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+.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
+
+Writing a New Recipe
+********************
+
+Recipes (``.bb`` files) are fundamental components in the Yocto Project
+environment. Each software component built by the OpenEmbedded build
+system requires a recipe to define the component. This section describes
+how to create, write, and test a new recipe.
+
+.. note::
+
+   For information on variables that are useful for recipes and for
+   information about recipe naming issues, see the
+   ":ref:`ref-manual/varlocality:recipes`" section of the Yocto Project
+   Reference Manual.
+
+Overview
+========
+
+The following figure shows the basic process for creating a new recipe.
+The remainder of the section provides details for the steps.
+
+.. image:: figures/recipe-workflow.png
+   :align: center
+   :width: 50%
+
+Locate or Automatically Create a Base Recipe
+============================================
+
+You can always write a recipe from scratch. However, there are three choices
+that can help you quickly get started with a new recipe:
+
+-  ``devtool add``: A command that assists in creating a recipe and an
+   environment conducive to development.
+
+-  ``recipetool create``: A command provided by the Yocto Project that
+   automates creation of a base recipe based on the source files.
+
+-  *Existing Recipes:* Location and modification of an existing recipe
+   that is similar in function to the recipe you need.
+
+.. note::
+
+   For information on recipe syntax, see the
+   ":ref:`dev-manual/new-recipe:recipe syntax`" section.
+
+Creating the Base Recipe Using ``devtool add``
+----------------------------------------------
+
+The ``devtool add`` command uses the same logic for auto-creating the
+recipe as ``recipetool create``, which is listed below. Additionally,
+however, ``devtool add`` sets up an environment that makes it easy for
+you to patch the source and to make changes to the recipe as is often
+necessary when adding a recipe to build a new piece of software to be
+included in a build.
+
+You can find a complete description of the ``devtool add`` command in
+the ":ref:`sdk-manual/extensible:a closer look at \`\`devtool add\`\``" section
+in the Yocto Project Application Development and the Extensible Software
+Development Kit (eSDK) manual.
+
+Creating the Base Recipe Using ``recipetool create``
+----------------------------------------------------
+
+``recipetool create`` automates creation of a base recipe given a set of
+source code files. As long as you can extract or point to the source
+files, the tool will construct a recipe and automatically configure all
+pre-build information into the recipe. For example, suppose you have an
+application that builds using Autotools. Creating the base recipe using
+``recipetool`` results in a recipe that has the pre-build dependencies,
+license requirements, and checksums configured.
+
+To run the tool, you just need to be in your :term:`Build Directory` and
+have sourced the build environment setup script (i.e.
+:ref:`structure-core-script`). To get help on the tool, use the following
+command::
+
+   $ recipetool -h
+   NOTE: Starting bitbake server...
+   usage: recipetool [-d] [-q] [--color COLOR] [-h] <subcommand> ...
+
+   OpenEmbedded recipe tool
+
+   options:
+     -d, --debug     Enable debug output
+     -q, --quiet     Print only errors
+     --color COLOR   Colorize output (where COLOR is auto, always, never)
+     -h, --help      show this help message and exit
+
+   subcommands:
+     create          Create a new recipe
+     newappend       Create a bbappend for the specified target in the specified
+                       layer
+     setvar          Set a variable within a recipe
+     appendfile      Create/update a bbappend to replace a target file
+     appendsrcfiles  Create/update a bbappend to add or replace source files
+     appendsrcfile   Create/update a bbappend to add or replace a source file
+   Use recipetool <subcommand> --help to get help on a specific command
+
+Running ``recipetool create -o OUTFILE`` creates the base recipe and
+locates it properly in the layer that contains your source files.
+Here are some syntax examples:
+
+ - Use this syntax to generate a recipe based on source. Once generated,
+   the recipe resides in the existing source code layer::
+
+      recipetool create -o OUTFILE source
+
+ - Use this syntax to generate a recipe using code that
+   you extract from source. The extracted code is placed in its own layer
+   defined by :term:`EXTERNALSRC`::
+
+      recipetool create -o OUTFILE -x EXTERNALSRC source
+
+ - Use this syntax to generate a recipe based on source. The options
+   direct ``recipetool`` to generate debugging information. Once generated,
+   the recipe resides in the existing source code layer::
+
+      recipetool create -d -o OUTFILE source
+
+Locating and Using a Similar Recipe
+-----------------------------------
+
+Before writing a recipe from scratch, it is often useful to discover
+whether someone else has already written one that meets (or comes close
+to meeting) your needs. The Yocto Project and OpenEmbedded communities
+maintain many recipes that might be candidates for what you are doing.
+You can find a good central index of these recipes in the
+:oe_layerindex:`OpenEmbedded Layer Index <>`.
+
+Working from an existing recipe or a skeleton recipe is the best way to
+get started. Here are some points on both methods:
+
+-  *Locate and modify a recipe that is close to what you want to do:*
+   This method works when you are familiar with the current recipe
+   space. The method does not work so well for those new to the Yocto
+   Project or writing recipes.
+
+   Some risks associated with this method are using a recipe that has
+   areas totally unrelated to what you are trying to accomplish with
+   your recipe, not recognizing areas of the recipe that you might have
+   to add from scratch, and so forth. All these risks stem from
+   unfamiliarity with the existing recipe space.
+
+-  *Use and modify the following skeleton recipe:* If for some reason
+   you do not want to use ``recipetool`` and you cannot find an existing
+   recipe that is close to meeting your needs, you can use the following
+   structure to provide the fundamental areas of a new recipe::
+
+      DESCRIPTION = ""
+      HOMEPAGE = ""
+      LICENSE = ""
+      SECTION = ""
+      DEPENDS = ""
+      LIC_FILES_CHKSUM = ""
+
+      SRC_URI = ""
+
+Storing and Naming the Recipe
+=============================
+
+Once you have your base recipe, you should put it in your own layer and
+name it appropriately. Locating it correctly ensures that the
+OpenEmbedded build system can find it when you use BitBake to process
+the recipe.
+
+-  *Storing Your Recipe:* The OpenEmbedded build system locates your
+   recipe through the layer's ``conf/layer.conf`` file and the
+   :term:`BBFILES` variable. This
+   variable sets up a path from which the build system can locate
+   recipes. Here is the typical use::
+
+      BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
+                  ${LAYERDIR}/recipes-*/*/*.bbappend"
+
+   Consequently, you need to be sure you locate your new recipe inside
+   your layer such that it can be found.
+
+   You can find more information on how layers are structured in the
+   ":ref:`dev-manual/layers:understanding and creating layers`" section.
+
+-  *Naming Your Recipe:* When you name your recipe, you need to follow
+   this naming convention::
+
+      basename_version.bb
+
+   Use lower-cased characters and do not include the reserved suffixes
+   ``-native``, ``-cross``, ``-initial``, or ``-dev`` casually (i.e. do not use
+   them as part of your recipe name unless the string applies). Here are some
+   examples:
+
+   .. code-block:: none
+
+      cups_1.7.0.bb
+      gawk_4.0.2.bb
+      irssi_0.8.16-rc1.bb
+
+Running a Build on the Recipe
+=============================
+
+Creating a new recipe is usually an iterative process that requires
+using BitBake to process the recipe multiple times in order to
+progressively discover and add information to the recipe file.
+
+Assuming you have sourced the build environment setup script (i.e.
+:ref:`structure-core-script`) and you are in the :term:`Build Directory`, use
+BitBake to process your recipe. All you need to provide is the
+``basename`` of the recipe as described in the previous section::
+
+   $ bitbake basename
+
+During the build, the OpenEmbedded build system creates a temporary work
+directory for each recipe
+(``${``\ :term:`WORKDIR`\ ``}``)
+where it keeps extracted source files, log files, intermediate
+compilation and packaging files, and so forth.
+
+The path to the per-recipe temporary work directory depends on the
+context in which it is being built. The quickest way to find this path
+is to have BitBake return it by running the following::
+
+   $ bitbake -e basename | grep ^WORKDIR=
+
+As an example, assume a Source Directory
+top-level folder named ``poky``, a default :term:`Build Directory` at
+``poky/build``, and a ``qemux86-poky-linux`` machine target system.
