blob: db27ab65387e9966d623ebf7c9a67e173d3fb4fd [file] [log] [blame]
Mauro Carvalho Chehab609d99a2016-09-19 08:07:56 -03001.. _submittingpatches:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002
Jonathan Corbet89edeed2016-10-26 16:37:53 -06003Submitting patches: the essential guide to getting your code into the kernel
4============================================================================
Linus Torvalds1da177e2005-04-16 15:20:36 -07005
6For a person or company who wishes to submit a change to the Linux
7kernel, the process can sometimes be daunting if you're not familiar
8with "the system." This text is a collection of suggestions which
9can greatly increase the chances of your change being accepted.
10
Jonathan Corbetd00c4552014-12-23 08:54:36 -070011This document contains a large number of suggestions in a relatively terse
12format. For detailed information on how the kernel development process
Mauro Carvalho Chehab0e4f07a2016-10-18 09:05:32 -020013works, see :ref:`Documentation/process <development_process_main>`.
Mauro Carvalho Chehab8c27cef2016-10-18 10:12:27 -020014Also, read :ref:`Documentation/process/submit-checklist.rst <submitchecklist>`
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -030015for a list of items to check before
Jonathan Corbetd00c4552014-12-23 08:54:36 -070016submitting code. If you are submitting a driver, also read
Mauro Carvalho Chehab8c27cef2016-10-18 10:12:27 -020017:ref:`Documentation/process/submitting-drivers.rst <submittingdrivers>`;
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -030018for device tree binding patches, read
Jonathan Corbet082bd1c2014-12-23 09:27:04 -070019Documentation/devicetree/bindings/submitting-patches.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030021Many of these steps describe the default behavior of the ``git`` version
22control system; if you use ``git`` to prepare your patches, you'll find much
Josh Triplett8e3072a2014-04-03 14:48:30 -070023of the mechanical work done for you, though you'll still need to prepare
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030024and document a sensible set of patches. In general, use of ``git`` will make
Jonathan Corbetd00c4552014-12-23 08:54:36 -070025your life as a kernel developer easier.
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700270) Obtain a current source tree
28-------------------------------
29
30If you do not have a repository with the current kernel source handy, use
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030031``git`` to obtain one. You'll want to start with the mainline repository,
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030032which can be grabbed with::
Jonathan Corbet7994cc12014-12-23 08:43:41 -070033
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030034 git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Jonathan Corbet7994cc12014-12-23 08:43:41 -070035
36Note, however, that you may not want to develop against the mainline tree
37directly. Most subsystem maintainers run their own trees and want to see
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030038patches prepared against those trees. See the **T:** entry for the subsystem
Jonathan Corbet7994cc12014-12-23 08:43:41 -070039in the MAINTAINERS file to find that tree, or simply ask the maintainer if
40the tree is not listed there.
41
42It is still possible to download kernel releases via tarballs (as described
43in the next section), but that is the hard way to do kernel development.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300451) ``diff -up``
46---------------
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030048If you must generate your patches by hand, use ``diff -up`` or ``diff -uprN``
Jonathan Corbet7994cc12014-12-23 08:43:41 -070049to create patches. Git generates patches in this form by default; if
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030050you're using ``git``, you can skip this section entirely.
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52All changes to the Linux kernel occur in the form of patches, as
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030053generated by :manpage:`diff(1)`. When creating your patch, make sure to
54create it in "unified diff" format, as supplied by the ``-u`` argument
55to :manpage:`diff(1)`.
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030056Also, please use the ``-p`` argument which shows which C function each
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030057change is in - that makes the resultant ``diff`` a lot easier to read.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058Patches should be based in the root kernel source directory,
59not in any lower subdirectory.
60
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030061To create a patch for a single file, it is often sufficient to do::
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Jonathan Corbetd00c4552014-12-23 08:54:36 -070063 SRCTREE= linux
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 MYFILE= drivers/net/mydriver.c
65
66 cd $SRCTREE
67 cp $MYFILE $MYFILE.orig
68 vi $MYFILE # make your change
69 cd ..
70 diff -up $SRCTREE/$MYFILE{.orig,} > /tmp/patch
71
72To create a patch for multiple files, you should unpack a "vanilla",
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030073or unmodified kernel source tree, and generate a ``diff`` against your
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030074own source tree. For example::
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
Jonathan Corbetd00c4552014-12-23 08:54:36 -070076 MYSRC= /devel/linux
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
Jonathan Corbetd00c4552014-12-23 08:54:36 -070078 tar xvfz linux-3.19.tar.gz
79 mv linux-3.19 linux-3.19-vanilla
80 diff -uprN -X linux-3.19-vanilla/Documentation/dontdiff \
81 linux-3.19-vanilla $MYSRC > /tmp/patch
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030083``dontdiff`` is a list of files which are generated by the kernel during
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030084the build process, and should be ignored in any :manpage:`diff(1)`-generated
Jonathan Corbetd00c4552014-12-23 08:54:36 -070085patch.
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
87Make sure your patch does not include any extra files which do not
88belong in a patch submission. Make sure to review your patch -after-
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030089generating it with :manpage:`diff(1)`, to ensure accuracy.
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Josh Triplett8e3072a2014-04-03 14:48:30 -070091If your changes produce a lot of deltas, you need to split them into
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030092individual patches which modify things in logical stages; see
93:ref:`split_changes`. This will facilitate review by other kernel developers,
Josh Triplett8e3072a2014-04-03 14:48:30 -070094very important if you want your patch accepted.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -030096If you're using ``git``, ``git rebase -i`` can help you with this process. If
97you're not using ``git``, ``quilt`` <http://savannah.nongnu.org/projects/quilt>
Josh Triplett8e3072a2014-04-03 14:48:30 -070098is another popular alternative.
