docs/submittingpatches.rst - platform/external/mesa3d - Git at Google

 Submitting Patches
 ==================

 .. _guidelines:

 Basic guidelines
 ----------------

 -  Patches should not mix code changes with code formatting changes
    (except, perhaps, in very trivial cases.)
 -  Code patches should follow Mesa :doc:`coding
    conventions <codingstyle>`.
 -  Whenever possible, patches should only affect individual Mesa/Gallium
    components.
 -  Patches should never introduce build breaks and should be bisectable
    (see ``git bisect``.)
 -  Patches should be properly :ref:`formatted <formatting>`.
 -  Patches should be sufficiently :ref:`tested <testing>` before
    submitting.
 -  Patches should be :ref:`submitted <submit>` via a merge request for
    :ref:`review <reviewing>`.

 .. _formatting:

 Patch formatting
 ----------------

 -  Lines should be limited to 75 characters or less so that git logs
    displayed in 80-column terminals avoid line wrapping. Note that git
    log uses 4 spaces of indentation (4 + 75 < 80).
 -  The first line should be a short, concise summary of the change
    prefixed with a module name. Examples:

    ::

       mesa: Add support for querying GL_VERTEX_ATTRIB_ARRAY_LONG

       gallium: add PIPE_CAP_DEVICE_RESET_STATUS_QUERY

       i965: Fix missing type in local variable declaration.

 -  Subsequent patch comments should describe the change in more detail,
    if needed. For example:

    ::

       i965: Remove end-of-thread SEND alignment code.

       This was present in Eric's initial implementation of the compaction code
       for Sandybridge (commit 077d01b6). There is no documentation saying this
       is necessary, and removing it causes no regressions in piglit on any
       platform.

 -  A "Signed-off-by:" line is not required, but not discouraged either.
 -  If a patch addresses an issue in GitLab, use the Closes: tag For
    example:

    ::

       Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/1

    Prefer the full URL to just ``Closes: #1``, since the URL makes it
    easier to get to the bug page from ``git log``

    **Do not use the ``Fixes:`` tag for this!** Mesa already uses
    ``Fixes:`` for something else.
    See :ref:`below <fixes>`.

 -  If there have been several revisions to a patch during the review
    process, they should be noted such as in this example:

    ::

       st/mesa: add ARB_texture_stencil8 support (v4)

       if we support stencil texturing, enable texture_stencil8
       there is no requirement to support native S8 for this,
       the texture can be converted to x24s8 fine.

       v2: fold fixes from Marek in:
          a) put S8 last in the list
          b) fix renderable to always test for d/s renderable
            fixup the texture case to use a stencil only format
            for picking the format for the texture view.
       v3: hit fallback for getteximage
       v4: put s8 back in front, it shouldn't get picked now (Ilia)

 -  If someone tested your patch, document it with a line like this:

    ::

       Tested-by: Joe Hacker <jhacker@foo.com>

 -  If the patch was reviewed (usually the case) or acked by someone,
    that should be documented with:

    ::

       Reviewed-by: Joe Hacker <jhacker@foo.com>
       Acked-by: Joe Hacker <jhacker@foo.com>

 -  When updating a merge request add all the tags (``Acked-by:``, ``Reviewed-by:``,
    ``Fixes:``, ``Cc: mesa-stable`` and/or other) to the commit messages.
    This provides reviewers with quick feedback if the patch has already
    been reviewed.

 .. _fixes:

 The ``Fixes:`` tag
 ------------------

 If a patch addresses a issue introduced with earlier commit, that
 should be noted in the commit message. For example::

     Fixes: d7b3707c612 ("util/disk_cache: use stat() to check if entry is a directory")

 You can produce those fixes lines by running this command once::

     git config --global alias.fixes "show -s --pretty='format:Fixes: %h (\"%s\")'"

 After that, using ``git fixes <sha1>`` will print the full line for you.

