[mesa.git] / docs / submittingpatches.html
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2 <html lang="en">
3 <head>
4 <meta http-equiv="content-type" content="text/html; charset=utf-8">
5 <title>Submitting Patches</title>
6 <link rel="stylesheet" type="text/css" href="mesa.css">
7 </head>
8 <body>
10 <div class="header">
11 The Mesa 3D Graphics Library
12 </div>
14 <iframe src="contents.html"></iframe>
15 <div class="content">
17 <h1>Submitting Patches</h1>
20 <ul>
21 <li><a href="#guidelines">Basic guidelines</a>
22 <li><a href="#formatting">Patch formatting</a>
23 <li><a href="#testing">Testing Patches</a>
24 <li><a href="#submit">Submitting Patches</a>
25 <li><a href="#reviewing">Reviewing Patches</a>
26 <li><a href="#nominations">Nominating a commit for a stable branch</a>
27 <li><a href="#criteria">Criteria for accepting patches to the stable branch</a>
28 <li><a href="#backports">Sending backports for the stable branch</a>
29 <li><a href="#gittips">Git tips</a>
30 </ul>
32 <h2 id="guidelines">Basic guidelines</h2>
34 <ul>
35 <li>Patches should not mix code changes with code formatting changes (except,
36 perhaps, in very trivial cases.)
37 <li>Code patches should follow Mesa
38 <a href="codingstyle.html" target="_parent">coding conventions</a>.
39 <li>Whenever possible, patches should only affect individual Mesa/Gallium
40 components.
41 <li>Patches should never introduce build breaks and should be bisectable (see
42 <code>git bisect</code>.)
43 <li>Patches should be properly <a href="#formatting">formatted</a>.
44 <li>Patches should be sufficiently <a href="#testing">tested</a> before submitting.
45 <li>Patches should be <a href="#submit">submitted</a>
46 to <a href="#mailing">mesa-dev</a> or with
47 a <a href="#merge-request">merge request</a>
48 for <a href="#reviewing">review</a>.
50 </ul>
52 <h2 id="formatting">Patch formatting</h2>
54 <ul>
55 <li>Lines should be limited to 75 characters or less so that git logs
56 displayed in 80-column terminals avoid line wrapping. Note that git
57 log uses 4 spaces of indentation (4 + 75 &lt; 80).
58 <li>The first line should be a short, concise summary of the change prefixed
59 with a module name. Examples:
60 <pre>
61 mesa: Add support for querying GL_VERTEX_ATTRIB_ARRAY_LONG
65 i965: Fix missing type in local variable declaration.
66 </pre>
67 <li>Subsequent patch comments should describe the change in more detail,
68 if needed. For example:
69 <pre>
70 i965: Remove end-of-thread SEND alignment code.
72 This was present in Eric's initial implementation of the compaction code
73 for Sandybridge (commit 077d01b6). There is no documentation saying this
74 is necessary, and removing it causes no regressions in piglit on any
75 platform.
76 </pre>
77 <li>A "Signed-off-by:" line is not required, but not discouraged either.
78 <li>If a patch addresses a bugzilla issue, that should be noted in the
79 patch comment. For example:
80 <pre>
81 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89689
82 </pre>
83 <li>If a patch addresses a issue introduced with earlier commit, that should be
84 noted in the patch comment. For example:
85 <pre>
86 Fixes: d7b3707c612 "util/disk_cache: use stat() to check if entry is a directory"
87 </pre>
88 <li>You can produce those fixes lines by running
89 <pre>git config --global alias.fixes "show -s --pretty='format:Fixes: %h (\"%s\")'"</pre>
90 once and then using <pre>git fixes &lt;sha1&gt;</pre>
91 <li>If there have been several revisions to a patch during the review
92 process, they should be noted such as in this example:
93 <pre>
94 st/mesa: add ARB_texture_stencil8 support (v4)
96 if we support stencil texturing, enable texture_stencil8
97 there is no requirement to support native S8 for this,
98 the texture can be converted to x24s8 fine.
100 v2: fold fixes from Marek in:
101 a) put S8 last in the list
102 b) fix renderable to always test for d/s renderable
103 fixup the texture case to use a stencil only format
104 for picking the format for the texture view.
105 v3: hit fallback for getteximage
106 v4: put s8 back in front, it shouldn't get picked now (Ilia)
107 </pre>
108 <li>If someone tested your patch, document it with a line like this:
109 <pre>
110 Tested-by: Joe Hacker &lt;jhacker@foo.com&gt;
111 </pre>
112 <li>If the patch was reviewed (usually the case) or acked by someone,
113 that should be documented with:
114 <pre>
115 Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
116 Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
117 </pre>
118 <li>If sending later revision of a patch, add all the tags - ack, r-b,
119 Cc: mesa-stable and/or other. This provides reviewers with quick feedback if the
120 patch has already been reviewed.
