striplevel to use when applying the
7115         patch. The default level is 1.
7116
7117      -  ``patchdir`` - Specifies the directory in which the patch should
7118         be applied. The default is ``${``\ :term:`S`\ ``}``.
7119
7120      Here are options specific to recipes building code from a revision
7121      control system:
7122
7123      -  ``mindate`` - Apply the patch only if
7124         :term:`SRCDATE` is equal to or greater than
7125         ``mindate``.
7126
7127      -  ``maxdate`` - Apply the patch only if :term:`SRCDATE` is not later
7128         than ``maxdate``.
7129
7130      -  ``minrev`` - Apply the patch only if :term:`SRCREV` is equal to or
7131         greater than ``minrev``.
7132
7133      -  ``maxrev`` - Apply the patch only if :term:`SRCREV` is not later
7134         than ``maxrev``.
7135
7136      -  ``rev`` - Apply the patch only if :term:`SRCREV` is equal to
7137         ``rev``.
7138
7139      -  ``notrev`` - Apply the patch only if :term:`SRCREV` is not equal to
7140         ``rev``.
7141
7142      .. note::
7143
7144         If you want the build system to pick up files specified through
7145         a :term:`SRC_URI` statement from your append file, you need to be
7146         sure to extend the :term:`FILESPATH` variable by also using the
7147         :term:`FILESEXTRAPATHS` variable from within your append file.
7148
7149   :term:`SRC_URI_OVERRIDES_PACKAGE_ARCH`
7150      By default, the OpenEmbedded build system automatically detects
7151      whether :term:`SRC_URI` contains files that are machine-specific. If so,
7152      the build system automatically changes :term:`PACKAGE_ARCH`. Setting this
7153      variable to "0" disables this behavior.
7154
7155   :term:`SRCDATE`
7156      The date of the source code used to build the package. This variable
7157      applies only if the source was fetched from a Source Code Manager
7158      (SCM).
7159
7160   :term:`SRCPV`
7161      Returns the version string of the current package. This string is
7162      used to help define the value of :term:`PV`.
7163
7164      The :term:`SRCPV` variable is defined in the ``meta/conf/bitbake.conf``
7165      configuration file in the :term:`Source Directory` as
7166      follows::
7167
7168         SRCPV = "${@bb.fetch2.get_srcrev(d)}"
7169
7170      Recipes that need to define :term:`PV` do so with the help of the
7171      :term:`SRCPV`. For example, the ``ofono`` recipe (``ofono_git.bb``)
7172      located in ``meta/recipes-connectivity`` in the Source Directory
7173      defines :term:`PV` as follows::
7174
7175         PV = "0.12-git${SRCPV}"
7176
7177   :term:`SRCREV`
7178      The revision of the source code used to build the package. This
7179      variable applies to Subversion, Git, Mercurial, and Bazaar only. Note
7180      that if you want to build a fixed revision and you want to avoid
7181      performing a query on the remote repository every time BitBake parses
7182      your recipe, you should specify a :term:`SRCREV` that is a full revision
7183      identifier and not just a tag.
7184
7185      .. note::
7186
7187         For information on limitations when inheriting the latest revision
7188         of software using :term:`SRCREV`, see the :term:`AUTOREV` variable
7189         description and the
7190         ":ref:`dev-manual/common-tasks:automatically incrementing a package version number`"
7191         section, which is in the Yocto Project Development Tasks Manual.
7192
7193   :term:`SRCTREECOVEREDTASKS`
7194      A list of tasks that are typically not relevant (and therefore skipped)
7195      when building using the :ref:`externalsrc <ref-classes-externalsrc>`
7196      class. The default value as set in that class file is the set of tasks
7197      that are rarely needed when using external source::
7198
7199         SRCTREECOVEREDTASKS ?= "do_patch do_unpack do_fetch"
7200
7201      The notable exception is when processing external kernel source as
7202      defined in the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
7203      class file (formatted for aesthetics)::
7204
7205         SRCTREECOVEREDTASKS += "\
7206           do_validate_branches \
7207           do_kernel_configcheck \
7208           do_kernel_checkout \
7209           do_fetch \
7210           do_unpack \
7211           do_patch \
7212         "
7213
7214      See the associated :term:`EXTERNALSRC` and :term:`EXTERNALSRC_BUILD`
7215      variables for more information.
7216
7217   :term:`SSTATE_DIR`
7218      The directory for the shared state cache.
7219
7220   :term:`SSTATE_MIRROR_ALLOW_NETWORK`
7221      If set to "1", allows fetches from mirrors that are specified in
7222      :term:`SSTATE_MIRRORS` to work even when
7223      fetching from the network is disabled by setting :term:`BB_NO_NETWORK` to
7224      "1". Using the :term:`SSTATE_MIRROR_ALLOW_NETWORK` variable is useful if
7225      you have set :term:`SSTATE_MIRRORS` to point to an internal server for
7226      your shared state cache, but you want to disable any other fetching
7227      from the network.
7228
7229   :term:`SSTATE_MIRRORS`
7230      Configures the OpenEmbedded build system to search other mirror
7231      locations for prebuilt cache data objects before building out the
7232      data. This variable works like fetcher :term:`MIRRORS`
7233      and :term:`PREMIRRORS` and points to the cache
7234      locations to check for the shared state (sstate) objects.
7235
7236      You can specify a filesystem directory or a remote URL such as HTTP
7237      or FTP. The locations you specify need to contain the shared state
7238      cache (sstate-cache) results from previous builds. The sstate-cache
7239      you point to can also be from builds on other machines.
7240
7241      When pointing to sstate build artifacts on another machine that uses
7242      a different GCC version for native builds, you must configure
7243      :term:`SSTATE_MIRRORS` with a regular expression that maps local search
7244      paths to server paths. The paths need to take into account
7245      :term:`NATIVELSBSTRING` set by the
7246      :ref:`uninative <ref-classes-uninative>` class. For example, the
7247      following maps the local search path ``universal-4.9`` to the
7248      server-provided path server_url_sstate_path::
7249
7250         SSTATE_MIRRORS ?= "file://universal-4.9/(.*) https://server_url_sstate_path/universal-4.8/\1"
7251
7252      If a mirror uses the same structure as
7253      :term:`SSTATE_DIR`, you need to add "PATH" at the
7254      end as shown in the examples below. The build system substitutes the
7255      correct path within the directory structure.
7256      ::
7257
7258         SSTATE_MIRRORS ?= "\
7259             file://.* https://someserver.tld/share/sstate/PATH;downloadfilename=PATH \
7260             file://.* file:///some-local-dir/sstate/PATH"
7261
7262   :term:`SSTATE_SCAN_FILES`
7263      Controls the list of files the OpenEmbedded build system scans for
7264      hardcoded installation paths. The variable uses a space-separated
7265      list of filenames (not paths) with standard wildcard characters
7266      allowed.
7267
7268      During a build, the OpenEmbedded build system creates a shared state
7269      (sstate) object during the first stage of preparing the sysroots.
7270      That object is scanned for hardcoded paths for original installation
7271      locations. The list of files that are scanned for paths is controlled
7272      by the :term:`SSTATE_SCAN_FILES` variable. Typically, recipes add files
7273      they want to be scanned to the value of :term:`SSTATE_SCAN_FILES` rather
7274      than the variable being comprehensively set. The
7275      :ref:`sstate <ref-classes-sstate>` class specifies the default list
7276      of files.
7277
7278      For details on the process, see the
7279      :ref:`staging <ref-classes-staging>` class.
7280
7281   :term:`STAGING_BASE_LIBDIR_NATIVE`
7282      Specifies the path to the ``/lib`` subdirectory of the sysroot
7283      directory for the build host.
7284
7285   :term:`STAGING_BASELIBDIR`
7286      Specifies the path to the ``/lib`` subdirectory of the sysroot
7287      directory for the target for which the current recipe is being built
7288      (:term:`STAGING_DIR_HOST`).
7289
7290   :term:`STAGING_BINDIR`
7291      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7292      directory for the target for which the current recipe is being built
7293      (:term:`STAGING_DIR_HOST`).
7294
7295   :term:`STAGING_BINDIR_CROSS`
7296      Specifies the path to the directory containing binary configuration
7297      scripts. These scripts provide configuration information for other
7298      software that wants to make use of libraries or include files
7299      provided by the software associated with the script.
7300
7301      .. note::
7302
7303         This style of build configuration has been largely replaced by
7304         ``pkg-config``. Consequently, if ``pkg-config`` is supported by the
7305         library to which you are linking, it is recommended you use
7306         ``pkg-config`` instead of a provided configuration script.
7307
7308   :term:`STAGING_BINDIR_NATIVE`
7309      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7310      directory for the build host.
7311
7312   :term:`STAGING_DATADIR`
7313      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7314      directory for the target for which the current recipe is being built
7315      (:term:`STAGING_DIR_HOST`).
7316
7317   :term:`STAGING_DATADIR_NATIVE`
7318      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7319      directory for the build host.
7320
7321   :term:`STAGING_DIR`
7322      Helps construct the ``recipe-sysroots`` directory, which is used
7323      during packaging.