 The stable tag
 ~~~~~~~~~~~~~~

 If you want a commit to be applied to a stable branch, you should add an
 appropriate note to the commit message.

 Using a ``Fixes:`` tag as described in :ref:`Patch formatting <formatting>`
 is the preferred way to nominate a commit that should be backported.
 There are scripts that will figure out which releases to apply the patch
 to automatically, so you don't need to figure it out.

 Alternatively, you may use a "CC:" tag. Here are some examples of such a
 note::

     Cc: mesa-stable
     Cc: 20.0 <mesa-stable>
     CC: 20.0 19.3 <mesa-stable>

 Using the CC tag **should** include the stable branches you want to
 nominate the patch to. If you do not provide any version it is nominated
 to all active stable branches.

 .. _testing:

 Testing Patches
 ---------------

 It should go without saying that patches must be tested. In general, do
 whatever testing is prudent.

 You should always run the Mesa test suite before submitting patches. The
 test suite can be run using the 'meson test' command. All tests must
 pass before patches will be accepted, this may mean you have to update
 the tests themselves.

 Whenever possible and applicable, test the patch with
 `Piglit <https://piglit.freedesktop.org>`__ and/or
 `dEQP <https://android.googlesource.com/platform/external/deqp/>`__ to
 check for regressions.

 As mentioned at the beginning, patches should be bisectable. A good way
 to test this is to make use of the \`git rebase\` command, to run your
 tests on each commit. Assuming your branch is based off
 ``origin/master``, you can run:

 ::

    $ git rebase --interactive --exec "meson test -C build/" origin/master

 replacing ``"meson test"`` with whatever other test you want to run.

 .. _submit:

 Submitting Patches
 ------------------

 Patches are submitted to the Mesa project via a
 `GitLab <https://gitlab.freedesktop.org/mesa/mesa>`__ Merge Request.

 Add labels to your MR to help reviewers find it. For example:

 -  Mesa changes affecting all drivers: mesa
 -  Hardware vendor specific code: amd, intel, nvidia, ...
 -  Driver specific code: anvil, freedreno, i965, iris, radeonsi, radv,
    vc4, ...
 -  Other tag examples: gallium, util

 Tick the following when creating the MR. It allows developers to rebase
 your work on top of master.

 ::

    Allow commits from members who can merge to the target branch

 If you revise your patches based on code review and push an update to
 your branch, you should maintain a **clean** history in your patches.
 There should not be "fixup" patches in the history. The series should be
 buildable and functional after every commit whenever you push the
 branch.

 It is your responsibility to keep the MR alive and making progress, as
 there are no guarantees that a Mesa dev will independently take interest
 in it.

 Some other notes:

 -  Make changes and update your branch based on feedback
 -  After an update, for the feedback you handled, close the feedback
    discussion with the "Resolve Discussion" button. This way the
    reviewers know which feedback got handled and which didn't.
 -  Old, stale MR may be closed, but you can reopen it if you still want
    to pursue the changes
 -  You should periodically check to see if your MR needs to be rebased
 -  Make sure your MR is closed if your patches get pushed outside of
    GitLab
 -  Please send MRs from a personal fork rather than from the main Mesa
    repository, as it clutters it unnecessarily.

 .. _reviewing:

 Reviewing Patches
 -----------------

 To participate in code review, you can monitor the GitLab Mesa `Merge
 Requests <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests>`__
 page, and/or register for notifications in your GitLab settings.

 When you've reviewed a patch, please be unambiguous about your review.
 That is, state either

 ::

    Reviewed-by: Joe Hacker <jhacker@foo.com>

 or

 ::

    Acked-by: Joe Hacker <jhacker@foo.com>

 Rather than saying just "LGTM" or "Seems OK".

 If small changes are suggested, it's OK to say something like:

 ::

    With the above fixes, Reviewed-by: Joe Hacker <jhacker@foo.com>

 which tells the patch author that the patch can be committed, as long as
 the issues are resolved first.

 These Reviewed-by, Acked-by, and Tested-by tags should also be amended
 into commits in a MR before it is merged.

