1 .. _submittingpatches: 1 .. _submittingpatches:
2 2
3 Submitting patches: the essential guide to get 3 Submitting patches: the essential guide to getting your code into the kernel
4 ============================================== 4 ============================================================================
5 5
6 For a person or company who wishes to submit a 6 For a person or company who wishes to submit a change to the Linux
7 kernel, the process can sometimes be daunting 7 kernel, the process can sometimes be daunting if you're not familiar
8 with "the system." This text is a collection 8 with "the system." This text is a collection of suggestions which
9 can greatly increase the chances of your chang 9 can greatly increase the chances of your change being accepted.
10 10
11 This document contains a large number of sugge 11 This document contains a large number of suggestions in a relatively terse
12 format. For detailed information on how the k 12 format. For detailed information on how the kernel development process
13 works, see Documentation/process/development-p !! 13 works, see :doc:`development-process`. Also, read :doc:`submit-checklist`
14 Documentation/process/submit-checklist.rst !! 14 for a list of items to check before submitting code. If you are submitting
15 for a list of items to check before submitting !! 15 a driver, also read :doc:`submitting-drivers`; for device tree binding patches,
16 For device tree binding patches, read !! 16 read :doc:`submitting-patches`.
17 Documentation/devicetree/bindings/submitting-p <<
18 17
19 This documentation assumes that you're using ` 18 This documentation assumes that you're using ``git`` to prepare your patches.
20 If you're unfamiliar with ``git``, you would b 19 If you're unfamiliar with ``git``, you would be well-advised to learn how to
21 use it, it will make your life as a kernel dev 20 use it, it will make your life as a kernel developer and in general much
22 easier. 21 easier.
23 22
24 Some subsystems and maintainer trees have addi <<
25 their workflow and expectations, see <<
26 :ref:`Documentation/process/maintainer-handboo <<
27 <<
28 Obtain a current source tree 23 Obtain a current source tree
29 ---------------------------- 24 ----------------------------
30 25
31 If you do not have a repository with the curre 26 If you do not have a repository with the current kernel source handy, use
32 ``git`` to obtain one. You'll want to start w 27 ``git`` to obtain one. You'll want to start with the mainline repository,
33 which can be grabbed with:: 28 which can be grabbed with::
34 29
35 git clone git://git.kernel.org/pub/scm/linux 30 git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
36 31
37 Note, however, that you may not want to develo 32 Note, however, that you may not want to develop against the mainline tree
38 directly. Most subsystem maintainers run thei 33 directly. Most subsystem maintainers run their own trees and want to see
39 patches prepared against those trees. See the 34 patches prepared against those trees. See the **T:** entry for the subsystem
40 in the MAINTAINERS file to find that tree, or 35 in the MAINTAINERS file to find that tree, or simply ask the maintainer if
41 the tree is not listed there. 36 the tree is not listed there.
42 37
43 .. _describe_changes: 38 .. _describe_changes:
44 39
45 Describe your changes 40 Describe your changes
46 --------------------- 41 ---------------------
47 42
48 Describe your problem. Whether your patch is 43 Describe your problem. Whether your patch is a one-line bug fix or
49 5000 lines of a new feature, there must be an 44 5000 lines of a new feature, there must be an underlying problem that
50 motivated you to do this work. Convince the r 45 motivated you to do this work. Convince the reviewer that there is a
51 problem worth fixing and that it makes sense f 46 problem worth fixing and that it makes sense for them to read past the
52 first paragraph. 47 first paragraph.
53 48
54 Describe user-visible impact. Straight up cra 49 Describe user-visible impact. Straight up crashes and lockups are
55 pretty convincing, but not all bugs are that b 50 pretty convincing, but not all bugs are that blatant. Even if the
56 problem was spotted during code review, descri 51 problem was spotted during code review, describe the impact you think
57 it can have on users. Keep in mind that the m 52 it can have on users. Keep in mind that the majority of Linux
58 installations run kernels from secondary stabl 53 installations run kernels from secondary stable trees or
59 vendor/product-specific trees that cherry-pick 54 vendor/product-specific trees that cherry-pick only specific patches
60 from upstream, so include anything that could 55 from upstream, so include anything that could help route your change
61 downstream: provoking circumstances, excerpts 56 downstream: provoking circumstances, excerpts from dmesg, crash
62 descriptions, performance regressions, latency 57 descriptions, performance regressions, latency spikes, lockups, etc.
63 58
64 Quantify optimizations and trade-offs. If you 59 Quantify optimizations and trade-offs. If you claim improvements in
65 performance, memory consumption, stack footpri 60 performance, memory consumption, stack footprint, or binary size,
66 include numbers that back them up. But also d 61 include numbers that back them up. But also describe non-obvious
67 costs. Optimizations usually aren't free but 62 costs. Optimizations usually aren't free but trade-offs between CPU,
68 memory, and readability; or, when it comes to 63 memory, and readability; or, when it comes to heuristics, between
69 different workloads. Describe the expected do 64 different workloads. Describe the expected downsides of your
70 optimization so that the reviewer can weigh co 65 optimization so that the reviewer can weigh costs against benefits.
71 66
72 Once the problem is established, describe what 67 Once the problem is established, describe what you are actually doing
73 about it in technical detail. It's important 68 about it in technical detail. It's important to describe the change
74 in plain English for the reviewer to verify th 69 in plain English for the reviewer to verify that the code is behaving
75 as you intend it to. 70 as you intend it to.
76 71
77 The maintainer will thank you if you write you 72 The maintainer will thank you if you write your patch description in a
78 form which can be easily pulled into Linux's s 73 form which can be easily pulled into Linux's source code management
79 system, ``git``, as a "commit log". See :ref: 74 system, ``git``, as a "commit log". See :ref:`the_canonical_patch_format`.
80 75
81 Solve only one problem per patch. If your des 76 Solve only one problem per patch. If your description starts to get
82 long, that's a sign that you probably need to 77 long, that's a sign that you probably need to split up your patch.
83 See :ref:`split_changes`. 78 See :ref:`split_changes`.
84 79
85 When you submit or resubmit a patch or patch s 80 When you submit or resubmit a patch or patch series, include the
86 complete patch description and justification f 81 complete patch description and justification for it. Don't just
87 say that this is version N of the patch (serie 82 say that this is version N of the patch (series). Don't expect the
88 subsystem maintainer to refer back to earlier 83 subsystem maintainer to refer back to earlier patch versions or referenced
89 URLs to find the patch description and put tha 84 URLs to find the patch description and put that into the patch.
90 I.e., the patch (series) and its description s 85 I.e., the patch (series) and its description should be self-contained.
91 This benefits both the maintainers and reviewe 86 This benefits both the maintainers and reviewers. Some reviewers
92 probably didn't even receive earlier versions 87 probably didn't even receive earlier versions of the patch.
93 88
94 Describe your changes in imperative mood, e.g. 89 Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
95 instead of "[This patch] makes xyzzy do frotz" 90 instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
96 to do frotz", as if you are giving orders to t 91 to do frotz", as if you are giving orders to the codebase to change
97 its behaviour. 92 its behaviour.
98 93
>> 94 If the patch fixes a logged bug entry, refer to that bug entry by
>> 95 number and URL. If the patch follows from a mailing list discussion,
>> 96 give a URL to the mailing list archive; use the https://lkml.kernel.org/
>> 97 redirector with a ``Message-Id``, to ensure that the links cannot become
>> 98 stale.
>> 99
>> 100 However, try to make your explanation understandable without external
>> 101 resources. In addition to giving a URL to a mailing list archive or
>> 102 bug, summarize the relevant points of the discussion that led to the
>> 103 patch as submitted.