7324
7325      For information on how staging for recipe-specific sysroots occurs,
7326      see the :ref:`ref-tasks-populate_sysroot`
7327      task, the ":ref:`sdk-manual/extensible:sharing files between recipes`"
7328      section in the Yocto Project Development Tasks Manual, the
7329      ":ref:`overview-manual/concepts:configuration, compilation, and staging`"
7330      section in the Yocto Project Overview and Concepts Manual, and the
7331      :term:`SYSROOT_DIRS` variable.
7332
7333      .. note::
7334
7335         Recipes should never write files directly under the :term:`STAGING_DIR`
7336         directory because the OpenEmbedded build system manages the
7337         directory automatically. Instead, files should be installed to
7338         ``${``\ :term:`D`\ ``}`` within your recipe's :ref:`ref-tasks-install`
7339         task and then the OpenEmbedded build system will stage a subset of
7340         those files into the sysroot.
7341
7342   :term:`STAGING_DIR_HOST`
7343      Specifies the path to the sysroot directory for the system on which
7344      the component is built to run (the system that hosts the component).
7345      For most recipes, this sysroot is the one in which that recipe's
7346      :ref:`ref-tasks-populate_sysroot` task copies
7347      files. Exceptions include ``-native`` recipes, where the
7348      ``do_populate_sysroot`` task instead uses
7349      :term:`STAGING_DIR_NATIVE`. Depending on
7350      the type of recipe and the build target, :term:`STAGING_DIR_HOST` can
7351      have the following values:
7352
7353      -  For recipes building for the target machine, the value is
7354         "${:term:`STAGING_DIR`}/${:term:`MACHINE`}".
7355
7356      -  For native recipes building for the build host, the value is empty
7357         given the assumption that when building for the build host, the
7358         build host's own directories should be used.
7359
7360         .. note::
7361
7362            ``-native`` recipes are not installed into host paths like such
7363            as ``/usr``. Rather, these recipes are installed into
7364            :term:`STAGING_DIR_NATIVE`. When compiling ``-native`` recipes,
7365            standard build environment variables such as
7366            :term:`CPPFLAGS` and
7367            :term:`CFLAGS` are set up so that both host paths
7368            and :term:`STAGING_DIR_NATIVE` are searched for libraries and
7369            headers using, for example, GCC's ``-isystem`` option.
7370
7371            Thus, the emphasis is that the ``STAGING_DIR*`` variables
7372            should be viewed as input variables by tasks such as
7373            :ref:`ref-tasks-configure`,
7374            :ref:`ref-tasks-compile`, and
7375            :ref:`ref-tasks-install`. Having the real system
7376            root correspond to :term:`STAGING_DIR_HOST` makes conceptual sense
7377            for ``-native`` recipes, as they make use of host headers and
7378            libraries.
7379
7380   :term:`STAGING_DIR_NATIVE`
7381      Specifies the path to the sysroot directory used when building
7382      components that run on the build host itself.
7383
7384   :term:`STAGING_DIR_TARGET`
7385      Specifies the path to the sysroot used for the system for which the
7386      component generates code. For components that do not generate code,
7387      which is the majority, :term:`STAGING_DIR_TARGET` is set to match
7388      :term:`STAGING_DIR_HOST`.
7389
7390      Some recipes build binaries that can run on the target system but
7391      those binaries in turn generate code for another different system
7392      (e.g. cross-canadian recipes). Using terminology from GNU, the
7393      primary system is referred to as the "HOST" and the secondary, or
7394      different, system is referred to as the "TARGET". Thus, the binaries
7395      run on the "HOST" system and generate binaries for the "TARGET"
7396      system. The :term:`STAGING_DIR_HOST` variable points to the sysroot used
7397      for the "HOST" system, while :term:`STAGING_DIR_TARGET` points to the
7398      sysroot used for the "TARGET" system.
7399
7400   :term:`STAGING_ETCDIR_NATIVE`
7401      Specifies the path to the ``/etc`` subdirectory of the sysroot
7402      directory for the build host.
7403
7404   :term:`STAGING_EXECPREFIXDIR`
7405      Specifies the path to the ``/usr`` subdirectory of the sysroot
7406      directory for the target for which the current recipe is being built
7407      (:term:`STAGING_DIR_HOST`).
7408
7409   :term:`STAGING_INCDIR`
7410      Specifies the path to the ``/usr/include`` subdirectory of the
7411      sysroot directory for the target for which the current recipe being
7412      built (:term:`STAGING_DIR_HOST`).
7413
7414   :term:`STAGING_INCDIR_NATIVE`
7415      Specifies the path to the ``/usr/include`` subdirectory of the
7416      sysroot directory for the build host.
7417
7418   :term:`STAGING_KERNEL_BUILDDIR`
7419      Points to the directory containing the kernel build artifacts.
7420      Recipes building software that needs to access kernel build artifacts
7421      (e.g. ``systemtap-uprobes``) can look in the directory specified with
7422      the :term:`STAGING_KERNEL_BUILDDIR` variable to find these artifacts
7423      after the kernel has been built.
7424
7425   :term:`STAGING_KERNEL_DIR`
7426      The directory with kernel headers that are required to build
7427      out-of-tree modules.
7428
7429   :term:`STAGING_LIBDIR`
7430      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
7431      directory for the target for which the current recipe is being built
7432      (:term:`STAGING_DIR_HOST`).
7433
7434   :term:`STAGING_LIBDIR_NATIVE`
7435      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
7436      directory for the build host.
7437
7438   :term:`STAMP`
7439      Specifies the base path used to create recipe stamp files. The path
7440      to an actual stamp file is constructed by evaluating this string and
7441      then appending additional information. Currently, the default
7442      assignment for :term:`STAMP` as set in the ``meta/conf/bitbake.conf``
7443      file is::
7444
7445         STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
7446
7447      For information on how BitBake uses stamp files to determine if a
7448      task should be rerun, see the
7449      ":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`"
7450      section in the Yocto Project Overview and Concepts Manual.
7451
7452      See :term:`STAMPS_DIR`,
7453      :term:`MULTIMACH_TARGET_SYS`,
7454      :term:`PN`, :term:`EXTENDPE`,
7455      :term:`PV`, and :term:`PR` for related variable
7456      information.
7457
7458   :term:`STAMPS_DIR`
7459      Specifies the base directory in which the OpenEmbedded build system
7460      places stamps. The default directory is ``${TMPDIR}/stamps``.
7461
7462   :term:`STRIP`
7463      The minimal command and arguments to run ``strip``, which is used to
7464      strip symbols.
7465
7466   :term:`SUMMARY`
7467      The short (72 characters or less) summary of the binary package for
7468      packaging systems such as ``opkg``, ``rpm``, or ``dpkg``. By default,
7469      :term:`SUMMARY` is used to define the
7470      :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
7471      not set in the recipe.
7472
7473   :term:`SVNDIR`
7474      The directory in which files checked out of a Subversion system are
7475      stored.
7476
7477   :term:`SYSLINUX_DEFAULT_CONSOLE`
7478      Specifies the kernel boot default console. If you want to use a
7479      console other than the default, set this variable in your recipe as
7480      follows where "X" is the console number you want to use::
7481
7482         SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
7483
7484      The :ref:`syslinux <ref-classes-syslinux>` class initially sets
7485      this variable to null but then checks for a value later.
7486
7487   :term:`SYSLINUX_OPTS`
7488      Lists additional options to add to the syslinux file. You need to set
7489      this variable in your recipe. If you want to list multiple options,
7490      separate the options with a semicolon character (``;``).
7491
7492      The :ref:`syslinux <ref-classes-syslinux>` class uses this variable
7493      to create a set of options.
7494
7495   :term:`SYSLINUX_SERIAL`
7496      Specifies the alternate serial port or turns it off. To turn off
7497      serial, set this variable to an empty string in your recipe. The
7498      variable's default value is set in the
7499      :ref:`syslinux <ref-classes-syslinux>` class as follows::
7500
7501         SYSLINUX_SERIAL ?= "0 115200"
7502
7503      The class checks for and uses the variable as needed.
7504
7505   :term:`SYSLINUX_SERIAL_TTY`
7506      Specifies the alternate console=tty... kernel boot argument. The
7507      variable's default value is set in the
7508      :ref:`syslinux <ref-classes-syslinux>` class as follows::
7509
7510         SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
7511
7512      The class checks for and uses the variable as needed.
7513
7514   :term:`SYSLINUX_SPLASH`
7515      An ``.LSS`` file used as the background for the VGA boot menu when
7516      you use the boot menu. You need to set this variable in your recipe.
7517
7518      The :ref:`syslinux <ref-classes-syslinux>` class checks for this
7519      variable and if found, the OpenEmbedded build system installs the
7520      splash screen.
7521
7522   :term:`SYSROOT_DESTDIR`
7523      Points to the temporary directory under the work directory (default
7524      "``${``\ :term:`WORKDIR`\ ``}/sysroot-destdir``")
7525      where the files populated into the sysroot are assembled during the
7526      :ref:`ref-tasks-populate_sysroot` task.