Randy Dunlap84da7c02005-06-28 20:45:30 -070099
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300100.. _describe_changes:
Randy Dunlap84da7c02005-06-28 20:45:30 -0700101
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03001022) Describe your changes
103------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104
Johannes Weiner7b9828d2014-08-05 23:32:56 -0700105Describe your problem. Whether your patch is a one-line bug fix or
1065000 lines of a new feature, there must be an underlying problem that
107motivated you to do this work. Convince the reviewer that there is a
108problem worth fixing and that it makes sense for them to read past the
109first paragraph.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110
Johannes Weiner7b9828d2014-08-05 23:32:56 -0700111Describe user-visible impact. Straight up crashes and lockups are
112pretty convincing, but not all bugs are that blatant. Even if the
113problem was spotted during code review, describe the impact you think
114it can have on users. Keep in mind that the majority of Linux
115installations run kernels from secondary stable trees or
116vendor/product-specific trees that cherry-pick only specific patches
117from upstream, so include anything that could help route your change
118downstream: provoking circumstances, excerpts from dmesg, crash
119descriptions, performance regressions, latency spikes, lockups, etc.
120
121Quantify optimizations and trade-offs. If you claim improvements in
122performance, memory consumption, stack footprint, or binary size,
123include numbers that back them up. But also describe non-obvious
124costs. Optimizations usually aren't free but trade-offs between CPU,
125memory, and readability; or, when it comes to heuristics, between
126different workloads. Describe the expected downsides of your
127optimization so that the reviewer can weigh costs against benefits.
128
129Once the problem is established, describe what you are actually doing
130about it in technical detail. It's important to describe the change
131in plain English for the reviewer to verify that the code is behaving
132as you intend it to.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400134The maintainer will thank you if you write your patch description in a
135form which can be easily pulled into Linux's source code management
Akira Yokosawabb472002022-04-27 18:28:39 +0900136system, ``git``, as a "commit log". See :ref:`the_canonical_patch_format`.
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400137
Johannes Weiner7b9828d2014-08-05 23:32:56 -0700138Solve only one problem per patch. If your description starts to get
139long, that's a sign that you probably need to split up your patch.
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300140See :ref:`split_changes`.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
Randy Dunlapd89b1942010-08-09 17:20:21 -0700142When you submit or resubmit a patch or patch series, include the
143complete patch description and justification for it. Don't just
144say that this is version N of the patch (series). Don't expect the
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700145subsystem maintainer to refer back to earlier patch versions or referenced
Randy Dunlapd89b1942010-08-09 17:20:21 -0700146URLs to find the patch description and put that into the patch.
147I.e., the patch (series) and its description should be self-contained.
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700148This benefits both the maintainers and reviewers. Some reviewers
Randy Dunlapd89b1942010-08-09 17:20:21 -0700149probably didn't even receive earlier versions of the patch.
150
Josh Triplett74a475a2014-04-03 14:48:28 -0700151Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
152instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
153to do frotz", as if you are giving orders to the codebase to change
154its behaviour.
155
Randy Dunlapd89b1942010-08-09 17:20:21 -0700156If the patch fixes a logged bug entry, refer to that bug entry by
Josh Triplett9547c702014-04-03 14:48:29 -0700157number and URL. If the patch follows from a mailing list discussion,
158give a URL to the mailing list archive; use the https://lkml.kernel.org/
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300159redirector with a ``Message-Id``, to ensure that the links cannot become
Josh Triplett9547c702014-04-03 14:48:29 -0700160stale.
161
162However, try to make your explanation understandable without external
163resources. In addition to giving a URL to a mailing list archive or
164bug, summarize the relevant points of the discussion that led to the
165patch as submitted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Geert Uytterhoeven0af52702013-07-31 14:59:38 -0700167If you want to refer to a specific commit, don't just refer to the
168SHA-1 ID of the commit. Please also include the oneline summary of
169the commit, to make it easier for reviewers to know what it is about.
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300170Example::
Geert Uytterhoeven0af52702013-07-31 14:59:38 -0700171
172 Commit e21d2170f36602ae2708 ("video: remove unnecessary
173 platform_set_drvdata()") removed the unnecessary
174 platform_set_drvdata(), but left the variable "dev" unused,
175 delete it.
176
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700177You should also be sure to use at least the first twelve characters of the
178SHA-1 ID. The kernel repository holds a *lot* of objects, making
179collisions with shorter IDs a real possibility. Bear in mind that, even if
180there is no collision with your six-character ID now, that condition may
181change five years from now.
182
Jacob Keller8401aa12014-06-06 14:36:39 -0700183If your patch fixes a bug in a specific commit, e.g. you found an issue using
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300184``git bisect``, please use the 'Fixes:' tag with the first 12 characters of
185the SHA-1 ID, and the one line summary. For example::
Jacob Keller8401aa12014-06-06 14:36:39 -0700186
187 Fixes: e21d2170f366 ("video: remove unnecessary platform_set_drvdata()")
188
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300189The following ``git config`` settings can be used to add a pretty format for
190outputting the above style in the ``git log`` or ``git show`` commands::
Jacob Keller8401aa12014-06-06 14:36:39 -0700191
192 [core]
193 abbrev = 12
194 [pretty]
195 fixes = Fixes: %h (\"%s\")
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300197.. _split_changes:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03001993) Separate your changes
200------------------------
201
202Separate each **logical change** into a separate patch.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
204For example, if your changes include both bug fixes and performance
205enhancements for a single driver, separate those changes into two
206or more patches. If your changes include an API update, and a new
207driver which uses that new API, separate those into two patches.
208
209On the other hand, if you make a single change to numerous files,
210group those changes into a single patch. Thus a single logical change
211is contained within a single patch.
212
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700213The point to remember is that each patch should make an easily understood
214change that can be verified by reviewers. Each patch should be justifiable
215on its own merits.