>> 104
99 If you want to refer to a specific commit, don 105 If you want to refer to a specific commit, don't just refer to the
100 SHA-1 ID of the commit. Please also include th 106 SHA-1 ID of the commit. Please also include the oneline summary of
101 the commit, to make it easier for reviewers to 107 the commit, to make it easier for reviewers to know what it is about.
102 Example:: 108 Example::
103 109
104 Commit e21d2170f36602ae2708 ("video: r 110 Commit e21d2170f36602ae2708 ("video: remove unnecessary
105 platform_set_drvdata()") removed the u 111 platform_set_drvdata()") removed the unnecessary
106 platform_set_drvdata(), but left the v 112 platform_set_drvdata(), but left the variable "dev" unused,
107 delete it. 113 delete it.
108 114
109 You should also be sure to use at least the fi 115 You should also be sure to use at least the first twelve characters of the
110 SHA-1 ID. The kernel repository holds a *lot* 116 SHA-1 ID. The kernel repository holds a *lot* of objects, making
111 collisions with shorter IDs a real possibility 117 collisions with shorter IDs a real possibility. Bear in mind that, even if
112 there is no collision with your six-character 118 there is no collision with your six-character ID now, that condition may
113 change five years from now. 119 change five years from now.
114 120
115 If related discussions or any other background <<
116 can be found on the web, add 'Link:' tags poin <<
117 result of some earlier mailing list discussion <<
118 web, point to it. <<
119 <<
120 When linking to mailing list archives, prefera <<
121 message archiver service. To create the link U <<
122 ``Message-ID`` header of the message without t <<
123 For example:: <<
124 <<
125 Link: https://lore.kernel.org/30th.anniver <<
126 <<
127 Please check the link to make sure that it is <<
128 to the relevant message. <<
129 <<
130 However, try to make your explanation understa <<
131 resources. In addition to giving a URL to a ma <<
132 summarize the relevant points of the discussio <<
133 patch as submitted. <<
134 <<
135 In case your patch fixes a bug, use the 'Close <<
136 the report in the mailing list archives or a p <<
137 <<
138 Closes: https://example.com/issues/123 <<
139 <<
140 Some bug trackers have the ability to close is <<
141 commit with such a tag is applied. Some bots m <<
142 also track such tags and take certain actions. <<
143 invalid URLs are forbidden. <<
144 <<
145 If your patch fixes a bug in a specific commit 121 If your patch fixes a bug in a specific commit, e.g. you found an issue using
146 ``git bisect``, please use the 'Fixes:' tag wi 122 ``git bisect``, please use the 'Fixes:' tag with the first 12 characters of
147 the SHA-1 ID, and the one line summary. Do no 123 the SHA-1 ID, and the one line summary. Do not split the tag across multiple
148 lines, tags are exempt from the "wrap at 75 co 124 lines, tags are exempt from the "wrap at 75 columns" rule in order to simplify
149 parsing scripts. For example:: 125 parsing scripts. For example::
150 126
151 Fixes: 54a4f0239f2e ("KVM: MMU: make k 127 Fixes: 54a4f0239f2e ("KVM: MMU: make kvm_mmu_zap_page() return the number of pages it actually freed")
152 128
153 The following ``git config`` settings can be u 129 The following ``git config`` settings can be used to add a pretty format for
154 outputting the above style in the ``git log`` 130 outputting the above style in the ``git log`` or ``git show`` commands::
155 131
156 [core] 132 [core]
157 abbrev = 12 133 abbrev = 12
158 [pretty] 134 [pretty]
159 fixes = Fixes: %h (\"%s\") 135 fixes = Fixes: %h (\"%s\")
160 136
161 An example call:: 137 An example call::
162 138
163 $ git log -1 --pretty=fixes 54a4f0239f 139 $ git log -1 --pretty=fixes 54a4f0239f2e
164 Fixes: 54a4f0239f2e ("KVM: MMU: make k 140 Fixes: 54a4f0239f2e ("KVM: MMU: make kvm_mmu_zap_page() return the number of pages it actually freed")
165 141
166 .. _split_changes: 142 .. _split_changes:
167 143
168 Separate your changes 144 Separate your changes
169 --------------------- 145 ---------------------
170 146
171 Separate each **logical change** into a separa 147 Separate each **logical change** into a separate patch.
172 148
173 For example, if your changes include both bug 149 For example, if your changes include both bug fixes and performance
174 enhancements for a single driver, separate tho 150 enhancements for a single driver, separate those changes into two
175 or more patches. If your changes include an A 151 or more patches. If your changes include an API update, and a new
176 driver which uses that new API, separate those 152 driver which uses that new API, separate those into two patches.
177 153
178 On the other hand, if you make a single change 154 On the other hand, if you make a single change to numerous files,
179 group those changes into a single patch. Thus 155 group those changes into a single patch. Thus a single logical change
180 is contained within a single patch. 156 is contained within a single patch.
181 157
182 The point to remember is that each patch shoul 158 The point to remember is that each patch should make an easily understood
183 change that can be verified by reviewers. Eac 159 change that can be verified by reviewers. Each patch should be justifiable
184 on its own merits. 160 on its own merits.
185 161
186 If one patch depends on another patch in order 162 If one patch depends on another patch in order for a change to be
187 complete, that is OK. Simply note **"this pat 163 complete, that is OK. Simply note **"this patch depends on patch X"**
188 in your patch description. 164 in your patch description.
189 165
190 When dividing your change into a series of pat 166 When dividing your change into a series of patches, take special care to
191 ensure that the kernel builds and runs properl 167 ensure that the kernel builds and runs properly after each patch in the
192 series. Developers using ``git bisect`` to tr 168 series. Developers using ``git bisect`` to track down a problem can end up
193 splitting your patch series at any point; they 169 splitting your patch series at any point; they will not thank you if you
194 introduce bugs in the middle. 170 introduce bugs in the middle.
195 171
196 If you cannot condense your patch set into a s 172 If you cannot condense your patch set into a smaller set of patches,
197 then only post say 15 or so at a time and wait 173 then only post say 15 or so at a time and wait for review and integration.
198 174
199 175
200 176
201 Style-check your changes 177 Style-check your changes
202 ------------------------ 178 ------------------------
203 179
204 Check your patch for basic style violations, d 180 Check your patch for basic style violations, details of which can be
205 found in Documentation/process/coding-style.rs !! 181 found in
>> 182 :ref:`Documentation/process/coding-style.rst <codingstyle>`.
206 Failure to do so simply wastes 183 Failure to do so simply wastes
207 the reviewers time and will get your patch rej 184 the reviewers time and will get your patch rejected, probably
208 without even being read. 185 without even being read.
209 186
210 One significant exception is when moving code 187 One significant exception is when moving code from one file to
211 another -- in this case you should not modify 188 another -- in this case you should not modify the moved code at all in
212 the same patch which moves it. This clearly d 189 the same patch which moves it. This clearly delineates the act of
213 moving the code and your changes. This greatl 190 moving the code and your changes. This greatly aids review of the
214 actual differences and allows tools to better 191 actual differences and allows tools to better track the history of
215 the code itself. 192 the code itself.
216 193
217 Check your patches with the patch style checke 194 Check your patches with the patch style checker prior to submission
218 (scripts/checkpatch.pl). Note, though, that t 195 (scripts/checkpatch.pl). Note, though, that the style checker should be
219 viewed as a guide, not as a replacement for hu 196 viewed as a guide, not as a replacement for human judgment. If your code
220 looks better with a violation then its probabl 197 looks better with a violation then its probably best left alone.