7527
7528   :term:`SYSROOT_DIRS`
7529      Directories that are staged into the sysroot by the
7530      :ref:`ref-tasks-populate_sysroot` task. By
7531      default, the following directories are staged::
7532
7533         SYSROOT_DIRS = " \
7534             ${includedir} \
7535             ${libdir} \
7536             ${base_libdir} \
7537             ${nonarch_base_libdir} \
7538             ${datadir} \
7539             /sysroot-only \
7540             "
7541
7542   :term:`SYSROOT_DIRS_IGNORE`
7543      Directories that are not staged into the sysroot by the
7544      :ref:`ref-tasks-populate_sysroot` task. You
7545      can use this variable to exclude certain subdirectories of
7546      directories listed in :term:`SYSROOT_DIRS` from
7547      staging. By default, the following directories are not staged::
7548
7549         SYSROOT_DIRS_IGNORE = " \
7550             ${mandir} \
7551             ${docdir} \
7552             ${infodir} \
7553             ${datadir}/X11/locale \
7554             ${datadir}/applications \
7555             ${datadir}/bash-completion \
7556             ${datadir}/fonts \
7557             ${datadir}/gtk-doc/html \
7558             ${datadir}/installed-tests \
7559             ${datadir}/locale \
7560             ${datadir}/pixmaps \
7561             ${datadir}/terminfo \
7562             ${libdir}/${BPN}/ptest \
7563             "
7564
7565   :term:`SYSROOT_DIRS_NATIVE`
7566      Extra directories staged into the sysroot by the
7567      :ref:`ref-tasks-populate_sysroot` task for
7568      ``-native`` recipes, in addition to those specified in
7569      :term:`SYSROOT_DIRS`. By default, the following
7570      extra directories are staged::
7571
7572         SYSROOT_DIRS_NATIVE = " \
7573             ${bindir} \
7574             ${sbindir} \
7575             ${base_bindir} \
7576             ${base_sbindir} \
7577             ${libexecdir} \
7578             ${sysconfdir} \
7579             ${localstatedir} \
7580             "
7581
7582      .. note::
7583
7584         Programs built by ``-native`` recipes run directly from the sysroot
7585         (:term:`STAGING_DIR_NATIVE`), which is why additional directories
7586         containing program executables and supporting files need to be staged.
7587
7588   :term:`SYSROOT_PREPROCESS_FUNCS`
7589      A list of functions to execute after files are staged into the
7590      sysroot. These functions are usually used to apply additional
7591      processing on the staged files, or to stage additional files.
7592
7593   :term:`SYSTEMD_AUTO_ENABLE`
7594      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7595      this variable specifies whether the specified service in
7596      :term:`SYSTEMD_SERVICE` should start
7597      automatically or not. By default, the service is enabled to
7598      automatically start at boot time. The default setting is in the
7599      :ref:`systemd <ref-classes-systemd>` class as follows::
7600
7601         SYSTEMD_AUTO_ENABLE ??= "enable"
7602
7603      You can disable the service by setting the variable to "disable".
7604
7605   :term:`SYSTEMD_BOOT_CFG`
7606      When :term:`EFI_PROVIDER` is set to
7607      "systemd-boot", the :term:`SYSTEMD_BOOT_CFG` variable specifies the
7608      configuration file that should be used. By default, the
7609      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7610      :term:`SYSTEMD_BOOT_CFG` as follows::
7611
7612         SYSTEMD_BOOT_CFG ?= "${:term:`S`}/loader.conf"
7613
7614      For information on Systemd-boot, see the `Systemd-boot
7615      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7616
7617   :term:`SYSTEMD_BOOT_ENTRIES`
7618      When :term:`EFI_PROVIDER` is set to
7619      "systemd-boot", the :term:`SYSTEMD_BOOT_ENTRIES` variable specifies a
7620      list of entry files (``*.conf``) to install that contain one boot
7621      entry per file. By default, the
7622      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7623      :term:`SYSTEMD_BOOT_ENTRIES` as follows::
7624
7625          SYSTEMD_BOOT_ENTRIES ?= ""
7626
7627      For information on Systemd-boot, see the `Systemd-boot
7628      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7629
7630   :term:`SYSTEMD_BOOT_TIMEOUT`
7631      When :term:`EFI_PROVIDER` is set to
7632      "systemd-boot", the :term:`SYSTEMD_BOOT_TIMEOUT` variable specifies the
7633      boot menu timeout in seconds. By default, the
7634      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7635      :term:`SYSTEMD_BOOT_TIMEOUT` as follows::
7636
7637         SYSTEMD_BOOT_TIMEOUT ?= "10"
7638
7639      For information on Systemd-boot, see the `Systemd-boot
7640      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7641
7642   :term:`SYSTEMD_PACKAGES`
7643      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7644      this variable locates the systemd unit files when they are not found
7645      in the main recipe's package. By default, the :term:`SYSTEMD_PACKAGES`
7646      variable is set such that the systemd unit files are assumed to
7647      reside in the recipes main package::
7648
7649         SYSTEMD_PACKAGES ?= "${PN}"
7650
7651      If these unit files are not in this recipe's main package, you need
7652      to use :term:`SYSTEMD_PACKAGES` to list the package or packages in which
7653      the build system can find the systemd unit files.
7654
7655   :term:`SYSTEMD_SERVICE`
7656      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7657      this variable specifies the systemd service name for a package.
7658
7659      When you specify this file in your recipe, use a package name
7660      override to indicate the package to which the value applies. Here is
7661      an example from the connman recipe::
7662
7663         SYSTEMD_SERVICE:${PN} = "connman.service"
7664
7665   :term:`SYSVINIT_ENABLED_GETTYS`
7666      When using
7667      :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,
7668      specifies a space-separated list of the virtual terminals that should
7669      run a `getty <https://en.wikipedia.org/wiki/Getty_%28Unix%29>`__
7670      (allowing login), assuming :term:`USE_VT` is not set to
7671      "0".
7672
7673      The default value for :term:`SYSVINIT_ENABLED_GETTYS` is "1" (i.e. only
7674      run a getty on the first virtual terminal).
7675
7676   :term:`T`
7677      This variable points to a directory were BitBake places temporary
7678      files, which consist mostly of task logs and scripts, when building a
7679      particular recipe. The variable is typically set as follows::
7680
7681         T = "${WORKDIR}/temp"
7682
7683      The :term:`WORKDIR` is the directory into which
7684      BitBake unpacks and builds the recipe. The default ``bitbake.conf``
7685      file sets this variable.
7686
7687      The :term:`T` variable is not to be confused with the
7688      :term:`TMPDIR` variable, which points to the root of
7689      the directory tree where BitBake places the output of an entire
7690      build.
7691
7692   :term:`TARGET_ARCH`
7693      The target machine's architecture. The OpenEmbedded build system
7694      supports many architectures. Here is an example list of architectures
7695      supported. This list is by no means complete as the architecture is
7696      configurable:
7697
7698      - arm
7699      - i586
7700      - x86_64
7701      - powerpc
7702      - powerpc64
7703      - mips
7704      - mipsel
7705
7706      For additional information on machine architectures, see the
7707      :term:`TUNE_ARCH` variable.
7708
7709   :term:`TARGET_AS_ARCH`
7710      Specifies architecture-specific assembler flags for the target
7711      system. :term:`TARGET_AS_ARCH` is initialized from
7712      :term:`TUNE_ASARGS` by default in the BitBake
7713      configuration file (``meta/conf/bitbake.conf``)::
7714
7715         TARGET_AS_ARCH = "${TUNE_ASARGS}"
7716
7717   :term:`TARGET_CC_ARCH`
7718      Specifies architecture-specific C compiler flags for the target
7719      system. :term:`TARGET_CC_ARCH` is initialized from
7720      :term:`TUNE_CCARGS` by default.
7721
7722      .. note::
7723
7724         It is a common workaround to append :term:`LDFLAGS` to
7725         :term:`TARGET_CC_ARCH` in recipes that build software for the target that
7726         would not otherwise respect the exported :term:`LDFLAGS` variable.
7727
7728   :term:`TARGET_CC_KERNEL_ARCH`
7729      This is a specific kernel compiler flag for a CPU or Application
7730      Binary Interface (ABI) tune. The flag is used rarely and only for
7731      cases where a userspace :term:`TUNE_CCARGS` is not
7732      compatible with the kernel compilation. The :term:`TARGET_CC_KERNEL_ARCH`
7733      variable allows the kernel (and associated modules) to use a
7734      different configuration. See the
7735      ``meta/conf/machine/include/arm/feature-arm-thumb.inc`` file in the
7736      :term:`Source Directory` for an example.
7737
7738   :term:`TARGET_CFLAGS`
7739      Specifies the flags to pass to the C compiler when building for the
7740      target. When building in the target context,
7741      :term:`CFLAGS` is set to the value of this variable by
7742      default.
7743
7744      Additionally, the SDK's environment setup script sets the :term:`CFLAGS`
7745      variable in the environment to the :term:`TARGET_CFLAGS` value so that
7746      executables built using the SDK also have the flags applied.
7747
7748   :term:`TARGET_CPPFLAGS`
7749      Specifies the flags to pass to the C pre-processor (i.e. to both the
7750      C and the C++ compilers) when building for the target. When building
7751      in the target context, :term:`CPPFLAGS` is set to the
7752      value of this variable by default.
7753
7754      Additionally, the SDK's environment setup script sets the
7755      :term:`CPPFLAGS` variable in the environment to the :term:`TARGET_CPPFLAGS`
7756      value so that executables built using the SDK also have the flags
7757      applied.
7758
7759   :term:`TARGET_CXXFLAGS`
7760      Specifies the flags to pass to the C++ compiler when building for the
7761      target. When building in the target context,
7762      :term:`CXXFLAGS` is set to the value of this variable
7763      by default.
