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+.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
+
+Contributing a Change to a Component
+************************************
+
+Contributions to the Yocto Project and OpenEmbedded are very welcome.
+Because the system is extremely configurable and flexible, we recognize
+that developers will want to extend, configure or optimize it for their
+specific uses.
+
+Finding a Suitable Mailing List
+===============================
+
+The Yocto Project uses a mailing list and a patch-based workflow that is
+similar to the Linux kernel but contains important differences. In
+general, there is a mailing list through which you can submit patches. You
+should send patches to the appropriate mailing list so that they can be
+reviewed and merged by the appropriate maintainer. The specific mailing
+list you need to use depends on the location of the code you are
+changing. Each component (e.g. layer) should have a ``README`` file that
+indicates where to send the changes and which process to follow.
+
+You can send the patch to the mailing list using whichever approach you
+feel comfortable with to generate the patch. Once sent, the patch is
+usually reviewed by the community at large. If somebody has concerns
+with the patch, they will usually voice their concern over the mailing
+list. If a patch does not receive any negative reviews, the maintainer
+of the affected layer typically takes the patch, tests it, and then
+based on successful testing, merges the patch.
+
+The "poky" repository, which is the Yocto Project's reference build
+environment, is a hybrid repository that contains several individual
+pieces (e.g. BitBake, Metadata, documentation, and so forth) built using
+the combo-layer tool. The upstream location used for submitting changes
+varies by component:
+
+-  *Core Metadata:* Send your patch to the
+   :oe_lists:`openembedded-core </g/openembedded-core>`
+   mailing list. For example, a change to anything under the ``meta`` or
+   ``scripts`` directories should be sent to this mailing list.
+
+-  *BitBake:* For changes to BitBake (i.e. anything under the
+   ``bitbake`` directory), send your patch to the
+   :oe_lists:`bitbake-devel </g/bitbake-devel>`
+   mailing list.
+
+-  *"meta-\*" trees:* These trees contain Metadata. Use the
+   :yocto_lists:`poky </g/poky>` mailing list.
+
+-  *Documentation*: For changes to the Yocto Project documentation, use the
+   :yocto_lists:`docs </g/docs>` mailing list.
+
+For changes to other layers hosted in the Yocto Project source
+repositories (i.e. ``yoctoproject.org``) and tools use the
+:yocto_lists:`Yocto Project </g/yocto/>` general mailing list.
+
+.. note::
+
+   Sometimes a layer's documentation specifies to use a particular
+   mailing list. If so, use that list.
+
+For additional recipes that do not fit into the core Metadata, you
+should determine which layer the recipe should go into and submit the
+change in the manner recommended by the documentation (e.g. the
+``README`` file) supplied with the layer. If in doubt, please ask on the
+Yocto general mailing list or on the openembedded-devel mailing list.
+
+You can also push a change upstream and request a maintainer to pull the
+change into the component's upstream repository. You do this by pushing
+to a contribution repository that is upstream. See the
+":ref:`overview-manual/development-environment:git workflows and the yocto project`"
+section in the Yocto Project Overview and Concepts Manual for additional
+concepts on working in the Yocto Project development environment.
+
+Maintainers commonly use ``-next`` branches to test submissions prior to
+merging patches. Thus, you can get an idea of the status of a patch based on
+whether the patch has been merged into one of these branches. The commonly
+used testing branches for OpenEmbedded-Core are as follows:
+
+-  *openembedded-core "master-next" branch:* This branch is part of the
+   :oe_git:`openembedded-core </openembedded-core/>` repository and contains
+   proposed changes to the core metadata.
+
+-  *poky "master-next" branch:* This branch is part of the
+   :yocto_git:`poky </poky/>` repository and combines proposed
+   changes to BitBake, the core metadata and the poky distro.
+
+Similarly, stable branches maintained by the project may have corresponding
+``-next`` branches which collect proposed changes. For example,
+``&DISTRO_NAME_NO_CAP;-next`` and ``&DISTRO_NAME_NO_CAP_MINUS_ONE;-next``
+branches in both the "openembdedded-core" and "poky" repositories.
+
+Other layers may have similar testing branches but there is no formal
+requirement or standard for these so please check the documentation for the
+layers you are contributing to.
+
+The following sections provide procedures for submitting a change.
+
+Preparing Changes for Submission
+================================
+
+#. *Make Your Changes Locally:* Make your changes in your local Git
+   repository. You should make small, controlled, isolated changes.
+   Keeping changes small and isolated aids review, makes
+   merging/rebasing easier and keeps the change history clean should
+   anyone need to refer to it in future.
+
+#. *Stage Your Changes:* Stage your changes by using the ``git add``
+   command on each file you changed.
