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diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches index 36f1dedc944c..81455705e4a6 100644 --- a/Documentation/SubmittingPatches +++ b/Documentation/SubmittingPatches @@ -1,841 +1 @@ -.. _submittingpatches: - -How to Get Your Change Into the Linux Kernel or Care And Operation Of Your Linus Torvalds -========================================================================================= - -For a person or company who wishes to submit a change to the Linux -kernel, the process can sometimes be daunting if you're not familiar -with "the system." This text is a collection of suggestions which -can greatly increase the chances of your change being accepted. - -This document contains a large number of suggestions in a relatively terse -format. For detailed information on how the kernel development process -works, see :ref:`Documentation/development-process <development_process_main>`. -Also, read :ref:`Documentation/SubmitChecklist <submitchecklist>` -for a list of items to check before -submitting code. If you are submitting a driver, also read -:ref:`Documentation/SubmittingDrivers <submittingdrivers>`; -for device tree binding patches, read -Documentation/devicetree/bindings/submitting-patches.txt. - -Many of these steps describe the default behavior of the ``git`` version -control system; if you use ``git`` to prepare your patches, you'll find much -of the mechanical work done for you, though you'll still need to prepare -and document a sensible set of patches. In general, use of ``git`` will make -your life as a kernel developer easier. - -Creating and Sending your Change -******************************** - - -0) Obtain a current source tree -------------------------------- - -If you do not have a repository with the current kernel source handy, use -``git`` to obtain one. You'll want to start with the mainline repository, -which can be grabbed with:: - - git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git - -Note, however, that you may not want to develop against the mainline tree -directly. Most subsystem maintainers run their own trees and want to see -patches prepared against those trees. See the **T:** entry for the subsystem -in the MAINTAINERS file to find that tree, or simply ask the maintainer if -the tree is not listed there. - -It is still possible to download kernel releases via tarballs (as described -in the next section), but that is the hard way to do kernel development. - -1) ``diff -up`` ---------------- - -If you must generate your patches by hand, use ``diff -up`` or ``diff -uprN`` -to create patches. Git generates patches in this form by default; if -you're using ``git``, you can skip this section entirely. - -All changes to the Linux kernel occur in the form of patches, as -generated by :manpage:`diff(1)`. When creating your patch, make sure to -create it in "unified diff" format, as supplied by the ``-u`` argument -to :manpage:`diff(1)`. -Also, please use the ``-p`` argument which shows which C function each -change is in - that makes the resultant ``diff`` a lot easier to read. -Patches should be based in the root kernel source directory, -not in any lower subdirectory. - -To create a patch for a single file, it is often sufficient to do:: - - SRCTREE= linux - MYFILE= drivers/net/mydriver.c - - cd $SRCTREE - cp $MYFILE $MYFILE.orig - vi $MYFILE # make your change - cd .. - diff -up $SRCTREE/$MYFILE{.orig,} > /tmp/patch - -To create a patch for multiple files, you should unpack a "vanilla", -or unmodified kernel source tree, and generate a ``diff`` against your -own source tree. For example:: - - MYSRC= /devel/linux - - tar xvfz linux-3.19.tar.gz - mv linux-3.19 linux-3.19-vanilla - diff -uprN -X linux-3.19-vanilla/Documentation/dontdiff \ - linux-3.19-vanilla $MYSRC > /tmp/patch - -``dontdiff`` is a list of files which are generated by the kernel during -the build process, and should be ignored in any :manpage:`diff(1)`-generated -patch. - -Make sure your patch does not include any extra files which do not -belong in a patch submission. Make sure to review your patch -after- -generating it with :manpage:`diff(1)`, to ensure accuracy. - -If your changes produce a lot of deltas, you need to split them into -individual patches which modify things in logical stages; see -:ref:`split_changes`. This will facilitate review by other kernel developers, -very important if you want your patch accepted. - -If you're using ``git``, ``git rebase -i`` can help you with this process. If -you're not using ``git``, ``quilt`` <http://savannah.nongnu.org/projects/quilt> -is another popular alternative. - -.. _describe_changes: - -2) Describe your changes ------------------------- - -Describe your problem. Whether your patch is a one-line bug fix or -5000 lines of a new feature, there must be an underlying problem that -motivated you to do this work. Convince the reviewer that there is a -problem worth fixing and that it makes sense for them to read past the -first paragraph. - -Describe user-visible impact. Straight up crashes and lockups are -pretty convincing, but not all bugs are that blatant. Even if the -problem was spotted during code review, describe the impact you think -it