121 <li>In order for your patch to reach the prospective reviewer easier/faster,
122 use the script scripts/get_reviewer.pl to get a list of individuals and include
123 them in the CC list.
124 <p>
125 Please use common sense and do <strong>not</strong> blindly add everyone.
126 </p>
127 <pre>
128 $ scripts/get_reviewer.pl --help # to get the help screen
129 $ scripts/get_reviewer.pl -f src/egl/drivers/dri2/platform_android.c
130 Rob Herring &lt;robh@kernel.org&gt; (reviewer:ANDROID EGL SUPPORT,added_lines:188/700=27%,removed_lines:58/283=20%)
131 Tomasz Figa &lt;tfiga@chromium.org&gt; (reviewer:ANDROID EGL SUPPORT,authored:12/41=29%,added_lines:308/700=44%,removed_lines:115/283=41%)
132 Emil Velikov &lt;emil.l.velikov@gmail.com&gt; (authored:13/41=32%,removed_lines:76/283=27%)
133 </pre>
134 </ul>
138 <h2 id="testing">Testing Patches</h2>
140 <p>
141 It should go without saying that patches must be tested. In general,
142 do whatever testing is prudent.
143 </p>
145 <p>
146 You should always run the Mesa test suite before submitting patches.
147 The test suite can be run using the 'meson test' command. All tests
148 must pass before patches will be accepted, this may mean you have
149 to update the tests themselves.
150 </p>
152 <p>
153 Whenever possible and applicable, test the patch with
154 <a href="https://piglit.freedesktop.org">Piglit</a> and/or
155 <a href="https://android.googlesource.com/platform/external/deqp/">dEQP</a>
156 to check for regressions.
157 </p>
159 <p>
160 As mentioned at the begining, patches should be bisectable.
161 A good way to test this is to make use of the `git rebase` command,
162 to run your tests on each commit. Assuming your branch is based off
163 <code>origin/master</code>, you can run:
164 </p>
165 <pre>
166 $ git rebase --interactive --exec "meson test -C build/" origin/master
167 </pre>
168 <p>
169 replacing <code>"meson test"</code> with whatever other test you want to
170 run.
171 </p>
174 <h2 id="submit">Submitting Patches</h2>
176 <p>
177 Patches may be submitted to the Mesa project by
178 <a href="#mailing">email</a> or with a
179 GitLab <a href="#merge-request">merge request</a>. To prevent
180 duplicate code review, only use one method to submit your changes.
181 </p>
183 <h3 id="mailing">Mailing Patches</h3>
185 <p>
186 Patches may be sent to the mesa-dev mailing list for review:
187 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
188 mesa-dev@lists.freedesktop.org</a>.
189 When submitting a patch make sure to use
190 <a href="https://git-scm.com/docs/git-send-email">git send-email</a>
191 rather than attaching patches to emails. Sending patches as
192 attachments prevents people from being able to provide in-line review
194 </p>
196 <p>
197 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
198 etc patches show up as replies to the originals. This usually works well
199 when you're sending out updates to individual patches (as opposed to
200 re-sending the whole series). Using --in-reply-to makes
201 it harder for reviewers to accidentally review old patches.
202 </p>
204 <p>
205 When submitting follow-up patches you should also login to
206 <a href="https://patchwork.freedesktop.org">patchwork</a> and change the
207 state of your old patches to Superseded.
208 </p>
210 <p>
211 Some companies' mail server automatically append a legal disclaimer,
212 usually containing something along the lines of "The information in this
213 email is confidential" and "distribution is strictly prohibited".
214 </p>
215 <p>
216 These legal notices prevent us from being able to accept your patch,
217 rendering the whole process pointless. Please make sure these are
218 disabled before sending your patches. (Note that you may need to contact
219 your email administrator for this.)
220 </p>
222 <h3 id="merge-request">GitLab Merge Requests</h3>
224 <p>
225 <a href="https://gitlab.freedesktop.org/mesa/mesa">GitLab</a> Merge
226 Requests (MR) can also be used to submit patches for Mesa.
227 </p>
229 <p>
230 If the MR may have interest for most of the Mesa community, you can
231 send an email to the mesa-dev email list including a link to the MR.
232 Don't send the patch to mesa-dev, just the MR link.
233 </p>
234 <p>
235 Add labels to your MR to help reviewers find it. For example:
236 </p>
237 <ul>
238 <li>Mesa changes affecting all drivers: mesa
239 <li>Hardware vendor specific code: amd, intel, nvidia, ...