+
+#. *Commit Your Changes:* Commit the change by using the ``git commit``
+   command. Make sure your commit information follows standards by
+   following these accepted conventions:
+
+   -  Be sure to include a "Signed-off-by:" line in the same style as
+      required by the Linux kernel. This can be done by using the
+      ``git commit -s`` command. Adding this line signifies that you,
+      the submitter, have agreed to the Developer's Certificate of
+      Origin 1.1 as follows:
+
+      .. code-block:: none
+
+         Developer's Certificate of Origin 1.1
+
+         By making a contribution to this project, I certify that:
+
+         (a) The contribution was created in whole or in part by me and I
+             have the right to submit it under the open source license
+             indicated in the file; or
+
+         (b) The contribution is based upon previous work that, to the best
+             of my knowledge, is covered under an appropriate open source
+             license and I have the right under that license to submit that
+             work with modifications, whether created in whole or in part
+             by me, under the same open source license (unless I am
+             permitted to submit under a different license), as indicated
+             in the file; or
+
+         (c) The contribution was provided directly to me by some other
+             person who certified (a), (b) or (c) and I have not modified
+             it.
+
+         (d) I understand and agree that this project and the contribution
+             are public and that a record of the contribution (including all
+             personal information I submit with it, including my sign-off) is
+             maintained indefinitely and may be redistributed consistent with
+             this project or the open source license(s) involved.
+
+   -  Provide a single-line summary of the change and, if more
+      explanation is needed, provide more detail in the body of the
+      commit. This summary is typically viewable in the "shortlist" of
+      changes. Thus, providing something short and descriptive that
+      gives the reader a summary of the change is useful when viewing a
+      list of many commits. You should prefix this short description
+      with the recipe name (if changing a recipe), or else with the
+      short form path to the file being changed.
+
+   -  For the body of the commit message, provide detailed information
+      that describes what you changed, why you made the change, and the
+      approach you used. It might also be helpful if you mention how you
+      tested the change. Provide as much detail as you can in the body
+      of the commit message.
+
+      .. note::
+
+         You do not need to provide a more detailed explanation of a
+         change if the change is minor to the point of the single line
+         summary providing all the information.
+
+   -  If the change addresses a specific bug or issue that is associated
+      with a bug-tracking ID, include a reference to that ID in your
+      detailed description. For example, the Yocto Project uses a
+      specific convention for bug references --- any commit that addresses
+      a specific bug should use the following form for the detailed
+      description. Be sure to use the actual bug-tracking ID from
+      Bugzilla for bug-id::
+
+         Fixes [YOCTO #bug-id]
+
+         detailed description of change
+
+Using Email to Submit a Patch
+=============================
+
+Depending on the components changed, you need to submit the email to a
+specific mailing list. For some guidance on which mailing list to use,
+see the ":ref:`contributor-guide/submit-change:finding a suitable mailing list`"
+section above. For a description of all the available
+mailing lists, see the ":ref:`Mailing Lists <resources-mailinglist>`" section in the
+Yocto Project Reference Manual.
+
+Here is the general procedure on how to submit a patch through email
+without using the scripts once the steps in
+":ref:`contributor-guide/submit-change:preparing changes for submission`"
+have been followed:
+
+#. *Format the Commit:* Format the commit into an email message. To
+   format commits, use the ``git format-patch`` command. When you
+   provide the command, you must include a revision list or a number of
+   patches as part of the command. For example, either of these two
+   commands takes your most recent single commit and formats it as an
+   email message in the current directory::
+
+      $ git format-patch -1
+
+   or ::
+
+      $ git format-patch HEAD~
+
+   After the command is run, the current directory contains a numbered
+   ``.patch`` file for the commit.
+
+   If you provide several commits as part of the command, the
+   ``git format-patch`` command produces a series of numbered files in
+   the current directory – one for each commit. If you have more than
+   one patch, you should also use the ``--cover`` option with the
+   command, which generates a cover letter as the first "patch" in the
+   series. You can then edit the cover letter to provide a description
+   for the series of patches. For information on the
+   ``git format-patch`` command, see ``GIT_FORMAT_PATCH(1)`` displayed
+   using the ``man git-format-patch`` command.
+
+   .. note::
+
+      If you are or will be a frequent contributor to the Yocto Project
+      or to OpenEmbedded, you might consider requesting a contrib area
+      and the necessary associated rights.
+
+#. *Send the patches via email:* Send the patches to the recipients and
+   relevant mailing lists by using the ``git send-email`` command.
+
+   .. note::
+
+      In order to use ``git send-email``, you must have the proper Git packages
+      installed on your host.
+      For Ubuntu, Debian, and Fedora the package is ``git-email``.