7764
7765      Additionally, the SDK's environment setup script sets the
7766      :term:`CXXFLAGS` variable in the environment to the :term:`TARGET_CXXFLAGS`
7767      value so that executables built using the SDK also have the flags
7768      applied.
7769
7770   :term:`TARGET_FPU`
7771      Specifies the method for handling FPU code. For FPU-less targets,
7772      which include most ARM CPUs, the variable must be set to "soft". If
7773      not, the kernel emulation gets used, which results in a performance
7774      penalty.
7775
7776   :term:`TARGET_LD_ARCH`
7777      Specifies architecture-specific linker flags for the target system.
7778      :term:`TARGET_LD_ARCH` is initialized from
7779      :term:`TUNE_LDARGS` by default in the BitBake
7780      configuration file (``meta/conf/bitbake.conf``)::
7781
7782         TARGET_LD_ARCH = "${TUNE_LDARGS}"
7783
7784   :term:`TARGET_LDFLAGS`
7785      Specifies the flags to pass to the linker when building for the
7786      target. When building in the target context,
7787      :term:`LDFLAGS` is set to the value of this variable
7788      by default.
7789
7790      Additionally, the SDK's environment setup script sets the
7791      :term:`LDFLAGS` variable in the environment to the
7792      :term:`TARGET_LDFLAGS` value so that executables built using the SDK also
7793      have the flags applied.
7794
7795   :term:`TARGET_OS`
7796      Specifies the target's operating system. The variable can be set to
7797      "linux" for glibc-based systems (GNU C Library) and to "linux-musl"
7798      for musl libc. For ARM/EABI targets, the possible values are
7799      "linux-gnueabi" and "linux-musleabi".
7800
7801   :term:`TARGET_PREFIX`
7802      Specifies the prefix used for the toolchain binary target tools.
7803
7804      Depending on the type of recipe and the build target,
7805      :term:`TARGET_PREFIX` is set as follows:
7806
7807      -  For recipes building for the target machine, the value is
7808         "${:term:`TARGET_SYS`}-".
7809
7810      -  For native recipes, the build system sets the variable to the
7811         value of :term:`BUILD_PREFIX`.
7812
7813      -  For native SDK recipes (``nativesdk``), the build system sets the
7814         variable to the value of :term:`SDK_PREFIX`.
7815
7816   :term:`TARGET_SYS`
7817      Specifies the system, including the architecture and the operating
7818      system, for which the build is occurring in the context of the
7819      current recipe.
7820
7821      The OpenEmbedded build system automatically sets this variable based
7822      on :term:`TARGET_ARCH`,
7823      :term:`TARGET_VENDOR`, and
7824      :term:`TARGET_OS` variables.
7825
7826      .. note::
7827
7828         You do not need to set the :term:`TARGET_SYS` variable yourself.
7829
7830      Consider these two examples:
7831
7832      -  Given a native recipe on a 32-bit, x86 machine running Linux, the
7833         value is "i686-linux".
7834
7835      -  Given a recipe being built for a little-endian, MIPS target
7836         running Linux, the value might be "mipsel-linux".
7837
7838   :term:`TARGET_VENDOR`
7839      Specifies the name of the target vendor.
7840
7841   :term:`TCLIBC`
7842      Specifies the GNU standard C library (``libc``) variant to use during
7843      the build process.
7844
7845      You can select "glibc", "musl", "newlib", or "baremetal".
7846
7847   :term:`TCLIBCAPPEND`
7848      Specifies a suffix to be appended onto the
7849      :term:`TMPDIR` value. The suffix identifies the
7850      ``libc`` variant for building. When you are building for multiple
7851      variants with the same :term:`Build Directory`, this
7852      mechanism ensures that output for different ``libc`` variants is kept
7853      separate to avoid potential conflicts.
7854
7855      In the ``defaultsetup.conf`` file, the default value of
7856      :term:`TCLIBCAPPEND` is "-${TCLIBC}". However, distros such as poky,
7857      which normally only support one ``libc`` variant, set
7858      :term:`TCLIBCAPPEND` to "" in their distro configuration file resulting
7859      in no suffix being applied.
7860
7861   :term:`TCMODE`
7862      Specifies the toolchain selector. :term:`TCMODE` controls the
7863      characteristics of the generated packages and images by telling the
7864      OpenEmbedded build system which toolchain profile to use. By default,
7865      the OpenEmbedded build system builds its own internal toolchain. The
7866      variable's default value is "default", which uses that internal
7867      toolchain.
7868
7869      .. note::
7870
7871         If :term:`TCMODE` is set to a value other than "default", then it is your
7872         responsibility to ensure that the toolchain is compatible with the
7873         default toolchain. Using older or newer versions of these
7874         components might cause build problems. See the Release Notes for
7875         the Yocto Project release for the specific components with which
7876         the toolchain must be compatible. To access the Release Notes, go
7877         to the :yocto_home:`Downloads </software-overview/downloads>`
7878         page on the Yocto Project website and click on the "RELEASE
7879         INFORMATION" link for the appropriate release.
7880
7881      The :term:`TCMODE` variable is similar to :term:`TCLIBC`,
7882      which controls the variant of the GNU standard C library (``libc``)
7883      used during the build process: ``glibc`` or ``musl``.
7884
7885      With additional layers, it is possible to use a pre-compiled external
7886      toolchain. One example is the Sourcery G++ Toolchain. The support for
7887      this toolchain resides in the separate Mentor Graphics
7888      ``meta-sourcery`` layer at
7889      https://github.com/MentorEmbedded/meta-sourcery/.
7890
7891      The layer's ``README`` file contains information on how to use the
7892      Sourcery G++ Toolchain as an external toolchain. In summary, you must
7893      be sure to add the layer to your ``bblayers.conf`` file in front of
7894      the ``meta`` layer and then set the ``EXTERNAL_TOOLCHAIN`` variable
7895      in your ``local.conf`` file to the location in which you installed
7896      the toolchain.
7897
7898      The fundamentals used for this example apply to any external
7899      toolchain. You can use ``meta-sourcery`` as a template for adding
7900      support for other external toolchains.
7901
7902   :term:`TEST_EXPORT_DIR`
7903      The location the OpenEmbedded build system uses to export tests when
7904      the :term:`TEST_EXPORT_ONLY` variable is set
7905      to "1".
7906
7907      The :term:`TEST_EXPORT_DIR` variable defaults to
7908      ``"${TMPDIR}/testimage/${PN}"``.
7909
7910   :term:`TEST_EXPORT_ONLY`
7911      Specifies to export the tests only. Set this variable to "1" if you
7912      do not want to run the tests but you want them to be exported in a
7913      manner that you to run them outside of the build system.
7914
7915   :term:`TEST_LOG_DIR`
7916      Holds the SSH log and the boot log for QEMU machines. The
7917      :term:`TEST_LOG_DIR` variable defaults to ``"${WORKDIR}/testimage"``.
7918
7919      .. note::
7920
7921         Actual test results reside in the task log (``log.do_testimage``),
7922         which is in the ``${WORKDIR}/temp/`` directory.
7923
7924   :term:`TEST_POWERCONTROL_CMD`
7925      For automated hardware testing, specifies the command to use to
7926      control the power of the target machine under test. Typically, this
7927      command would point to a script that performs the appropriate action
7928      (e.g. interacting with a web-enabled power strip). The specified
7929      command should expect to receive as the last argument "off", "on" or
7930      "cycle" specifying to power off, on, or cycle (power off and then
7931      power on) the device, respectively.
7932
7933   :term:`TEST_POWERCONTROL_EXTRA_ARGS`
7934      For automated hardware testing, specifies additional arguments to
7935      pass through to the command specified in
7936      :term:`TEST_POWERCONTROL_CMD`. Setting
7937      :term:`TEST_POWERCONTROL_EXTRA_ARGS` is optional. You can use it if you
7938      wish, for example, to separate the machine-specific and
7939      non-machine-specific parts of the arguments.
7940
7941   :term:`TEST_QEMUBOOT_TIMEOUT`
7942      The time in seconds allowed for an image to boot before automated
7943      runtime tests begin to run against an image. The default timeout
7944      period to allow the boot process to reach the login prompt is 500
7945      seconds. You can specify a different value in the ``local.conf``
7946      file.
7947
7948      For more information on testing images, see the
7949      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
7950      section in the Yocto Project Development Tasks Manual.
7951
7952   :term:`TEST_SERIALCONTROL_CMD`
7953      For automated hardware testing, specifies the command to use to
7954      connect to the serial console of the target machine under test. This
7955      command simply needs to connect to the serial console and forward
7956      that connection to standard input and output as any normal terminal
7957      program does.
7958
7959      For example, to use the Picocom terminal program on serial device
7960      ``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows::
7961
7962         TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
7963
7964   :term:`TEST_SERIALCONTROL_EXTRA_ARGS`
7965      For automated hardware testing, specifies additional arguments to
7966      pass through to the command specified in
7967      :term:`TEST_SERIALCONTROL_CMD`. Setting
7968      :term:`TEST_SERIALCONTROL_EXTRA_ARGS` is optional. You can use it if you
7969      wish, for example, to separate the machine-specific and
7970      non-machine-specific parts of the command.
