Currently we have a short paragraph saying that patches must include a Signed-off-by line, and merely link to the kernel documentation. The linked kernel docs have a lot of content beyond the part about sign-off an thus are misleading/distracting to QEMU contributors.
This introduces a dedicated 'code-provenance' page in QEMU talking about why we require sign-off, explaining the other tags we commonly use, and what to do in some edge cases. Signed-off-by: Daniel P. Berrangé <berra...@redhat.com> --- docs/devel/code-provenance.rst | 212 ++++++++++++++++++++++++++++++ docs/devel/index-process.rst | 1 + docs/devel/submitting-a-patch.rst | 19 +-- 3 files changed, 215 insertions(+), 17 deletions(-) create mode 100644 docs/devel/code-provenance.rst diff --git a/docs/devel/code-provenance.rst b/docs/devel/code-provenance.rst new file mode 100644 index 0000000000..7c42fae571 --- /dev/null +++ b/docs/devel/code-provenance.rst @@ -0,0 +1,212 @@ +.. _code-provenance: + +Code provenance +=============== + +Certifying patch submissions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The QEMU community **mandates** all contributors to certify provenance of +patch submissions they make to the project. To put it another way, +contributors must indicate that they are legally permitted to contribute to +the project. + +Certification is achieved with a low overhead by adding a single line to the +bottom of every git commit:: + + Signed-off-by: YOUR NAME <YOUR@EMAIL> + +The addition of this line asserts that the author of the patch is contributing +in accordance with the clauses specified in the +`Developer's Certificate of Origin <https://developercertificate.org>`__: + +.. _dco: + +:: + 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. + +It is generally expected that the name and email addresses used in one of the +``Signed-off-by`` lines, matches that of the git commit ``Author`` field. + +If the person sending the mail is not one of the patch authors, they are none +the less expected to add their own ``Signed-off-by`` to comply with the DCO +clause (c). + +Multiple authorship +~~~~~~~~~~~~~~~~~~~ + +It is not uncommon for a patch to have contributions from multiple authors. In +this scenario, git commits will usually be expected to have a ``Signed-off-by`` +line for each contributor involved in creation of the patch. Some edge cases: + + * The non-primary author's contributions were so trivial that they can be + considered not subject to copyright. In this case the secondary authors + need not include a ``Signed-off-by``. + + This case most commonly applies where QEMU reviewers give short snippets + of code as suggested fixes to a patch. The reviewers don't need to have + their own ``Signed-off-by`` added unless their code suggestion was + unusually large, but it is common to add ``Suggested-by`` as a credit + for non-trivial code. + + * Both contributors work for the same employer and the employer requires + copyright assignment. + + It can be said that in this case a ``Signed-off-by`` is indicating that + the person has permission to contribute from their employer who is the + copyright holder. It is none the less still preferable to include a + ``Signed-off-by`` for each contributor, as in some countries employees are + not able to assign copyright to their employer, and it also covers any + time invested outside working hours. + +When multiple ``Signed-off-by`` tags are present, they should be strictly kept +in order of authorship, from oldest to newest. + +Other commit tags +~~~~~~~~~~~~~~~~~ + +While the ``Signed-off-by`` tag is mandatory, there are a number of other tags +that are commonly used during QEMU development: + + * **``Reviewed-by``**: when a QEMU community member reviews a patch on the + mailing list, if they consider the patch acceptable, they should send an + email reply containing a ``Reviewed-by`` tag. Subsystem maintainers who + review a patch should add this even if they are also adding their + ``Signed-off-by`` to the same commit. + + * **``Acked-by``**: when a QEMU subsystem maintainer approves a patch that + touches their subsystem, but intends to allow a different maintainer to + queue it and send a pull request, they would send a mail containing a + ``Acked-by`` tag. Where a patch touches multiple subsystems, ``Acked-by`` + only implies review of the maintainers' own areas of responsibility. If a + maintainer wants to indicate they have done a full review they should use + a ``Reviewed-by`` tag. + + * **``Tested-by``**: when a QEMU community member has functionally tested the + behaviour of the patch in some manner, they should send an email reply + containing a ``Tested-by`` tag. + + * **``Reported-by``**: when a QEMU community member reports a problem via the + mailing list, or some other informal channel that is not the issue tracker, + it is good practice to credit them by including a ``Reported-by`` tag on + any patch fixing the issue. When the problem is reported via the GitLab + issue tracker, however, it is sufficient to just include a link to the + issue. + + * **``Suggested-by``**: when a reviewer or other 3rd party makes non-trivial + suggestions for how to change a patch, it is good practice to credit them + by including a ``Suggested-by`` tag. + +Subsystem maintainer requirements +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +When a subsystem maintainer accepts a patch from a contributor, in addition to +the normal code review