+Furthermore, suppose your recipe is named ``foo_1.3.0.bb``. In this
+case, the work directory the build system uses to build the package
+would be as follows::
+
+   poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
+
+Inside this directory you can find sub-directories such as ``image``,
+``packages-split``, and ``temp``. After the build, you can examine these
+to determine how well the build went.
+
+.. note::
+
+   You can find log files for each task in the recipe's ``temp``
+   directory (e.g. ``poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0/temp``).
+   Log files are named ``log.taskname`` (e.g. ``log.do_configure``,
+   ``log.do_fetch``, and ``log.do_compile``).
+
+You can find more information about the build process in
+":doc:`/overview-manual/development-environment`"
+chapter of the Yocto Project Overview and Concepts Manual.
+
+Fetching Code
+=============
+
+The first thing your recipe must do is specify how to fetch the source
+files. Fetching is controlled mainly through the
+:term:`SRC_URI` variable. Your recipe
+must have a :term:`SRC_URI` variable that points to where the source is
+located. For a graphical representation of source locations, see the
+":ref:`overview-manual/concepts:sources`" section in
+the Yocto Project Overview and Concepts Manual.
+
+The :ref:`ref-tasks-fetch` task uses the prefix of each entry in the
+:term:`SRC_URI` variable value to determine which
+:ref:`fetcher <bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
+to use to get your source files. It is the :term:`SRC_URI` variable that triggers
+the fetcher. The :ref:`ref-tasks-patch` task uses the variable after source is
+fetched to apply patches. The OpenEmbedded build system uses
+:term:`FILESOVERRIDES` for scanning directory locations for local files in
+:term:`SRC_URI`.
+
+The :term:`SRC_URI` variable in your recipe must define each unique location
+for your source files. It is good practice to not hard-code version
+numbers in a URL used in :term:`SRC_URI`. Rather than hard-code these
+values, use ``${``\ :term:`PV`\ ``}``,
+which causes the fetch process to use the version specified in the
+recipe filename. Specifying the version in this manner means that
+upgrading the recipe to a future version is as simple as renaming the
+recipe to match the new version.
+
+Here is a simple example from the
+``meta/recipes-devtools/strace/strace_5.5.bb`` recipe where the source
+comes from a single tarball. Notice the use of the
+:term:`PV` variable::
+
+   SRC_URI = "https://strace.io/files/${PV}/strace-${PV}.tar.xz \
+
+Files mentioned in :term:`SRC_URI` whose names end in a typical archive
+extension (e.g. ``.tar``, ``.tar.gz``, ``.tar.bz2``, ``.zip``, and so
+forth), are automatically extracted during the
+:ref:`ref-tasks-unpack` task. For
+another example that specifies these types of files, see the
+":ref:`dev-manual/new-recipe:building an autotooled package`" section.
+
+Another way of specifying source is from an SCM. For Git repositories,
+you must specify :term:`SRCREV` and you should specify :term:`PV` to include
+the revision with :term:`SRCPV`. Here is an example from the recipe
+``meta/recipes-core/musl/gcompat_git.bb``::
+
+   SRC_URI = "git://git.adelielinux.org/adelie/gcompat.git;protocol=https;branch=current"
+
+   PV = "1.0.0+1.1+git${SRCPV}"
+   SRCREV = "af5a49e489fdc04b9cf02547650d7aeaccd43793"
+
+If your :term:`SRC_URI` statement includes URLs pointing to individual files
+fetched from a remote server other than a version control system,
+BitBake attempts to verify the files against checksums defined in your
+recipe to ensure they have not been tampered with or otherwise modified
+since the recipe was written. Multiple checksums are supported:
+``SRC_URI[md5sum]``, ``SRC_URI[sha1sum]``, ``SRC_URI[sha256sum]``.
+``SRC_URI[sha384sum]`` and ``SRC_URI[sha512sum]``, but only
+``SRC_URI[sha256sum]`` is commonly used.
+
+.. note::
+
+   ``SRC_URI[md5sum]`` used to also be commonly used, but it is deprecated
+   and should be replaced by ``SRC_URI[sha256sum]`` when updating existing
+   recipes.
+
+If your :term:`SRC_URI` variable points to more than a single URL (excluding
+SCM URLs), you need to provide the ``sha256`` checksum for each URL. For these
+cases, you provide a name for each URL as part of the :term:`SRC_URI` and then
+reference that name in the subsequent checksum statements. Here is an example
+combining lines from the files ``git.inc`` and ``git_2.24.1.bb``::
+
+   SRC_URI = "${KERNELORG_MIRROR}/software/scm/git/git-${PV}.tar.gz;name=tarball \
+              ${KERNELORG_MIRROR}/software/scm/git/git-manpages-${PV}.tar.gz;name=manpages"
+
+   SRC_URI[tarball.sha256sum] = "ad5334956301c86841eb1e5b1bb20884a6bad89a10a6762c958220c7cf64da02"
+   SRC_URI[manpages.sha256sum] = "9a7ae3a093bea39770eb96ca3e5b40bff7af0b9f6123f089d7821d0e5b8e1230"
+
+The proper value for the ``sha256`` checksum might be available together
+with other signatures on the download page for the upstream source (e.g.
+``md5``, ``sha1``, ``sha256``, ``GPG``, and so forth). Because the
+OpenEmbedded build system typically only deals with ``sha256sum``,
+you should verify all the signatures you find by hand.
+
+If no :term:`SRC_URI` checksums are specified when you attempt to build the
+recipe, or you provide an incorrect checksum, the build will produce an
+error for each missing or incorrect checksum. As part of the error
+message, the build system provides the checksum string corresponding to
+the fetched file. Once you have the correct checksums, you can copy and
+paste them into your recipe and then run the build again to continue.
+
+.. note::
+
+   As mentioned, if the upstream source provides signatures for
+   verifying the downloaded source code, you should verify those
+   manually before setting the checksum values in the recipe and
+   continuing with the build.
+
+This final example is a bit more complicated and is from the
+``meta/recipes-sato/rxvt-unicode/rxvt-unicode_9.20.bb`` recipe. The
+example's :term:`SRC_URI` statement identifies multiple files as the source
+files for the recipe: a tarball, a patch file, a desktop file, and an icon::
+
+   SRC_URI = "http://dist.schmorp.de/rxvt-unicode/Attic/rxvt-unicode-${PV}.tar.bz2 \
+              file://xwc.patch \
+              file://rxvt.desktop \
+              file://rxvt.png"
+
+When you specify local files using the ``file://`` URI protocol, the
+build system fetches files from the local machine. The path is relative
+to the :term:`FILESPATH` variable
+and searches specific directories in a certain order:
+``${``\ :term:`BP`\ ``}``,
+``${``\ :term:`BPN`\ ``}``, and
+``files``. The directories are assumed to be subdirectories of the
+directory in which the recipe or append file resides. For another
+example that specifies these types of files, see the
+"`building a single .c file package`_" section.
+
+The previous example also specifies a patch file. Patch files are files
+whose names usually end in ``.patch`` or ``.diff`` but can end with
+compressed suffixes such as ``diff.gz`` and ``patch.bz2``, for example.
+The build system automatically applies patches as described in the
+":ref:`dev-manual/new-recipe:patching code`" section.
+
+Fetching Code Through Firewalls
+-------------------------------
+
+Some users are behind firewalls and need to fetch code through a proxy.
+See the ":doc:`/ref-manual/faq`" chapter for advice.
+
+Limiting the Number of Parallel Connections
+-------------------------------------------
+
+Some users are behind firewalls or use servers where the number of parallel
+connections is limited. In such cases, you can limit the number of fetch
+tasks being run in parallel by adding the following to your ``local.conf``
+file::
+
+   do_fetch[number_threads] = "4"
+
+Unpacking Code
+==============
+
+During the build, the
+:ref:`ref-tasks-unpack` task unpacks
+the source with ``${``\ :term:`S`\ ``}``
+pointing to where it is unpacked.
+
+If you are fetching your source files from an upstream source archived
+tarball and the tarball's internal structure matches the common
+convention of a top-level subdirectory named
+``${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
+then you do not need to set :term:`S`. However, if :term:`SRC_URI` specifies to
+fetch source from an archive that does not use this convention, or from
+an SCM like Git or Subversion, your recipe needs to define :term:`S`.
+
+If processing your recipe using BitBake successfully unpacks the source
+files, you need to be sure that the directory pointed to by ``${S}``
+matches the structure of the source.