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217If one patch depends on another patch in order for a change to be
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300218complete, that is OK. Simply note **"this patch depends on patch X"**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219in your patch description.
220
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700221When dividing your change into a series of patches, take special care to
222ensure that the kernel builds and runs properly after each patch in the
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300223series. Developers using ``git bisect`` to track down a problem can end up
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700224splitting your patch series at any point; they will not thank you if you
225introduce bugs in the middle.
226
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800227If you cannot condense your patch set into a smaller set of patches,
228then only post say 15 or so at a time and wait for review and integration.
229
230
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03002324) Style-check your changes
233---------------------------
Andy Whitcroft0a920b52007-06-01 00:46:48 -0700234
235Check your patch for basic style violations, details of which can be
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -0300236found in
Mauro Carvalho Chehab8c27cef2016-10-18 10:12:27 -0200237:ref:`Documentation/process/coding-style.rst <codingstyle>`.
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -0300238Failure to do so simply wastes
Linus Nilssonf56d35e2007-07-21 17:49:06 +0200239the reviewers time and will get your patch rejected, probably
Andy Whitcroft0a920b52007-06-01 00:46:48 -0700240without even being read.
241
Jonathan Corbet6de16eb2014-12-23 08:38:24 -0700242One significant exception is when moving code from one file to
243another -- in this case you should not modify the moved code at all in
244the same patch which moves it. This clearly delineates the act of
245moving the code and your changes. This greatly aids review of the
246actual differences and allows tools to better track the history of
247the code itself.
Andy Whitcroft0a920b52007-06-01 00:46:48 -0700248
Jonathan Corbet6de16eb2014-12-23 08:38:24 -0700249Check your patches with the patch style checker prior to submission
250(scripts/checkpatch.pl). Note, though, that the style checker should be
251viewed as a guide, not as a replacement for human judgment. If your code
252looks better with a violation then its probably best left alone.
253
254The checker reports at three levels:
255 - ERROR: things that are very likely to be wrong
256 - WARNING: things requiring careful review
257 - CHECK: things requiring thought
258
259You should be able to justify all violations that remain in your
260patch.
Andy Whitcroft0a920b52007-06-01 00:46:48 -0700261
262
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03002635) Select the recipients for your patch
264---------------------------------------
Andy Whitcroft0a920b52007-06-01 00:46:48 -0700265
Jonathan Corbetccae8612014-12-23 08:49:18 -0700266You should always copy the appropriate subsystem maintainer(s) on any patch
267to code that they maintain; look through the MAINTAINERS file and the
268source code revision history to see who those maintainers are. The
269script scripts/get_maintainer.pl can be very useful at this step. If you
Sébastien Hindererd6eff072015-07-08 21:12:32 +0200270cannot find a maintainer for the subsystem you are working on, Andrew
Jonathan Corbetccae8612014-12-23 08:49:18 -0700271Morton (akpm@linux-foundation.org) serves as a maintainer of last resort.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272
Jonathan Corbetccae8612014-12-23 08:49:18 -0700273You should also normally choose at least one mailing list to receive a copy
274of your patch set. linux-kernel@vger.kernel.org functions as a list of
275last resort, but the volume on that list has caused a number of developers
276to tune it out. Look in the MAINTAINERS file for a subsystem-specific
277list; your patch will probably get more attention there. Please do not
278spam unrelated lists, though.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279
Jonathan Corbetccae8612014-12-23 08:49:18 -0700280Many kernel-related lists are hosted on vger.kernel.org; you can find a
281list of them at http://vger.kernel.org/vger-lists.html. There are
282kernel-related lists hosted elsewhere as well, though.
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800283
284Do not send more than 15 patches at once to the vger mailing lists!!!
285
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286Linus Torvalds is the final arbiter of all changes accepted into the
Stefan Bellere00bfcb2014-12-17 17:13:56 -0800287Linux kernel. His e-mail address is <torvalds@linux-foundation.org>.
Jonathan Corbetccae8612014-12-23 08:49:18 -0700288He gets a lot of e-mail, and, at this point, very few patches go through
289Linus directly, so typically you should do your best to -avoid-
Stefan Bellere00bfcb2014-12-17 17:13:56 -0800290sending him e-mail.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
Jonathan Corbetccae8612014-12-23 08:49:18 -0700292If you have a patch that fixes an exploitable security bug, send that patch
293to security@kernel.org. For severe bugs, a short embargo may be considered
Nik Nyby253508c2015-06-26 12:05:39 -0400294to allow distributors to get the patch out to users; in such cases,
Jonathan Corbetccae8612014-12-23 08:49:18 -0700295obviously, the patch should not be sent to any public lists.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296
Jonathan Corbetccae8612014-12-23 08:49:18 -0700297Patches that fix a severe bug in a released kernel should be directed
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300298toward the stable maintainers by putting a line like this::
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
Jonathan Corbetccae8612014-12-23 08:49:18 -0700300 Cc: stable@vger.kernel.org
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301
Luke Dashjr8cda4c32015-05-14 18:58:01 +0000302into the sign-off area of your patch (note, NOT an email recipient). You
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -0300303should also read
Mauro Carvalho Chehab8c27cef2016-10-18 10:12:27 -0200304:ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -0300305in addition to this file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306
Jonathan Corbetccae8612014-12-23 08:49:18 -0700307Note, however, that some subsystem maintainers want to come to their own
308conclusions on which patches should go to the stable trees. The networking
309maintainer, in particular, would rather not see individual developers
310adding lines like the above to their patches.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311
Jonathan Corbetccae8612014-12-23 08:49:18 -0700312If changes affect userland-kernel interfaces, please send the MAN-PAGES
313maintainer (as listed in the MAINTAINERS file) a man-pages patch, or at
314least a notification of the change, so that some information makes its way
315into the manual pages. User-space API changes should also be copied to
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300316linux-api@vger.kernel.org.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
318For small patches you may want to CC the Trivial Patch Monkey
Markus Heidelberg82d27b22009-06-12 01:02:34 +0200319trivial@kernel.org which collects "trivial" patches. Have a look
320into the MAINTAINERS file for its current manager.