7971
7972   :term:`TEST_SERVER_IP`
7973      The IP address of the build machine (host machine). This IP address
7974      is usually automatically detected. However, if detection fails, this
7975      variable needs to be set to the IP address of the build machine (i.e.
7976      where the build is taking place).
7977
7978      .. note::
7979
7980         The :term:`TEST_SERVER_IP` variable is only used for a small number of
7981         tests such as the "dnf" test suite, which needs to download packages
7982         from ``WORKDIR/oe-rootfs-repo``.
7983
7984   :term:`TEST_SUITES`
7985      An ordered list of tests (modules) to run against an image when
7986      performing automated runtime testing.
7987
7988      The OpenEmbedded build system provides a core set of tests that can
7989      be used against images.
7990
7991      .. note::
7992
7993         Currently, there is only support for running these tests under
7994         QEMU.
7995
7996      Tests include ``ping``, ``ssh``, ``df`` among others. You can add
7997      your own tests to the list of tests by appending :term:`TEST_SUITES` as
7998      follows::
7999
8000         TEST_SUITES:append = " mytest"
8001
8002      Alternatively, you can
8003      provide the "auto" option to have all applicable tests run against
8004      the image.
8005      ::
8006
8007         TEST_SUITES:append = " auto"
8008
8009      Using this option causes the
8010      build system to automatically run tests that are applicable to the
8011      image. Tests that are not applicable are skipped.
8012
8013      The order in which tests are run is important. Tests that depend on
8014      another test must appear later in the list than the test on which
8015      they depend. For example, if you append the list of tests with two
8016      tests (``test_A`` and ``test_B``) where ``test_B`` is dependent on
8017      ``test_A``, then you must order the tests as follows::
8018
8019         TEST_SUITES = "test_A test_B"
8020
8021      For more information on testing images, see the
8022      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
8023      section in the Yocto Project Development Tasks Manual.
8024
8025   :term:`TEST_TARGET`
8026      Specifies the target controller to use when running tests against a
8027      test image. The default controller to use is "qemu"::
8028
8029         TEST_TARGET = "qemu"
8030
8031      A target controller is a class that defines how an image gets
8032      deployed on a target and how a target is started. A layer can extend
8033      the controllers by adding a module in the layer's
8034      ``/lib/oeqa/controllers`` directory and by inheriting the
8035      ``BaseTarget`` class, which is an abstract class that cannot be used
8036      as a value of :term:`TEST_TARGET`.
8037
8038      You can provide the following arguments with :term:`TEST_TARGET`:
8039
8040      -  *"qemu":* Boots a QEMU image and runs the tests. See the
8041         ":ref:`dev-manual/common-tasks:enabling runtime tests on qemu`" section
8042         in the Yocto Project Development Tasks Manual for more
8043         information.
8044
8045      -  *"simpleremote":* Runs the tests on target hardware that is
8046         already up and running. The hardware can be on the network or it
8047         can be a device running an image on QEMU. You must also set
8048         :term:`TEST_TARGET_IP` when you use
8049         "simpleremote".
8050
8051         .. note::
8052
8053            This argument is defined in
8054            ``meta/lib/oeqa/controllers/simpleremote.py``.
8055
8056      For information on running tests on hardware, see the
8057      ":ref:`dev-manual/common-tasks:enabling runtime tests on hardware`"
8058      section in the Yocto Project Development Tasks Manual.
8059
8060   :term:`TEST_TARGET_IP`
8061      The IP address of your hardware under test. The :term:`TEST_TARGET_IP`
8062      variable has no effect when :term:`TEST_TARGET` is
8063      set to "qemu".
8064
8065      When you specify the IP address, you can also include a port. Here is
8066      an example::
8067
8068         TEST_TARGET_IP = "192.168.1.4:2201"
8069
8070      Specifying a port is
8071      useful when SSH is started on a non-standard port or in cases when
8072      your hardware under test is behind a firewall or network that is not
8073      directly accessible from your host and you need to do port address
8074      translation.
8075
8076   :term:`TESTIMAGE_AUTO`
8077      Automatically runs the series of automated tests for images when an
8078      image is successfully built. Setting :term:`TESTIMAGE_AUTO` to "1" causes
8079      any image that successfully builds to automatically boot under QEMU.
8080      Using the variable also adds in dependencies so that any SDK for
8081      which testing is requested is automatically built first.
8082
8083      These tests are written in Python making use of the ``unittest``
8084      module, and the majority of them run commands on the target system
8085      over ``ssh``. You can set this variable to "1" in your ``local.conf``
8086      file in the :term:`Build Directory` to have the
8087      OpenEmbedded build system automatically run these tests after an
8088      image successfully builds:
8089
8090         TESTIMAGE_AUTO = "1"
8091
8092      For more information
8093      on enabling, running, and writing these tests, see the
8094      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
8095      section in the Yocto Project Development Tasks Manual and the
8096      ":ref:`ref-classes-testimage*`" section.
8097
8098   :term:`THISDIR`
8099      The directory in which the file BitBake is currently parsing is
8100      located. Do not manually set this variable.
8101
8102   :term:`TIME`
8103      The time the build was started. Times appear using the hour, minute,
8104      and second (HMS) format (e.g. "140159" for one minute and fifty-nine
8105      seconds past 1400 hours).
8106
8107   :term:`TMPDIR`
8108      This variable is the base directory the OpenEmbedded build system
8109      uses for all build output and intermediate files (other than the
8110      shared state cache). By default, the :term:`TMPDIR` variable points to
8111      ``tmp`` within the :term:`Build Directory`.
8112
8113      If you want to establish this directory in a location other than the
8114      default, you can uncomment and edit the following statement in the
8115      ``conf/local.conf`` file in the :term:`Source Directory`::
8116
8117         #TMPDIR = "${TOPDIR}/tmp"
8118
8119      An example use for this scenario is to set :term:`TMPDIR` to a local disk,
8120      which does not use NFS, while having the Build Directory use NFS.
8121
8122      The filesystem used by :term:`TMPDIR` must have standard filesystem
8123      semantics (i.e. mixed-case files are unique, POSIX file locking, and
8124      persistent inodes). Due to various issues with NFS and bugs in some
8125      implementations, NFS does not meet this minimum requirement.
8126      Consequently, :term:`TMPDIR` cannot be on NFS.
8127
8128   :term:`TOOLCHAIN_HOST_TASK`
8129      This variable lists packages the OpenEmbedded build system uses when
8130      building an SDK, which contains a cross-development environment. The
8131      packages specified by this variable are part of the toolchain set
8132      that runs on the :term:`SDKMACHINE`, and each
8133      package should usually have the prefix ``nativesdk-``. For example,
8134      consider the following command when building an SDK::
8135
8136         $ bitbake -c populate_sdk imagename
8137
8138      In this case, a default list of packages is
8139      set in this variable, but you can add additional packages to the
8140      list. See the
8141      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8142      in the Yocto Project Application Development and the Extensible
8143      Software Development Kit (eSDK) manual for more information.
8144
8145      For background information on cross-development toolchains in the
8146      Yocto Project development environment, see the
8147      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8148      section in the Yocto Project Overview and Concepts Manual. For
8149      information on setting up a cross-development environment, see the
8150      :doc:`/sdk-manual/index` manual.
8151
8152      Note that this variable applies to building an SDK, not an eSDK,
8153      in which case the term:`TOOLCHAIN_HOST_TASK_ESDK` setting should be
8154      used instead.
8155
8156   :term:`TOOLCHAIN_HOST_TASK_ESDK`
8157      This variable allows to extend what is installed in the host
8158      portion of an eSDK. This is similar to :term:`TOOLCHAIN_HOST_TASK`
8159      applying to SDKs.
8160
8161   :term:`TOOLCHAIN_OUTPUTNAME`
8162      This variable defines the name used for the toolchain output. The
8163      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class sets
8164      the :term:`TOOLCHAIN_OUTPUTNAME` variable as follows::
8165
8166         TOOLCHAIN_OUTPUTNAME ?= "${SDK_NAME}-toolchain-${SDK_VERSION}"
8167
8168      See
8169      the :term:`SDK_NAME` and
8170      :term:`SDK_VERSION` variables for additional
8171      information.
8172
8173   :term:`TOOLCHAIN_TARGET_TASK`
8174      This variable lists packages the OpenEmbedded build system uses when
8175      it creates the target part of an SDK (i.e. the part built for the
8176      target hardware), which includes libraries and headers. Use this
8177      variable to add individual packages to the part of the SDK that runs
8178      on the target. See the
8179      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8180      in the Yocto Project Application Development and the Extensible
8181      Software Development Kit (eSDK) manual for more information.
8182
8183      For background information on cross-development toolchains in the
8184      Yocto Project development environment, see the
8185      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8186      section in the Yocto Project Overview and Concepts Manual. For
8187      information on setting up a cross-development environment, see the
8188      :doc:`/sdk-manual/index` manual.
8189
8190   :term:`TRANSLATED_TARGET_ARCH`
8191      A sanitized version of :term:`TARGET_ARCH`. This
8192      variable is used where the architecture is needed in a value where
8193      underscores are not allowed, for example within package filenames. In
8194      this case, dash characters replace any underscore characters used in
8195      :term:`TARGET_ARCH`.
8196
8197      Do not edit this variable.
8198
8199   :term:`TUNE_ARCH`
8200      The GNU canonical architecture for a specific architecture (i.e.
8201      ``arm``, ``armeb``, ``mips``, ``mips64``, and so forth). BitBake uses
8202      this value to setup configuration.
