with "the system." This text is a collection of suggestions which
can greatly increase the chances of your change being accepted.
-If you are submitting a driver, also read Documentation/SubmittingDrivers.
+Read Documentation/SubmitChecklist for a list of items to check
+before submitting code. If you are submitting a driver, also read
+Documentation/SubmittingDrivers.
Quilt:
http://savannah.nongnu.org/projects/quilt
-Randy Dunlap's patch scripts:
-http://www.xenotime.net/linux/scripts/patching-scripts-002.tar.gz
-
Andrew Morton's patch scripts:
-http://www.zip.com.au/~akpm/linux/patches/patch-scripts-0.20
+http://userweb.kernel.org/~akpm/stuff/patch-scripts.tar.gz
+Instead of these scripts, quilt is the recommended patch management
+tool (see above).
things like "update driver X", "bug fix for driver X", or "this patch
includes updates for subsystem X. Please apply."
+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 #15, below.
+
If your description starts to get long, that's a sign that you probably
need to split up your patch. See #3, next.
3) Separate your changes.
-Separate each logical change into its own patch.
+Separate _logical changes_ into a single patch file.
For example, if your changes include both bug fixes and performance
enhancements for a single driver, separate those changes into two
complete, that is OK. Simply note "this patch depends on patch X"
in your patch description.
+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.
-4) Select e-mail destination.
+Check your patch for basic style violations, details of which can be
+found in Documentation/CodingStyle. Failure to do so simply wastes
+the reviewers time and will get your patch rejected, probably
+without even being read.
+
+At a minimum you should check your patches with the patch style
+checker prior to submission (scripts/checkpatch.pl). You should
+be able to justify all violations that remain in your patch.
+
+
+
+5) Select e-mail destination.
Look through the MAINTAINERS file and the source code, and determine
if your change applies to a specific subsystem of the kernel, with
linux-kernel@vger.kernel.org. Most kernel developers monitor this
e-mail list, and can comment on your changes.
+
+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@osdl.org>. He gets
-a lot of e-mail, so typically you should do your best to -avoid- sending
-him e-mail.
+Linux kernel. His e-mail address is <torvalds@linux-foundation.org>.
+He gets a lot of e-mail, so typically you should do your best to -avoid-
+sending him e-mail.
Patches which are bug fixes, are "obvious" changes, or similarly
require little discussion should be sent or CC'd to Linus. Patches
-5) Select your CC (e-mail carbon copy) list.
+6) Select your CC (e-mail carbon copy) list.
Unless you have a reason NOT to do so, CC linux-kernel@vger.kernel.org.
MAINTAINERS file for a mailing list that relates specifically to
your change.
+Majordomo lists of VGER.KERNEL.ORG at:
+ <http://vger.kernel.org/vger-lists.html>
+
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.
-Even if the maintainer did not respond in step #4, make sure to ALWAYS
+Even if the maintainer did not respond in step #5, make sure to ALWAYS
copy the maintainer when you change their code.
For small patches you may want to CC the Trivial Patch Monkey
-trivial@rustcorp.com.au set up by Rusty Russell; which collects "trivial"
-patches. Trivial patches must qualify for one of the following rules:
+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 which could break grep(1).
+ Spelling fixes which could break 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 (eg. check_region).
+ Removing use of deprecated functions/macros (eg. check_region)
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
+ Any fix by the author/maintainer of the file (ie. patch monkey
in re-transmission mode)
-URL: <http://www.kernel.org/pub/linux/kernel/people/rusty/trivial/>
-
-6) No MIME, no links, no compression, no attachments. Just plain text.
+7) 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
Exception: If your mailer is mangling patches then someone may ask
you to re-send them using MIME.
+See Documentation/email-clients.txt for hints about configuring
+your e-mail client so that it sends your patches untouched.
+8) E-mail size.
-7) E-mail size.
-
-When sending patches to Linus, always follow step #6.
+When sending patches to Linus, always follow step #7.
Large changes are not appropriate for mailing lists, and some
-maintainers. If your patch, uncompressed, exceeds 40 kB in size,
+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.
-8) Name your kernel version.
+9) Name your kernel version.
It is important to note, either in the subject line or in the patch
description, the kernel version to which this patch applies.
-9) Don't get discouraged. Re-submit.
+10) Don't get discouraged. Re-submit.
After you have submitted your change, be patient and wait. If Linus
likes your change and applies it, it will appear in the next version
It is quite common for Linus to "drop" your patch without comment.
That's the nature of the system. If he drops your patch, it could be
due to
-* Your patch did not apply cleanly to the latest kernel version
+* Your patch did not apply cleanly to the latest kernel version.
* Your patch was not sufficiently discussed on linux-kernel.
-* A style issue (see section 2),
-* An e-mail formatting issue (re-read this section)
-* A technical problem with your change
-* He gets tons of e-mail, and yours got lost in the shuffle
-* You are being annoying (See Figure 1)
+* A style issue (see section 2).