can have on users. Keep in mind that the majority of Linux -installations run kernels from secondary stable trees or -vendor/product-specific trees that cherry-pick only specific patches -from upstream, so include anything that could help route your change -downstream: provoking circumstances, excerpts from dmesg, crash -descriptions, performance regressions, latency spikes, lockups, etc. - -Quantify optimizations and trade-offs. If you claim improvements in -performance, memory consumption, stack footprint, or binary size, -include numbers that back them up. But also describe non-obvious -costs. Optimizations usually aren't free but trade-offs between CPU, -memory, and readability; or, when it comes to heuristics, between -different workloads. Describe the expected downsides of your -optimization so that the reviewer can weigh costs against benefits. - -Once the problem is established, describe what you are actually doing -about it in technical detail. It's important to describe the change -in plain English for the reviewer to verify that the code is behaving -as you intend it to. - -The maintainer will thank you if you write your patch description in a -form which can be easily pulled into Linux's source code management -system, ``git``, as a "commit log". See :ref:`explicit_in_reply_to`. - -Solve only one problem per patch. If your description starts to get -long, that's a sign that you probably need to split up your patch. -See :ref:`split_changes`. - -When you submit or resubmit a patch or patch series, include the -complete patch description and justification for it. Don't just -say that this is version N of the patch (series). Don't expect the -subsystem maintainer to refer back to earlier patch versions or referenced -URLs to find the patch description and put that into the patch. -I.e., the patch (series) and its description should be self-contained. -This benefits both the maintainers and reviewers. Some reviewers -probably didn't even receive earlier versions of the patch. - -Describe your changes in imperative mood, e.g. "make xyzzy do frotz" -instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy -to do frotz", as if you are giving orders to the codebase to change -its behaviour. - -If the patch fixes a logged bug entry, refer to that bug entry by -number and URL. If the patch follows from a mailing list discussion, -give a URL to the mailing list archive; use the https://lkml.kernel.org/ -redirector with a ``Message-Id``, to ensure that the links cannot become -stale. - -However, try to make your explanation understandable without external -resources. In addition to giving a URL to a mailing list archive or -bug, summarize the relevant points of the discussion that led to the -patch as submitted. - -If you want to refer to a specific commit, don't just refer to the -SHA-1 ID of the commit. Please also include the oneline summary of -the commit, to make it easier for reviewers to know what it is about. -Example:: - - Commit e21d2170f36602ae2708 ("video: remove unnecessary - platform_set_drvdata()") removed the unnecessary - platform_set_drvdata(), but left the variable "dev" unused, - delete it. - -You should also be sure to use at least the first twelve characters of the -SHA-1 ID. The kernel repository holds a *lot* of objects, making -collisions with shorter IDs a real possibility. Bear in mind that, even if -there is no collision with your six-character ID now, that condition may -change five years from now. - -If your patch fixes a bug in a specific commit, e.g. you found an issue using -``git bisect``, please use the 'Fixes:' tag with the first 12 characters of -the SHA-1 ID, and the one line summary. For example:: - - Fixes: e21d2170f366 ("video: remove unnecessary platform_set_drvdata()") - -The following ``git config`` settings can be used to add a pretty format for -outputting the above style in the ``git log`` or ``git show`` commands:: - - [core] - abbrev = 12 - [pretty] - fixes = Fixes: %h (\"%s\") - -.. _split_changes: - -3) Separate your changes ------------------------- - -Separate each **logical change** into a separate patch. - -For example, if your changes include both bug fixes and performance -enhancements for a single driver, separate those changes into two -or more patches. If your changes include an API update, and a new -driver which uses that new API, separate those into two patches. - -On the other hand, if you make a single change to numerous files, -group those changes into a single patch. Thus a single logical change -is contained within a single patch. - -The point to remember is that each patch should make an easily understood -change that can be verified by reviewers. Each patch should be justifiable -on its own merits. - -If one patch depends on another patch in order for a change to be -complete, that is OK. Simply note **"this patch depends on patch X"** -in your patch description. - -When dividing your change into a series of patches, take special care to -ensure that the kernel builds and runs properly after each patch in the -series. Developers using ``git bisect`` to track down a problem can end up -splitting your patch series at any point; they will not thank you if you -introduce bugs in the middle. - -If