221 198
222 The checker reports at three levels: 199 The checker reports at three levels:
223 - ERROR: things that are very likely to be wr 200 - ERROR: things that are very likely to be wrong
224 - WARNING: things requiring careful review 201 - WARNING: things requiring careful review
225 - CHECK: things requiring thought 202 - CHECK: things requiring thought
226 203
227 You should be able to justify all violations t 204 You should be able to justify all violations that remain in your
228 patch. 205 patch.
229 206
230 207
231 Select the recipients for your patch 208 Select the recipients for your patch
232 ------------------------------------ 209 ------------------------------------
233 210
234 You should always copy the appropriate subsyst !! 211 You should always copy the appropriate subsystem maintainer(s) on any patch
235 any patch to code that they maintain; look thr !! 212 to code that they maintain; look through the MAINTAINERS file and the
236 source code revision history to see who those !! 213 source code revision history to see who those maintainers are. The
237 scripts/get_maintainer.pl can be very useful a !! 214 script scripts/get_maintainer.pl can be very useful at this step. If you
238 patches as arguments to scripts/get_maintainer !! 215 cannot find a maintainer for the subsystem you are working on, Andrew
239 maintainer for the subsystem you are working o !! 216 Morton (akpm@linux-foundation.org) serves as a maintainer of last resort.
240 (akpm@linux-foundation.org) serves as a mainta !! 217
241 !! 218 You should also normally choose at least one mailing list to receive a copy
242 linux-kernel@vger.kernel.org should be used by !! 219 of your patch set. linux-kernel@vger.kernel.org functions as a list of
243 volume on that list has caused a number of dev !! 220 last resort, but the volume on that list has caused a number of developers
244 do not spam unrelated lists and unrelated peop !! 221 to tune it out. Look in the MAINTAINERS file for a subsystem-specific
245 !! 222 list; your patch will probably get more attention there. Please do not
246 Many kernel-related lists are hosted at kernel !! 223 spam unrelated lists, though.
247 of them at https://subspace.kernel.org. There !! 224
248 hosted elsewhere as well, though. !! 225 Many kernel-related lists are hosted on vger.kernel.org; you can find a
>> 226 list of them at http://vger.kernel.org/vger-lists.html. There are
>> 227 kernel-related lists hosted elsewhere as well, though.
>> 228
>> 229 Do not send more than 15 patches at once to the vger mailing lists!!!
249 230
250 Linus Torvalds is the final arbiter of all cha 231 Linus Torvalds is the final arbiter of all changes accepted into the
251 Linux kernel. His e-mail address is <torvalds@ 232 Linux kernel. His e-mail address is <torvalds@linux-foundation.org>.
252 He gets a lot of e-mail, and, at this point, v 233 He gets a lot of e-mail, and, at this point, very few patches go through
253 Linus directly, so typically you should do you 234 Linus directly, so typically you should do your best to -avoid-
254 sending him e-mail. 235 sending him e-mail.
255 236
256 If you have a patch that fixes an exploitable 237 If you have a patch that fixes an exploitable security bug, send that patch
257 to security@kernel.org. For severe bugs, a sh 238 to security@kernel.org. For severe bugs, a short embargo may be considered
258 to allow distributors to get the patch out to 239 to allow distributors to get the patch out to users; in such cases,
259 obviously, the patch should not be sent to any 240 obviously, the patch should not be sent to any public lists. See also
260 Documentation/process/security-bugs.rst. !! 241 :doc:`/admin-guide/security-bugs`.
261 242
262 Patches that fix a severe bug in a released ke 243 Patches that fix a severe bug in a released kernel should be directed
263 toward the stable maintainers by putting a lin 244 toward the stable maintainers by putting a line like this::
264 245
265 Cc: stable@vger.kernel.org 246 Cc: stable@vger.kernel.org
266 247
267 into the sign-off area of your patch (note, NO 248 into the sign-off area of your patch (note, NOT an email recipient). You
268 should also read Documentation/process/stable- !! 249 should also read
269 in addition to this document. !! 250 :ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`
>> 251 in addition to this file.
270 252
271 If changes affect userland-kernel interfaces, 253 If changes affect userland-kernel interfaces, please send the MAN-PAGES
272 maintainer (as listed in the MAINTAINERS file) 254 maintainer (as listed in the MAINTAINERS file) a man-pages patch, or at
273 least a notification of the change, so that so 255 least a notification of the change, so that some information makes its way
274 into the manual pages. User-space API changes 256 into the manual pages. User-space API changes should also be copied to
275 linux-api@vger.kernel.org. 257 linux-api@vger.kernel.org.
276 258
>> 259 For small patches you may want to CC the Trivial Patch Monkey
>> 260 trivial@kernel.org which collects "trivial" patches. Have a look
>> 261 into the MAINTAINERS file for its current manager.
>> 262
>> 263 Trivial patches must qualify for one of the following rules:
>> 264
>> 265 - Spelling fixes in documentation
>> 266 - Spelling fixes for errors which could break :manpage:`grep(1)`
>> 267 - Warning fixes (cluttering with useless warnings is bad)
>> 268 - Compilation fixes (only if they are actually correct)
>> 269 - Runtime fixes (only if they actually fix things)
>> 270 - Removing use of deprecated functions/macros
>> 271 - Contact detail and documentation fixes
>> 272 - Non-portable code replaced by portable code (even in arch-specific,
>> 273 since people copy, as long as it's trivial)
>> 274 - Any fix by the author/maintainer of the file (ie. patch monkey
>> 275 in re-transmission mode)
>> 276
>> 277
277 278
278 No MIME, no links, no compression, no attachme 279 No MIME, no links, no compression, no attachments. Just plain text
279 ---------------------------------------------- 280 -------------------------------------------------------------------
280 281
281 Linus and other kernel developers need to be a 282 Linus and other kernel developers need to be able to read and comment
282 on the changes you are submitting. It is impo 283 on the changes you are submitting. It is important for a kernel
283 developer to be able to "quote" your changes, 284 developer to be able to "quote" your changes, using standard e-mail
284 tools, so that they may comment on specific po 285 tools, so that they may comment on specific portions of your code.
285 286
286 For this reason, all patches should be submitt 287 For this reason, all patches should be submitted by e-mail "inline". The
287 easiest way to do this is with ``git send-emai 288 easiest way to do this is with ``git send-email``, which is strongly
288 recommended. An interactive tutorial for ``gi 289 recommended. An interactive tutorial for ``git send-email`` is available at
289 https://git-send-email.io. 290 https://git-send-email.io.
290 291
291 If you choose not to use ``git send-email``: 292 If you choose not to use ``git send-email``:
292 293
293 .. warning:: 294 .. warning::
294 295
295 Be wary of your editor's word-wrap corruptin 296 Be wary of your editor's word-wrap corrupting your patch,
296 if you choose to cut-n-paste your patch. 297 if you choose to cut-n-paste your patch.
297 298
298 Do not attach the patch as a MIME attachment, 299 Do not attach the patch as a MIME attachment, compressed or not.
299 Many popular e-mail applications will not alwa 300 Many popular e-mail applications will not always transmit a MIME
300 attachment as plain text, making it impossible 301 attachment as plain text, making it impossible to comment on your
301 code. A MIME attachment also takes Linus a bi 302 code. A MIME attachment also takes Linus a bit more time to process,
302 decreasing the likelihood of your MIME-attache 303 decreasing the likelihood of your MIME-attached change being accepted.
303 304
304 Exception: If your mailer is mangling patches 305 Exception: If your mailer is mangling patches then someone may ask
305 you to re-send them using MIME. 306 you to re-send them using MIME.
306 307
307 See Documentation/process/email-clients.rst fo !! 308 See :doc:`/process/email-clients` for hints about configuring your e-mail
308 your e-mail client so that it sends your patch !! 309 client so that it sends your patches untouched.
309 310
310 Respond to review comments 311 Respond to review comments
311 -------------------------- 312 --------------------------
312 313
313 Your patch will almost certainly get comments 314 Your patch will almost certainly get comments from reviewers on ways in
314 which the patch can be improved, in the form o 315 which the patch can be improved, in the form of a reply to your email. You must
315 respond to those comments; ignoring reviewers 316 respond to those comments; ignoring reviewers is a good way to get ignored in
316 return. You can simply reply to their emails t 317 return. You can simply reply to their emails to answer their comments. Review
317 comments or questions that do not lead to a co 318 comments or questions that do not lead to a code change should almost certainly
318 bring about a comment or changelog entry so th 319 bring about a comment or changelog entry so that the next reviewer better
319 understands what is going on. 320 understands what is going on.
320 321
321 Be sure to tell the reviewers what changes you 322 Be sure to tell the reviewers what changes you are making and to thank them
322 for their time. Code review is a tiring and t 323 for their time. Code review is a tiring and time-consuming process, and
323 reviewers sometimes get grumpy. Even in that 324 reviewers sometimes get grumpy. Even in that case, though, respond
324 politely and address the problems they have po !! 325 politely and address the problems they have pointed out.
325 version, add a ``patch changelog`` to the cove <<
326 explaining difference against previous submiss <<
327 :ref:`the_canonical_patch_format`). <<
328 Notify people that commented on your patch abo <<
329 the patches CC list. <<
330 326
331 See Documentation/process/email-clients.rst fo !! 327 See :doc:`email-clients` for recommendations on email
332 clients and mailing list etiquette. 328 clients and mailing list etiquette.
333 329
334 .. _interleaved_replies: <<
335 <<
336 Use trimmed interleaved replies in email discu <<
337 ---------------------------------------------- <<
338 Top-posting is strongly discouraged in Linux k <<
339 discussions. Interleaved (or "inline") replies <<
340 easier to follow. For more details see: <<
341 https://en.wikipedia.org/wiki/Posting_style#In <<
342 <<
343 As is frequently quoted on the mailing list:: <<
344 <<
345 A: http://en.wikipedia.org/wiki/Top_post <<
346 Q: Were do I find info about this thing call <<
347 A: Because it messes up the order in which p <<
348 Q: Why is top-posting such a bad thing? <<
349 A: Top-posting. <<
350 Q: What is the most annoying thing in e-mail <<
351 <<
352 Similarly, please trim all unneeded quotations <<
353 to your reply. This makes responses easier to <<
354 space. For more details see: http://daringfire <<
355 <<
356 A: No. <<
357 Q: Should I include quotations after my repl <<
358 <<
359 .. _resend_reminders: <<
360 330
361 Don't get discouraged - or impatient 331 Don't get discouraged - or impatient
362 ------------------------------------ 332 ------------------------------------
363 333
364 After you have submitted your change, be patie 334 After you have submitted your change, be patient and wait. Reviewers are
365 busy people and may not get to your patch righ 335 busy people and may not get to your patch right away.
366 336
367 Once upon a time, patches used to disappear in 337 Once upon a time, patches used to disappear into the void without comment,
368 but the development process works more smoothl 338 but the development process works more smoothly than that now. You should
369 receive comments within a few weeks (typically !! 339 receive comments within a week or so; if that does not happen, make sure
370 happen, make sure that you have sent your patc !! 340 that you have sent your patches to the right place. Wait for a minimum of
371 Wait for a minimum of one week before resubmit !! 341 one week before resubmitting or pinging reviewers - possibly longer during
372 - possibly longer during busy times like merge !! 342 busy times like merge windows.
373 <<
374 It's also ok to resend the patch or the patch <<
375 weeks with the word "RESEND" added to the subj <<
376 <<
377 [PATCH Vx RESEND] sub/sys: Condensed patch <<
378 <<
379 Don't add "RESEND" when you are submitting a m <<
380 patch or patch series - "RESEND" only applies <<
381 patch or patch series which have not been modi <<
382 previous submission. <<
383 343
384 344
385 Include PATCH in the subject 345 Include PATCH in the subject
386 ----------------------------- 346 -----------------------------
387 347
388 Due to high e-mail traffic to Linus, and to li 348 Due to high e-mail traffic to Linus, and to linux-kernel, it is common
389 convention to prefix your subject line with [P 349 convention to prefix your subject line with [PATCH]. This lets Linus
390 and other kernel developers more easily distin 350 and other kernel developers more easily distinguish patches from other
391 e-mail discussions. 351 e-mail discussions.
392 352
393 ``git send-email`` will do this for you automa 353 ``git send-email`` will do this for you automatically.
394 354
395 355
396 Sign your work - the Developer's Certificate o 356 Sign your work - the Developer's Certificate of Origin
397 ---------------------------------------------- 357 ------------------------------------------------------
398 358
399 To improve tracking of who did what, especiall 359 To improve tracking of who did what, especially with patches that can
400 percolate to their final resting place in the 360 percolate to their final resting place in the kernel through several
401 layers of maintainers, we've introduced a "sig 361 layers of maintainers, we've introduced a "sign-off" procedure on
402 patches that are being emailed around. 362 patches that are being emailed around.
403 363
404 The sign-off is a simple line at the end of th 364 The sign-off is a simple line at the end of the explanation for the
405 patch, which certifies that you wrote it or ot 365 patch, which certifies that you wrote it or otherwise have the right to
406 pass it on as an open-source patch. The rules 366 pass it on as an open-source patch. The rules are pretty simple: if you
407 can certify the below: 367 can certify the below:
408 368
409 Developer's Certificate of Origin 1.1 369 Developer's Certificate of Origin 1.1
410 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 370 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
411 371
412 By making a contribution to this project, I ce 372 By making a contribution to this project, I certify that:
413 373
414 (a) The contribution was created in wh 374 (a) The contribution was created in whole or in part by me and I
415 have the right to submit it under 375 have the right to submit it under the open source license
416 indicated in the file; or 376 indicated in the file; or
417 377
418 (b) The contribution is based upon pre 378 (b) The contribution is based upon previous work that, to the best
419 of my knowledge, is covered under 379 of my knowledge, is covered under an appropriate open source
420 license and I have the right under 380 license and I have the right under that license to submit that
421 work with modifications, whether c 381 work with modifications, whether created in whole or in part
422 by me, under the same open source 382 by me, under the same open source license (unless I am
423 permitted to submit under a differ 383 permitted to submit under a different license), as indicated
424 in the file; or 384 in the file; or
425 385
426 (c) The contribution was provided dire 386 (c) The contribution was provided directly to me by some other
427 person who certified (a), (b) or ( 387 person who certified (a), (b) or (c) and I have not modified
428 it. 388 it.
429 389
430 (d) I understand and agree that this p 390 (d) I understand and agree that this project and the contribution
431 are public and that a record of th 391 are public and that a record of the contribution (including all
432 personal information I submit with 392 personal information I submit with it, including my sign-off) is
433 maintained indefinitely and may be 393 maintained indefinitely and may be redistributed consistent with
434 this project or the open source li 394 this project or the open source license(s) involved.
435 395
436 then you just add a line saying:: 396 then you just add a line saying::
437 397
438 Signed-off-by: Random J Developer <rand 398 Signed-off-by: Random J Developer <random@developer.example.org>
439 399
440 using a known identity (sorry, no anonymous co !! 400 using your real name (sorry, no pseudonyms or anonymous contributions.)
441 This will be done for you automatically if you 401 This will be done for you automatically if you use ``git commit -s``.
442 Reverts should also include "Signed-off-by". ` <<
443 for you. <<
444 402
445 Some people also put extra tags at the end. T 403 Some people also put extra tags at the end. They'll just be ignored for
446 now, but you can do this to mark internal comp 404 now, but you can do this to mark internal company procedures or just
447 point out some special detail about the sign-o 405 point out some special detail about the sign-off.
448 406
449 Any further SoBs (Signed-off-by:'s) following <<
450 people handling and transporting the patch, bu <<
451 development. SoB chains should reflect the **r <<
452 as it was propagated to the maintainers and ul <<
453 the first SoB entry signalling primary authors <<
454 <<
455 407
456 When to use Acked-by:, Cc:, and Co-developed-b 408 When to use Acked-by:, Cc:, and Co-developed-by:
457 ---------------------------------------------- 409 ------------------------------------------------
458 410
459 The Signed-off-by: tag indicates that the sign 411 The Signed-off-by: tag indicates that the signer was involved in the
460 development of the patch, or that he/she was i 412 development of the patch, or that he/she was in the patch's delivery path.
461 413
462 If a person was not directly involved in the p 414 If a person was not directly involved in the preparation or handling of a
463 patch but wishes to signify and record their a 415 patch but wishes to signify and record their approval of it then they can
464 ask to have an Acked-by: line added to the pat 416 ask to have an Acked-by: line added to the patch's changelog.
465 417
466 Acked-by: is often used by the maintainer of t 418 Acked-by: is often used by the maintainer of the affected code when that
467 maintainer neither contributed to nor forwarde 419 maintainer neither contributed to nor forwarded the patch.
468 420
469 Acked-by: is not as formal as Signed-off-by:. 421 Acked-by: is not as formal as Signed-off-by:. It is a record that the acker
470 has at least reviewed the patch and has indica 422 has at least reviewed the patch and has indicated acceptance. Hence patch
471 mergers will sometimes manually convert an ack 423 mergers will sometimes manually convert an acker's "yep, looks good to me"
472 into an Acked-by: (but note that it is usually 424 into an Acked-by: (but note that it is usually better to ask for an
473 explicit ack). 425 explicit ack).
474 426
475 Acked-by: does not necessarily indicate acknow 427 Acked-by: does not necessarily indicate acknowledgement of the entire patch.
476 For example, if a patch affects multiple subsy 428 For example, if a patch affects multiple subsystems and has an Acked-by: from
477 one subsystem maintainer then this usually ind 429 one subsystem maintainer then this usually indicates acknowledgement of just
478 the part which affects that maintainer's code. 430 the part which affects that maintainer's code. Judgement should be used here.
479 When in doubt people should refer to the origi 431 When in doubt people should refer to the original discussion in the mailing
480 list archives. 432 list archives.
481 433
482 If a person has had the opportunity to comment 434 If a person has had the opportunity to comment on a patch, but has not
483 provided such comments, you may optionally add 435 provided such comments, you may optionally add a ``Cc:`` tag to the patch.
484 This is the only tag which might be added with 436 This is the only tag which might be added without an explicit action by the
485 person it names - but it should indicate that 437 person it names - but it should indicate that this person was copied on the
486 patch. This tag documents that potentially in 438 patch. This tag documents that potentially interested parties
487 have been included in the discussion. 439 have been included in the discussion.
488 440
489 Co-developed-by: states that the patch was co- 441 Co-developed-by: states that the patch was co-created by multiple developers;
490 it is used to give attribution to co-authors ( !! 442 it is a used to give attribution to co-authors (in addition to the author
491 attributed by the From: tag) when several peop 443 attributed by the From: tag) when several people work on a single patch. Since
492 Co-developed-by: denotes authorship, every Co- 444 Co-developed-by: denotes authorship, every Co-developed-by: must be immediately
493 followed by a Signed-off-by: of the associated 445 followed by a Signed-off-by: of the associated co-author. Standard sign-off
494 procedure applies, i.e. the ordering of Signed 446 procedure applies, i.e. the ordering of Signed-off-by: tags should reflect the
495 chronological history of the patch insofar as 447 chronological history of the patch insofar as possible, regardless of whether
496 the author is attributed via From: or Co-devel 448 the author is attributed via From: or Co-developed-by:. Notably, the last
497 Signed-off-by: must always be that of the deve 449 Signed-off-by: must always be that of the developer submitting the patch.
498 450
499 Note, the From: tag is optional when the From: 451 Note, the From: tag is optional when the From: author is also the person (and
500 email) listed in the From: line of the email h 452 email) listed in the From: line of the email header.
501 453
502 Example of a patch submitted by the From: auth 454 Example of a patch submitted by the From: author::
503 455
504 <changelog> 456 <changelog>
505 457
506 Co-developed-by: First Co-Author <first 458 Co-developed-by: First Co-Author <first@coauthor.example.org>
507 Signed-off-by: First Co-Author <first@c 459 Signed-off-by: First Co-Author <first@coauthor.example.org>
508 Co-developed-by: Second Co-Author <seco 460 Co-developed-by: Second Co-Author <second@coauthor.example.org>
509 Signed-off-by: Second Co-Author <second 461 Signed-off-by: Second Co-Author <second@coauthor.example.org>
510 Signed-off-by: From Author <from@author 462 Signed-off-by: From Author <from@author.example.org>
511 463
512 Example of a patch submitted by a Co-developed 464 Example of a patch submitted by a Co-developed-by: author::
513 465
514 From: From Author <from@author.example. 466 From: From Author <from@author.example.org>
515 467
516 <changelog> 468 <changelog>
517 469
518 Co-developed-by: Random Co-Author <rand 470 Co-developed-by: Random Co-Author <random@coauthor.example.org>
519 Signed-off-by: Random Co-Author <random 471 Signed-off-by: Random Co-Author <random@coauthor.example.org>
520 Signed-off-by: From Author <from@author 472 Signed-off-by: From Author <from@author.example.org>
521 Co-developed-by: Submitting Co-Author < 473 Co-developed-by: Submitting Co-Author <sub@coauthor.example.org>
522 Signed-off-by: Submitting Co-Author <su 474 Signed-off-by: Submitting Co-Author <sub@coauthor.example.org>
523 475
524 476
525 Using Reported-by:, Tested-by:, Reviewed-by:, 477 Using Reported-by:, Tested-by:, Reviewed-by:, Suggested-by: and Fixes:
526 ---------------------------------------------- 478 ----------------------------------------------------------------------
527 479
528 The Reported-by tag gives credit to people who 480 The Reported-by tag gives credit to people who find bugs and report them and it
529 hopefully inspires them to help us again in th !! 481 hopefully inspires them to help us again in the future. Please note that if
530 bugs; please do not use it to credit feature r !! 482 the bug was reported in private, then ask for permission first before using the
531 followed by a Closes: tag pointing to the repo !! 483 Reported-by tag.
532 available on the web. The Link: tag can be use <<
533 fixes a part of the issue(s) being reported. P <<
534 reported in private, then ask for permission f <<
535 tag. <<
536 484
537 A Tested-by: tag indicates that the patch has 485 A Tested-by: tag indicates that the patch has been successfully tested (in
538 some environment) by the person named. This t 486 some environment) by the person named. This tag informs maintainers that
539 some testing has been performed, provides a me 487 some testing has been performed, provides a means to locate testers for
540 future patches, and ensures credit for the tes 488 future patches, and ensures credit for the testers.