+
+Patching Code
+=============
+
+Sometimes it is necessary to patch code after it has been fetched. Any
+files mentioned in :term:`SRC_URI` whose names end in ``.patch`` or
+``.diff`` or compressed versions of these suffixes (e.g. ``diff.gz``,
+``patch.bz2``, etc.) are treated as patches. The
+:ref:`ref-tasks-patch` task
+automatically applies these patches.
+
+The build system should be able to apply patches with the "-p1" option
+(i.e. one directory level in the path will be stripped off). If your
+patch needs to have more directory levels stripped off, specify the
+number of levels using the "striplevel" option in the :term:`SRC_URI` entry
+for the patch. Alternatively, if your patch needs to be applied in a
+specific subdirectory that is not specified in the patch file, use the
+"patchdir" option in the entry.
+
+As with all local files referenced in
+:term:`SRC_URI` using ``file://``,
+you should place patch files in a directory next to the recipe either
+named the same as the base name of the recipe
+(:term:`BP` and
+:term:`BPN`) or "files".
+
+Licensing
+=========
+
+Your recipe needs to define variables related to the license
+under whith the software is distributed. See the
+:ref:`contributor-guide/recipe-style-guide:recipe license fields`
+section in the Contributor Guide for details.
+
+Dependencies
+============
+
+Most software packages have a short list of other packages that they
+require, which are called dependencies. These dependencies fall into two
+main categories: build-time dependencies, which are required when the
+software is built; and runtime dependencies, which are required to be
+installed on the target in order for the software to run.
+
+Within a recipe, you specify build-time dependencies using the
+:term:`DEPENDS` variable. Although there are nuances,
+items specified in :term:`DEPENDS` should be names of other
+recipes. It is important that you specify all build-time dependencies
+explicitly.
+
+Another consideration is that configure scripts might automatically
+check for optional dependencies and enable corresponding functionality
+if those dependencies are found. If you wish to make a recipe that is
+more generally useful (e.g. publish the recipe in a layer for others to
+use), instead of hard-disabling the functionality, you can use the
+:term:`PACKAGECONFIG` variable to allow functionality and the
+corresponding dependencies to be enabled and disabled easily by other
+users of the recipe.
+
+Similar to build-time dependencies, you specify runtime dependencies
+through a variable -
+:term:`RDEPENDS`, which is
+package-specific. All variables that are package-specific need to have
+the name of the package added to the end as an override. Since the main
+package for a recipe has the same name as the recipe, and the recipe's
+name can be found through the
+``${``\ :term:`PN`\ ``}`` variable, then
+you specify the dependencies for the main package by setting
+``RDEPENDS:${PN}``. If the package were named ``${PN}-tools``, then you
+would set ``RDEPENDS:${PN}-tools``, and so forth.
+
+Some runtime dependencies will be set automatically at packaging time.
+These dependencies include any shared library dependencies (i.e. if a
+package "example" contains "libexample" and another package "mypackage"
+contains a binary that links to "libexample" then the OpenEmbedded build
+system will automatically add a runtime dependency to "mypackage" on
+"example"). See the
+":ref:`overview-manual/concepts:automatically added runtime dependencies`"
+section in the Yocto Project Overview and Concepts Manual for further
+details.
+
+Configuring the Recipe
+======================
+
+Most software provides some means of setting build-time configuration
+options before compilation. Typically, setting these options is
+accomplished by running a configure script with options, or by modifying
+a build configuration file.
+
+.. note::
+
+   As of Yocto Project Release 1.7, some of the core recipes that
+   package binary configuration scripts now disable the scripts due to
+   the scripts previously requiring error-prone path substitution. The
+   OpenEmbedded build system uses ``pkg-config`` now, which is much more
+   robust. You can find a list of the ``*-config`` scripts that are disabled
+   in the ":ref:`migration-1.7-binary-configuration-scripts-disabled`" section
+   in the Yocto Project Reference Manual.
+
+A major part of build-time configuration is about checking for
+build-time dependencies and possibly enabling optional functionality as
+a result. You need to specify any build-time dependencies for the
+software you are building in your recipe's
+:term:`DEPENDS` value, in terms of
+other recipes that satisfy those dependencies. You can often find
+build-time or runtime dependencies described in the software's
+documentation.
+
+The following list provides configuration items of note based on how
+your software is built:
+
+-  *Autotools:* If your source files have a ``configure.ac`` file, then
+   your software is built using Autotools. If this is the case, you just
+   need to modify the configuration.
+
+   When using Autotools, your recipe needs to inherit the
+   :ref:`ref-classes-autotools` class and it does not have to
+   contain a :ref:`ref-tasks-configure` task. However, you might still want to
+   make some adjustments. For example, you can set :term:`EXTRA_OECONF` or
+   :term:`PACKAGECONFIG_CONFARGS` to pass any needed configure options that
+   are specific to the recipe.
+
+-  *CMake:* If your source files have a ``CMakeLists.txt`` file, then
+   your software is built using CMake. If this is the case, you just
+   need to modify the configuration.
+
+   When you use CMake, your recipe needs to inherit the
+   :ref:`ref-classes-cmake` class and it does not have to contain a
+   :ref:`ref-tasks-configure` task. You can make some adjustments by setting
+   :term:`EXTRA_OECMAKE` to pass any needed configure options that are
+   specific to the recipe.
+
+   .. note::
+
+      If you need to install one or more custom CMake toolchain files
+      that are supplied by the application you are building, install the
+      files to ``${D}${datadir}/cmake/Modules`` during :ref:`ref-tasks-install`.
+
+-  *Other:* If your source files do not have a ``configure.ac`` or
+   ``CMakeLists.txt`` file, then your software is built using some
+   method other than Autotools or CMake. If this is the case, you
+   normally need to provide a
+   :ref:`ref-tasks-configure` task
+   in your recipe unless, of course, there is nothing to configure.
+
+   Even if your software is not being built by Autotools or CMake, you
+   still might not need to deal with any configuration issues. You need
+   to determine if configuration is even a required step. You might need
+   to modify a Makefile or some configuration file used for the build to
+   specify necessary build options. Or, perhaps you might need to run a
+   provided, custom configure script with the appropriate options.
+
+   For the case involving a custom configure script, you would run
+   ``./configure --help`` and look for the options you need to set.
+
+Once configuration succeeds, it is always good practice to look at the
+``log.do_configure`` file to ensure that the appropriate options have
+been enabled and no additional build-time dependencies need to be added
+to :term:`DEPENDS`. For example, if the configure script reports that it
+found something not mentioned in :term:`DEPENDS`, or that it did not find
+something that it needed for some desired optional functionality, then
+you would need to add those to :term:`DEPENDS`. Looking at the log might
+also reveal items being checked for, enabled, or both that you do not
+want, or items not being found that are in :term:`DEPENDS`, in which case
+you would need to look at passing extra options to the configure script
+as needed. For reference information on configure options specific to
+the software you are building, you can consult the output of the
+``./configure --help`` command within ``${S}`` or consult the software's
+upstream documentation.
+
+Using Headers to Interface with Devices
+=======================================
+
+If your recipe builds an application that needs to communicate with some
+device or needs an API into a custom kernel, you will need to provide
+appropriate header files. Under no circumstances should you ever modify
+the existing
+``meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc`` file.
+These headers are used to build ``libc`` and must not be compromised
+with custom or machine-specific header information. If you customize
+``libc`` through modified headers all other applications that use
+``libc`` thus become affected.
+
+.. note::
+
+   Never copy and customize the ``libc`` header file (i.e.
+   ``meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc``).
+
+The correct way to interface to a device or custom kernel is to use a
+separate package that provides the additional headers for the driver or
+other unique interfaces. When doing so, your application also becomes
+responsible for creating a dependency on that specific provider.
+
+Consider the following:
+
+-  Never modify ``linux-libc-headers.inc``. Consider that file to be
+   part of the ``libc`` system, and not something you use to access the
+   kernel directly. You should access ``libc`` through specific ``libc``
+   calls.
+
+-  Applications that must talk directly to devices should either provide
+   necessary headers themselves, or establish a dependency on a special
+   headers package that is specific to that driver.
+
+For example, suppose you want to modify an existing header that adds I/O
+control or network support. If the modifications are used by a small
+number programs, providing a unique version of a header is easy and has
+little impact. When doing so, bear in mind the guidelines in the
+previous list.
+
+.. note::
+
+   If for some reason your changes need to modify the behavior of the ``libc``,
+   and subsequently all other applications on the system, use a ``.bbappend``
+   to modify the ``linux-kernel-headers.inc`` file. However, take care to not
+   make the changes machine specific.
+
+Consider a case where your kernel is older and you need an older
+``libc`` ABI. The headers installed by your recipe should still be a
+standard mainline kernel, not your own custom one.
+
+When you use custom kernel headers you need to get them from
+:term:`STAGING_KERNEL_DIR`,
+which is the directory with kernel headers that are required to build
+out-of-tree modules. Your recipe will also need the following::
+
+   do_configure[depends] += "virtual/kernel:do_shared_workdir"
+
+Compilation
+===========
+
+During a build, the :ref:`ref-tasks-compile` task happens after source is fetched,
+unpacked, and configured. If the recipe passes through :ref:`ref-tasks-compile`
+successfully, nothing needs to be done.
+
+However, if the compile step fails, you need to diagnose the failure.
+Here are some common issues that cause failures.
+
+.. note::
+
+   For cases where improper paths are detected for configuration files
+   or for when libraries/headers cannot be found, be sure you are using
+   the more robust ``pkg-config``. See the note in section
+   ":ref:`dev-manual/new-recipe:Configuring the Recipe`" for additional information.
+
+-  *Parallel build failures:* These failures manifest themselves as
+   intermittent errors, or errors reporting that a file or directory
+   that should be created by some other part of the build process could
+   not be found. This type of failure can occur even if, upon
+   inspection, the file or directory does exist after the build has
+   failed, because that part of the build process happened in the wrong
+   order.
+
+   To fix the problem, you need to either satisfy the missing dependency
+   in the Makefile or whatever script produced the Makefile, or (as a
+   workaround) set :term:`PARALLEL_MAKE` to an empty string::
+
+      PARALLEL_MAKE = ""
+
+   For information on parallel Makefile issues, see the
+   ":ref:`dev-manual/debugging:debugging parallel make races`" section.
+
+-  *Improper host path usage:* This failure applies to recipes building
+   for the target or ":ref:`ref-classes-nativesdk`" only. The
+   failure occurs when the compilation process uses improper headers,
+   libraries, or other files from the host system when cross-compiling for
+   the target.
+
+   To fix the problem, examine the ``log.do_compile`` file to identify
+   the host paths being used (e.g. ``/usr/include``, ``/usr/lib``, and
+   so forth) and then either add configure options, apply a patch, or do
+   both.
+
+-  *Failure to find required libraries/headers:* If a build-time
+   dependency is missing because it has not been declared in
+   :term:`DEPENDS`, or because the
+   dependency exists but the path used by the build process to find the
+   file is incorrect and the configure step did not detect it, the
+   compilation process could fail. For either of these failures, the
+   compilation process notes that files could not be found. In these
+   cases, you need to go back and add additional options to the
+   configure script as well as possibly add additional build-time
+   dependencies to :term:`DEPENDS`.
+
+   Occasionally, it is necessary to apply a patch to the source to
+   ensure the correct paths are used. If you need to specify paths to
+   find files staged into the sysroot from other recipes, use the
+   variables that the OpenEmbedded build system provides (e.g.
+   :term:`STAGING_BINDIR`, :term:`STAGING_INCDIR`, :term:`STAGING_DATADIR`, and so
+   forth).
+
+Installing
+==========
+
+During :ref:`ref-tasks-install`, the task copies the built files along with their
+hierarchy to locations that would mirror their locations on the target
+device. The installation process copies files from the
+``${``\ :term:`S`\ ``}``,
+``${``\ :term:`B`\ ``}``, and
+``${``\ :term:`WORKDIR`\ ``}``
+directories to the ``${``\ :term:`D`\ ``}``
+directory to create the structure as it should appear on the target
+system.
+
+How your software is built affects what you must do to be sure your
+software is installed correctly. The following list describes what you
+must do for installation depending on the type of build system used by
+the software being built:
+
+-  *Autotools and CMake:* If the software your recipe is building uses
+   Autotools or CMake, the OpenEmbedded build system understands how to
+   install the software. Consequently, you do not have to have a
+   :ref:`ref-tasks-install` task as part of your recipe. You just need to make
+   sure the install portion of the build completes with no issues.
+   However, if you wish to install additional files not already being
+   installed by ``make install``, you should do this using a
+   ``do_install:append`` function using the install command as described
+   in the "Manual" bulleted item later in this list.
+
+-  *Other (using* ``make install``\ *)*: You need to define a :ref:`ref-tasks-install`
+   function in your recipe. The function should call
+   ``oe_runmake install`` and will likely need to pass in the
+   destination directory as well. How you pass that path is dependent on
+   how the ``Makefile`` being run is written (e.g. ``DESTDIR=${D}``,
+   ``PREFIX=${D}``, ``INSTALLROOT=${D}``, and so forth).
+
+   For an example recipe using ``make install``, see the
+   ":ref:`dev-manual/new-recipe:building a makefile-based package`" section.
+
+-  *Manual:* You need to define a :ref:`ref-tasks-install` function in your
+   recipe. The function must first use ``install -d`` to create the
+   directories under
+   ``${``\ :term:`D`\ ``}``. Once the
+   directories exist, your function can use ``install`` to manually
+   install the built software into the directories.
+
+   You can find more information on ``install`` at
+   https://www.gnu.org/software/coreutils/manual/html_node/install-invocation.html.
+
+For the scenarios that do not use Autotools or CMake, you need to track
+the installation and diagnose and fix any issues until everything
+installs correctly. You need to look in the default location of
+``${D}``, which is ``${WORKDIR}/image``, to be sure your files have been
+installed correctly.
+
+.. note::
+
+   -  During the installation process, you might need to modify some of
+      the installed files to suit the target layout. For example, you
+      might need to replace hard-coded paths in an initscript with
+      values of variables provided by the build system, such as
+      replacing ``/usr/bin/`` with ``${bindir}``. If you do perform such
+      modifications during :ref:`ref-tasks-install`, be sure to modify the
+      destination file after copying rather than before copying.
+      Modifying after copying ensures that the build system can
+      re-execute :ref:`ref-tasks-install` if needed.
+
+   -  ``oe_runmake install``, which can be run directly or can be run
+      indirectly by the :ref:`ref-classes-autotools` and
+      :ref:`ref-classes-cmake` classes, runs ``make install`` in parallel.
+      Sometimes, a Makefile can have missing dependencies between targets that
+      can result in race conditions. If you experience intermittent failures
+      during :ref:`ref-tasks-install`, you might be able to work around them by
+      disabling parallel Makefile installs by adding the following to the
+      recipe::
+
+         PARALLEL_MAKEINST = ""
+
+      See :term:`PARALLEL_MAKEINST` for additional information.
+
+   -  If you need to install one or more custom CMake toolchain files
+      that are supplied by the application you are building, install the
+      files to ``${D}${datadir}/cmake/Modules`` during
+      :ref:`ref-tasks-install`.
+
+Enabling System Services
+========================
+
+If you want to install a service, which is a process that usually starts
+on boot and runs in the background, then you must include some
+additional definitions in your recipe.
+
+If you are adding services and the service initialization script or the
+service file itself is not installed, you must provide for that
+installation in your recipe using a ``do_install:append`` function. If
+your recipe already has a :ref:`ref-tasks-install` function, update the function
+near its end rather than adding an additional ``do_install:append``
+function.
+
+When you create the installation for your services, you need to
+accomplish what is normally done by ``make install``. In other words,
+make sure your installation arranges the output similar to how it is
+arranged on the target system.
+
+The OpenEmbedded build system provides support for starting services two
+different ways:
+
+-  *SysVinit:* SysVinit is a system and service manager that manages the
+   init system used to control the very basic functions of your system.
+   The init program is the first program started by the Linux kernel
+   when the system boots. Init then controls the startup, running and
+   shutdown of all other programs.
+
+   To enable a service using SysVinit, your recipe needs to inherit the
+   :ref:`ref-classes-update-rc.d` class. The class helps
+   facilitate safely installing the package on the target.