8203
8204      :term:`TUNE_ARCH` definitions are specific to a given architecture. The
8205      definitions can be a single static definition, or can be dynamically
8206      adjusted. You can see details for a given CPU family by looking at
8207      the architecture's ``README`` file. For example, the
8208      ``meta/conf/machine/include/mips/README`` file in the
8209      :term:`Source Directory` provides information for
8210      :term:`TUNE_ARCH` specific to the ``mips`` architecture.
8211
8212      :term:`TUNE_ARCH` is tied closely to
8213      :term:`TARGET_ARCH`, which defines the target
8214      machine's architecture. The BitBake configuration file
8215      (``meta/conf/bitbake.conf``) sets :term:`TARGET_ARCH` as follows::
8216
8217         TARGET_ARCH = "${TUNE_ARCH}"
8218
8219      The following list, which is by no means complete since architectures
8220      are configurable, shows supported machine architectures:
8221
8222      - arm
8223      - i586
8224      - x86_64
8225      - powerpc
8226      - powerpc64
8227      - mips
8228      - mipsel
8229
8230   :term:`TUNE_ASARGS`
8231      Specifies architecture-specific assembler flags for the target
8232      system. The set of flags is based on the selected tune features.
8233      :term:`TUNE_ASARGS` is set using the tune include files, which are
8234      typically under ``meta/conf/machine/include/`` and are influenced
8235      through :term:`TUNE_FEATURES`. For example, the
8236      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8237      for the x86 architecture as follows::
8238
8239         TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
8240
8241      .. note::
8242
8243         Board Support Packages (BSPs) select the tune. The selected tune,
8244         in turn, affects the tune variables themselves (i.e. the tune can
8245         supply its own set of flags).
8246
8247   :term:`TUNE_CCARGS`
8248      Specifies architecture-specific C compiler flags for the target
8249      system. The set of flags is based on the selected tune features.
8250      :term:`TUNE_CCARGS` is set using the tune include files, which are
8251      typically under ``meta/conf/machine/include/`` and are influenced
8252      through :term:`TUNE_FEATURES`.
8253
8254      .. note::
8255
8256         Board Support Packages (BSPs) select the tune. The selected tune,
8257         in turn, affects the tune variables themselves (i.e. the tune can
8258         supply its own set of flags).
8259
8260   :term:`TUNE_FEATURES`
8261      Features used to "tune" a compiler for optimal use given a specific
8262      processor. The features are defined within the tune files and allow
8263      arguments (i.e. ``TUNE_*ARGS``) to be dynamically generated based on
8264      the features.
8265
8266      The OpenEmbedded build system verifies the features to be sure they
8267      are not conflicting and that they are supported.
8268
8269      The BitBake configuration file (``meta/conf/bitbake.conf``) defines
8270      :term:`TUNE_FEATURES` as follows::
8271
8272         TUNE_FEATURES ??= "${TUNE_FEATURES:tune-${DEFAULTTUNE}}"
8273
8274      See the :term:`DEFAULTTUNE` variable for more information.
8275
8276   :term:`TUNE_LDARGS`
8277      Specifies architecture-specific linker flags for the target system.
8278      The set of flags is based on the selected tune features.
8279      :term:`TUNE_LDARGS` is set using the tune include files, which are
8280      typically under ``meta/conf/machine/include/`` and are influenced
8281      through :term:`TUNE_FEATURES`. For example, the
8282      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8283      for the x86 architecture as follows::
8284
8285         TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
8286
8287      .. note::
8288
8289         Board Support Packages (BSPs) select the tune. The selected tune,
8290         in turn, affects the tune variables themselves (i.e. the tune can
8291         supply its own set of flags).
8292
8293   :term:`TUNE_PKGARCH`
8294      The package architecture understood by the packaging system to define
8295      the architecture, ABI, and tuning of output packages. The specific
8296      tune is defined using the "_tune" override as follows::
8297
8298         TUNE_PKGARCH:tune-tune = "tune"
8299
8300      These tune-specific package architectures are defined in the machine
8301      include files. Here is an example of the "core2-32" tuning as used in
8302      the ``meta/conf/machine/include/x86/tune-core2.inc`` file::
8303
8304         TUNE_PKGARCH:tune-core2-32 = "core2-32"
8305
8306   :term:`TUNECONFLICTS[feature]`
8307      Specifies CPU or Application Binary Interface (ABI) tuning features
8308      that conflict with feature.
8309
8310      Known tuning conflicts are specified in the machine include files in
8311      the :term:`Source Directory`. Here is an example from
8312      the ``meta/conf/machine/include/mips/arch-mips.inc`` include file
8313      that lists the "o32" and "n64" features as conflicting with the "n32"
8314      feature::
8315
8316         TUNECONFLICTS[n32] = "o32 n64"
8317
8318   :term:`TUNEVALID[feature]`
8319      Specifies a valid CPU or Application Binary Interface (ABI) tuning
8320      feature. The specified feature is stored as a flag. Valid features
8321      are specified in the machine include files (e.g.
8322      ``meta/conf/machine/include/arm/arch-arm.inc``). Here is an example
8323      from that file::
8324
8325         TUNEVALID[bigendian] = "Enable big-endian mode."
8326
8327      See the machine include files in the :term:`Source Directory`
8328      for these features.
8329
8330   :term:`UBOOT_CONFIG`
8331      Configures the :term:`UBOOT_MACHINE` and can
8332      also define :term:`IMAGE_FSTYPES` for individual
8333      cases.
8334
8335      Following is an example from the ``meta-fsl-arm`` layer. ::
8336
8337         UBOOT_CONFIG ??= "sd"
8338         UBOOT_CONFIG[sd] = "mx6qsabreauto_config,sdcard"
8339         UBOOT_CONFIG[eimnor] = "mx6qsabreauto_eimnor_config"
8340         UBOOT_CONFIG[nand] = "mx6qsabreauto_nand_config,ubifs"
8341         UBOOT_CONFIG[spinor] = "mx6qsabreauto_spinor_config"
8342
8343      In this example, "sd" is selected as the configuration of the possible four for the
8344      :term:`UBOOT_MACHINE`. The "sd" configuration defines
8345      "mx6qsabreauto_config" as the value for :term:`UBOOT_MACHINE`, while the
8346      "sdcard" specifies the :term:`IMAGE_FSTYPES` to use for the U-Boot image.
8347
8348      For more information on how the :term:`UBOOT_CONFIG` is handled, see the
8349      :ref:`uboot-config <ref-classes-uboot-config>`
8350      class.
8351
8352   :term:`UBOOT_DTB_LOADADDRESS`
8353      Specifies the load address for the dtb image used by U-Boot. During FIT
8354      image creation, the :term:`UBOOT_DTB_LOADADDRESS` variable is used in
8355      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify
8356      the load address to be used in
8357      creating the dtb sections of Image Tree Source for the FIT image.
8358
8359   :term:`UBOOT_DTBO_LOADADDRESS`
8360      Specifies the load address for the dtbo image used by U-Boot.  During FIT
8361      image creation, the :term:`UBOOT_DTBO_LOADADDRESS` variable is used in
8362      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the load address to be used in
8363      creating the dtbo sections of Image Tree Source for the FIT image.
8364
8365   :term:`UBOOT_ENTRYPOINT`
8366      Specifies the entry point for the U-Boot image. During U-Boot image
8367      creation, the :term:`UBOOT_ENTRYPOINT` variable is passed as a
8368      command-line parameter to the ``uboot-mkimage`` utility.
8369
8370   :term:`UBOOT_LOADADDRESS`
8371      Specifies the load address for the U-Boot image. During U-Boot image
8372      creation, the :term:`UBOOT_LOADADDRESS` variable is passed as a
8373      command-line parameter to the ``uboot-mkimage`` utility.
8374
8375   :term:`UBOOT_LOCALVERSION`
8376      Appends a string to the name of the local version of the U-Boot
8377      image. For example, assuming the version of the U-Boot image built
8378      was "2013.10", the full version string reported by U-Boot would be
8379      "2013.10-yocto" given the following statement::
8380
8381         UBOOT_LOCALVERSION = "-yocto"
8382
8383   :term:`UBOOT_MACHINE`
8384      Specifies the value passed on the ``make`` command line when building
8385      a U-Boot image. The value indicates the target platform
8386      configuration. You typically set this variable from the machine
8387      configuration file (i.e. ``conf/machine/machine_name.conf``).
8388
8389      Please see the "Selection of Processor Architecture and Board Type"
8390      section in the U-Boot README for valid values for this variable.
8391
8392   :term:`UBOOT_MAKE_TARGET`
8393      Specifies the target called in the ``Makefile``. The default target
8394      is "all".
8395
8396   :term:`UBOOT_MKIMAGE`
8397      Specifies the name of the mkimage command as used by the
8398      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to assemble
8399      the FIT image. This can be used to substitute an alternative command, wrapper
8400      script or function if desired. The default is "uboot-mkimage".
8401
8402   :term:`UBOOT_MKIMAGE_DTCOPTS`
8403      Options for the device tree compiler passed to mkimage '-D'
8404      feature while creating FIT image in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class.