541 489
542 Reviewed-by:, instead, indicates that the patc 490 Reviewed-by:, instead, indicates that the patch has been reviewed and found
543 acceptable according to the Reviewer's Stateme 491 acceptable according to the Reviewer's Statement:
544 492
545 Reviewer's statement of oversight 493 Reviewer's statement of oversight
546 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 494 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
547 495
548 By offering my Reviewed-by: tag, I state that: 496 By offering my Reviewed-by: tag, I state that:
549 497
550 (a) I have carried out a technical re 498 (a) I have carried out a technical review of this patch to
551 evaluate its appropriateness and 499 evaluate its appropriateness and readiness for inclusion into
552 the mainline kernel. 500 the mainline kernel.
553 501
554 (b) Any problems, concerns, or questi 502 (b) Any problems, concerns, or questions relating to the patch
555 have been communicated back to th 503 have been communicated back to the submitter. I am satisfied
556 with the submitter's response to 504 with the submitter's response to my comments.
557 505
558 (c) While there may be things that co 506 (c) While there may be things that could be improved with this
559 submission, I believe that it is, 507 submission, I believe that it is, at this time, (1) a
560 worthwhile modification to the ke 508 worthwhile modification to the kernel, and (2) free of known
561 issues which would argue against 509 issues which would argue against its inclusion.
562 510
563 (d) While I have reviewed the patch a 511 (d) While I have reviewed the patch and believe it to be sound, I
564 do not (unless explicitly stated 512 do not (unless explicitly stated elsewhere) make any
565 warranties or guarantees that it 513 warranties or guarantees that it will achieve its stated
566 purpose or function properly in a 514 purpose or function properly in any given situation.
567 515
568 A Reviewed-by tag is a statement of opinion th 516 A Reviewed-by tag is a statement of opinion that the patch is an
569 appropriate modification of the kernel without 517 appropriate modification of the kernel without any remaining serious
570 technical issues. Any interested reviewer (wh 518 technical issues. Any interested reviewer (who has done the work) can
571 offer a Reviewed-by tag for a patch. This tag 519 offer a Reviewed-by tag for a patch. This tag serves to give credit to
572 reviewers and to inform maintainers of the deg 520 reviewers and to inform maintainers of the degree of review which has been
573 done on the patch. Reviewed-by: tags, when su 521 done on the patch. Reviewed-by: tags, when supplied by reviewers known to
574 understand the subject area and to perform tho 522 understand the subject area and to perform thorough reviews, will normally
575 increase the likelihood of your patch getting 523 increase the likelihood of your patch getting into the kernel.
576 524
577 Both Tested-by and Reviewed-by tags, once rece 525 Both Tested-by and Reviewed-by tags, once received on mailing list from tester
578 or reviewer, should be added by author to the 526 or reviewer, should be added by author to the applicable patches when sending
579 next versions. However if the patch has chang 527 next versions. However if the patch has changed substantially in following
580 version, these tags might not be applicable an 528 version, these tags might not be applicable anymore and thus should be removed.
581 Usually removal of someone's Tested-by or Revi 529 Usually removal of someone's Tested-by or Reviewed-by tags should be mentioned
582 in the patch changelog (after the '---' separa 530 in the patch changelog (after the '---' separator).
583 531
584 A Suggested-by: tag indicates that the patch i 532 A Suggested-by: tag indicates that the patch idea is suggested by the person
585 named and ensures credit to the person for the 533 named and ensures credit to the person for the idea. Please note that this
586 tag should not be added without the reporter's 534 tag should not be added without the reporter's permission, especially if the
587 idea was not posted in a public forum. That sa 535 idea was not posted in a public forum. That said, if we diligently credit our
588 idea reporters, they will, hopefully, be inspi 536 idea reporters, they will, hopefully, be inspired to help us again in the
589 future. 537 future.
590 538
591 A Fixes: tag indicates that the patch fixes an 539 A Fixes: tag indicates that the patch fixes an issue in a previous commit. It
592 is used to make it easy to determine where a b 540 is used to make it easy to determine where a bug originated, which can help
593 review a bug fix. This tag also assists the st 541 review a bug fix. This tag also assists the stable kernel team in determining
594 which stable kernel versions should receive yo 542 which stable kernel versions should receive your fix. This is the preferred
595 method for indicating a bug fixed by the patch 543 method for indicating a bug fixed by the patch. See :ref:`describe_changes`
596 for more details. 544 for more details.
597 545
598 Note: Attaching a Fixes: tag does not subvert <<
599 process nor the requirement to Cc: stable@vger <<
600 patch candidates. For more information, please <<
601 Documentation/process/stable-kernel-rules.rst. <<
602 <<
603 .. _the_canonical_patch_format: 546 .. _the_canonical_patch_format:
604 547
605 The canonical patch format 548 The canonical patch format
606 -------------------------- 549 --------------------------
607 550
608 This section describes how the patch itself sh 551 This section describes how the patch itself should be formatted. Note
609 that, if you have your patches stored in a ``g 552 that, if you have your patches stored in a ``git`` repository, proper patch
610 formatting can be had with ``git format-patch` 553 formatting can be had with ``git format-patch``. The tools cannot create
611 the necessary text, though, so read the instru 554 the necessary text, though, so read the instructions below anyway.
612 555
613 The canonical patch subject line is:: 556 The canonical patch subject line is::
614 557
615 Subject: [PATCH 001/123] subsystem: summar 558 Subject: [PATCH 001/123] subsystem: summary phrase
616 559
617 The canonical patch message body contains the 560 The canonical patch message body contains the following:
618 561
619 - A ``from`` line specifying the patch autho 562 - A ``from`` line specifying the patch author, followed by an empty
620 line (only needed if the person sending th 563 line (only needed if the person sending the patch is not the author).
621 564
622 - The body of the explanation, line wrapped 565 - The body of the explanation, line wrapped at 75 columns, which will
623 be copied to the permanent changelog to de 566 be copied to the permanent changelog to describe this patch.
624 567
625 - An empty line. 568 - An empty line.
626 569
627 - The ``Signed-off-by:`` lines, described ab 570 - The ``Signed-off-by:`` lines, described above, which will
628 also go in the changelog. 571 also go in the changelog.
629 572
630 - A marker line containing simply ``---``. 573 - A marker line containing simply ``---``.
631 574
632 - Any additional comments not suitable for t 575 - Any additional comments not suitable for the changelog.
633 576
634 - The actual patch (``diff`` output). 577 - The actual patch (``diff`` output).
635 578
636 The Subject line format makes it very easy to 579 The Subject line format makes it very easy to sort the emails
637 alphabetically by subject line - pretty much a 580 alphabetically by subject line - pretty much any email reader will
638 support that - since because the sequence numb 581 support that - since because the sequence number is zero-padded,
639 the numerical and alphabetic sort is the same. 582 the numerical and alphabetic sort is the same.
640 583
641 The ``subsystem`` in the email's Subject shoul 584 The ``subsystem`` in the email's Subject should identify which
642 area or subsystem of the kernel is being patch 585 area or subsystem of the kernel is being patched.
643 586
644 The ``summary phrase`` in the email's Subject 587 The ``summary phrase`` in the email's Subject should concisely
645 describe the patch which that email contains. 588 describe the patch which that email contains. The ``summary
646 phrase`` should not be a filename. Do not use 589 phrase`` should not be a filename. Do not use the same ``summary
647 phrase`` for every patch in a whole patch seri 590 phrase`` for every patch in a whole patch series (where a ``patch
648 series`` is an ordered sequence of multiple, r 591 series`` is an ordered sequence of multiple, related patches).