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300321
Markus Heidelberg82d27b22009-06-12 01:02:34 +0200322Trivial patches must qualify for one of the following rules:
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300323
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300324- Spelling fixes in documentation
325- Spelling fixes for errors which could break :manpage:`grep(1)`
326- Warning fixes (cluttering with useless warnings is bad)
327- Compilation fixes (only if they are actually correct)
328- Runtime fixes (only if they actually fix things)
329- Removing use of deprecated functions/macros
330- Contact detail and documentation fixes
331- Non-portable code replaced by portable code (even in arch-specific,
332 since people copy, as long as it's trivial)
333- Any fix by the author/maintainer of the file (ie. patch monkey
334 in re-transmission mode)
Randy Dunlap84da7c02005-06-28 20:45:30 -0700335
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
337
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03003386) No MIME, no links, no compression, no attachments. Just plain text
339----------------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340
341Linus and other kernel developers need to be able to read and comment
342on the changes you are submitting. It is important for a kernel
343developer to be able to "quote" your changes, using standard e-mail
344tools, so that they may comment on specific portions of your code.
345
Sébastien Hindererbdc89212015-07-12 17:44:15 +0200346For this reason, all patches should be submitted by e-mail "inline".
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300347
348.. warning::
349
350 Be wary of your editor's word-wrap corrupting your patch,
351 if you choose to cut-n-paste your patch.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352
353Do not attach the patch as a MIME attachment, compressed or not.
354Many popular e-mail applications will not always transmit a MIME
355attachment as plain text, making it impossible to comment on your
356code. A MIME attachment also takes Linus a bit more time to process,
357decreasing the likelihood of your MIME-attached change being accepted.
358
359Exception: If your mailer is mangling patches then someone may ask
360you to re-send them using MIME.
361
Mauro Carvalho Chehab8c27cef2016-10-18 10:12:27 -0200362See :ref:`Documentation/process/email-clients.rst <email_clients>`
Mauro Carvalho Chehabdca22a62016-09-21 08:51:05 -0300363for hints about configuring your e-mail client so that it sends your patches
364untouched.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03003667) E-mail size
367--------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368
369Large changes are not appropriate for mailing lists, and some
Randy Dunlap4932be72009-10-01 15:44:06 -0700370maintainers. If your patch, uncompressed, exceeds 300 kB in size,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371it is preferred that you store your patch on an Internet-accessible
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700372server, and provide instead a URL (link) pointing to your patch. But note
373that if your patch exceeds 300 kB, it almost certainly needs to be broken up
374anyway.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03003768) Respond to review comments
377-----------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378
Jonathan Corbet0eea2312014-12-23 08:52:01 -0700379Your patch will almost certainly get comments from reviewers on ways in
380which the patch can be improved. You must respond to those comments;
381ignoring reviewers is a good way to get ignored in return. Review comments
382or questions that do not lead to a code change should almost certainly
383bring about a comment or changelog entry so that the next reviewer better
384understands what is going on.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
Jonathan Corbet0eea2312014-12-23 08:52:01 -0700386Be sure to tell the reviewers what changes you are making and to thank them
387for their time. Code review is a tiring and time-consuming process, and
388reviewers sometimes get grumpy. Even in that case, though, respond
389politely and address the problems they have pointed out.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390
391
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -03003929) Don't get discouraged - or impatient
393---------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394
Jonathan Corbet0eea2312014-12-23 08:52:01 -0700395After you have submitted your change, be patient and wait. Reviewers are
396busy people and may not get to your patch right away.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397
Jonathan Corbet0eea2312014-12-23 08:52:01 -0700398Once upon a time, patches used to disappear into the void without comment,
399but the development process works more smoothly than that now. You should
400receive comments within a week or so; if that does not happen, make sure
401that you have sent your patches to the right place. Wait for a minimum of
402one week before resubmitting or pinging reviewers - possibly longer during
403busy times like merge windows.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404
405
Jonathan Corbetccae8612014-12-23 08:49:18 -070040610) Include PATCH in the subject
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700407--------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408
409Due to high e-mail traffic to Linus, and to linux-kernel, it is common
410convention to prefix your subject line with [PATCH]. This lets Linus
411and other kernel developers more easily distinguish patches from other
412e-mail discussions.
413
414
415
Frank Rowandbc7938d2017-07-20 18:30:55 -070041611) Sign your work - the Developer's Certificate of Origin
Jonathan Corbet89edeed2016-10-26 16:37:53 -0600417----------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
419To improve tracking of who did what, especially with patches that can
420percolate to their final resting place in the kernel through several
421layers of maintainers, we've introduced a "sign-off" procedure on
422patches that are being emailed around.
423
424The sign-off is a simple line at the end of the explanation for the
425patch, which certifies that you wrote it or otherwise have the right to
Zac Storerdb12fb82011-08-13 12:34:45 -0700426pass it on as an open-source patch. The rules are pretty simple: if you
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427can certify the below:
428
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300429Developer's Certificate of Origin 1.1
430^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300432By making a contribution to this project, I certify that:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433
434 (a) The contribution was created in whole or in part by me and I
435 have the right to submit it under the open source license
436 indicated in the file; or
437
438 (b) The contribution is based upon previous work that, to the best
439 of my knowledge, is covered under an appropriate open source
440 license and I have the right under that license to submit that
441 work with modifications, whether created in whole or in part
442 by me, under the same open source license (unless I am
443 permitted to submit under a different license), as indicated
444 in the file; or
445
446 (c) The contribution was provided directly to me by some other
447 person who certified (a), (b) or (c) and I have not modified
448 it.