+
+   You will need to set the
+   :term:`INITSCRIPT_PACKAGES`,
+   :term:`INITSCRIPT_NAME`,
+   and
+   :term:`INITSCRIPT_PARAMS`
+   variables within your recipe.
+
+-  *systemd:* System Management Daemon (systemd) was designed to replace
+   SysVinit and to provide enhanced management of services. For more
+   information on systemd, see the systemd homepage at
+   https://freedesktop.org/wiki/Software/systemd/.
+
+   To enable a service using systemd, your recipe needs to inherit the
+   :ref:`ref-classes-systemd` class. See the ``systemd.bbclass`` file
+   located in your :term:`Source Directory` section for more information.
+
+Packaging
+=========
+
+Successful packaging is a combination of automated processes performed
+by the OpenEmbedded build system and some specific steps you need to
+take. The following list describes the process:
+
+-  *Splitting Files*: The :ref:`ref-tasks-package` task splits the files produced
+   by the recipe into logical components. Even software that produces a
+   single binary might still have debug symbols, documentation, and
+   other logical components that should be split out. The :ref:`ref-tasks-package`
+   task ensures that files are split up and packaged correctly.
+
+-  *Running QA Checks*: The :ref:`ref-classes-insane` class adds a
+   step to the package generation process so that output quality
+   assurance checks are generated by the OpenEmbedded build system. This
+   step performs a range of checks to be sure the build's output is free
+   of common problems that show up during runtime. For information on
+   these checks, see the :ref:`ref-classes-insane` class and
+   the ":ref:`ref-manual/qa-checks:qa error and warning messages`"
+   chapter in the Yocto Project Reference Manual.
+
+-  *Hand-Checking Your Packages*: After you build your software, you
+   need to be sure your packages are correct. Examine the
+   ``${``\ :term:`WORKDIR`\ ``}/packages-split``
+   directory and make sure files are where you expect them to be. If you
+   discover problems, you can set
+   :term:`PACKAGES`,
+   :term:`FILES`,
+   ``do_install(:append)``, and so forth as needed.
+
+-  *Splitting an Application into Multiple Packages*: If you need to
+   split an application into several packages, see the
+   ":ref:`dev-manual/new-recipe:splitting an application into multiple packages`"
+   section for an example.
+
+-  *Installing a Post-Installation Script*: For an example showing how
+   to install a post-installation script, see the
+   ":ref:`dev-manual/new-recipe:post-installation scripts`" section.
+
+-  *Marking Package Architecture*: Depending on what your recipe is
+   building and how it is configured, it might be important to mark the
+   packages produced as being specific to a particular machine, or to
+   mark them as not being specific to a particular machine or
+   architecture at all.
+
+   By default, packages apply to any machine with the same architecture
+   as the target machine. When a recipe produces packages that are
+   machine-specific (e.g. the
+   :term:`MACHINE` value is passed
+   into the configure script or a patch is applied only for a particular
+   machine), you should mark them as such by adding the following to the
+   recipe::
+
+      PACKAGE_ARCH = "${MACHINE_ARCH}"
+
+   On the other hand, if the recipe produces packages that do not
+   contain anything specific to the target machine or architecture at
+   all (e.g. recipes that simply package script files or configuration
+   files), you should use the :ref:`ref-classes-allarch` class to
+   do this for you by adding this to your recipe::
+
+      inherit allarch
+
+   Ensuring that the package architecture is correct is not critical
+   while you are doing the first few builds of your recipe. However, it
+   is important in order to ensure that your recipe rebuilds (or does
+   not rebuild) appropriately in response to changes in configuration,
+   and to ensure that you get the appropriate packages installed on the
+   target machine, particularly if you run separate builds for more than
+   one target machine.
+
+Sharing Files Between Recipes
+=============================
+
+Recipes often need to use files provided by other recipes on the build
+host. For example, an application linking to a common library needs
+access to the library itself and its associated headers. The way this
+access is accomplished is by populating a sysroot with files. Each
+recipe has two sysroots in its work directory, one for target files
+(``recipe-sysroot``) and one for files that are native to the build host
+(``recipe-sysroot-native``).
+
+.. note::
+
+   You could find the term "staging" used within the Yocto project
+   regarding files populating sysroots (e.g. the :term:`STAGING_DIR`
+   variable).
+
+Recipes should never populate the sysroot directly (i.e. write files
+into sysroot). Instead, files should be installed into standard
+locations during the
+:ref:`ref-tasks-install` task within
+the ``${``\ :term:`D`\ ``}`` directory. The
+reason for this limitation is that almost all files that populate the
+sysroot are cataloged in manifests in order to ensure the files can be
+removed later when a recipe is either modified or removed. Thus, the
+sysroot is able to remain free from stale files.
+
+A subset of the files installed by the :ref:`ref-tasks-install` task are
+used by the :ref:`ref-tasks-populate_sysroot` task as defined by the
+:term:`SYSROOT_DIRS` variable to automatically populate the sysroot. It
+is possible to modify the list of directories that populate the sysroot.
+The following example shows how you could add the ``/opt`` directory to
+the list of directories within a recipe::
+
+   SYSROOT_DIRS += "/opt"
+
+.. note::
+
+   The `/sysroot-only` is to be used by recipes that generate artifacts
+   that are not included in the target filesystem, allowing them to share
+   these artifacts without needing to use the :term:`DEPLOY_DIR`.
+
+For a more complete description of the :ref:`ref-tasks-populate_sysroot`
+task and its associated functions, see the
+:ref:`staging <ref-classes-staging>` class.
+
+Using Virtual Providers
+=======================
+
+Prior to a build, if you know that several different recipes provide the
+same functionality, you can use a virtual provider (i.e. ``virtual/*``)
+as a placeholder for the actual provider. The actual provider is
+determined at build-time.
+
+A common scenario where a virtual provider is used would be for the kernel
+recipe. Suppose you have three kernel recipes whose :term:`PN` values map to
+``kernel-big``, ``kernel-mid``, and ``kernel-small``. Furthermore, each of
+these recipes in some way uses a :term:`PROVIDES` statement that essentially
+identifies itself as being able to provide ``virtual/kernel``. Here is one way
+through the :ref:`ref-classes-kernel` class::
+
+   PROVIDES += "virtual/kernel"
+
+Any recipe that inherits the :ref:`ref-classes-kernel` class is
+going to utilize a :term:`PROVIDES` statement that identifies that recipe as
+being able to provide the ``virtual/kernel`` item.
+
+Now comes the time to actually build an image and you need a kernel
+recipe, but which one? You can configure your build to call out the
+kernel recipe you want by using the :term:`PREFERRED_PROVIDER` variable. As
+an example, consider the :yocto_git:`x86-base.inc
+</poky/tree/meta/conf/machine/include/x86/x86-base.inc>` include file, which is a
+machine (i.e. :term:`MACHINE`) configuration file. This include file is the
+reason all x86-based machines use the ``linux-yocto`` kernel. Here are the
+relevant lines from the include file::
+
+   PREFERRED_PROVIDER_virtual/kernel ??= "linux-yocto"
+   PREFERRED_VERSION_linux-yocto ??= "4.15%"
+
+When you use a virtual provider, you do not have to "hard code" a recipe
+name as a build dependency. You can use the
+:term:`DEPENDS` variable to state the
+build is dependent on ``virtual/kernel`` for example::
+
+   DEPENDS = "virtual/kernel"
+
+During the build, the OpenEmbedded build system picks
+the correct recipe needed for the ``virtual/kernel`` dependency based on
+the :term:`PREFERRED_PROVIDER` variable. If you want to use the small kernel
+mentioned at the beginning of this section, configure your build as
+follows::
+
+   PREFERRED_PROVIDER_virtual/kernel ??= "kernel-small"
+
+.. note::
+
+   Any recipe that :term:`PROVIDES` a ``virtual/*`` item that is ultimately not
+   selected through :term:`PREFERRED_PROVIDER` does not get built. Preventing these
+   recipes from building is usually the desired behavior since this mechanism's
+   purpose is to select between mutually exclusive alternative providers.
+
+The following lists specific examples of virtual providers:
+
+-  ``virtual/kernel``: Provides the name of the kernel recipe to use
+   when building a kernel image.
+
+-  ``virtual/bootloader``: Provides the name of the bootloader to use
+   when building an image.
+
+-  ``virtual/libgbm``: Provides ``gbm.pc``.