8405      If :term:`UBOOT_MKIMAGE_DTCOPTS` is not set then kernel-fitimage will not
8406      pass the ``-D`` option to mkimage.
8407
8408   :term:`UBOOT_MKIMAGE_SIGN`
8409      Specifies the name of the mkimage command as used by the
8410      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to sign
8411      the FIT image after it has been assembled (if enabled). This can be used
8412      to substitute an alternative command, wrapper script or function if
8413      desired. The default is "${:term:`UBOOT_MKIMAGE`}".
8414
8415   :term:`UBOOT_MKIMAGE_SIGN_ARGS`
8416      Optionally specifies additional arguments for the
8417      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to pass to the
8418      mkimage command when signing the FIT image.
8419
8420   :term:`UBOOT_RD_ENTRYPOINT`
8421      Specifies the entrypoint for the RAM disk image.
8422      During FIT image creation, the
8423      :term:`UBOOT_RD_ENTRYPOINT` variable is used
8424      in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the
8425      entrypoint to be used in creating the Image Tree Source for
8426      the FIT image.
8427
8428   :term:`UBOOT_RD_LOADADDRESS`
8429      Specifies the load address for the RAM disk image.
8430      During FIT image creation, the
8431      :term:`UBOOT_RD_LOADADDRESS` variable is used
8432      in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the
8433      load address to be used in creating the Image Tree Source for
8434      the FIT image.
8435
8436   :term:`UBOOT_SIGN_ENABLE`
8437      Enable signing of FIT image. The default value is "0".
8438
8439   :term:`UBOOT_SIGN_KEYDIR`
8440      Location of the directory containing the RSA key and
8441      certificate used for signing FIT image.
8442
8443   :term:`UBOOT_SIGN_KEYNAME`
8444      The name of keys used for signing U-Boot FIT image stored in
8445      :term:`UBOOT_SIGN_KEYDIR` directory. For e.g. dev.key key and dev.crt
8446      certificate stored in :term:`UBOOT_SIGN_KEYDIR` directory will have
8447      :term:`UBOOT_SIGN_KEYNAME` set to "dev".
8448
8449   :term:`UBOOT_SUFFIX`
8450      Points to the generated U-Boot extension. For example, ``u-boot.sb``
8451      has a ``.sb`` extension.
8452
8453      The default U-Boot extension is ``.bin``
8454
8455   :term:`UBOOT_TARGET`
8456      Specifies the target used for building U-Boot. The target is passed
8457      directly as part of the "make" command (e.g. SPL and AIS). If you do
8458      not specifically set this variable, the OpenEmbedded build process
8459      passes and uses "all" for the target during the U-Boot building
8460      process.
8461
8462   :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`
8463      Specifies a list of options that, if reported by the configure script
8464      as being invalid, should not generate a warning during the
8465      :ref:`ref-tasks-configure` task. Normally, invalid
8466      configure options are simply not passed to the configure script (e.g.
8467      should be removed from :term:`EXTRA_OECONF` or
8468      :term:`PACKAGECONFIG_CONFARGS`).
8469      However, there are common options that are passed to all
8470      configure scripts at a class level, but might not be valid for some
8471      configure scripts. Therefore warnings about these options are useless.
8472      For these cases, the options are added to :term:`UNKNOWN_CONFIGURE_OPT_IGNORE`.
8473
8474      The configure arguments check that uses
8475      :term:`UNKNOWN_CONFIGURE_OPT_IGNORE` is part of the
8476      :ref:`insane <ref-classes-insane>` class and is only enabled if the
8477      recipe inherits the :ref:`autotools <ref-classes-autotools>` class.
8478
8479   :term:`UPDATERCPN`
8480      For recipes inheriting the
8481      :ref:`update-rc.d <ref-classes-update-rc.d>` class, :term:`UPDATERCPN`
8482      specifies the package that contains the initscript that is enabled.
8483
8484      The default value is "${PN}". Given that almost all recipes that
8485      install initscripts package them in the main package for the recipe,
8486      you rarely need to set this variable in individual recipes.
8487
8488   :term:`UPSTREAM_CHECK_COMMITS`
8489      You can perform a per-recipe check for what the latest upstream
8490      source code version is by calling ``devtool latest-version recipe``. If
8491      the recipe source code is provided from Git repositories, but
8492      releases are not identified by Git tags, set :term:`UPSTREAM_CHECK_COMMITS`
8493      to ``1`` in the recipe, and the OpenEmbedded build system
8494      will compare the latest commit with the one currently specified
8495      by the recipe (:term:`SRCREV`).
8496      ::
8497
8498         UPSTREAM_CHECK_COMMITS = "1"
8499
8500   :term:`UPSTREAM_CHECK_GITTAGREGEX`
8501      You can perform a per-recipe check for what the latest upstream
8502      source code version is by calling ``devtool latest-version recipe``. If
8503      the recipe source code is provided from Git repositories, the
8504      OpenEmbedded build system determines the latest upstream version by
8505      picking the latest tag from the list of all repository tags.
8506
8507      You can use the :term:`UPSTREAM_CHECK_GITTAGREGEX` variable to provide a
8508      regular expression to filter only the relevant tags should the
8509      default filter not work correctly.
8510      ::
8511
8512         UPSTREAM_CHECK_GITTAGREGEX = "git_tag_regex"
8513
8514   :term:`UPSTREAM_CHECK_REGEX`
8515      Use the :term:`UPSTREAM_CHECK_REGEX` variable to specify a different
8516      regular expression instead of the default one when the package
8517      checking system is parsing the page found using
8518      :term:`UPSTREAM_CHECK_URI`.
8519      ::
8520
8521         UPSTREAM_CHECK_REGEX = "package_regex"
8522
8523   :term:`UPSTREAM_CHECK_URI`
8524      You can perform a per-recipe check for what the latest upstream
8525      source code version is by calling ``devtool latest-version recipe``. If
8526      the source code is provided from tarballs, the latest version is
8527      determined by fetching the directory listing where the tarball is and
8528      attempting to find a later tarball. When this approach does not work,
8529      you can use :term:`UPSTREAM_CHECK_URI` to provide a different URI that
8530      contains the link to the latest tarball.
8531      ::
8532
8533         UPSTREAM_CHECK_URI = "recipe_url"
8534
8535   :term:`UPSTREAM_VERSION_UNKNOWN`
8536      You can perform a per-recipe check for what the latest upstream
8537      source code version is by calling ``devtool latest-version recipe``.
8538      If no combination of the :term:`UPSTREAM_CHECK_URI`, :term:`UPSTREAM_CHECK_REGEX`,
8539      :term:`UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
8540      the recipe allows to determine what the latest upstream version is,
8541      you can set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1`` in the recipe
8542      to acknowledge that the check cannot be performed.
8543      ::
8544
8545         UPSTREAM_VERSION_UNKNOWN = "1"
8546
8547   :term:`USE_DEVFS`
8548      Determines if ``devtmpfs`` is used for ``/dev`` population. The
8549      default value used for :term:`USE_DEVFS` is "1" when no value is
8550      specifically set. Typically, you would set :term:`USE_DEVFS` to "0" for a
8551      statically populated ``/dev`` directory.
8552
8553      See the ":ref:`dev-manual/common-tasks:selecting a device manager`" section in
8554      the Yocto Project Development Tasks Manual for information on how to
8555      use this variable.
8556
8557   :term:`USE_VT`
8558      When using
8559      :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,
8560      determines whether or not to run a
8561      `getty <https://en.wikipedia.org/wiki/Getty_%28Unix%29>`__ on any
8562      virtual terminals in order to enable logging in through those
8563      terminals.
8564
8565      The default value used for :term:`USE_VT` is "1" when no default value is
8566      specifically set. Typically, you would set :term:`USE_VT` to "0" in the
8567      machine configuration file for machines that do not have a graphical
8568      display attached and therefore do not need virtual terminal
8569      functionality.
8570
8571   :term:`USER_CLASSES`
8572      A list of classes to globally inherit. These classes are used by the
8573      OpenEmbedded build system to enable extra features.
8574
8575      The default list is set in your ``local.conf`` file::
8576
8577         USER_CLASSES ?= "buildstats"
8578
8579      For more information, see
8580      ``meta-poky/conf/local.conf.sample`` in the :term:`Source Directory`.
8581
8582   :term:`USERADD_ERROR_DYNAMIC`
8583      If set to ``error``, forces the OpenEmbedded build system to produce
8584      an error if the user identification (``uid``) and group
8585      identification (``gid``) values are not defined in any of the files
8586      listed in :term:`USERADD_UID_TABLES` and
8587      :term:`USERADD_GID_TABLES`. If set to
8588      ``warn``, a warning will be issued instead.
8589
8590      The default behavior for the build system is to dynamically apply
8591      ``uid`` and ``gid`` values. Consequently, the
8592      :term:`USERADD_ERROR_DYNAMIC` variable is by default not set. If you plan
8593      on using statically assigned ``gid`` and ``uid`` values, you should
8594      set the :term:`USERADD_ERROR_DYNAMIC` variable in your ``local.conf``
8595      file as follows::
8596
8597         USERADD_ERROR_DYNAMIC = "error"
8598
8599      Overriding the
8600      default behavior implies you are going to also take steps to set
8601      static ``uid`` and ``gid`` values through use of the
8602      :term:`USERADDEXTENSION`,
8603      :term:`USERADD_UID_TABLES`, and
8604      :term:`USERADD_GID_TABLES` variables.