449
Stefan Bellere00bfcb2014-12-17 17:13:56 -0800450 (d) I understand and agree that this project and the contribution
451 are public and that a record of the contribution (including all
452 personal information I submit with it, including my sign-off) is
453 maintained indefinitely and may be redistributed consistent with
454 this project or the open source license(s) involved.
Linus Torvaldscbd83da2005-06-13 17:51:55 -0700455
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300456then you just add a line saying::
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457
Alexey Dobriyan9fd55592005-06-25 14:59:34 -0700458 Signed-off-by: Random J Developer <random@developer.example.org>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459
Greg KHaf45f322006-09-12 20:35:52 -0700460using your real name (sorry, no pseudonyms or anonymous contributions.)
461
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462Some people also put extra tags at the end. They'll just be ignored for
463now, but you can do this to mark internal company procedures or just
Stefan Bellere00bfcb2014-12-17 17:13:56 -0800464point out some special detail about the sign-off.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465
Willy Tarreauadbd5882008-06-03 00:20:28 +0200466If you are a subsystem or branch maintainer, sometimes you need to slightly
467modify patches you receive in order to merge them, because the code is not
468exactly the same in your tree and the submitters'. If you stick strictly to
469rule (c), you should ask the submitter to rediff, but this is a totally
470counter-productive waste of time and energy. Rule (b) allows you to adjust
471the code, but then it is very impolite to change one submitter's code and
472make him endorse your bugs. To solve this problem, it is recommended that
473you add a line between the last Signed-off-by header and yours, indicating
474the nature of your changes. While there is nothing mandatory about this, it
475seems like prepending the description with your mail and/or name, all
476enclosed in square brackets, is noticeable enough to make it obvious that
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300477you are responsible for last-minute changes. Example::
Willy Tarreauadbd5882008-06-03 00:20:28 +0200478
479 Signed-off-by: Random J Developer <random@developer.example.org>
480 [lucky@maintainer.example.org: struct foo moved from foo.c to foo.h]
481 Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org>
482
Jeremiah Mahler305af082014-05-22 00:04:26 -0700483This practice is particularly helpful if you maintain a stable branch and
Willy Tarreauadbd5882008-06-03 00:20:28 +0200484want at the same time to credit the author, track changes, merge the fix,
485and protect the submitter from complaints. Note that under no circumstances
486can you change the author's identity (the From header), as it is the one
487which appears in the changelog.
488
Jeremiah Mahler305af082014-05-22 00:04:26 -0700489Special note to back-porters: It seems to be a common and useful practice
Willy Tarreauadbd5882008-06-03 00:20:28 +0200490to insert an indication of the origin of a patch at the top of the commit
491message (just after the subject line) to facilitate tracking. For instance,
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300492here's what we see in a 3.x-stable release::
Willy Tarreauadbd5882008-06-03 00:20:28 +0200493
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300494 Date: Tue Oct 7 07:26:38 2014 -0400
Willy Tarreauadbd5882008-06-03 00:20:28 +0200495
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700496 libata: Un-break ATA blacklist
Willy Tarreauadbd5882008-06-03 00:20:28 +0200497
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700498 commit 1c40279960bcd7d52dbdf1d466b20d24b99176c8 upstream.
Willy Tarreauadbd5882008-06-03 00:20:28 +0200499
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300500And here's what might appear in an older kernel once a patch is backported::
Willy Tarreauadbd5882008-06-03 00:20:28 +0200501
502 Date: Tue May 13 22:12:27 2008 +0200
503
504 wireless, airo: waitbusy() won't delay
505
506 [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a]
507
508Whatever the format, this information provides a valuable help to people
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700509tracking your trees, and to people trying to troubleshoot bugs in your
Willy Tarreauadbd5882008-06-03 00:20:28 +0200510tree.
511
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512
Jonathan Corbetccae8612014-12-23 08:49:18 -070051312) When to use Acked-by: and Cc:
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700514---------------------------------
Andy Whitcroft0a920b52007-06-01 00:46:48 -0700515
Andrew Morton0f44cd22007-06-08 13:46:45 -0700516The Signed-off-by: tag indicates that the signer was involved in the
517development of the patch, or that he/she was in the patch's delivery path.
518
519If a person was not directly involved in the preparation or handling of a
520patch but wishes to signify and record their approval of it then they can
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700521ask to have an Acked-by: line added to the patch's changelog.
Andrew Morton0f44cd22007-06-08 13:46:45 -0700522
523Acked-by: is often used by the maintainer of the affected code when that
524maintainer neither contributed to nor forwarded the patch.
525
526Acked-by: is not as formal as Signed-off-by:. It is a record that the acker
527has at least reviewed the patch and has indicated acceptance. Hence patch
528mergers will sometimes manually convert an acker's "yep, looks good to me"
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700529into an Acked-by: (but note that it is usually better to ask for an
530explicit ack).
Andrew Morton0f44cd22007-06-08 13:46:45 -0700531
532Acked-by: does not necessarily indicate acknowledgement of the entire patch.
533For example, if a patch affects multiple subsystems and has an Acked-by: from
534one subsystem maintainer then this usually indicates acknowledgement of just
535the part which affects that maintainer's code. Judgement should be used here.
Jonathan Corbetef402032008-03-28 11:22:38 -0600536When in doubt people should refer to the original discussion in the mailing
Andrew Morton0f44cd22007-06-08 13:46:45 -0700537list archives.
538
Jonathan Corbetef402032008-03-28 11:22:38 -0600539If a person has had the opportunity to comment on a patch, but has not
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300540provided such comments, you may optionally add a ``Cc:`` tag to the patch.
Jonathan Corbetef402032008-03-28 11:22:38 -0600541This is the only tag which might be added without an explicit action by the
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700542person it names - but it should indicate that this person was copied on the
543patch. This tag documents that potentially interested parties
544have been included in the discussion.