you cannot condense your patch set into a smaller set of patches, -then only post say 15 or so at a time and wait for review and integration. - - - -4) Style-check your changes ---------------------------- - -Check your patch for basic style violations, details of which can be -found in -:ref:`Documentation/CodingStyle <codingstyle>`. -Failure to do so simply wastes -the reviewers time and will get your patch rejected, probably -without even being read. - -One significant exception is when moving code from one file to -another -- in this case you should not modify the moved code at all in -the same patch which moves it. This clearly delineates the act of -moving the code and your changes. This greatly aids review of the -actual differences and allows tools to better track the history of -the code itself. - -Check your patches with the patch style checker prior to submission -(scripts/checkpatch.pl). Note, though, that the style checker should be -viewed as a guide, not as a replacement for human judgment. If your code -looks better with a violation then its probably best left alone. - -The checker reports at three levels: - - ERROR: things that are very likely to be wrong - - WARNING: things requiring careful review - - CHECK: things requiring thought - -You should be able to justify all violations that remain in your -patch. - - -5) Select the recipients for your patch ---------------------------------------- - -You should always copy the appropriate subsystem maintainer(s) on any patch -to code that they maintain; look through the MAINTAINERS file and the -source code revision history to see who those maintainers are. The -script scripts/get_maintainer.pl can be very useful at this step. If you -cannot find a maintainer for the subsystem you are working on, Andrew -Morton (akpm@linux-foundation.org) serves as a maintainer of last resort. - -You should also normally choose at least one mailing list to receive a copy -of your patch set. linux-kernel@vger.kernel.org functions as a list of -last resort, but the volume on that list has caused a number of developers -to tune it out. Look in the MAINTAINERS file for a subsystem-specific -list; your patch will probably get more attention there. Please do not -spam unrelated lists, though. - -Many kernel-related lists are hosted on vger.kernel.org; you can find a -list of them at http://vger.kernel.org/vger-lists.html. There are -kernel-related lists hosted elsewhere as well, though. - -Do not send more than 15 patches at once to the vger mailing lists!!! - -Linus Torvalds is the final arbiter of all changes accepted into the -Linux kernel. His e-mail address is <torvalds@linux-foundation.org>. -He gets a lot of e-mail, and, at this point, very few patches go through -Linus directly, so typically you should do your best to -avoid- -sending him e-mail. - -If you have a patch that fixes an exploitable security bug, send that patch -to security@kernel.org. For severe bugs, a short embargo may be considered -to allow distributors to get the patch out to users; in such cases, -obviously, the patch should not be sent to any public lists. - -Patches that fix a severe bug in a released kernel should be directed -toward the stable maintainers by putting a line like this:: - - Cc: stable@vger.kernel.org - -into the sign-off area of your patch (note, NOT an email recipient). You -should also read -:ref:`Documentation/stable_kernel_rules.txt <stable_kernel_rules>` -in addition to this file. - -Note, however, that some subsystem maintainers want to come to their own -conclusions on which patches should go to the stable trees. The networking -maintainer, in particular, would rather not see individual developers -adding lines like the above to their patches. - -If changes affect userland-kernel interfaces, please send the MAN-PAGES -maintainer (as listed in the MAINTAINERS file) a man-pages patch, or at -least a notification of the change, so that some information makes its way -into the manual pages. User-space API changes should also be copied to -linux-api@vger.kernel.org. - -For small patches you may want to CC the Trivial Patch Monkey -trivial@kernel.org which collects "trivial" patches. Have a look -into the MAINTAINERS file for its current manager. - -Trivial patches must qualify for one of the following rules: - -- Spelling fixes in documentation -- Spelling fixes for errors which could break :manpage:`grep(1)` -- Warning fixes (cluttering with useless warnings is bad) -- Compilation fixes (only if they are actually correct) -- Runtime fixes (only if they actually fix things) -- Removing use of deprecated functions/macros -- Contact detail and documentation fixes -- Non-portable code replaced by portable code (even in arch-specific, - since people copy, as long as it's trivial) -- Any fix by the author/maintainer of the file (ie. patch monkey - in re-transmission mode) - - - -6) No MIME, no links, no compression, no attachments. Just plain text ----------------------------------------------------------------------- - -Linus and other kernel developers need to be able to read and comment -on the changes you are submitting. It is important for a kernel -developer to be able to "quote" your changes, using standard e-mail -tools, so that they may comment on specific portions of your code. - -For this reason, all patches should be submitted by e-mail "inline". - -.. warning:: - - Be wary of your editor's word-wrap corrupting your patch, - if you choose to cut-n-paste your patch. - -Do not attach the patch as a MIME attachment, compressed or not. -Many popular e-mail applications will not always transmit a MIME -attachment as plain text, making it impossible to comment on your -code. A MIME attachment also takes Linus a bit more time to process, -decreasing the likelihood of your MIME-attached change being accepted. - -Exception: If your mailer is mangling patches then someone may ask -you to re-send them using MIME. - -See :ref:`Documentation/email-clients.txt <email_clients>` -for hints about configuring your e-mail client so that it sends your patches -untouched. - -7) E-mail size --------------- - -Large changes are not appropriate for mailing lists, and some -maintainers. If your patch, uncompressed, exceeds 300 kB in size, -it is preferred that you store your patch on an Internet-accessible -server, and provide instead a URL (link) pointing to your patch. But note -that if your patch exceeds 300 kB, it almost certainly needs to be broken up -anyway. - -8) Respond to review comments ------------------------------ - -Your patch will almost certainly get comments from reviewers on ways in -which the patch can be improved. You must respond to those comments; -ignoring reviewers is a good way to get ignored in return. Review comments -or questions that do not lead to a code change should almost certainly -bring about a comment or changelog entry so that the next reviewer better -understands what is going on. - -Be sure to tell the reviewers what changes you are making and to thank them -for their time. Code review is a tiring and time-consuming process, and -reviewers sometimes get grumpy. Even in that case, though, respond -politely and address the problems they have pointed out. - - -9) Don't get discouraged - or impatient ---------------------------------------- - -After you have submitted your change, be patient and wait. Reviewers are -busy people and may not get to your patch right away. - -Once upon a time, patches used to disappear into the void without comment, -but the development process works more smoothly than that now. You should -receive comments within a week or so; if that does not happen, make sure -that you have sent your patches to the right place. Wait for a minimum of -one week before resubmitting or pinging reviewers - possibly longer during -busy times like merge windows. - - -10) Include PATCH in the subject --------------------------------- - -Due to high e-mail traffic to Linus, and to linux-kernel, it is common -convention to prefix your subject line with [PATCH]. This lets Linus -and other kernel developers more easily distinguish patches from other -e-mail discussions. - - - -11) Sign your work ------------------- - -To improve tracking of who did what, especially with patches that can -percolate to their final resting place in the kernel through several -layers of maintainers, we've introduced a "sign-off" procedure on -patches that are being emailed around. - -The sign-off is a simple line at the end of the explanation for the -patch, which certifies that you wrote it or otherwise have the right to -pass it on as an open-source patch. The rules are pretty simple: if you -can certify the below: - -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. - -then you just add a line saying:: - - Signed-off-by: Random J Developer <random@developer.example.org> - -using your real name (sorry, no pseudonyms or anonymous contributions.) - -Some people also put extra tags at the end. They'll just be ignored for -now, but you can do this to mark internal company procedures or just -point out some special detail about the sign-off. - -If you are a subsystem or branch maintainer, sometimes you need to slightly -modify patches you receive in order to merge them, because the code is not -exactly the same in your tree and the submitters'. If you stick strictly to -rule (c), you should ask the submitter to rediff, but this is a totally -counter-productive waste of time and energy. Rule (b) allows you to adjust -the code, but then it is very impolite to change one submitter's code and -make him endorse your bugs. To solve this problem, it is recommended that -you add a line between the last Signed-off-by header and yours, indicating -the nature of your changes. While there is nothing mandatory about this, it -seems like prepending the description with your mail and/or name, all -enclosed in square brackets, is noticeable enough to make it obvious that -you are responsible for last-minute changes. Example:: - - Signed-off-by: Random J Developer <random@developer.example.org> - [lucky@maintainer.example.org: struct foo moved from foo.c to foo.h] - Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org> - -This practice is particularly helpful if you maintain a stable branch and -want at the same time to credit the author, track changes, merge the fix, -and protect the submitter from complaints. Note that under no circumstances -can you change the author's identity (the From header), as it is the one -which appears in the changelog. - -Special note to back-porters: It seems to be a common and useful practice -to insert an indication of the origin of a patch at the top of the commit -message (just after the subject line) to facilitate tracking. For instance, -here's what we see in a 3.x-stable release:: - - Date: Tue Oct 7 07:26:38 2014 -0400 - - libata: Un-break ATA blacklist - - commit 1c40279960bcd7d52dbdf1d466b20d24b99176c8 upstream. - -And here's what might appear in an older kernel once a patch is backported:: - - Date: Tue May 13 22:12:27 2008 +0200 - - wireless, airo: waitbusy() won't delay - - [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a] - -Whatever the format, this information provides a valuable help to people -tracking your trees, and to people trying to troubleshoot bugs in your -tree. - - -12) When to use Acked-by: and Cc: ---------------------------------- - -The Signed-off-by: tag indicates that the signer was involved in the -development of the patch, or that he/she was in the patch's delivery path. - -If a person was not directly involved in the preparation or handling of a -patch but wishes to signify and record their approval of it then they can -ask to have an Acked-by: line added to the patch's changelog. - -Acked-by: is often used by the maintainer of the affected code when that -maintainer neither contributed to nor forwarded the patch. - -Acked-by: is not as formal as Signed-off-by:. It is a record that the acker -has at least reviewed the patch and has indicated acceptance. Hence patch -mergers will sometimes manually convert an acker's "yep, looks good to me" -into an Acked-by: (but note that it is usually better to ask for an -explicit ack). - -Acked-by: does not necessarily indicate acknowledgement of the entire patch. -For example, if a patch affects multiple subsystems and has an Acked-by: from -one subsystem maintainer then this usually indicates acknowledgement of just -the part which affects that maintainer's code. Judgement should be used here. -When in doubt people should refer to the original discussion in the mailing -list archives. - -If a person has had the opportunity to comment on a patch, but has not -provided such comments, you may optionally add a ``Cc:`` tag to the patch. -This is the only tag which might be added without an explicit action by the -person it names - but it should indicate that this person was copied on the -patch. This tag documents that potentially interested parties -have been included in the discussion. - - -13) Using Reported-by:, Tested-by:, Reviewed-by:, Suggested-by: and Fixes: --------------------------------------------------------------------------- - -The Reported-by tag gives credit to people who find bugs and report them and it -hopefully inspires them to help us again in the future. Please note that if -the bug was reported in private, then ask for permission first before using the -Reported-by tag. - -A Tested-by: tag indicates that the patch has been successfully tested (in -some environment) by the person named. This tag informs maintainers that -some testing has been performed, provides a means to locate testers for -future patches, and ensures credit for the testers. - -Reviewed-by:, instead, indicates that the patch has been reviewed and found -acceptable according to the Reviewer's Statement: - -Reviewer's statement of oversight -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -By offering my Reviewed-by: tag, I state that: - - (a) I have carried out a technical review of this patch to - evaluate its appropriateness and readiness for inclusion into - the mainline kernel. - - (b) Any problems, concerns, or questions relating to the patch - have been communicated back to the submitter. I am satisfied - with the submitter's response to my comments. - - (c) While there may be things that could be improved with this - submission, I believe that it is, at this time, (1) a - worthwhile modification to the kernel, and (2) free of known - issues which would argue against its inclusion. - - (d) While I have reviewed the patch and believe it to be sound, I - do not (unless explicitly stated elsewhere) make any - warranties or guarantees that it will achieve its stated - purpose or function properly in any given situation. - -A Reviewed-by tag is a statement of opinion that the patch is an -appropriate modification of the kernel without any remaining serious -technical issues. Any interested reviewer (who has done the work) can -offer a Reviewed-by tag for a patch. This tag serves to give credit to -reviewers and to inform maintainers of the degree of review which has been -done on the patch. Reviewed-by: tags, when supplied by reviewers known to -understand the subject area and to perform thorough reviews, will normally -increase the likelihood of your patch getting into the kernel. - -A Suggested-by: tag indicates that the patch idea is suggested by the person -named and ensures credit to the person for the idea. Please note that this -tag should not be added without the reporter's permission, especially if the -idea was not posted in a public forum. That said, if we diligently credit our -idea reporters, they will, hopefully, be