8605
8606      .. note::
8607
8608         There is a difference in behavior between setting
8609         :term:`USERADD_ERROR_DYNAMIC` to ``error`` and setting it to ``warn``.
8610         When it is set to ``warn``, the build system will report a warning for
8611         every undefined ``uid`` and ``gid`` in any recipe. But when it is set
8612         to ``error``, it will only report errors for recipes that are actually
8613         built.
8614         This saves you from having to add static IDs for recipes that you
8615         know will never be built.
8616
8617   :term:`USERADD_GID_TABLES`
8618      Specifies a password file to use for obtaining static group
8619      identification (``gid``) values when the OpenEmbedded build system
8620      adds a group to the system during package installation.
8621
8622      When applying static group identification (``gid``) values, the
8623      OpenEmbedded build system looks in :term:`BBPATH` for a
8624      ``files/group`` file and then applies those ``uid`` values. Set the
8625      variable as follows in your ``local.conf`` file::
8626
8627
8628         USERADD_GID_TABLES = "files/group"
8629
8630      .. note::
8631
8632         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
8633         causes the build system to use static ``gid`` values.
8634
8635   :term:`USERADD_PACKAGES`
8636      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
8637      this variable specifies the individual packages within the recipe
8638      that require users and/or groups to be added.
8639
8640      You must set this variable if the recipe inherits the class. For
8641      example, the following enables adding a user for the main package in
8642      a recipe::
8643
8644         USERADD_PACKAGES = "${PN}"
8645
8646      .. note::
8647
8648         It follows that if you are going to use the :term:`USERADD_PACKAGES`
8649         variable, you need to set one or more of the :term:`USERADD_PARAM`,
8650         :term:`GROUPADD_PARAM`, or :term:`GROUPMEMS_PARAM` variables.
8651
8652   :term:`USERADD_PARAM`
8653      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
8654      this variable specifies for a package what parameters should pass to
8655      the ``useradd`` command if you add a user to the system when the
8656      package is installed.
8657
8658      Here is an example from the ``dbus`` recipe::
8659
8660         USERADD_PARAM:${PN} = "--system --home ${localstatedir}/lib/dbus \
8661                                --no-create-home --shell /bin/false \
8662                                --user-group messagebus"
8663
8664      For information on the
8665      standard Linux shell command ``useradd``, see
8666      https://linux.die.net/man/8/useradd.
8667
8668   :term:`USERADD_UID_TABLES`
8669      Specifies a password file to use for obtaining static user
8670      identification (``uid``) values when the OpenEmbedded build system
8671      adds a user to the system during package installation.
8672
8673      When applying static user identification (``uid``) values, the
8674      OpenEmbedded build system looks in :term:`BBPATH` for a
8675      ``files/passwd`` file and then applies those ``uid`` values. Set the
8676      variable as follows in your ``local.conf`` file::
8677
8678         USERADD_UID_TABLES = "files/passwd"
8679
8680      .. note::
8681
8682         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
8683         causes the build system to use static ``uid`` values.
8684
8685   :term:`USERADDEXTENSION`
8686      When set to "useradd-staticids", causes the OpenEmbedded build system
8687      to base all user and group additions on a static ``passwd`` and
8688      ``group`` files found in :term:`BBPATH`.
8689
8690      To use static user identification (``uid``) and group identification
8691      (``gid``) values, set the variable as follows in your ``local.conf``
8692      file: USERADDEXTENSION = "useradd-staticids"
8693
8694      .. note::
8695
8696         Setting this variable to use static ``uid`` and ``gid``
8697         values causes the OpenEmbedded build system to employ the
8698         :ref:`ref-classes-useradd` class.
8699
8700      If you use static ``uid`` and ``gid`` information, you must also
8701      specify the ``files/passwd`` and ``files/group`` files by setting the
8702      :term:`USERADD_UID_TABLES` and
8703      :term:`USERADD_GID_TABLES` variables.
8704      Additionally, you should also set the
8705      :term:`USERADD_ERROR_DYNAMIC` variable.
8706
8707   :term:`VOLATILE_LOG_DIR`
8708      Specifies the persistence of the target's ``/var/log`` directory,
8709      which is used to house postinstall target log files.
8710
8711      By default, :term:`VOLATILE_LOG_DIR` is set to "yes", which means the
8712      file is not persistent. You can override this setting by setting the
8713      variable to "no" to make the log directory persistent.
8714
8715   :term:`WARN_QA`
8716      Specifies the quality assurance checks whose failures are reported as
8717      warnings by the OpenEmbedded build system. You set this variable in
8718      your distribution configuration file. For a list of the checks you
8719      can control with this variable, see the
8720      ":ref:`ref-classes-insane`" section.
8721
8722   :term:`WKS_FILE`
8723      Specifies the location of the Wic kickstart file that is used by the
8724      OpenEmbedded build system to create a partitioned image
8725      (``image.wic``). For information on how to create a partitioned
8726      image, see the
8727      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
8728      section in the Yocto Project Development Tasks Manual. For details on
8729      the kickstart file format, see the ":doc:`/ref-manual/kickstart`" Chapter.
8730
8731   :term:`WKS_FILE_DEPENDS`
8732      When placed in the recipe that builds your image, this variable lists
8733      build-time dependencies. The :term:`WKS_FILE_DEPENDS` variable is only
8734      applicable when Wic images are active (i.e. when
8735      :term:`IMAGE_FSTYPES` contains entries related
8736      to Wic). If your recipe does not create Wic images, the variable has
8737      no effect.
8738
8739      The :term:`WKS_FILE_DEPENDS` variable is similar to the
8740      :term:`DEPENDS` variable. When you use the variable in
8741      your recipe that builds the Wic image, dependencies you list in the
8742      :term:`WKS_FILE_DEPENDS` variable are added to the :term:`DEPENDS` variable.
8743
8744      With the :term:`WKS_FILE_DEPENDS` variable, you have the possibility to
8745      specify a list of additional dependencies (e.g. native tools,
8746      bootloaders, and so forth), that are required to build Wic images.
8747      Following is an example::
8748
8749         WKS_FILE_DEPENDS = "some-native-tool"
8750
8751      In the
8752      previous example, some-native-tool would be replaced with an actual
8753      native tool on which the build would depend.
8754
8755   :term:`WORKDIR`
8756      The pathname of the work directory in which the OpenEmbedded build
8757      system builds a recipe. This directory is located within the
8758      :term:`TMPDIR` directory structure and is specific to
8759      the recipe being built and the system for which it is being built.
8760
8761      The :term:`WORKDIR` directory is defined as follows::
8762
8763         ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
8764
8765      The actual directory depends on several things:
8766
8767      -  :term:`TMPDIR`: The top-level build output directory
8768      -  :term:`MULTIMACH_TARGET_SYS`: The target system identifier
8769      -  :term:`PN`: The recipe name
8770      -  :term:`EXTENDPE`: The epoch - (if :term:`PE` is not specified, which
8771         is usually the case for most recipes, then `EXTENDPE` is blank)
8772      -  :term:`PV`: The recipe version
8773      -  :term:`PR`: The recipe revision
8774
8775      As an example, assume a Source Directory top-level folder name
8776      ``poky``, a default Build Directory at ``poky/build``, and a
8777      ``qemux86-poky-linux`` machine target system. Furthermore, suppose
8778      your recipe is named ``foo_1.3.0-r0.bb``. In this case, the work
8779      directory the build system uses to build the package would be as
8780      follows::
8781
8782         poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
8783
8784   :term:`XSERVER`
8785      Specifies the packages that should be installed to provide an X
8786      server and drivers for the current machine, assuming your image
8787      directly includes ``packagegroup-core-x11-xserver`` or, perhaps
8788      indirectly, includes "x11-base" in
8789      :term:`IMAGE_FEATURES`.
8790
8791      The default value of :term:`XSERVER`, if not specified in the machine
8792      configuration, is "xserver-xorg xf86-video-fbdev xf86-input-evdev".
8793
8794   :term:`XZ_THREADS`
8795      Specifies the number of parallel threads that should be used when
8796      using xz compression.
8797
8798      By default this scales with core count, but is never set less than 2
8799      to ensure that multi-threaded mode is always used so that the output
8800      file contents are deterministic. Builds will work with a value of 1
8801      but the output will differ compared to the output from the compression
8802      generated when more than one thread is used.
8803
8804      On systems where many tasks run in parallel, setting a limit to this
8805      can be helpful in controlling system resource usage.
8806
8807    :term:`XZ_MEMLIMIT`
8808      Specifies the maximum memory the xz compression should use as a percentage
8809      of system memory. If unconstrained the xz compressor can use large amounts of
8810      memory and become problematic with parallelism elsewhere in the build.
8811      "50%" has been found to be a good value.
8812
8813   :term:`ZSTD_THREADS`
8814      Specifies the number of parallel threads that should be used when
8815      using ZStandard compression.
8816
8817      By default this scales with core count, but is never set less than 2
8818      to ensure that multi-threaded mode is always used so that the output
8819      file contents are deterministic. Builds will work with a value of 1
8820      but the output will differ compared to the output from the compression
8821      generated when more than one thread is used.
8822
8823      On systems where many tasks run in parallel, setting a limit to this
8824      can be helpful in controlling system resource usage.
8825
8826