649 592
650 Bear in mind that the ``summary phrase`` of yo 593 Bear in mind that the ``summary phrase`` of your email becomes a
651 globally-unique identifier for that patch. It 594 globally-unique identifier for that patch. It propagates all the way
652 into the ``git`` changelog. The ``summary phr 595 into the ``git`` changelog. The ``summary phrase`` may later be used in
653 developer discussions which refer to the patch 596 developer discussions which refer to the patch. People will want to
654 google for the ``summary phrase`` to read disc 597 google for the ``summary phrase`` to read discussion regarding that
655 patch. It will also be the only thing that pe 598 patch. It will also be the only thing that people may quickly see
656 when, two or three months later, they are goin 599 when, two or three months later, they are going through perhaps
657 thousands of patches using tools such as ``git 600 thousands of patches using tools such as ``gitk`` or ``git log
658 --oneline``. 601 --oneline``.
659 602
660 For these reasons, the ``summary`` must be no 603 For these reasons, the ``summary`` must be no more than 70-75
661 characters, and it must describe both what the 604 characters, and it must describe both what the patch changes, as well
662 as why the patch might be necessary. It is ch 605 as why the patch might be necessary. It is challenging to be both
663 succinct and descriptive, but that is what a w 606 succinct and descriptive, but that is what a well-written summary
664 should do. 607 should do.
665 608
666 The ``summary phrase`` may be prefixed by tags 609 The ``summary phrase`` may be prefixed by tags enclosed in square
667 brackets: "Subject: [PATCH <tag>...] <summary 610 brackets: "Subject: [PATCH <tag>...] <summary phrase>". The tags are
668 not considered part of the summary phrase, but 611 not considered part of the summary phrase, but describe how the patch
669 should be treated. Common tags might include 612 should be treated. Common tags might include a version descriptor if
670 the multiple versions of the patch have been s 613 the multiple versions of the patch have been sent out in response to
671 comments (i.e., "v1, v2, v3"), or "RFC" to ind 614 comments (i.e., "v1, v2, v3"), or "RFC" to indicate a request for
672 comments. !! 615 comments. If there are four patches in a patch series the individual
673 !! 616 patches may be numbered like this: 1/4, 2/4, 3/4, 4/4. This assures
674 If there are four patches in a patch series th !! 617 that developers understand the order in which the patches should be
675 be numbered like this: 1/4, 2/4, 3/4, 4/4. Thi !! 618 applied and that they have reviewed or applied all of the patches in
676 understand the order in which the patches shou !! 619 the patch series.
677 they have reviewed or applied all of the patch <<
678 620
679 Here are some good example Subjects:: !! 621 A couple of example Subjects::
680 622
681 Subject: [PATCH 2/5] ext2: improve scalabi 623 Subject: [PATCH 2/5] ext2: improve scalability of bitmap searching
682 Subject: [PATCH v2 01/27] x86: fix eflags 624 Subject: [PATCH v2 01/27] x86: fix eflags tracking
683 Subject: [PATCH v2] sub/sys: Condensed pat <<
684 Subject: [PATCH v2 M/N] sub/sys: Condensed <<
685 625
686 The ``from`` line must be the very first line 626 The ``from`` line must be the very first line in the message body,
687 and has the form: 627 and has the form:
688 628
689 From: Patch Author <author@example.com> 629 From: Patch Author <author@example.com>
690 630
691 The ``from`` line specifies who will be credit 631 The ``from`` line specifies who will be credited as the author of the
692 patch in the permanent changelog. If the ``fr 632 patch in the permanent changelog. If the ``from`` line is missing,
693 then the ``From:`` line from the email header 633 then the ``From:`` line from the email header will be used to determine
694 the patch author in the changelog. 634 the patch author in the changelog.
695 635
696 The explanation body will be committed to the 636 The explanation body will be committed to the permanent source
697 changelog, so should make sense to a competent !! 637 changelog, so should make sense to a competent reader who has long
698 forgotten the immediate details of the discuss !! 638 since forgotten the immediate details of the discussion that might
699 this patch. Including symptoms of the failure !! 639 have led to this patch. Including symptoms of the failure which the
700 (kernel log messages, oops messages, etc.) are !! 640 patch addresses (kernel log messages, oops messages, etc.) is
701 people who might be searching the commit logs !! 641 especially useful for people who might be searching the commit logs
702 patch. The text should be written in such deta !! 642 looking for the applicable patch. If a patch fixes a compile failure,
703 weeks, months or even years later, it can give !! 643 it may not be necessary to include _all_ of the compile failures; just
704 details to grasp the reasoning for **why** the !! 644 enough that it is likely that someone searching for the patch can find
705 !! 645 it. As in the ``summary phrase``, it is important to be both succinct as
706 If a patch fixes a compile failure, it may not !! 646 well as descriptive.
707 _all_ of the compile failures; just enough tha !! 647
708 someone searching for the patch can find it. A !! 648 The ``---`` marker line serves the essential purpose of marking for patch
709 phrase``, it is important to be both succinct !! 649 handling tools where the changelog message ends.
710 !! 650
711 The ``---`` marker line serves the essential p !! 651 One good use for the additional comments after the ``---`` marker is for
712 patch handling tools where the changelog messa !! 652 a ``diffstat``, to show what files have changed, and the number of
713 !! 653 inserted and deleted lines per file. A ``diffstat`` is especially useful
714 One good use for the additional comments after !! 654 on bigger patches. Other comments relevant only to the moment or the
715 for a ``diffstat``, to show what files have ch !! 655 maintainer, not suitable for the permanent changelog, should also go
716 inserted and deleted lines per file. A ``diffs !! 656 here. A good example of such comments might be ``patch changelogs``
717 on bigger patches. If you are going to include !! 657 which describe what has changed between the v1 and v2 version of the
718 ``---`` marker, please use ``diffstat`` option !! 658 patch.
719 filenames are listed from the top of the kerne <<
720 use too much horizontal space (easily fit in 8 <<
721 indentation). (``git`` generates appropriate d <<
722 <<
723 Other comments relevant only to the moment or <<
724 suitable for the permanent changelog, should a <<
725 example of such comments might be ``patch chan <<
726 what has changed between the v1 and v2 version <<
727 <<
728 Please put this information **after** the ``-- <<
729 the changelog from the rest of the patch. The <<
730 not part of the changelog which gets committed <<
731 additional information for the reviewers. If i <<
732 commit tags, it needs manual interaction to re <<
733 the separator line, it gets automatically stri <<
734 patch:: <<
735 <<
736 <commit message> <<
737 ... <<
738 Signed-off-by: Author <author@mail> <<
739 --- <<
740 V2 -> V3: Removed redundant helper function <<
741 V1 -> V2: Cleaned up coding style and addres <<
742 659
743 path/to/file | 5+++-- !! 660 If you are going to include a ``diffstat`` after the ``---`` marker, please
744 ... !! 661 use ``diffstat`` options ``-p 1 -w 70`` so that filenames are listed from
>> 662 the top of the kernel source tree and don't use too much horizontal
>> 663 space (easily fit in 80 columns, maybe with some indentation). (``git``
>> 664 generates appropriate diffstats by default.)
745 665
746 See more details on the proper patch format in 666 See more details on the proper patch format in the following
747 references. 667 references.