Andrew Morton0f44cd22007-06-08 13:46:45 -0700545
Jonathan Corbetef402032008-03-28 11:22:38 -0600546
Jonathan Corbetccae8612014-12-23 08:49:18 -070054713) Using Reported-by:, Tested-by:, Reviewed-by:, Suggested-by: and Fixes:
Jonathan Corbetd00c4552014-12-23 08:54:36 -0700548--------------------------------------------------------------------------
Jonathan Corbetbbb0a4242009-01-16 09:49:50 -0700549
Dan Carpenterd75ef702014-10-29 13:01:36 +0300550The Reported-by tag gives credit to people who find bugs and report them and it
551hopefully inspires them to help us again in the future. Please note that if
552the bug was reported in private, then ask for permission first before using the
553Reported-by tag.
Jonathan Corbetef402032008-03-28 11:22:38 -0600554
555A Tested-by: tag indicates that the patch has been successfully tested (in
556some environment) by the person named. This tag informs maintainers that
557some testing has been performed, provides a means to locate testers for
558future patches, and ensures credit for the testers.
559
560Reviewed-by:, instead, indicates that the patch has been reviewed and found
561acceptable according to the Reviewer's Statement:
562
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300563Reviewer's statement of oversight
564^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jonathan Corbetef402032008-03-28 11:22:38 -0600565
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300566By offering my Reviewed-by: tag, I state that:
Jonathan Corbetef402032008-03-28 11:22:38 -0600567
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300568 (a) I have carried out a technical review of this patch to
Jonathan Corbetef402032008-03-28 11:22:38 -0600569 evaluate its appropriateness and readiness for inclusion into
570 the mainline kernel.
571
572 (b) Any problems, concerns, or questions relating to the patch
573 have been communicated back to the submitter. I am satisfied
574 with the submitter's response to my comments.
575
576 (c) While there may be things that could be improved with this
577 submission, I believe that it is, at this time, (1) a
578 worthwhile modification to the kernel, and (2) free of known
579 issues which would argue against its inclusion.
580
581 (d) While I have reviewed the patch and believe it to be sound, I
582 do not (unless explicitly stated elsewhere) make any
583 warranties or guarantees that it will achieve its stated
584 purpose or function properly in any given situation.
585
586A Reviewed-by tag is a statement of opinion that the patch is an
587appropriate modification of the kernel without any remaining serious
588technical issues. Any interested reviewer (who has done the work) can
589offer a Reviewed-by tag for a patch. This tag serves to give credit to
590reviewers and to inform maintainers of the degree of review which has been
591done on the patch. Reviewed-by: tags, when supplied by reviewers known to
592understand the subject area and to perform thorough reviews, will normally
Pavel Machek5801da12009-06-04 16:26:50 +0200593increase the likelihood of your patch getting into the kernel.
Jonathan Corbetef402032008-03-28 11:22:38 -0600594
Mugunthan V N8543ae12013-04-29 16:18:17 -0700595A Suggested-by: tag indicates that the patch idea is suggested by the person
596named and ensures credit to the person for the idea. Please note that this
597tag should not be added without the reporter's permission, especially if the
598idea was not posted in a public forum. That said, if we diligently credit our
599idea reporters, they will, hopefully, be inspired to help us again in the
600future.
601
Jacob Keller8401aa12014-06-06 14:36:39 -0700602A Fixes: tag indicates that the patch fixes an issue in a previous commit. It
603is used to make it easy to determine where a bug originated, which can help
604review a bug fix. This tag also assists the stable kernel team in determining
605which stable kernel versions should receive your fix. This is the preferred
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300606method for indicating a bug fixed by the patch. See :ref:`describe_changes`
607for more details.
Jacob Keller8401aa12014-06-06 14:36:39 -0700608
Jonathan Corbetef402032008-03-28 11:22:38 -0600609
Jonathan Corbetccae8612014-12-23 08:49:18 -070061014) The canonical patch format
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700611------------------------------
612
613This section describes how the patch itself should be formatted. Note
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300614that, if you have your patches stored in a ``git`` repository, proper patch
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300615formatting can be had with ``git format-patch``. The tools cannot create
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700616the necessary text, though, so read the instructions below anyway.
Randy Dunlap84da7c02005-06-28 20:45:30 -0700617
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300618The canonical patch subject line is::
Paul Jackson75f84262005-10-02 18:01:42 -0700619
Paul Jacksond6b9acc2005-10-03 00:29:10 -0700620 Subject: [PATCH 001/123] subsystem: summary phrase
Paul Jackson75f84262005-10-02 18:01:42 -0700621
622The canonical patch message body contains the following:
623
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300624 - A ``from`` line specifying the patch author (only needed if the person
Jonathan Corbetccae8612014-12-23 08:49:18 -0700625 sending the patch is not the author).
Paul Jackson75f84262005-10-02 18:01:42 -0700626
627 - An empty line.
628
Joe Perches2a076f42015-04-16 12:44:28 -0700629 - The body of the explanation, line wrapped at 75 columns, which will
630 be copied to the permanent changelog to describe this patch.
Paul Jackson75f84262005-10-02 18:01:42 -0700631
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300632 - The ``Signed-off-by:`` lines, described above, which will
Paul Jackson75f84262005-10-02 18:01:42 -0700633 also go in the changelog.
634
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300635 - A marker line containing simply ``---``.
Paul Jackson75f84262005-10-02 18:01:42 -0700636
637 - Any additional comments not suitable for the changelog.
638
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300639 - The actual patch (``diff`` output).
Paul Jackson75f84262005-10-02 18:01:42 -0700640
641The Subject line format makes it very easy to sort the emails
642alphabetically by subject line - pretty much any email reader will
643support that - since because the sequence number is zero-padded,
644the numerical and alphabetic sort is the same.