inspired to help us again in the -future. - -A Fixes: tag indicates that the patch fixes an issue in a previous commit. It -is used to make it easy to determine where a bug originated, which can help -review a bug fix. This tag also assists the stable kernel team in determining -which stable kernel versions should receive your fix. This is the preferred -method for indicating a bug fixed by the patch. See :ref:`describe_changes` -for more details. - - -14) The canonical patch format ------------------------------- - -This section describes how the patch itself should be formatted. Note -that, if you have your patches stored in a ``git`` repository, proper patch -formatting can be had with ``git format-patch``. The tools cannot create -the necessary text, though, so read the instructions below anyway. - -The canonical patch subject line is:: - - Subject: [PATCH 001/123] subsystem: summary phrase - -The canonical patch message body contains the following: - - - A ``from`` line specifying the patch author (only needed if the person - sending the patch is not the author). - - - An empty line. - - - The body of the explanation, line wrapped at 75 columns, which will - be copied to the permanent changelog to describe this patch. - - - The ``Signed-off-by:`` lines, described above, which will - also go in the changelog. - - - A marker line containing simply ``---``. - - - Any additional comments not suitable for the changelog. - - - The actual patch (``diff`` output). - -The Subject line format makes it very easy to sort the emails -alphabetically by subject line - pretty much any email reader will -support that - since because the sequence number is zero-padded, -the numerical and alphabetic sort is the same. - -The ``subsystem`` in the email's Subject should identify which -area or subsystem of the kernel is being patched. - -The ``summary phrase`` in the email's Subject should concisely -describe the patch which that email contains. The ``summary -phrase`` should not be a filename. Do not use the same ``summary -phrase`` for every patch in a whole patch series (where a ``patch -series`` is an ordered sequence of multiple, related patches). - -Bear in mind that the ``summary phrase`` of your email becomes a -globally-unique identifier for that patch. It propagates all the way -into the ``git`` changelog. The ``summary phrase`` may later be used in -developer discussions which refer to the patch. People will want to -google for the ``summary phrase`` to read discussion regarding that -patch. It will also be the only thing that people may quickly see -when, two or three months later, they are going through perhaps -thousands of patches using tools such as ``gitk`` or ``git log ---oneline``. - -For these reasons, the ``summary`` must be no more than 70-75 -characters, and it must describe both what the patch changes, as well -as why the patch might be necessary. It is challenging to be both -succinct and descriptive, but that is what a well-written summary -should do. - -The ``summary phrase`` may be prefixed by tags enclosed in square -brackets: "Subject: [PATCH <tag>...] <summary phrase>". The tags are -not considered part of the summary phrase, but describe how the patch -should be treated. Common tags might include a version descriptor if -the multiple versions of the patch have been sent out in response to -comments (i.e., "v1, v2, v3"), or "RFC" to indicate a request for -comments. If there are four patches in a patch series the individual -patches may be numbered like this: 1/4, 2/4, 3/4, 4/4. This assures -that developers understand the order in which the patches should be -applied and that they have reviewed or applied all of the patches in -the patch series. - -A couple of example Subjects:: - - Subject: [PATCH 2/5] ext2: improve scalability of bitmap searching - Subject: [PATCH v2 01/27] x86: fix eflags tracking - -The ``from`` line must be the very first line in the message body, -and has the form: - - From: Original Author <author@example.com> - -The ``from`` line specifies who will be credited as the author of the -patch in the permanent changelog. If the ``from`` line is missing, -then the ``From:`` line from the email header will be used to determine -the patch author in the changelog. - -The explanation body will be committed to the permanent source -changelog, so should make sense to a competent reader who has long -since forgotten the immediate details of the discussion that might -have led to this patch. Including symptoms of the failure which the -patch addresses (kernel log messages, oops messages, etc.) is -especially useful for people who might be searching the commit logs -looking for the applicable patch. If a patch fixes a compile failure, -it may not be necessary to include _all_ of the compile failures; just -enough that it is likely that someone searching for the patch can find -it. As in the ``summary phrase``, it is important to be both succinct as -well as descriptive. - -The ``---`` marker line serves the essential purpose of marking for patch -handling tools where the changelog message ends. - -One good use for the additional comments after the ``---`` marker is for -a ``diffstat``, to show what files have changed, and the