 When providing a Reviewed-by, Acked-by, or Tested-by tag in a GitLab MR,
 enclose the tag in backticks:

 ::

    `Reviewed-by: Joe Hacker <jhacker@example.com>`

 This is the markdown format for literal, and will prevent GitLab from
 hiding the < and > symbols.

 Review by non-experts is encouraged. Understanding how someone else goes
 about solving a problem is a great way to learn your way around the
 project. The submitter is expected to evaluate whether they have an
 appropriate amount of review feedback from people who also understand
 the code before merging their patches.

 Nominating a commit for a stable branch
 ---------------------------------------

 There are several ways to nominate a patch for inclusion in the stable
 branch and release. In order or preference:

 - By adding the ``Fixes:`` tag in the commit message as described above, if you are fixing
   a specific commit.
 - By adding the ``Cc: mesa-stable`` tag in the commit message as described above.
 - By submitting a merge request against the ``staging/year.quarter``
   branch on GitLab.

 Please **DO NOT** send patches to mesa-stable@lists.freedesktop.org, it
 is not monitored actively and is a historical artifact.

 If you are not the author of the original patch, please Cc: them in your
 nomination request.

 The current patch status can be observed in the :ref:`staging
 branch <stagingbranch>`.

 .. _criteria:

 Criteria for accepting patches to the stable branch
 ---------------------------------------------------

 Mesa has a designated release manager for each stable branch, and the
 release manager is the only developer that should be pushing changes to
 these branches. Everyone else should nominate patches using the
 mechanism described above. The following rules define which patches are
 accepted and which are not. The stable-release manager is also given
 broad discretion in rejecting patches that have been nominated.

 -  Patch must conform with the :ref:`Basic guidelines <guidelines>`
 -  Patch must have landed in master first. In case where the original
    patch is too large and/or otherwise contradicts with the rules set
    within, a backport is appropriate.
 -  It must not introduce a regression - be that build or runtime wise.

    .. note::
       If the regression is due to faulty piglit/dEQP/CTS/other test
       the latter must be fixed first. A reference to the offending test(s)
       and respective fix(es) should be provided in the nominated patch.

 -  Patch cannot be larger than 100 lines.
 -  Patches that move code around with no functional change should be
    rejected.
 -  Patch must be a bug fix and not a new feature.

    .. note::
       An exception to this rule, are hardware-enabling "features". For
       example, :ref:`backports <backports>` of new code to support a
       newly-developed hardware product can be accepted if they can be
       reasonably determined not to have effects on other hardware.

 -  Patch must be reviewed, For example, the commit message has
    Reviewed-by, Signed-off-by, or Tested-by tags from someone but the
    author.
 -  Performance patches are considered only if they provide information
    about the hardware, program in question and observed improvement. Use
    numbers to represent your measurements.

 If the patch complies with the rules it will be
 :ref:`cherry-picked <pickntest>`. Alternatively the release
 manager will reply to the patch in question stating why the patch has
 been rejected or would request a backport. The stable-release manager
 may at times need to force-push changes to the stable branches, for
 example, to drop a previously-picked patch that was later identified as
 causing a regression). These force-pushes may cause changes to be lost
 from the stable branch if developers push things directly. Consider
 yourself warned.

 .. _backports:

 Sending backports for the stable branch
 ---------------------------------------

 By default merge conflicts are resolved by the stable-release manager.
 The release maintainer should resolve trivial conflicts, but for complex
 conflicts they should ask the original author to provide a backport or
 de-nominate the patch.

 For patches that either need to be nominated after they've landed in
 master, or that are known ahead of time to not not apply cleanly to a
 stable branch (such as due to a rename), using a GitLab MR is most