points, they are expected to validate the presence of +suitable ``Signed-off-by`` tags. + +At the time they queue the patch in their subsystem tree, the maintainer +**must** also then add their own ``Signed-off-by`` to indicate that they have +done the aforementioned validation. This is in addition to any of their own +``Reviewed-by`` tags the subsystem maintainer may wish to include. + +Tools for adding ``Signed-off-by`` +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +There are a variety of ways tools can support adding ``Signed-off-by`` tags +for patches, avoiding the need for contributors to manually type in this +repetitive text each time. + +git commands +^^^^^^^^^^^^ + +When creating, or amending, a commit the ``-s`` flag to ``git commit`` will +append a suitable line matching the configuring git author details. + +If preparing patches using the ``git format-patch`` tool, the ``-s`` flag can +be used to append a suitable line in the emails it creates, without modifying +the local commits. Alternatively to modify all the local commits on a branch:: + + git rebase master -x 'git commit --amend --no-edit -s' + +emacs +^^^^^ + +In the file ``$HOME/.emacs.d/abbrev_defs`` add:: + + (define-abbrev-table 'global-abbrev-table + '( + ("8rev" "Reviewed-by: YOUR NAME <y...@email.addr>" nil 1) + ("8ack" "Acked-by: YOUR NAME <y...@email.addr>" nil 1) + ("8test" "Tested-by: YOUR NAME <y...@email.addr>" nil 1) + ("8sob" "Signed-off-by: YOUR NAME <y...@email.addr>" nil 1) + )) + +with this change, if you type (for example) ``8rev`` followed by ``<space>`` +or ``<enter>`` it will expand to the whole phrase. + +vim +^^^ + +In the file ``$HOME/.vimrc`` add:: + + iabbrev 8rev Reviewed-by: YOUR NAME <y...@email.addr> + iabbrev 8ack Acked-by: YOUR NAME <y...@email.addr> + iabbrev 8test Tested-by: YOUR NAME <y...@email.addr> + iabbrev 8sob Signed-off-by: YOUR NAME <y...@email.addr> + +with this change, if you type (for example) ``8rev`` followed by ``<space>`` +or ``<enter>`` it will expand to the whole phrase. + +Re-starting abandoned work +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +For a variety of reasons there are some patches that get submitted to QEMU but +never merged. An unrelated contributor may decide (months or years later) to +continue working from the abandoned patch and re-submit it with extra changes. + +The general principles when picking up abandoned work are: + + * Continue to credit the original author for their work, by maintaining their + original ``Signed-off-by`` + * Indicate where the original patch was obtained from (mailing list, bug + tracker, author's git repo, etc) when sending it for review + * Acknowledge the extra work of the new contributor by including their + ``Signed-off-by`` in the patch in addition to the orignal author's + * Indicate who is responsible for what parts of the patch. This is typically + done via a note in the commit message, just prior to the new contributor's + ``Signed-off-by``:: + + Signed-off-by: Some Person <some.per...@example.com> + [Rebased and added support for 'foo'] + Signed-off-by: New Person <new.per...@mycorp.test> + +In complicated cases, or if otherwise unsure, ask for advice on the project +mailing list. + +It is also recommended to attempt to contact the original author to let them +know you are interested in taking over their work, in case they still intended +to return to the work, or had any suggestions about the best way to continue. diff --git a/docs/devel/index-process.rst b/docs/devel/index-process.rst index 362f97ee30..b54e58105e 100644 --- a/docs/devel/index-process.rst +++ b/docs/devel/index-process.rst @@ -13,6 +13,7 @@ Notes about how to interact with the community and how and where to submit patch maintainers style submitting-a-patch + code-provenance trivial-patches stable-process submitting-a-pull-request diff --git a/docs/devel/submitting-a-patch.rst b/docs/devel/submitting-a-patch.rst index 83e9092b8c..2cc4d53ff6 100644 --- a/docs/devel/submitting-a-patch.rst +++ b/docs/devel/submitting-a-patch.rst @@ -322,23 +322,8 @@ Patch emails must include a ``Signed-off-by:`` line Your patches **must** include a Signed-off-by: line. This is a hard requirement because it's how you say "I'm legally okay to contribute -this and happy for it to go into QEMU". The process is modelled after -the `Linux kernel -<http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/SubmittingPatches?id=f6f94e2ab1b33f0082ac22d71f66385a60d8157f#n297>`__ -policy. - -If you wrote the patch, make sure your "From:" and "Signed-off-by:" -lines use the same spelling. It's okay if you subscribe or contribute to -the list via more than one address, but using multiple addresses in one -commit just confuses things. If someone else wrote the patch, git will -include a "From:" line in the body of the email (different from your -envelope From:) that will give credit to the correct author; but again, -that author's Signed-off-by: line is mandatory, with the same spelling. - -There are various tooling options for automatically adding these tags -include using ``git commit -s`` or ``git format-patch -s``. For more -information see `SubmittingPatches 1.12 -<http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/SubmittingPatches?id=f6f94e2ab1b33f0082ac22d71f66385a60d8157f#n297>`__. +this and happy for it to go into QEMU". For full guidance, read the +:ref:`code-provenance` documentation. .. _include_a_meaningful_cover_letter: -- 2.43.0