number of -inserted and deleted lines per file. A ``diffstat`` is especially useful -on bigger patches. Other comments relevant only to the moment or the -maintainer, not suitable for the permanent changelog, should also go -here. A good example of such comments might be ``patch changelogs`` -which describe what has changed between the v1 and v2 version of the -patch. - -If you are going to include a ``diffstat`` after the ``---`` marker, please -use ``diffstat`` options ``-p 1 -w 70`` so that filenames are listed from -the top of the kernel source tree and don't use too much horizontal -space (easily fit in 80 columns, maybe with some indentation). (``git`` -generates appropriate diffstats by default.) - -See more details on the proper patch format in the following -references. - -.. _explicit_in_reply_to: - -15) Explicit In-Reply-To headers --------------------------------- - -It can be helpful to manually add In-Reply-To: headers to a patch -(e.g., when using ``git send-email``) to associate the patch with -previous relevant discussion, e.g. to link a bug fix to the email with -the bug report. However, for a multi-patch series, it is generally -best to avoid using In-Reply-To: to link to older versions of the -series. This way multiple versions of the patch don't become an -unmanageable forest of references in email clients. If a link is -helpful, you can use the https://lkml.kernel.org/ redirector (e.g., in -the cover email text) to link to an earlier version of the patch series. - - -16) Sending ``git pull`` requests ---------------------------------- - -If you have a series of patches, it may be most convenient to have the -maintainer pull them directly into the subsystem repository with a -``git pull`` operation. Note, however, that pulling patches from a developer -requires a higher degree of trust than taking patches from a mailing list. -As a result, many subsystem maintainers are reluctant to take pull -requests, especially from new, unknown developers. If in doubt you can use -the pull request as the cover letter for a normal posting of the patch -series, giving the maintainer the option of using either. - -A pull request should have [GIT] or [PULL] in the subject line. The -request itself should include the repository name and the branch of -interest on a single line; it should look something like:: - - Please pull from - - git://jdelvare.pck.nerim.net/jdelvare-2.6 i2c-for-linus - - to get these changes: - -A pull request should also include an overall message saying what will be -included in the request, a ``git shortlog`` listing of the patches -themselves, and a ``diffstat`` showing the overall effect of the patch series. -The easiest way to get all this information together is, of course, to let -``git`` do it for you with the ``git request-pull`` command. - -Some maintainers (including Linus) want to see pull requests from signed -commits; that increases their confidence that the request actually came -from you. Linus, in particular, will not pull from public hosting sites -like GitHub in the absence of a signed tag. - -The first step toward creating such tags is to make a GNUPG key and get it -signed by one or more core kernel developers. This step can be hard for -new developers, but there is no way around it. Attending conferences can -be a good way to find developers who can sign your key. - -Once you have prepared a patch series in ``git`` that you wish to have somebody -pull, create a signed tag with ``git tag -s``. This will create a new tag -identifying the last commit in the series and containing a signature -created with your private key. You will also have the opportunity to add a -changelog-style message to the tag; this is an ideal place to describe the -effects of the pull request as a whole. - -If the tree the maintainer will be pulling from is not the repository you -are working from, don't forget to push the signed tag explicitly to the -public tree. - -When generating your pull request, use the signed tag as the target. A -command like this will do the trick:: - - git request-pull master git://my.public.tree/linux.git my-signed-tag - - -REFERENCES -********** - -Andrew Morton, "The perfect patch" (tpp). - <http://www.ozlabs.org/~akpm/stuff/tpp.txt> - -Jeff Garzik, "Linux kernel patch submission format". - <http://linux.yyz.us/patch-format.html> - -Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer". - <http://www.kroah.com/log/linux/maintainer.html> - - <http://www.kroah.com/log/linux/maintainer-02.html> - - <http://www.kroah.com/log/linux/maintainer-03.html> - - <http://www.kroah.com/log/linux/maintainer-04.html> - - <http://www.kroah.com/log/linux/maintainer-05.html> - - <http://www.kroah.com/log/linux/maintainer-06.html> - -NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people! - <https://lkml.org/lkml/2005/7/11/336> - -Kernel Documentation/CodingStyle: - :ref:`Documentation/CodingStyle <codingstyle>` - -Linus Torvalds's mail on the canonical patch format: - <http://lkml.org/lkml/2005/4/7/183> - -Andi Kleen, "On submitting kernel patches" - Some strategies to get difficult or controversial changes in. - - http://halobates.de/on-submitting-patches.pdf - +This file has moved to process/submitting-patches.rst |