+
+   The ``git send-email`` command sends email by using a local or remote
+   Mail Transport Agent (MTA) such as ``msmtp``, ``sendmail``, or
+   through a direct ``smtp`` configuration in your Git ``~/.gitconfig``
+   file. If you are submitting patches through email only, it is very
+   important that you submit them without any whitespace or HTML
+   formatting that either you or your mailer introduces. The maintainer
+   that receives your patches needs to be able to save and apply them
+   directly from your emails. A good way to verify that what you are
+   sending will be applicable by the maintainer is to do a dry run and
+   send them to yourself and then save and apply them as the maintainer
+   would.
+
+   The ``git send-email`` command is the preferred method for sending
+   your patches using email since there is no risk of compromising
+   whitespace in the body of the message, which can occur when you use
+   your own mail client. The command also has several options that let
+   you specify recipients and perform further editing of the email
+   message. For information on how to use the ``git send-email``
+   command, see ``GIT-SEND-EMAIL(1)`` displayed using the
+   ``man git-send-email`` command.
+
+The Yocto Project uses a `Patchwork instance <https://patchwork.yoctoproject.org/>`__
+to track the status of patches submitted to the various mailing lists and to
+support automated patch testing. Each submitted patch is checked for common
+mistakes and deviations from the expected patch format and submitters are
+notified by patchtest if such mistakes are found. This process helps to
+reduce the burden of patch review on maintainers.
+
+.. note::
+
+   This system is imperfect and changes can sometimes get lost in the flow.
+   Asking about the status of a patch or change is reasonable if the change
+   has been idle for a while with no feedback.
+
+Using Scripts to Push a Change Upstream and Request a Pull
+==========================================================
+
+For larger patch series it is preferable to send a pull request which not
+only includes the patch but also a pointer to a branch that can be pulled
+from. This involves making a local branch for your changes, pushing this
+branch to an accessible repository and then using the ``create-pull-request``
+and ``send-pull-request`` scripts from openembedded-core to create and send a
+patch series with a link to the branch for review.
+
+Follow this procedure to push a change to an upstream "contrib" Git
+repository once the steps in
+":ref:`contributor-guide/submit-change:preparing changes for submission`"
+have been followed:
+
+.. note::
+
+   You can find general Git information on how to push a change upstream
+   in the
+   `Git Community Book <https://git-scm.com/book/en/v2/Distributed-Git-Distributed-Workflows>`__.
+
+#. *Push Your Commits to a "Contrib" Upstream:* If you have arranged for
+   permissions to push to an upstream contrib repository, push the
+   change to that repository::
+
+      $ git push upstream_remote_repo local_branch_name
+
+   For example, suppose you have permissions to push
+   into the upstream ``meta-intel-contrib`` repository and you are
+   working in a local branch named `your_name`\ ``/README``. The following
+   command pushes your local commits to the ``meta-intel-contrib``
+   upstream repository and puts the commit in a branch named
+   `your_name`\ ``/README``::
+
+      $ git push meta-intel-contrib your_name/README
+
+#. *Determine Who to Notify:* Determine the maintainer or the mailing
+   list that you need to notify for the change.
+
+   Before submitting any change, you need to be sure who the maintainer
+   is or what mailing list that you need to notify. Use either these
+   methods to find out:
+
+   -  *Maintenance File:* Examine the ``maintainers.inc`` file, which is
+      located in the :term:`Source Directory` at
+      ``meta/conf/distro/include``, to see who is responsible for code.
+
+   -  *Search by File:* Using :ref:`overview-manual/development-environment:git`, you can
+      enter the following command to bring up a short list of all
+      commits against a specific file::
+
+         git shortlog -- filename
+
+      Just provide the name of the file for which you are interested. The
+      information returned is not ordered by history but does include a
+      list of everyone who has committed grouped by name. From the list,
+      you can see who is responsible for the bulk of the changes against
+      the file.
+
+   -  *Examine the List of Mailing Lists:* For a list of the Yocto
+      Project and related mailing lists, see the ":ref:`Mailing
+      lists <resources-mailinglist>`" section in
+      the Yocto Project Reference Manual.
+
+#. *Make a Pull Request:* Notify the maintainer or the mailing list that
+   you have pushed a change by making a pull request.
+
+   The Yocto Project provides two scripts that conveniently let you
+   generate and send pull requests to the Yocto Project. These scripts
+   are ``create-pull-request`` and ``send-pull-request``. You can find
+   these scripts in the ``scripts`` directory within the
+   :term:`Source Directory` (e.g.
+   ``poky/scripts``).
+
+   Using these scripts correctly formats the requests without
+   introducing any whitespace or HTML formatting. The maintainer that
+   receives your patches either directly or through the mailing list
+   needs to be able to save and apply them directly from your emails.
+   Using these scripts is the preferred method for sending patches.
