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1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases.These patches will be merged automatically in the corresponding common kernels. If the patch is alreadyin upstream Linux, post a backport of the patch that conforms to the patch requirements below.

   • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,additions ofEXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so includethe new driver or changes to an existing driver in the same patchset as the export.
   • When sending patches upstream, the commit message must contain a clear case for why the patchis needed and beneficial to the community. Enabling out-of-tree drivers or functionality is notnot a persuasive case.

2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these arefixing an Android-specific bug, these are very unlikely to be accepted unless they have beencoordinated withkernel-team@android.com. If you want to proceed, post a patch that conforms to thepatch requirements below.

• All patches must conform to the Linux kernel coding standards and passscript/checkpatch.pl
• Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures(seehttps://source.android.com/setup/build/building-kernels)
• If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch:UPSTREAM:,BACKPORT:,FROMGIT:,FROMLIST:, orANDROID:.
• All patches must have aChange-Id: tag (seehttps://gerrit-review.googlesource.com/Documentation/user-changeid.html)
• If an Android bug has been assigned, there must be aBug: tag.
• All patches must have aSigned-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

• If the patch is a cherry-pick from Linux mainline with no changes at all
  • tag the patch subject withUPSTREAM:.
  • add upstream commit information with a(cherry picked from commit ...) line
  • Example:
    • if the upstream commit message is

        important patch from upstream        This is the detailed description of the important patch        Signed-off-by: Fred Jones <fred.jones@foo.org>

• then Joe Smith would upload the patch for the common kernel as

        UPSTREAM: important patch from upstream        This is the detailed description of the important patch        Signed-off-by: Fred Jones <fred.jones@foo.org>        Bug: 135791357        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)        Signed-off-by: Joe Smith <joe.smith@foo.org>

• If the patch requires any changes from the upstream version, tag the patch withBACKPORT:instead ofUPSTREAM:.
  • use the same tags asUPSTREAM:
  • add comments about the changes under the(cherry picked from commit ...) line
  • Example:

        BACKPORT: important patch from upstream        This is the detailed description of the important patch        Signed-off-by: Fred Jones <fred.jones@foo.org>        Bug: 135791357        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)        [joe: Resolved minor conflict in drivers/foo/bar.c ]        Signed-off-by: Joe Smith <joe.smith@foo.org>

• If the patch has been merged into an upstream maintainer tree, but has not yetbeen merged into Linux mainline
  • tag the patch subject withFROMGIT:
  • add info on where the patch came from as(cherry picked from commit <sha1> <repo> <branch>). Thismust be a stable maintainer branch (not rebased, so don't uselinux-next for example).
  • if changes were required, useBACKPORT: FROMGIT:
  • Example:
    • if the commit message in the maintainer tree is

        important patch from upstream        This is the detailed description of the important patch        Signed-off-by: Fred Jones <fred.jones@foo.org>

• then Joe Smith would upload the patch for the common kernel as

        FROMGIT: important patch from upstream        This is the detailed description of the important patch        Signed-off-by: Fred Jones <fred.jones@foo.org>        Bug: 135791357        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01        Signed-off-by: Joe Smith <joe.smith@foo.org>

• If the patch has been submitted to LKML, but not accepted into any maintainer tree
  • tag the patch subject withFROMLIST:
  • add aLink: tag with a link to the submittal on lore.kernel.org
  • add aBug: tag with the Android bug (required for patches not accepted intoa maintainer tree)
  • if changes were required, useBACKPORT: FROMLIST:
  • Example:

        FROMLIST: important patch from upstream        This is the detailed description of the important patch        Signed-off-by: Fred Jones <fred.jones@foo.org>        Bug: 135791357        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01        Signed-off-by: Joe Smith <joe.smith@foo.org>

• If the patch is fixing a bug to Android-specific code
  • tag the patch subject withANDROID:
  • add aFixes: tag that cites the patch with the bug
  • Example:

        ANDROID: fix android-specific bug in foobar.c        This is the detailed description of the important fix        Fixes: 1234abcd2468 ("foobar: add cool feature")        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01        Signed-off-by: Joe Smith <joe.smith@foo.org>

• If the patch is a new feature
  • tag the patch subject withANDROID:
  • add aBug: tag with the Android bug (required for android-specific features)