240 <li>Driver specific code: anvil, freedreno, i965, iris, radeonsi,
241 radv, vc4, ...
242 <li>Other tag examples: gallium, util
243 </ul>
244 <p>
245 Tick the following when creating the MR. It allows developers to
246 rebase your work on top of master.
247 </p>
248 <pre>Allow commits from members who can merge to the target branch</pre>
249 <p>
250 If you revise your patches based on code review and push an update
251 to your branch, you should maintain a <strong>clean</strong> history
252 in your patches. There should not be "fixup" patches in the history.
253 The series should be buildable and functional after every commit
254 whenever you push the branch.
255 </p>
256 <p>
257 It is your responsibility to keep the MR alive and making progress,
258 as there are no guarantees that a Mesa dev will independently take
259 interest in it.
260 </p>
261 <p>
262 Some other notes:
263 </p>
264 <ul>
265 <li>Make changes and update your branch based on feedback
266 <li>After an update, for the feedback you handled, close the
267 feedback discussion with the "Resolve Discussion" button. This way
268 the reviewers know which feedback got handled and which didn't.
269 <li>Old, stale MR may be closed, but you can reopen it if you
270 still want to pursue the changes
271 <li>You should periodically check to see if your MR needs to be
272 rebased
273 <li>Make sure your MR is closed if your patches get pushed outside
274 of GitLab
275 <li>Please send MRs from a personal fork rather than from the main
276 Mesa repository, as it clutters it unnecessarily.
277 </ul>
279 <h2 id="reviewing">Reviewing Patches</h2>
281 <p>
282 To participate in code review, you should monitor the
283 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
284 mesa-dev</a> email list and the GitLab
285 Mesa <a href="https://gitlab.freedesktop.org/mesa/mesa/merge_requests">Merge
286 Requests</a> page.
287 </p>
289 <p>
290 When you've reviewed a patch on the mailing list, please be unambiguous
291 about your review. That is, state either
292 </p>
293 <pre>
294 Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
295 </pre>
296 or
297 <pre>
298 Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
299 </pre>
300 <p>
301 Rather than saying just "LGTM" or "Seems OK".
302 </p>
304 <p>
305 If small changes are suggested, it's OK to say something like:
306 </p>
307 <pre>
308 With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
309 </pre>
310 <p>
311 which tells the patch author that the patch can be committed, as long
312 as the issues are resolved first.
313 </p>
315 <p>
316 These Reviewed-by, Acked-by, and Tested-by tags should also be amended
317 into commits in a MR before it is merged.
318 </p>
320 <p>
321 When providing a Reviewed-by, Acked-by, or Tested-by tag in a gitlab MR,
322 enclose the tag in backticks:
323 </p>
324 <pre>
325 `Reviewed-by: Joe Hacker &lt;jhacker@example.com&gt;`</pre>
326 <p>
327 This is the markdown format for literal, and will prevent gitlab from hiding
328 the &lt; and &gt; symbols.
329 </p>
331 <p>
332 Review by non-experts is encouraged. Understanding how someone else
333 goes about solving a problem is a great way to learn your way around
334 the project. The submitter is expected to evaluate whether they have
335 an appropriate amount of review feedback from people who also
336 understand the code before merging their patches.
337 </p>
339 <h2 id="nominations">Nominating a commit for a stable branch</h2>
341 <p>
342 There are three ways to nominate a patch for inclusion in the stable branch and
343 release.
344 </p>
345 <ul>
346 <li> By adding the Cc: mesa-stable@ tag as described below.
347 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
348 <li> Forwarding the patch from the mesa-dev@ mailing list.
349 </li>
350 </ul>
351 <p>
352 Note: resending patch identical to one on mesa-dev@ or one that differs only
353 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
354 </p>
355 <p>
356 If you are not the author of the original patch, please Cc: them in your
357 nomination request.
358 </p>
360 <p>
361 The current patch status can be observed in the <a href="releasing.html#stagingbranch">staging branch</a>.
362 </p>
364 <h3 id="thetag">The stable tag</h3>
366 <p>
367 If you want a commit to be applied to a stable branch,
368 you should add an appropriate note to the commit message.
369 </p>
371 <p>
372 Here are some examples of such a note:
373 </p>
374 <pre>
375 CC: &lt;mesa-stable@lists.freedesktop.org&gt;
376 </pre>
378 Simply adding the CC to the mesa-stable list address is adequate to nominate
379 the commit for all the active stable branches. If the commit is not applicable
380 for said branch the stable-release manager will reply stating so.