+
+-  ``virtual/egl``: Provides ``egl.pc`` and possibly ``wayland-egl.pc``.
+
+-  ``virtual/libgl``: Provides ``gl.pc`` (i.e. libGL).
+
+-  ``virtual/libgles1``: Provides ``glesv1_cm.pc`` (i.e. libGLESv1_CM).
+
+-  ``virtual/libgles2``: Provides ``glesv2.pc`` (i.e. libGLESv2).
+
+.. note::
+
+   Virtual providers only apply to build time dependencies specified with
+   :term:`PROVIDES` and :term:`DEPENDS`. They do not apply to runtime
+   dependencies specified with :term:`RPROVIDES` and :term:`RDEPENDS`.
+
+Properly Versioning Pre-Release Recipes
+=======================================
+
+Sometimes the name of a recipe can lead to versioning problems when the
+recipe is upgraded to a final release. For example, consider the
+``irssi_0.8.16-rc1.bb`` recipe file in the list of example recipes in
+the ":ref:`dev-manual/new-recipe:storing and naming the recipe`" section.
+This recipe is at a release candidate stage (i.e. "rc1"). When the recipe is
+released, the recipe filename becomes ``irssi_0.8.16.bb``. The version
+change from ``0.8.16-rc1`` to ``0.8.16`` is seen as a decrease by the
+build system and package managers, so the resulting packages will not
+correctly trigger an upgrade.
+
+In order to ensure the versions compare properly, the recommended
+convention is to use a tilde (``~``) character as follows::
+
+  PV = 0.8.16~rc1
+
+This way ``0.8.16~rc1`` sorts before ``0.8.16``. See the
+":ref:`contributor-guide/recipe-style-guide:version policy`" section in the
+Yocto Project and OpenEmbedded Contributor Guide for more details about
+versioning code corresponding to a pre-release or to a specific Git commit.
+
+Post-Installation Scripts
+=========================
+
+Post-installation scripts run immediately after installing a package on
+the target or during image creation when a package is included in an
+image. To add a post-installation script to a package, add a
+``pkg_postinst:``\ `PACKAGENAME`\ ``()`` function to the recipe file
+(``.bb``) and replace `PACKAGENAME` with the name of the package you want
+to attach to the ``postinst`` script. To apply the post-installation
+script to the main package for the recipe, which is usually what is
+required, specify
+``${``\ :term:`PN`\ ``}`` in place of
+PACKAGENAME.
+
+A post-installation function has the following structure::
+
+   pkg_postinst:PACKAGENAME() {
+       # Commands to carry out
+   }
+
+The script defined in the post-installation function is called when the
+root filesystem is created. If the script succeeds, the package is
+marked as installed.
+
+.. note::
+
+   Any RPM post-installation script that runs on the target should
+   return a 0 exit code. RPM does not allow non-zero exit codes for
+   these scripts, and the RPM package manager will cause the package to
+   fail installation on the target.
+
+Sometimes it is necessary for the execution of a post-installation
+script to be delayed until the first boot. For example, the script might
+need to be executed on the device itself. To delay script execution
+until boot time, you must explicitly mark post installs to defer to the
+target. You can use ``pkg_postinst_ontarget()`` or call
+``postinst_intercept delay_to_first_boot`` from ``pkg_postinst()``. Any
+failure of a ``pkg_postinst()`` script (including exit 1) triggers an
+error during the
+:ref:`ref-tasks-rootfs` task.
+
+If you have recipes that use ``pkg_postinst`` function and they require
+the use of non-standard native tools that have dependencies during
+root filesystem construction, you need to use the
+:term:`PACKAGE_WRITE_DEPS`
+variable in your recipe to list these tools. If you do not use this
+variable, the tools might be missing and execution of the
+post-installation script is deferred until first boot. Deferring the
+script to the first boot is undesirable and impossible for read-only
+root filesystems.
+
+.. note::
+
+   There is equivalent support for pre-install, pre-uninstall, and post-uninstall
+   scripts by way of ``pkg_preinst``, ``pkg_prerm``, and ``pkg_postrm``,
+   respectively. These scrips work in exactly the same way as does
+   ``pkg_postinst`` with the exception that they run at different times. Also,
+   because of when they run, they are not applicable to being run at image
+   creation time like ``pkg_postinst``.
+
+Testing
+=======
+
+The final step for completing your recipe is to be sure that the
+software you built runs correctly. To accomplish runtime testing, add
+the build's output packages to your image and test them on the target.
+
+For information on how to customize your image by adding specific
+packages, see ":ref:`dev-manual/customizing-images:customizing images`" section.
+
+Examples
+========
+
+To help summarize how to write a recipe, this section provides some
+recipe examples given various scenarios:
+
+-  `Building a single .c file package`_
+
+-  `Building a Makefile-based package`_
+
+-  `Building an Autotooled package`_
+
+-  `Building a Meson package`_
+
+-  `Splitting an application into multiple packages`_
+
+-  `Packaging externally produced binaries`_
+
+Building a Single .c File Package
+---------------------------------
+
+Building an application from a single file that is stored locally (e.g. under
+``files``) requires a recipe that has the file listed in the :term:`SRC_URI`
+variable. Additionally, you need to manually write the :ref:`ref-tasks-compile`
+and :ref:`ref-tasks-install` tasks. The :term:`S` variable defines the
+directory containing the source code, which is set to :term:`WORKDIR` in this
+case --- the directory BitBake uses for the build::
+
+   SUMMARY = "Simple helloworld application"
+   SECTION = "examples"
+   LICENSE = "MIT"
+   LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
+
+   SRC_URI = "file://helloworld.c"
+
+   S = "${WORKDIR}"
+
+   do_compile() {
+       ${CC} ${LDFLAGS} helloworld.c -o helloworld
+   }
+
+   do_install() {
+       install -d ${D}${bindir}
+       install -m 0755 helloworld ${D}${bindir}
+   }
+
+By default, the ``helloworld``, ``helloworld-dbg``, and ``helloworld-dev`` packages
+are built. For information on how to customize the packaging process, see the
+":ref:`dev-manual/new-recipe:splitting an application into multiple packages`"
+section.
+
+Building a Makefile-Based Package
+---------------------------------
+
+Applications built with GNU ``make`` require a recipe that has the source archive
+listed in :term:`SRC_URI`. You do not need to add a :ref:`ref-tasks-compile`
+step since by default BitBake starts the ``make`` command to compile the
+application. If you need additional ``make`` options, you should store them in
+the :term:`EXTRA_OEMAKE` or :term:`PACKAGECONFIG_CONFARGS` variables. BitBake
+passes these options into the GNU ``make`` invocation. Note that a
+:ref:`ref-tasks-install` task is still required. Otherwise, BitBake runs an
+empty :ref:`ref-tasks-install` task by default.
+
+Some applications might require extra parameters to be passed to the
+compiler. For example, the application might need an additional header
+path. You can accomplish this by adding to the :term:`CFLAGS` variable. The
+following example shows this::
+
+   CFLAGS:prepend = "-I ${S}/include "
+
+In the following example, ``lz4`` is a makefile-based package::
+
+   SUMMARY = "Extremely Fast Compression algorithm"
+   DESCRIPTION = "LZ4 is a very fast lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems."