748 668
749 .. _backtraces: <<
750 <<
751 Backtraces in commit messages <<
752 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <<
753 <<
754 Backtraces help document the call chain leadin <<
755 not all backtraces are helpful. For example, e <<
756 unique and obvious. Copying the full dmesg out <<
757 adds distracting information like timestamps, <<
758 stack dumps. <<
759 <<
760 Therefore, the most useful backtraces should d <<
761 information from the dump, which makes it easi <<
762 issue. Here is an example of a well-trimmed ba <<
763 <<
764 unchecked MSR access error: WRMSR to 0xd51 ( <<
765 at rIP: 0xffffffffae059994 (native_write_msr <<
766 Call Trace: <<
767 mba_wrmsr <<
768 update_domains <<
769 rdtgroup_mkdir <<
770 <<
771 .. _explicit_in_reply_to: 669 .. _explicit_in_reply_to:
772 670
773 Explicit In-Reply-To headers 671 Explicit In-Reply-To headers
774 ---------------------------- 672 ----------------------------
775 673
776 It can be helpful to manually add In-Reply-To: 674 It can be helpful to manually add In-Reply-To: headers to a patch
777 (e.g., when using ``git send-email``) to assoc 675 (e.g., when using ``git send-email``) to associate the patch with
778 previous relevant discussion, e.g. to link a b 676 previous relevant discussion, e.g. to link a bug fix to the email with
779 the bug report. However, for a multi-patch se 677 the bug report. However, for a multi-patch series, it is generally
780 best to avoid using In-Reply-To: to link to ol 678 best to avoid using In-Reply-To: to link to older versions of the
781 series. This way multiple versions of the pat 679 series. This way multiple versions of the patch don't become an
782 unmanageable forest of references in email cli 680 unmanageable forest of references in email clients. If a link is
783 helpful, you can use the https://lore.kernel.o !! 681 helpful, you can use the https://lkml.kernel.org/ redirector (e.g., in
784 the cover email text) to link to an earlier ve 682 the cover email text) to link to an earlier version of the patch series.
785 683
786 684
787 Providing base tree information 685 Providing base tree information
788 ------------------------------- 686 -------------------------------
789 687
790 When other developers receive your patches and 688 When other developers receive your patches and start the review process,
791 it is absolutely necessary for them to know wh !! 689 it is often useful for them to know where in the tree history they
792 commit/branch your work applies on, considerin !! 690 should place your work. This is particularly useful for automated CI
793 maintainer trees present nowadays. Note again !! 691 processes that attempt to run a series of tests in order to establish
794 MAINTAINERS file explained above. !! 692 the quality of your submission before the maintainer starts the review.
795 <<
796 This is even more important for automated CI p <<
797 run a series of tests in order to establish th <<
798 submission before the maintainer starts the re <<
799 693
800 If you are using ``git format-patch`` to gener 694 If you are using ``git format-patch`` to generate your patches, you can
801 automatically include the base tree informatio 695 automatically include the base tree information in your submission by
802 using the ``--base`` flag. The easiest and mos 696 using the ``--base`` flag. The easiest and most convenient way to use
803 this option is with topical branches:: 697 this option is with topical branches::
804 698
805 $ git checkout -t -b my-topical-branch mas 699 $ git checkout -t -b my-topical-branch master
806 Branch 'my-topical-branch' set up to track 700 Branch 'my-topical-branch' set up to track local branch 'master'.
807 Switched to a new branch 'my-topical-branc 701 Switched to a new branch 'my-topical-branch'
808 702
809 [perform your edits and commits] 703 [perform your edits and commits]
810 704
811 $ git format-patch --base=auto --cover-let 705 $ git format-patch --base=auto --cover-letter -o outgoing/ master
812 outgoing/0000-cover-letter.patch 706 outgoing/0000-cover-letter.patch
813 outgoing/0001-First-Commit.patch 707 outgoing/0001-First-Commit.patch
814 outgoing/... 708 outgoing/...
815 709
816 When you open ``outgoing/0000-cover-letter.pat 710 When you open ``outgoing/0000-cover-letter.patch`` for editing, you will
817 notice that it will have the ``base-commit:`` 711 notice that it will have the ``base-commit:`` trailer at the very
818 bottom, which provides the reviewer and the CI 712 bottom, which provides the reviewer and the CI tools enough information
819 to properly perform ``git am`` without worryin 713 to properly perform ``git am`` without worrying about conflicts::
820 714
821 $ git checkout -b patch-review [base-commi 715 $ git checkout -b patch-review [base-commit-id]
822 Switched to a new branch 'patch-review' 716 Switched to a new branch 'patch-review'
823 $ git am patches.mbox 717 $ git am patches.mbox
824 Applying: First Commit 718 Applying: First Commit
825 Applying: ... 719 Applying: ...
826 720
827 Please see ``man git-format-patch`` for more i 721 Please see ``man git-format-patch`` for more information about this
828 option. 722 option.
829 723
830 .. note:: 724 .. note::
831 725
832 The ``--base`` feature was introduced in g 726 The ``--base`` feature was introduced in git version 2.9.0.
833 727
834 If you are not using git to format your patche 728 If you are not using git to format your patches, you can still include
835 the same ``base-commit`` trailer to indicate t 729 the same ``base-commit`` trailer to indicate the commit hash of the tree
836 on which your work is based. You should add it 730 on which your work is based. You should add it either in the cover
837 letter or in the first patch of the series and 731 letter or in the first patch of the series and it should be placed
838 either below the ``---`` line or at the very b 732 either below the ``---`` line or at the very bottom of all other
839 content, right before your email signature. 733 content, right before your email signature.
840 734
841 Make sure that base commit is in an official m <<
842 and not in some internal, accessible only to y <<
843 would be worthless. <<
844 <<
845 Tooling <<
846 ------- <<
847 <<
848 Many of the technical aspects of this process <<
849 b4, documented at <https://b4.docs.kernel.org/ <<
850 help with things like tracking dependencies, r <<
851 with formatting and sending mails. <<
852 735
853 References 736 References
854 ---------- 737 ----------
855 738
856 Andrew Morton, "The perfect patch" (tpp). 739 Andrew Morton, "The perfect patch" (tpp).
857 <https://www.ozlabs.org/~akpm/stuff/tpp.txt> 740 <https://www.ozlabs.org/~akpm/stuff/tpp.txt>
858 741
859 Jeff Garzik, "Linux kernel patch submission fo 742 Jeff Garzik, "Linux kernel patch submission format".
860 <https://web.archive.org/web/20180829112450/ 743 <https://web.archive.org/web/20180829112450/http://linux.yyz.us/patch-format.html>
861 744
862 Greg Kroah-Hartman, "How to piss off a kernel 745 Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer".
863 <http://www.kroah.com/log/linux/maintainer.h 746 <http://www.kroah.com/log/linux/maintainer.html>
864 747
865 <http://www.kroah.com/log/linux/maintainer-0 748 <http://www.kroah.com/log/linux/maintainer-02.html>
866 749
867 <http://www.kroah.com/log/linux/maintainer-0 750 <http://www.kroah.com/log/linux/maintainer-03.html>
868 751
869 <http://www.kroah.com/log/linux/maintainer-0 752 <http://www.kroah.com/log/linux/maintainer-04.html>
870 753
871 <http://www.kroah.com/log/linux/maintainer-0 754 <http://www.kroah.com/log/linux/maintainer-05.html>
872 755
873 <http://www.kroah.com/log/linux/maintainer-0 756 <http://www.kroah.com/log/linux/maintainer-06.html>
874 757
875 Kernel Documentation/process/coding-style.rst !! 758 NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people!
>> 759 <https://lkml.org/lkml/2005/7/11/336>
>> 760
>> 761 Kernel Documentation/process/coding-style.rst:
>> 762 :ref:`Documentation/process/coding-style.rst <codingstyle>`
876 763
877 Linus Torvalds's mail on the canonical patch f 764 Linus Torvalds's mail on the canonical patch format:
878 <https://lore.kernel.org/r/Pine.LNX.4.58.0504 !! 765 <http://lkml.org/lkml/2005/4/7/183>
879 766
880 Andi Kleen, "On submitting kernel patches" 767 Andi Kleen, "On submitting kernel patches"
881 Some strategies to get difficult or controve 768 Some strategies to get difficult or controversial changes in.
882 769
883 http://halobates.de/on-submitting-patches.pd 770 http://halobates.de/on-submitting-patches.pdf
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