382 This "CC" syntax for patch nomination will cause patches to automatically be
383 copied to the mesa-stable@ mailing list when you use "git send-email" to send
384 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
385 won't have any negative effect on the patch nomination.
387 <p>
388 Note: by removing the tag [as the commit is pushed] the patch is
389 <strong>explicitly</strong> rejected from inclusion in the stable branch(es).
390 Thus, drop the line <strong>only</strong> if you want to cancel the nomination.
391 </p>
393 Alternatively, if one uses the "Fixes" tag as described in the "Patch formatting"
394 section, it nominates a commit for all active stable branches that include the
395 commit that is referred to.
397 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
399 Mesa has a designated release manager for each stable branch, and the release
400 manager is the only developer that should be pushing changes to these branches.
401 Everyone else should nominate patches using the mechanism described above.
403 The following rules define which patches are accepted and which are not. The
404 stable-release manager is also given broad discretion in rejecting patches
405 that have been nominated.
407 <ul>
408 <li>Patch must conform with the <a href="#guidelines">Basic guidelines</a></li>
410 <li>Patch must have landed in master first. In case where the original
411 patch is too large and/or otherwise contradicts with the rules set within, a
412 backport is appropriate.</li>
414 <li>It must not introduce a regression - be that build or runtime wise.
416 Note: If the regression is due to faulty piglit/dEQP/CTS/other test the
417 latter must be fixed first. A reference to the offending test(s) and
418 respective fix(es) should be provided in the nominated patch.</li>
420 <li>Patch cannot be larger than 100 lines.</li>
422 <li>Patches that move code around with no functional change should be
423 rejected.</li>
425 <li>Patch must be a bug fix and not a new feature.
427 Note: An exception to this rule, are hardware-enabling "features". For
428 example, <a href="#backports">backports</a> of new code to support a
429 newly-developed hardware product can be accepted if they can be reasonably
430 determined not to have effects on other hardware.</li>
432 <li>Patch must be reviewed, For example, the commit message has Reviewed-by,
433 Signed-off-by, or Tested-by tags from someone but the author.</li>
435 <li>Performance patches are considered only if they provide information
436 about the hardware, program in question and observed improvement. Use numbers
437 to represent your measurements.</li>
438 </ul>
440 If the patch complies with the rules it will be
441 <a href="releasing.html#pickntest">cherry-picked</a>. Alternatively the release
442 manager will reply to the patch in question stating why the patch has been
443 rejected or would request a backport.
445 A summary of all the picked/rejected patches will be presented in the
446 <a href="releasing.html#prerelease">pre-release</a> announcement.
448 The stable-release manager may at times need to force-push changes to the
449 stable branches, for example, to drop a previously-picked patch that was later
450 identified as causing a regression). These force-pushes may cause changes to
451 be lost from the stable branch if developers push things directly. Consider
452 yourself warned.
454 <h2 id="backports">Sending backports for the stable branch</h2>
455 <p>
456 By default merge conflicts are resolved by the stable-release manager. In which
457 case he/she should provide a comment about the changes required, alongside the
458 <code>Conflicts</code> section. Summary of which will be provided in the
459 <a href="releasing.html#prerelease">pre-release</a> announcement.
460 </p>
462 <p>
463 Developers are interested in sending backports are recommended to use either a
464 <code>[BACKPORT #branch]</code> subject prefix or provides similar information
465 within the commit summary.
466 </p>
468 <h2 id="gittips">Git tips</h2>
470 <ul>
471 <li><code>git rebase -i ...</code> is your friend. Don't be afraid to use it.
472 <li>Apply a fixup to commit FOO.
473 <pre>
474 git add ...
475 git commit --fixup=FOO
476 git rebase -i --autosquash ...
477 </pre>
478 <li>Test for build breakage between patches e.g last 8 commits.
479 <pre>
480 git rebase -i --exec="ninja -C build/" HEAD~8
481 </pre>
482 <li>Sets the default mailing address for your repo.
483 <pre>
484 git config --local sendemail.to mesa-dev@lists.freedesktop.org
485 </pre>
486 <li> Add version to subject line of patch series in this case for the last 8
487 commits before sending.
488 <pre>
489 git send-email --subject-prefix="PATCH v4" HEAD~8
490 git send-email -v4 @~8 # shorter version, inherited from git format-patch
491 </pre>
492 <li> Configure git to use the get_reviewer.pl script interactively. Thus you
493 can avoid adding the world to the CC list.
494 <pre>
495 git config sendemail.cccmd "./scripts/get_reviewer.pl -i"
496 </pre>
497 </ul>
500 </div>
501 </body>
502 </html>