 appropriate. The MR should be based on and target the
 staging/year.quarter branch, not on the year.quarter branch, per the
 stable branch policy. Assigning the MR to release maintainer for said
 branch or mentioning them is helpful, but not required.

 Git tips
 --------

 -  ``git rebase -i ...`` is your friend. Don't be afraid to use it.
 -  Apply a fixup to commit FOO.

    .. code-block:: console

       git add ...
       git commit --fixup=FOO
       git rebase -i --autosquash ...

 -  Test for build breakage between patches e.g last 8 commits.

    .. code-block:: console

       git rebase -i --exec="ninja -C build/" HEAD~8
	Submitting Patches
	==================

	.. _guidelines:

	Basic guidelines
	----------------

	- Patches should not mix code changes with code formatting changes
	(except, perhaps, in very trivial cases.)
	- Code patches should follow Mesa :doc:`coding
	conventions <codingstyle>`.
	- Whenever possible, patches should only affect individual Mesa/Gallium
	components.
	- Patches should never introduce build breaks and should be bisectable
	(see ``git bisect``.)
	- Patches should be properly :ref:`formatted <formatting>`.
	- Patches should be sufficiently :ref:`tested <testing>` before
	submitting.
	- Patches should be :ref:`submitted <submit>` via a merge request for
	:ref:`review <reviewing>`.

	.. _formatting:

	Patch formatting
	----------------

	- Lines should be limited to 75 characters or less so that git logs
	displayed in 80-column terminals avoid line wrapping. Note that git
	log uses 4 spaces of indentation (4 + 75 < 80).
	- The first line should be a short, concise summary of the change
	prefixed with a module name. Examples:

	::

	mesa: Add support for querying GL_VERTEX_ATTRIB_ARRAY_LONG

	gallium: add PIPE_CAP_DEVICE_RESET_STATUS_QUERY

	i965: Fix missing type in local variable declaration.

	- Subsequent patch comments should describe the change in more detail,
	if needed. For example:

	::

	i965: Remove end-of-thread SEND alignment code.

	This was present in Eric's initial implementation of the compaction code
	for Sandybridge (commit 077d01b6). There is no documentation saying this
	is necessary, and removing it causes no regressions in piglit on any
	platform.

	- A "Signed-off-by:" line is not required, but not discouraged either.
	- If a patch addresses an issue in GitLab, use the Closes: tag For
	example:

	::

	Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/1

	Prefer the full URL to just ``Closes: #1``, since the URL makes it
	easier to get to the bug page from ``git log``

	Do not use the ``Fixes:`` tag for this! Mesa already uses
	``Fixes:`` for something else.
	See :ref:`below <fixes>`.

	- If there have been several revisions to a patch during the review
	process, they should be noted such as in this example:

	::

	st/mesa: add ARB_texture_stencil8 support (v4)

	if we support stencil texturing, enable texture_stencil8
	there is no requirement to support native S8 for this,
	the texture can be converted to x24s8 fine.

	v2: fold fixes from Marek in:
	a) put S8 last in the list
	b) fix renderable to always test for d/s renderable
	fixup the texture case to use a stencil only format
	for picking the format for the texture view.
	v3: hit fallback for getteximage
	v4: put s8 back in front, it shouldn't get picked now (Ilia)

	- If someone tested your patch, document it with a line like this:

	::

	Tested-by: Joe Hacker <jhacker@foo.com>

	- If the patch was reviewed (usually the case) or acked by someone,
	that should be documented with:

	::

	Reviewed-by: Joe Hacker <jhacker@foo.com>
	Acked-by: Joe Hacker <jhacker@foo.com>

	- When updating a merge request add all the tags (``Acked-by:``, ``Reviewed-by:``,
	``Fixes:``, ``Cc: mesa-stable`` and/or other) to the commit messages.
	This provides reviewers with quick feedback if the patch has already
	been reviewed.

	.. _fixes:

	The ``Fixes:`` tag
	------------------

	If a patch addresses a issue introduced with earlier commit, that
	should be noted in the commit message. For example::

	Fixes: d7b3707c612 ("util/disk_cache: use stat() to check if entry is a directory")

	You can produce those fixes lines by running this command once::

	git config --global alias.fixes "show -s --pretty='format:Fixes: %h (\"%s\")'"

	After that, using ``git fixes <sha1>`` will print the full line for you.

	The stable tag
	~~~~~~~~~~~~~~