+   HOMEPAGE = "https://github.com/lz4/lz4"
+
+   LICENSE = "BSD-2-Clause | GPL-2.0-only"
+   LIC_FILES_CHKSUM = "file://lib/LICENSE;md5=ebc2ea4814a64de7708f1571904b32cc \
+                       file://programs/COPYING;md5=b234ee4d69f5fce4486a80fdaf4a4263 \
+                       file://LICENSE;md5=d57c0d21cb917fb4e0af2454aa48b956 \
+                       "
+
+   PE = "1"
+
+   SRCREV = "d44371841a2f1728a3f36839fd4b7e872d0927d3"
+
+   SRC_URI = "git://github.com/lz4/lz4.git;branch=release;protocol=https \
+              file://CVE-2021-3520.patch \
+              "
+   UPSTREAM_CHECK_GITTAGREGEX = "v(?P<pver>.*)"
+
+   S = "${WORKDIR}/git"
+
+   CVE_STATUS[CVE-2014-4715] = "fixed-version: Fixed in r118, which is larger than the current version"
+
+   EXTRA_OEMAKE = "PREFIX=${prefix} CC='${CC}' CFLAGS='${CFLAGS}' DESTDIR=${D} LIBDIR=${libdir} INCLUDEDIR=${includedir} BUILD_STATIC=no"
+
+   do_install() {
+           oe_runmake install
+   }
+
+   BBCLASSEXTEND = "native nativesdk"
+
+Building an Autotooled Package
+------------------------------
+
+Applications built with the Autotools such as ``autoconf`` and ``automake``
+require a recipe that has a source archive listed in :term:`SRC_URI` and also
+inherit the :ref:`ref-classes-autotools` class, which contains the definitions
+of all the steps needed to build an Autotool-based application. The result of
+the build is automatically packaged. And, if the application uses NLS for
+localization, packages with local information are generated (one package per
+language). Here is one example: (``hello_2.3.bb``)::
+
+   SUMMARY = "GNU Helloworld application"
+   SECTION = "examples"
+   LICENSE = "GPL-2.0-or-later"
+   LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"
+
+   SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz"
+
+   inherit autotools gettext
+
+The variable :term:`LIC_FILES_CHKSUM` is used to track source license changes
+as described in the ":ref:`dev-manual/licenses:tracking license changes`"
+section in the Yocto Project Overview and Concepts Manual. You can quickly
+create Autotool-based recipes in a manner similar to the previous example.
+
+.. _ref-building-meson-package:
+
+Building a Meson Package
+------------------------
+
+Applications built with the `Meson build system <https://mesonbuild.com/>`__
+just need a recipe that has sources described in :term:`SRC_URI` and inherits
+the :ref:`ref-classes-meson` class.
+
+The :oe_git:`ipcalc recipe </meta-openembedded/tree/meta-networking/recipes-support/ipcalc>`
+is a simple example of an application without dependencies::
+
+   SUMMARY = "Tool to assist in network address calculations for IPv4 and IPv6."
+   HOMEPAGE = "https://gitlab.com/ipcalc/ipcalc"
+
+   SECTION = "net"
+
+   LICENSE = "GPL-2.0-only"
+   LIC_FILES_CHKSUM = "file://COPYING;md5=b234ee4d69f5fce4486a80fdaf4a4263"
+
+   SRC_URI = "git://gitlab.com/ipcalc/ipcalc.git;protocol=https;branch=master"
+   SRCREV = "4c4261a47f355946ee74013d4f5d0494487cc2d6"
+
+   S = "${WORKDIR}/git"
+
+   inherit meson
+
+Applications with dependencies are likely to inherit the
+:ref:`ref-classes-pkgconfig` class, as ``pkg-config`` is the default method
+used by Meson to find dependencies and compile applications against them.
+
+Splitting an Application into Multiple Packages
+-----------------------------------------------
+
+You can use the variables :term:`PACKAGES` and :term:`FILES` to split an
+application into multiple packages.
+
+Here is an example that uses the ``libxpm`` recipe. By default,
+this recipe generates a single package that contains the library along
+with a few binaries. You can modify the recipe to split the binaries
+into separate packages::
+
+   require xorg-lib-common.inc
+
+   SUMMARY = "Xpm: X Pixmap extension library"
+   LICENSE = "MIT"
+   LIC_FILES_CHKSUM = "file://COPYING;md5=51f4270b012ecd4ab1a164f5f4ed6cf7"
+   DEPENDS += "libxext libsm libxt"
+   PE = "1"
+
+   XORG_PN = "libXpm"
+
+   PACKAGES =+ "sxpm cxpm"
+   FILES:cxpm = "${bindir}/cxpm"
+   FILES:sxpm = "${bindir}/sxpm"
+
+In the previous example, we want to ship the ``sxpm`` and ``cxpm``
+binaries in separate packages. Since ``bindir`` would be packaged into
+the main :term:`PN` package by default, we prepend the :term:`PACKAGES` variable
+so additional package names are added to the start of list. This results
+in the extra ``FILES:*`` variables then containing information that
+define which files and directories go into which packages. Files
+included by earlier packages are skipped by latter packages. Thus, the
+main :term:`PN` package does not include the above listed files.
+
+Packaging Externally Produced Binaries
+--------------------------------------
+
+Sometimes, you need to add pre-compiled binaries to an image. For
+example, suppose that there are binaries for proprietary code,
+created by a particular division of a company. Your part of the company
+needs to use those binaries as part of an image that you are building
+using the OpenEmbedded build system. Since you only have the binaries
+and not the source code, you cannot use a typical recipe that expects to
+fetch the source specified in
+:term:`SRC_URI` and then compile it.
+
+One method is to package the binaries and then install them as part of
+the image. Generally, it is not a good idea to package binaries since,
+among other things, it can hinder the ability to reproduce builds and
+could lead to compatibility problems with ABI in the future. However,
+sometimes you have no choice.
+
+The easiest solution is to create a recipe that uses the
+:ref:`ref-classes-bin-package` class and to be sure that you are using default
+locations for build artifacts.  In most cases, the
+:ref:`ref-classes-bin-package` class handles "skipping" the configure and
+compile steps as well as sets things up to grab packages from the appropriate
+area. In particular, this class sets ``noexec`` on both the
+:ref:`ref-tasks-configure` and :ref:`ref-tasks-compile` tasks, sets
+``FILES:${PN}`` to "/" so that it picks up all files, and sets up a
+:ref:`ref-tasks-install` task, which effectively copies all files from ``${S}``
+to ``${D}``. The :ref:`ref-classes-bin-package` class works well when the files
+extracted into ``${S}`` are already laid out in the way they should be laid out
+on the target. For more information on these variables, see the :term:`FILES`,
+:term:`PN`, :term:`S`, and :term:`D` variables in the Yocto Project Reference
+Manual's variable glossary.
+
+.. note::
+
+   -  Using :term:`DEPENDS` is a good
+      idea even for components distributed in binary form, and is often
+      necessary for shared libraries. For a shared library, listing the
+      library dependencies in :term:`DEPENDS` makes sure that the libraries
+      are available in the staging sysroot when other recipes link
+      against the library, which might be necessary for successful
+      linking.
+
+   -  Using :term:`DEPENDS` also allows runtime dependencies between
+      packages to be added automatically. See the
+      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
+      section in the Yocto Project Overview and Concepts Manual for more
+      information.
+
+If you cannot use the :ref:`ref-classes-bin-package` class, you need to be sure you are
+doing the following:
+
+-  Create a recipe where the
+   :ref:`ref-tasks-configure` and
+   :ref:`ref-tasks-compile` tasks do
+   nothing: It is usually sufficient to just not define these tasks in
+   the recipe, because the default implementations do nothing unless a
+   Makefile is found in
+   ``${``\ :term:`S`\ ``}``.
+
+   If ``${S}`` might contain a Makefile, or if you inherit some class
+   that replaces :ref:`ref-tasks-configure` and :ref:`ref-tasks-compile` with custom
+   versions, then you can use the
+   ``[``\ :ref:`noexec <bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]``
+   flag to turn the tasks into no-ops, as follows::
+
+      do_configure[noexec] = "1"
+      do_compile[noexec] = "1"
+
+   Unlike :ref:`bitbake-user-manual/bitbake-user-manual-metadata:deleting a task`,
+   using the flag preserves the dependency chain from the :ref:`ref-tasks-fetch`,
+   :ref:`ref-tasks-unpack`, and :ref:`ref-tasks-patch` tasks to the
+   :ref:`ref-tasks-install` task.
+
+-  Make sure your :ref:`ref-tasks-install` task installs the binaries
+   appropriately.
+
+-  Ensure that you set up :term:`FILES`
+   (usually
+   ``FILES:${``\ :term:`PN`\ ``}``) to
+   point to the files you have installed, which of course depends on
+   where you have installed them and whether those files are in
+   different locations than the defaults.
+
+Following Recipe Style Guidelines
+=================================
+
+When writing recipes, it is good to conform to existing style guidelines.
+See the ":doc:`../contributor-guide/recipe-style-guide`" in the Yocto Project
+and OpenEmbedded Contributor Guide for reference.
+
+It is common for existing recipes to deviate a bit from this style.
+However, aiming for at least a consistent style is a good idea. Some
+practices, such as omitting spaces around ``=`` operators in assignments
+or ordering recipe components in an erratic way, are widely seen as poor
+style.