645
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300646The ``subsystem`` in the email's Subject should identify which
Paul Jacksond6b9acc2005-10-03 00:29:10 -0700647area or subsystem of the kernel is being patched.
648
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300649The ``summary phrase`` in the email's Subject should concisely
650describe the patch which that email contains. The ``summary
651phrase`` should not be a filename. Do not use the same ``summary
652phrase`` for every patch in a whole patch series (where a ``patch
653series`` is an ordered sequence of multiple, related patches).
Paul Jacksond6b9acc2005-10-03 00:29:10 -0700654
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300655Bear in mind that the ``summary phrase`` of your email becomes a
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400656globally-unique identifier for that patch. It propagates all the way
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300657into the ``git`` changelog. The ``summary phrase`` may later be used in
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400658developer discussions which refer to the patch. People will want to
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300659google for the ``summary phrase`` to read discussion regarding that
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400660patch. It will also be the only thing that people may quickly see
661when, two or three months later, they are going through perhaps
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300662thousands of patches using tools such as ``gitk`` or ``git log
663--oneline``.
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400664
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300665For these reasons, the ``summary`` must be no more than 70-75
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400666characters, and it must describe both what the patch changes, as well
667as why the patch might be necessary. It is challenging to be both
668succinct and descriptive, but that is what a well-written summary
669should do.
670
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300671The ``summary phrase`` may be prefixed by tags enclosed in square
Alex Henriee12d7462015-09-20 14:11:19 +0200672brackets: "Subject: [PATCH <tag>...] <summary phrase>". The tags are
673not considered part of the summary phrase, but describe how the patch
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400674should be treated. Common tags might include a version descriptor if
675the multiple versions of the patch have been sent out in response to
676comments (i.e., "v1, v2, v3"), or "RFC" to indicate a request for
677comments. If there are four patches in a patch series the individual
678patches may be numbered like this: 1/4, 2/4, 3/4, 4/4. This assures
679that developers understand the order in which the patches should be
680applied and that they have reviewed or applied all of the patches in
681the patch series.
Paul Jacksond6b9acc2005-10-03 00:29:10 -0700682
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300683A couple of example Subjects::
Paul Jacksond6b9acc2005-10-03 00:29:10 -0700684
Alex Henriee12d7462015-09-20 14:11:19 +0200685 Subject: [PATCH 2/5] ext2: improve scalability of bitmap searching
686 Subject: [PATCH v2 01/27] x86: fix eflags tracking
Paul Jackson75f84262005-10-02 18:01:42 -0700687
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300688The ``from`` line must be the very first line in the message body,
Paul Jackson75f84262005-10-02 18:01:42 -0700689and has the form:
690
691 From: Original Author <author@example.com>
692
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300693The ``from`` line specifies who will be credited as the author of the
694patch in the permanent changelog. If the ``from`` line is missing,
695then the ``From:`` line from the email header will be used to determine
Paul Jackson75f84262005-10-02 18:01:42 -0700696the patch author in the changelog.
697
698The explanation body will be committed to the permanent source
699changelog, so should make sense to a competent reader who has long
700since forgotten the immediate details of the discussion that might
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400701have led to this patch. Including symptoms of the failure which the
702patch addresses (kernel log messages, oops messages, etc.) is
703especially useful for people who might be searching the commit logs
704looking for the applicable patch. If a patch fixes a compile failure,
705it may not be necessary to include _all_ of the compile failures; just
706enough that it is likely that someone searching for the patch can find
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300707it. As in the ``summary phrase``, it is important to be both succinct as
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400708well as descriptive.
Paul Jackson75f84262005-10-02 18:01:42 -0700709
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300710The ``---`` marker line serves the essential purpose of marking for patch
Paul Jackson75f84262005-10-02 18:01:42 -0700711handling tools where the changelog message ends.
712
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300713One good use for the additional comments after the ``---`` marker is for
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300714a ``diffstat``, to show what files have changed, and the number of
715inserted and deleted lines per file. A ``diffstat`` is especially useful
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400716on bigger patches. Other comments relevant only to the moment or the
717maintainer, not suitable for the permanent changelog, should also go
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300718here. A good example of such comments might be ``patch changelogs``
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400719which describe what has changed between the v1 and v2 version of the
720patch.
721
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300722If you are going to include a ``diffstat`` after the ``---`` marker, please
723use ``diffstat`` options ``-p 1 -w 70`` so that filenames are listed from
Theodore Ts'o2ae19ac2009-04-16 07:44:45 -0400724the top of the kernel source tree and don't use too much horizontal
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300725space (easily fit in 80 columns, maybe with some indentation). (``git``
Josh Triplett8e3072a2014-04-03 14:48:30 -0700726generates appropriate diffstats by default.)
Paul Jackson75f84262005-10-02 18:01:42 -0700727
728See more details on the proper patch format in the following
729references.
730
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300731.. _explicit_in_reply_to:
732
Chris Metcalfd7ac8d82015-11-05 15:21:47 -050073315) Explicit In-Reply-To headers
734--------------------------------
Paul Jackson75f84262005-10-02 18:01:42 -0700735
Chris Metcalfd7ac8d82015-11-05 15:21:47 -0500736It can be helpful to manually add In-Reply-To: headers to a patch
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300737(e.g., when using ``git send-email``) to associate the patch with
Chris Metcalfd7ac8d82015-11-05 15:21:47 -0500738previous relevant discussion, e.g. to link a bug fix to the email with
739the bug report. However, for a multi-patch series, it is generally
740best to avoid using In-Reply-To: to link to older versions of the
741series. This way multiple versions of the patch don't become an
742unmanageable forest of references in email clients. If a link is
743helpful, you can use the https://lkml.kernel.org/ redirector (e.g., in
744the cover email text) to link to an earlier version of the patch series.