	If you want a commit to be applied to a stable branch, you should add an
	appropriate note to the commit message.

	Using a ``Fixes:`` tag as described in :ref:`Patch formatting <formatting>`
	is the preferred way to nominate a commit that should be backported.
	There are scripts that will figure out which releases to apply the patch
	to automatically, so you don't need to figure it out.

	Alternatively, you may use a "CC:" tag. Here are some examples of such a
	note::

	Cc: mesa-stable
	Cc: 20.0 <mesa-stable>
	CC: 20.0 19.3 <mesa-stable>

	Using the CC tag should include the stable branches you want to
	nominate the patch to. If you do not provide any version it is nominated
	to all active stable branches.

	.. _testing:

	Testing Patches
	---------------

	It should go without saying that patches must be tested. In general, do
	whatever testing is prudent.

	You should always run the Mesa test suite before submitting patches. The
	test suite can be run using the 'meson test' command. All tests must
	pass before patches will be accepted, this may mean you have to update
	the tests themselves.

	Whenever possible and applicable, test the patch with
	`Piglit <https://piglit.freedesktop.org>`__ and/or
	`dEQP <https://android.googlesource.com/platform/external/deqp/>`__ to
	check for regressions.

	As mentioned at the beginning, patches should be bisectable. A good way
	to test this is to make use of the \`git rebase\` command, to run your
	tests on each commit. Assuming your branch is based off
	``origin/master``, you can run:

	::

	$ git rebase --interactive --exec "meson test -C build/" origin/master

	replacing ``"meson test"`` with whatever other test you want to run.

	.. _submit:

	Submitting Patches
	------------------

	Patches are submitted to the Mesa project via a
	`GitLab <https://gitlab.freedesktop.org/mesa/mesa>`__ Merge Request.

	Add labels to your MR to help reviewers find it. For example:

	- Mesa changes affecting all drivers: mesa
	- Hardware vendor specific code: amd, intel, nvidia, ...
	- Driver specific code: anvil, freedreno, i965, iris, radeonsi, radv,
	vc4, ...
	- Other tag examples: gallium, util

	Tick the following when creating the MR. It allows developers to rebase
	your work on top of master.

	::

	Allow commits from members who can merge to the target branch

	If you revise your patches based on code review and push an update to
	your branch, you should maintain a clean history in your patches.
	There should not be "fixup" patches in the history. The series should be
	buildable and functional after every commit whenever you push the
	branch.

	It is your responsibility to keep the MR alive and making progress, as
	there are no guarantees that a Mesa dev will independently take interest
	in it.

	Some other notes:

	- Make changes and update your branch based on feedback
	- After an update, for the feedback you handled, close the feedback
	discussion with the "Resolve Discussion" button. This way the
	reviewers know which feedback got handled and which didn't.
	- Old, stale MR may be closed, but you can reopen it if you still want
	to pursue the changes
	- You should periodically check to see if your MR needs to be rebased
	- Make sure your MR is closed if your patches get pushed outside of
	GitLab
	- Please send MRs from a personal fork rather than from the main Mesa
	repository, as it clutters it unnecessarily.

	.. _reviewing:

	Reviewing Patches
	-----------------

	To participate in code review, you can monitor the GitLab Mesa `Merge
	Requests <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests>`__
	page, and/or register for notifications in your GitLab settings.

	When you've reviewed a patch, please be unambiguous about your review.
	That is, state either

	::

	Reviewed-by: Joe Hacker <jhacker@foo.com>

	or

	::

	Acked-by: Joe Hacker <jhacker@foo.com>

	Rather than saying just "LGTM" or "Seems OK".

	If small changes are suggested, it's OK to say something like:

	::

	With the above fixes, Reviewed-by: Joe Hacker <jhacker@foo.com>

	which tells the patch author that the patch can be committed, as long as
	the issues are resolved first.

	These Reviewed-by, Acked-by, and Tested-by tags should also be amended
	into commits in a MR before it is merged.

	When providing a Reviewed-by, Acked-by, or Tested-by tag in a GitLab MR,
	enclose the tag in backticks:

	::

	`Reviewed-by: Joe Hacker <jhacker@example.com>`

	This is the markdown format for literal, and will prevent GitLab from
	hiding the < and > symbols.

	Review by non-experts is encouraged. Understanding how someone else goes
	about solving a problem is a great way to learn your way around the
	project. The submitter is expected to evaluate whether they have an
	appropriate amount of review feedback from people who also understand
	the code before merging their patches.

	Nominating a commit for a stable branch
	---------------------------------------

	There are several ways to nominate a patch for inclusion in the stable
	branch and release. In order or preference:

	- By adding the ``Fixes:`` tag in the commit message as described above, if you are fixing
	a specific commit.
	- By adding the ``Cc: mesa-stable`` tag in the commit message as described above.
	- By submitting a merge request against the ``staging/year.quarter``
	branch on GitLab.

	Please DO NOT send patches to mesa-stable@lists.freedesktop.org, it
	is not monitored actively and is a historical artifact.

	If you are not the author of the original patch, please Cc: them in your
	nomination request.

	The current patch status can be observed in the :ref:`staging
	branch <stagingbranch>`.

	.. _criteria:

	Criteria for accepting patches to the stable branch
	---------------------------------------------------

	Mesa has a designated release manager for each stable branch, and the
	release manager is the only developer that should be pushing changes to
	these branches. Everyone else should nominate patches using the
	mechanism described above. The following rules define which patches are
	accepted and which are not. The stable-release manager is also given
	broad discretion in rejecting patches that have been nominated.

	- Patch must conform with the :ref:`Basic guidelines <guidelines>`
	- Patch must have landed in master first. In case where the original
	patch is too large and/or otherwise contradicts with the rules set
	within, a backport is appropriate.
	- It must not introduce a regression - be that build or runtime wise.

	.. note::
	If the regression is due to faulty piglit/dEQP/CTS/other test
	the latter must be fixed first. A reference to the offending test(s)
	and respective fix(es) should be provided in the nominated patch.

	- Patch cannot be larger than 100 lines.
	- Patches that move code around with no functional change should be
	rejected.
	- Patch must be a bug fix and not a new feature.

	.. note::
	An exception to this rule, are hardware-enabling "features". For
	example, :ref:`backports <backports>` of new code to support a
	newly-developed hardware product can be accepted if they can be
	reasonably determined not to have effects on other hardware.

	- Patch must be reviewed, For example, the commit message has
	Reviewed-by, Signed-off-by, or Tested-by tags from someone but the
	author.
	- Performance patches are considered only if they provide information
	about the hardware, program in question and observed improvement. Use
	numbers to represent your measurements.

	If the patch complies with the rules it will be
	:ref:`cherry-picked <pickntest>`. Alternatively the release
	manager will reply to the patch in question stating why the patch has
	been rejected or would request a backport. The stable-release manager
	may at times need to force-push changes to the stable branches, for
	example, to drop a previously-picked patch that was later identified as
	causing a regression). These force-pushes may cause changes to be lost
	from the stable branch if developers push things directly. Consider
	yourself warned.

	.. _backports:

	Sending backports for the stable branch
	---------------------------------------

	By default merge conflicts are resolved by the stable-release manager.
	The release maintainer should resolve trivial conflicts, but for complex
	conflicts they should ask the original author to provide a backport or
	de-nominate the patch.

	For patches that either need to be nominated after they've landed in
	master, or that are known ahead of time to not not apply cleanly to a
	stable branch (such as due to a rename), using a GitLab MR is most
	appropriate. The MR should be based on and target the
	staging/year.quarter branch, not on the year.quarter branch, per the
	stable branch policy. Assigning the MR to release maintainer for said
	branch or mentioning them is helpful, but not required.

	Git tips
	--------

	- ``git rebase -i ...`` is your friend. Don't be afraid to use it.
	- Apply a fixup to commit FOO.

	.. code-block:: console

	git add ...
	git commit --fixup=FOO
	git rebase -i --autosquash ...

	- Test for build breakage between patches e.g last 8 commits.

	.. code-block:: console

	git rebase -i --exec="ninja -C build/" HEAD~8