+
+   First, create the pull request. For example, the following command
+   runs the script, specifies the upstream repository in the contrib
+   directory into which you pushed the change, and provides a subject
+   line in the created patch files::
+
+      $ poky/scripts/create-pull-request -u meta-intel-contrib -s "Updated Manual Section Reference in README"
+
+   Running this script forms ``*.patch`` files in a folder named
+   ``pull-``\ `PID` in the current directory. One of the patch files is a
+   cover letter.
+
+   Before running the ``send-pull-request`` script, you must edit the
+   cover letter patch to insert information about your change. After
+   editing the cover letter, send the pull request. For example, the
+   following command runs the script and specifies the patch directory
+   and email address. In this example, the email address is a mailing
+   list::
+
+      $ poky/scripts/send-pull-request -p ~/meta-intel/pull-10565 -t meta-intel@lists.yoctoproject.org
+
+   You need to follow the prompts as the script is interactive.
+
+   .. note::
+
+      For help on using these scripts, simply provide the ``-h``
+      argument as follows::
+
+              $ poky/scripts/create-pull-request -h
+              $ poky/scripts/send-pull-request -h
+
+Responding to Patch Review
+==========================
+
+You may get feedback on your submitted patches from other community members
+or from the automated patchtest service. If issues are identified in your
+patch then it is usually necessary to address these before the patch will be
+accepted into the project. In this case you should amend the patch according
+to the feedback and submit an updated version to the relevant mailing list,
+copying in the reviewers who provided feedback to the previous version of the
+patch.
+
+The patch should be amended using ``git commit --amend`` or perhaps ``git
+rebase`` for more expert git users. You should also modify the ``[PATCH]``
+tag in the email subject line when sending the revised patch to mark the new
+iteration as ``[PATCH v2]``, ``[PATCH v3]``, etc as appropriate. This can be
+done by passing the ``-v`` argument to ``git format-patch`` with a version
+number.
+
+Lastly please ensure that you also test your revised changes. In particular
+please don't just edit the patch file written out by ``git format-patch`` and
+resend it.
+
+Submitting Changes to Stable Release Branches
+=============================================
+
+The process for proposing changes to a Yocto Project stable branch differs
+from the steps described above. Changes to a stable branch must address
+identified bugs or CVEs and should be made carefully in order to avoid the
+risk of introducing new bugs or breaking backwards compatibility. Typically
+bug fixes must already be accepted into the master branch before they can be
+backported to a stable branch unless the bug in question does not affect the
+master branch or the fix on the master branch is unsuitable for backporting.
+
+The list of stable branches along with the status and maintainer for each
+branch can be obtained from the
+:yocto_wiki:`Releases wiki page </Releases>`.
+
+.. note::
+
+   Changes will not typically be accepted for branches which are marked as
+   End-Of-Life (EOL).
+
+With this in mind, the steps to submit a change for a stable branch are as
+follows:
+
+#. *Identify the bug or CVE to be fixed:* This information should be
+   collected so that it can be included in your submission.
+
+   See :ref:`dev-manual/vulnerabilities:checking for vulnerabilities`
+   for details about CVE tracking.
+
+#. *Check if the fix is already present in the master branch:* This will
+   result in the most straightforward path into the stable branch for the
+   fix.
+
+   #. *If the fix is present in the master branch --- submit a backport request
+      by email:* You should send an email to the relevant stable branch
+      maintainer and the mailing list with details of the bug or CVE to be
+      fixed, the commit hash on the master branch that fixes the issue and
+      the stable branches which you would like this fix to be backported to.
+
+   #. *If the fix is not present in the master branch --- submit the fix to the
+      master branch first:* This will ensure that the fix passes through the
+      project's usual patch review and test processes before being accepted.
+      It will also ensure that bugs are not left unresolved in the master
+      branch itself. Once the fix is accepted in the master branch a backport
+      request can be submitted as above.
+
+   #. *If the fix is unsuitable for the master branch --- submit a patch
+      directly for the stable branch:* This method should be considered as a
+      last resort. It is typically necessary when the master branch is using
+      a newer version of the software which includes an upstream fix for the
+      issue or when the issue has been fixed on the master branch in a way
+      that introduces backwards incompatible changes. In this case follow the
+      steps in ":ref:`contributor-guide/submit-change:preparing changes for submission`" and
+      ":ref:`contributor-guide/submit-change:using email to submit a patch`"
+      but modify the subject header of your patch
+      email to include the name of the stable branch which you are
+      targetting. This can be done using the ``--subject-prefix`` argument to
+      ``git format-patch``, for example to submit a patch to the dunfell
+      branch use
+      ``git format-patch --subject-prefix='&DISTRO_NAME_NO_CAP_MINUS_ONE;][PATCH' ...``.