745
746
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -030074716) Sending ``git pull`` requests
748---------------------------------
Randy Dunlap84da7c02005-06-28 20:45:30 -0700749
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700750If you have a series of patches, it may be most convenient to have the
751maintainer pull them directly into the subsystem repository with a
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300752``git pull`` operation. Note, however, that pulling patches from a developer
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700753requires a higher degree of trust than taking patches from a mailing list.
754As a result, many subsystem maintainers are reluctant to take pull
Jonathan Corbetb792ffe2014-12-23 09:28:40 -0700755requests, especially from new, unknown developers. If in doubt you can use
756the pull request as the cover letter for a normal posting of the patch
757series, giving the maintainer the option of using either.
Randy Dunlap14863612008-07-27 20:44:24 -0700758
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700759A pull request should have [GIT] or [PULL] in the subject line. The
760request itself should include the repository name and the branch of
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300761interest on a single line; it should look something like::
Randy Dunlap14863612008-07-27 20:44:24 -0700762
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700763 Please pull from
Randy Dunlap14863612008-07-27 20:44:24 -0700764
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700765 git://jdelvare.pck.nerim.net/jdelvare-2.6 i2c-for-linus
Randy Dunlap14863612008-07-27 20:44:24 -0700766
Jakub Wilk64e32892015-07-27 10:15:18 +0200767 to get these changes:
Randy Dunlap14863612008-07-27 20:44:24 -0700768
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700769A pull request should also include an overall message saying what will be
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300770included in the request, a ``git shortlog`` listing of the patches
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300771themselves, and a ``diffstat`` showing the overall effect of the patch series.
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700772The easiest way to get all this information together is, of course, to let
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300773``git`` do it for you with the ``git request-pull`` command.
Randy Dunlap14863612008-07-27 20:44:24 -0700774
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700775Some maintainers (including Linus) want to see pull requests from signed
776commits; that increases their confidence that the request actually came
777from you. Linus, in particular, will not pull from public hosting sites
778like GitHub in the absence of a signed tag.
Randy Dunlap14863612008-07-27 20:44:24 -0700779
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700780The first step toward creating such tags is to make a GNUPG key and get it
781signed by one or more core kernel developers. This step can be hard for
782new developers, but there is no way around it. Attending conferences can
783be a good way to find developers who can sign your key.
Randy Dunlap14863612008-07-27 20:44:24 -0700784
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300785Once you have prepared a patch series in ``git`` that you wish to have somebody
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300786pull, create a signed tag with ``git tag -s``. This will create a new tag
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700787identifying the last commit in the series and containing a signature
788created with your private key. You will also have the opportunity to add a
789changelog-style message to the tag; this is an ideal place to describe the
790effects of the pull request as a whole.
Randy Dunlap84da7c02005-06-28 20:45:30 -0700791
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700792If the tree the maintainer will be pulling from is not the repository you
793are working from, don't forget to push the signed tag explicitly to the
794public tree.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700796When generating your pull request, use the signed tag as the target. A
Mauro Carvalho Chehab59030192016-09-19 08:07:53 -0300797command like this will do the trick::
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798
Jonathan Corbet7994cc12014-12-23 08:43:41 -0700799 git request-pull master git://my.public.tree/linux.git my-signed-tag
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800800
801
Jonathan Corbet89edeed2016-10-26 16:37:53 -0600802References
803----------
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800804
805Andrew Morton, "The perfect patch" (tpp).
Mitchel Humpherys37c703f2014-04-03 14:50:40 -0700806 <http://www.ozlabs.org/~akpm/stuff/tpp.txt>
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800807
Pavel Machek8e9cb8f2006-09-29 02:01:29 -0700808Jeff Garzik, "Linux kernel patch submission format".
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800809 <http://linux.yyz.us/patch-format.html>
810
Pavel Machek8e9cb8f2006-09-29 02:01:29 -0700811Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer".
Vikram Narayananf5039932011-05-23 12:01:25 -0700812 <http://www.kroah.com/log/linux/maintainer.html>
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300813
Vikram Narayananf5039932011-05-23 12:01:25 -0700814 <http://www.kroah.com/log/linux/maintainer-02.html>
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300815
Vikram Narayananf5039932011-05-23 12:01:25 -0700816 <http://www.kroah.com/log/linux/maintainer-03.html>
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300817
Vikram Narayananf5039932011-05-23 12:01:25 -0700818 <http://www.kroah.com/log/linux/maintainer-04.html>
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300819
Vikram Narayananf5039932011-05-23 12:01:25 -0700820 <http://www.kroah.com/log/linux/maintainer-05.html>
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300821
Sudip Mukherjee7e0dae62014-09-07 11:26:12 -0700822 <http://www.kroah.com/log/linux/maintainer-06.html>
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800823
Randy Dunlapbc7455f2006-07-30 03:03:45 -0700824NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people!
Mitchel Humpherys37c703f2014-04-03 14:50:40 -0700825 <https://lkml.org/lkml/2005/7/11/336>
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800826
Mauro Carvalho Chehab8c27cef2016-10-18 10:12:27 -0200827Kernel Documentation/process/coding-style.rst:
828 :ref:`Documentation/process/coding-style.rst <codingstyle>`
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800829
Pavel Machek8e9cb8f2006-09-29 02:01:29 -0700830Linus Torvalds's mail on the canonical patch format:
Xose Vazquez Perez5b0ed2c2006-01-08 01:02:49 -0800831 <http://lkml.org/lkml/2005/4/7/183>
Andi Kleen95367272008-10-15 22:02:02 -0700832
833Andi Kleen, "On submitting kernel patches"
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300834 Some strategies to get difficult or controversial changes in.
Mauro Carvalho Chehab9b2c7672016-09-19 08:07:54 -0300835
Andi Kleen95367272008-10-15 22:02:02 -0700836 http://halobates.de/on-submitting-patches.pdf