+
+Recipe Syntax
+=============
+
+Understanding recipe file syntax is important for writing recipes. The
+following list overviews the basic items that make up a BitBake recipe
+file. For more complete BitBake syntax descriptions, see the
+":doc:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata`"
+chapter of the BitBake User Manual.
+
+-  *Variable Assignments and Manipulations:* Variable assignments allow
+   a value to be assigned to a variable. The assignment can be static
+   text or might include the contents of other variables. In addition to
+   the assignment, appending and prepending operations are also
+   supported.
+
+   The following example shows some of the ways you can use variables in
+   recipes::
+
+      S = "${WORKDIR}/postfix-${PV}"
+      CFLAGS += "-DNO_ASM"
+      CFLAGS:append = " --enable-important-feature"
+
+-  *Functions:* Functions provide a series of actions to be performed.
+   You usually use functions to override the default implementation of a
+   task function or to complement a default function (i.e. append or
+   prepend to an existing function). Standard functions use ``sh`` shell
+   syntax, although access to OpenEmbedded variables and internal
+   methods are also available.
+
+   Here is an example function from the ``sed`` recipe::
+
+      do_install () {
+          autotools_do_install
+          install -d ${D}${base_bindir}
+          mv ${D}${bindir}/sed ${D}${base_bindir}/sed
+          rmdir ${D}${bindir}/
+      }
+
+   It is
+   also possible to implement new functions that are called between
+   existing tasks as long as the new functions are not replacing or
+   complementing the default functions. You can implement functions in
+   Python instead of shell. Both of these options are not seen in the
+   majority of recipes.
+
+-  *Keywords:* BitBake recipes use only a few keywords. You use keywords
+   to include common functions (``inherit``), load parts of a recipe
+   from other files (``include`` and ``require``) and export variables
+   to the environment (``export``).
+
+   The following example shows the use of some of these keywords::
+
+      export POSTCONF = "${STAGING_BINDIR}/postconf"
+      inherit autoconf
+      require otherfile.inc
+
+-  *Comments (#):* Any lines that begin with the hash character (``#``)
+   are treated as comment lines and are ignored::
+
+      # This is a comment
+
+This next list summarizes the most important and most commonly used
+parts of the recipe syntax. For more information on these parts of the
+syntax, you can reference the
+":doc:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata`" chapter
+in the BitBake User Manual.
+
+-  *Line Continuation (\\):* Use the backward slash (``\``) character to
+   split a statement over multiple lines. Place the slash character at
+   the end of the line that is to be continued on the next line::
+
+       VAR = "A really long \
+              line"
+
+   .. note::
+
+      You cannot have any characters including spaces or tabs after the
+      slash character.
+
+-  *Using Variables (${VARNAME}):* Use the ``${VARNAME}`` syntax to
+   access the contents of a variable::
+
+      SRC_URI = "${SOURCEFORGE_MIRROR}/libpng/zlib-${PV}.tar.gz"
+
+   .. note::
+
+      It is important to understand that the value of a variable
+      expressed in this form does not get substituted automatically. The
+      expansion of these expressions happens on-demand later (e.g.
+      usually when a function that makes reference to the variable
+      executes). This behavior ensures that the values are most
+      appropriate for the context in which they are finally used. On the
+      rare occasion that you do need the variable expression to be
+      expanded immediately, you can use the
+      :=
+      operator instead of
+      =
+      when you make the assignment, but this is not generally needed.
+
+-  *Quote All Assignments ("value"):* Use double quotes around values in
+   all variable assignments (e.g. ``"value"``). Here is an example::
+
+      VAR1 = "${OTHERVAR}"
+      VAR2 = "The version is ${PV}"
+
+-  *Conditional Assignment (?=):* Conditional assignment is used to
+   assign a value to a variable, but only when the variable is currently
+   unset. Use the question mark followed by the equal sign (``?=``) to
+   make a "soft" assignment used for conditional assignment. Typically,
+   "soft" assignments are used in the ``local.conf`` file for variables
+   that are allowed to come through from the external environment.
+
+   Here is an example where ``VAR1`` is set to "New value" if it is
+   currently empty. However, if ``VAR1`` has already been set, it
+   remains unchanged::
+
+      VAR1 ?= "New value"
+
+   In this next example, ``VAR1`` is left with the value "Original value"::
+
+      VAR1 = "Original value"
+      VAR1 ?= "New value"
+
+-  *Appending (+=):* Use the plus character followed by the equals sign
+   (``+=``) to append values to existing variables.
+
+   .. note::
+
+      This operator adds a space between the existing content of the
+      variable and the new content.
+
+   Here is an example::
+
+      SRC_URI += "file://fix-makefile.patch"
+
+-  *Prepending (=+):* Use the equals sign followed by the plus character
+   (``=+``) to prepend values to existing variables.
+
+   .. note::
+
+      This operator adds a space between the new content and the
+      existing content of the variable.
+
+   Here is an example::
+
+      VAR =+ "Starts"
+
+-  *Appending (:append):* Use the ``:append`` operator to append values
+   to existing variables. This operator does not add any additional
+   space. Also, the operator is applied after all the ``+=``, and ``=+``
+   operators have been applied and after all ``=`` assignments have
+   occurred. This means that if ``:append`` is used in a recipe, it can
+   only be overridden by another layer using the special ``:remove``
+   operator, which in turn will prevent further layers from adding it back.
+
+   The following example shows the space being explicitly added to the
+   start to ensure the appended value is not merged with the existing
+   value::
+
+      CFLAGS:append = " --enable-important-feature"
+
+   You can also use
+   the ``:append`` operator with overrides, which results in the actions
+   only being performed for the specified target or machine::
+
+      CFLAGS:append:sh4 = " --enable-important-sh4-specific-feature"
+
+-  *Prepending (:prepend):* Use the ``:prepend`` operator to prepend
+   values to existing variables. This operator does not add any
+   additional space. Also, the operator is applied after all the ``+=``,
+   and ``=+`` operators have been applied and after all ``=``
+   assignments have occurred.
+
+   The following example shows the space being explicitly added to the
+   end to ensure the prepended value is not merged with the existing
+   value::
+
+      CFLAGS:prepend = "-I${S}/myincludes "
+
+   You can also use the
+   ``:prepend`` operator with overrides, which results in the actions
+   only being performed for the specified target or machine::
+
+      CFLAGS:prepend:sh4 = "-I${S}/myincludes "
+
+-  *Overrides:* You can use overrides to set a value conditionally,
+   typically based on how the recipe is being built. For example, to set
+   the :term:`KBRANCH` variable's
+   value to "standard/base" for any target
+   :term:`MACHINE`, except for
+   qemuarm where it should be set to "standard/arm-versatile-926ejs",
+   you would do the following::
+
+      KBRANCH = "standard/base"
+      KBRANCH:qemuarm = "standard/arm-versatile-926ejs"
+
+   Overrides are also used to separate
+   alternate values of a variable in other situations. For example, when
+   setting variables such as
+   :term:`FILES` and
+   :term:`RDEPENDS` that are
+   specific to individual packages produced by a recipe, you should
+   always use an override that specifies the name of the package.
+
+-  *Indentation:* Use spaces for indentation rather than tabs. For
+   shell functions, both currently work. However, it is a policy
+   decision of the Yocto Project to use tabs in shell functions. Realize
+   that some layers have a policy to use spaces for all indentation.
+
+-  *Using Python for Complex Operations:* For more advanced processing,
+   it is possible to use Python code during variable assignments (e.g.
+   search and replacement on a variable).
+
+   You indicate Python code using the ``${@python_code}`` syntax for the
+   variable assignment::
+
+      SRC_URI = "ftp://ftp.info-zip.org/pub/infozip/src/zip${@d.getVar('PV',1).replace('.', '')}.tgz
+
+-  *Shell Function Syntax:* Write shell functions as if you were writing
+   a shell script when you describe a list of actions to take. You
+   should ensure that your script works with a generic ``sh`` and that
+   it does not require any ``bash`` or other shell-specific
+   functionality. The same considerations apply to various system
+   utilities (e.g. ``sed``, ``grep``, ``awk``, and so forth) that you
+   might wish to use. If in doubt, you should check with multiple
+   implementations --- including those from BusyBox.
+