+* An e-mail formatting issue (re-read this section).
+* A technical problem with your change.
+* He gets tons of e-mail, and yours got lost in the shuffle.
+* You are being annoying.
When in doubt, solicit comments on linux-kernel mailing list.
-10) Include PATCH in the subject
+11) 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
-11) Sign your work
+12) 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
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 practise 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 practise
+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 2.6-stable :
+
+ Date: Tue May 13 19:10:30 2008 +0000
+
+ SCSI: libiscsi regression in 2.6.25: fix nop timer handling
+
+ commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream
+
+And here's what appears in 2.4 :
+
+ 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 trouble-shoot bugs in your
+tree.
+
+
+13) 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
+arrange 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:.
+
+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. This tag documents that potentially interested parties
+have been included in the discussion
+
-12) The canonical patch format
+14) Using Reported-by:, Tested-by: and Reviewed-by:
+
+If this patch fixes a problem reported by somebody else, consider adding a
+Reported-by: tag to credit the reporter for their contribution. Please
+note that this tag should not be added without the reporter's permission,
+especially if the problem was not reported in a public forum. That said,
+if we diligently credit our bug reporters, they will, hopefully, be
+inspired to help us again in the future.
+
+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.
+
+
+15) The canonical patch format
The canonical patch subject line is:
- Subject: [PATCH 001/123] [<area>:] <explanation>
+ Subject: [PATCH 001/123] subsystem: summary phrase
The canonical patch message body contains the following:
support that - since because the sequence number is zero-padded,
the numerical and alphabetic sort is the same.
-See further details on how to phrase the "<explanation>" in the
-"Subject:" line in Andrew Morton's "The perfect patch", referenced
-below.
+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: [PATCHv2 001/207] x86: fix eflags tracking
The "from" line must be the very first line in the message body,
and has the form:
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.
+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 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).
See more details on the proper patch format in the following
references.
-13) More references for submitting patches
+16) Sending "git pull" requests (from Linus emails)
-Andrew Morton, "The perfect patch" (tpp).
- <http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt>
+Please write the git repo address and branch name alone on the same line
+so that I can't even by mistake pull from the wrong branch, and so
+that a triple-click just selects the whole thing.
-Jeff Garzik, "Linux kernel patch submission format."
- <http://linux.yyz.us/patch-format.html>
+So the proper format is something along the lines of:
-Greg KH, "How to piss off a kernel subsystem maintainer"
- <http://www.kroah.com/log/2005/03/31/>
+ "Please pull from
-Kernel Documentation/CodingStyle
- <http://sosdg.org/~coywolf/lxr/source/Documentation/CodingStyle>
+ git://jdelvare.pck.nerim.net/jdelvare-2.6 i2c-for-linus
-Linus Torvald's mail on the canonical patch format:
- <http://lkml.org/lkml/2005/4/7/183>
+ to get these changes:"
+
+so that I don't have to hunt-and-peck for the address and inevitably
+get it wrong (actually, I've only gotten it wrong a few times, and
+checking against the diffstat tells me when I get it wrong, but I'm
+just a lot more comfortable when I don't have to "look for" the right
+thing to pull, and double-check that I have the right branch-name).
+
+
+Please use "git diff -M --stat --summary" to generate the diffstat:
+the -M enables rename detection, and the summary enables a summary of
+new/deleted or renamed files.
+With rename detection, the statistics are rather different [...]
+because git will notice that a fair number of the changes are renames.
-----------------------------------
SECTION 2 - HINTS, TIPS, AND TRICKS
Nuff said. If your code deviates too much from this, it is likely
to be rejected without further review, and without comment.
+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). The style checker should be viewed as
+a guide not as the final word. 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.
+
2) #ifdefs are ugly
limitations, and under gcc they are as cheap as macros.
Macros should only be used for cases where a static inline is clearly
-suboptimal [there a few, isolated cases of this in fast paths],
+suboptimal [there are a few, isolated cases of this in fast paths],
or where it is impossible to use a static inline function [such as
string-izing].
Don't try to anticipate nebulous future cases which may or may not
be useful: "Make it as simple as you can, and no simpler."
+
+
+----------------------
+SECTION 3 - REFERENCES
+----------------------
+
+Andrew Morton, "The perfect patch" (tpp).
+ <http://userweb.kernel.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/2005/03/31/>
+ <http://www.kroah.com/log/2005/07/08/>
+ <http://www.kroah.com/log/2005/10/19/>
+ <http://www.kroah.com/log/2006/01/11/>
+
+NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people!
+ <http://marc.theaimsgroup.com/?l=linux-kernel&m=112112749912944&w=2>
+
+Kernel Documentation/CodingStyle:
+ <http://users.sosdg.org/~qiyong/lxr/source/Documentation/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 controversal changes in.
+ http://halobates.de/on-submitting-patches.pdf
+
+--
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff