docs/submittingpatches.html

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  16
  17 <h1>Submitting Patches</h1>
  18
  19
  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>
  31
  32 <h2 id="guidelines">Basic guidelines</h2>
  33
  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>.
  49
  50 </ul>
  51
  52 <h2 id="formatting">Patch formatting</h2>
  53
  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
  62
  63     gallium: add PIPE_CAP_DEVICE_RESET_STATUS_QUERY
  64
  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.
  71
  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>If there have been several revisions to a patch during the review
  89 process, they should be noted such as in this example:
  90 <pre>
  91     st/mesa: add ARB_texture_stencil8 support (v4)
  92
  93     if we support stencil texturing, enable texture_stencil8
  94     there is no requirement to support native S8 for this,
  95     the texture can be converted to x24s8 fine.
  96
  97     v2: fold fixes from Marek in:
  98        a) put S8 last in the list
  99        b) fix renderable to always test for d/s renderable
 100         fixup the texture case to use a stencil only format
 101         for picking the format for the texture view.
 102     v3: hit fallback for getteximage
 103     v4: put s8 back in front, it shouldn't get picked now (Ilia)
 104 </pre>
 105 <li>If someone tested your patch, document it with a line like this:
 106 <pre>
 107     Tested-by: Joe Hacker &lt;jhacker@foo.com&gt;
 108 </pre>
 109 <li>If the patch was reviewed (usually the case) or acked by someone,
 110 that should be documented with:
 111 <pre>
 112     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 113     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 114 </pre>
 115 <li>If sending later revision of a patch, add all the tags - ack, r-b,
 116 Cc: mesa-stable and/or other. This provides reviewers with quick feedback if the
 117 patch has already been reviewed.
 118 <li>In order for your patch to reach the prospective reviewer easier/faster,
 119 use the script scripts/get_reviewer.pl to get a list of individuals and include
 120 them in the CC list.
 121 <p>
 122 Please use common sense and do <strong>not</strong> blindly add everyone.
 123 </p>
 124 <pre>
 125     $ scripts/get_reviewer.pl --help # to get the help screen
 126     $ scripts/get_reviewer.pl -f src/egl/drivers/dri2/platform_android.c
 127     Rob Herring &lt;robh@kernel.org&gt; (reviewer:ANDROID EGL SUPPORT,added_lines:188/700=27%,removed_lines:58/283=20%)
 128     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%)
 129     Emil Velikov &lt;emil.l.velikov@gmail.com&gt; (authored:13/41=32%,removed_lines:76/283=27%)
 130 </pre>
 131 </ul>
 132
 133
 134
 135 <h2 id="testing">Testing Patches</h2>
 136
 137 <p>
 138 It should go without saying that patches must be tested.  In general,
 139 do whatever testing is prudent.
 140 </p>
 141
 142 <p>
 143 You should always run the Mesa test suite before submitting patches.
 144 The test suite can be run using the 'meson test' command. All tests
 145 must pass before patches will be accepted, this may mean you have
 146 to update the tests themselves.
 147 </p>
 148
 149 <p>
 150 Whenever possible and applicable, test the patch with
 151 <a href="https://piglit.freedesktop.org">Piglit</a> and/or
 152 <a href="https://android.googlesource.com/platform/external/deqp/">dEQP</a>
 153 to check for regressions.
 154 </p>
 155
 156 <p>
 157 As mentioned at the begining, patches should be bisectable.
 158 A good way to test this is to make use of the `git rebase` command,
 159 to run your tests on each commit. Assuming your branch is based off
 160 <code>origin/master</code>, you can run:
 161 </p>
 162 <pre>
 163 $ git rebase --interactive --exec "meson test -C build/" origin/master
 164 </pre>
 165 <p>
 166 replacing <code>"meson test"</code> with whatever other test you want to
 167 run.
 168 </p>
 169
 170
 171 <h2 id="submit">Submitting Patches</h2>
 172
 173 <p>
 174 Patches may be submitted to the Mesa project by
 175 <a href="#mailing">email</a> or with a
 176 GitLab <a href="#merge-request">merge request</a>. To prevent
 177 duplicate code review, only use one method to submit your changes.
 178 </p>
 179
 180 <h3 id="mailing">Mailing Patches</h3>
 181
 182 <p>
 183 Patches may be sent to the mesa-dev mailing list for review:
 184 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 185 mesa-dev@lists.freedesktop.org</a>.
 186 When submitting a patch make sure to use
 187 <a href="https://git-scm.com/docs/git-send-email">git send-email</a>
 188 rather than attaching patches to emails. Sending patches as
 189 attachments prevents people from being able to provide in-line review
 190 comments.
 191 </p>
 192
 193 <p>
 194 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
 195 etc patches show up as replies to the originals. This usually works well
 196 when you're sending out updates to individual patches (as opposed to
 197 re-sending the whole series). Using --in-reply-to makes
 198 it harder for reviewers to accidentally review old patches.
 199 </p>
 200
 201 <p>
 202 When submitting follow-up patches you should also login to
 203 <a href="https://patchwork.freedesktop.org">patchwork</a> and change the
 204 state of your old patches to Superseded.
 205 </p>
 206
 207 <p>
 208 Some companies' mail server automatically append a legal disclaimer,
 209 usually containing something along the lines of "The information in this
 210 email is confidential" and "distribution is strictly prohibited".
 211 </p>
 212 <p>
 213 These legal notices prevent us from being able to accept your patch,
 214 rendering the whole process pointless. Please make sure these are
 215 disabled before sending your patches. (Note that you may need to contact
 216 your email administrator for this.)
 217 </p>
 218
 219 <h3 id="merge-request">GitLab Merge Requests</h3>
 220
 221 <p>
 222   <a href="https://gitlab.freedesktop.org/mesa/mesa">GitLab</a> Merge
 223   Requests (MR) can also be used to submit patches for Mesa.
 224 </p>
 225
 226 <p>
 227   If the MR may have interest for most of the Mesa community, you can
 228   send an email to the mesa-dev email list including a link to the MR.
 229   Don't send the patch to mesa-dev, just the MR link.
 230 </p>
 231 <p>
 232   Add labels to your MR to help reviewers find it. For example:
 233 </p>
 234 <ul>
 235   <li>Mesa changes affecting all drivers: mesa
 236   <li>Hardware vendor specific code: amd, intel, nvidia, ...
 237   <li>Driver specific code: anvil, freedreno, i965, iris, radeonsi,
 238     radv, vc4, ...
 239   <li>Other tag examples: gallium, util
 240 </ul>
 241 <p>
 242   Tick the following when creating the MR. It allows developers to
 243   rebase your work on top of master.
 244 </p>
 245 <pre>Allow commits from members who can merge to the target branch</pre>
 246 <p>
 247   If you revise your patches based on code review and push an update
 248   to your branch, you should maintain a <strong>clean</strong> history
 249   in your patches. There should not be "fixup" patches in the history.
 250   The series should be buildable and functional after every commit
 251   whenever you push the branch.
 252 </p>
 253 <p>
 254   It is your responsibility to keep the MR alive and making progress,
 255   as there are no guarantees that a Mesa dev will independently take
 256   interest in it.
 257 </p>
 258 <p>
 259   Some other notes:
 260 </p>
 261 <ul>
 262   <li>Make changes and update your branch based on feedback
 263   <li>After an update, for the feedback you handled, close the
 264     feedback discussion with the "Resolve Discussion" button. This way
 265     the reviewers know which feedback got handled and which didn't.
 266   <li>Old, stale MR may be closed, but you can reopen it if you
 267     still want to pursue the changes
 268   <li>You should periodically check to see if your MR needs to be
 269     rebased
 270   <li>Make sure your MR is closed if your patches get pushed outside
 271     of GitLab
 272   <li>Please send MRs from a personal fork rather than from the main
 273     Mesa repository, as it clutters it unnecessarily.
 274 </ul>
 275
 276 <h2 id="reviewing">Reviewing Patches</h2>
 277
 278 <p>
 279   To participate in code review, you should monitor the
 280   <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 281   mesa-dev</a> email list and the GitLab
 282   Mesa <a href="https://gitlab.freedesktop.org/mesa/mesa/merge_requests">Merge
 283   Requests</a> page.
 284 </p>
 285
 286 <p>
 287 When you've reviewed a patch on the mailing list, please be unambiguous
 288 about your review.  That is, state either
 289 </p>
 290 <pre>
 291     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 292 </pre>
 293 or
 294 <pre>
 295     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 296 </pre>
 297 <p>
 298 Rather than saying just "LGTM" or "Seems OK".
 299 </p>
 300
 301 <p>
 302 If small changes are suggested, it's OK to say something like:
 303 </p>
 304 <pre>
 305    With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 306 </pre>
 307 <p>
 308 which tells the patch author that the patch can be committed, as long
 309 as the issues are resolved first.
 310 </p>
 311
 312 <p>
 313 These Reviewed-by, Acked-by, and Tested-by tags should also be amended
 314 into commits in a MR before it is merged.
 315 </p>
 316
 317 <p>
 318 When providing a Reviewed-by, Acked-by, or Tested-by tag in a gitlab MR,
 319 enclose the tag in backticks:
 320 </p>
 321 <pre>
 322   `Reviewed-by: Joe Hacker &lt;jhacker@example.com&gt;`</pre>
 323 <p>
 324 This is the markdown format for literal, and will prevent gitlab from hiding
 325 the &lt; and &gt; symbols.
 326 </p>
 327
 328 <p>
 329 Review by non-experts is encouraged.  Understanding how someone else
 330 goes about solving a problem is a great way to learn your way around
 331 the project.  The submitter is expected to evaluate whether they have
 332 an appropriate amount of review feedback from people who also
 333 understand the code before merging their patches.
 334 </p>
 335
 336 <h2 id="nominations">Nominating a commit for a stable branch</h2>
 337
 338 <p>
 339 There are three ways to nominate a patch for inclusion in the stable branch and
 340 release.
 341 </p>
 342 <ul>
 343 <li> By adding the Cc: mesa-stable@ tag as described below.
 344 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
 345 <li> Forwarding the patch from the mesa-dev@ mailing list.
 346 </li>
 347 </ul>
 348 <p>
 349 Note: resending patch identical to one on mesa-dev@ or one that differs only
 350 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
 351 </p>
 352 <p>
 353 If you are not the author of the original patch, please Cc: them in your
 354 nomination request.
 355 </p>
 356
 357 <p>
 358 The current patch status can be observed in the <a href="releasing.html#stagingbranch">staging branch</a>.
 359 </p>
 360
 361 <h3 id="thetag">The stable tag</h3>
 362
 363 <p>
 364 If you want a commit to be applied to a stable branch,
 365 you should add an appropriate note to the commit message.
 366 </p>
 367
 368 <p>
 369 Here are some examples of such a note:
 370 </p>
 371 <pre>
 372 CC: &lt;mesa-stable@lists.freedesktop.org&gt;
 373 </pre>
 374
 375 Simply adding the CC to the mesa-stable list address is adequate to nominate
 376 the commit for all the active stable branches. If the commit is not applicable
 377 for said branch the stable-release manager will reply stating so.
 378
 379 This "CC" syntax for patch nomination will cause patches to automatically be
 380 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 381 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
 382 won't have any negative effect on the patch nomination.
 383
 384 <p>
 385 Note: by removing the tag [as the commit is pushed] the patch is
 386 <strong>explicitly</strong> rejected from inclusion in the stable branch(es).
 387 Thus, drop the line <strong>only</strong> if you want to cancel the nomination.
 388 </p>
 389
 390 Alternatively, if one uses the "Fixes" tag as described in the "Patch formatting"
 391 section, it nominates a commit for all active stable branches that include the
 392 commit that is referred to.
 393
 394 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
 395
 396 Mesa has a designated release manager for each stable branch, and the release
 397 manager is the only developer that should be pushing changes to these branches.
 398 Everyone else should nominate patches using the mechanism described above.
 399
 400 The following rules define which patches are accepted and which are not. The
 401 stable-release manager is also given broad discretion in rejecting patches
 402 that have been nominated.
 403
 404 <ul>
 405   <li>Patch must conform with the <a href="#guidelines">Basic guidelines</a></li>
 406
 407   <li>Patch must have landed in master first. In case where the original
 408   patch is too large and/or otherwise contradicts with the rules set within, a
 409   backport is appropriate.</li>
 410
 411   <li>It must not introduce a regression - be that build or runtime wise.
 412
 413   Note:  If the regression is due to faulty piglit/dEQP/CTS/other test the
 414   latter must be fixed first. A reference to the offending test(s) and
 415   respective fix(es) should be provided in the nominated patch.</li>
 416
 417   <li>Patch cannot be larger than 100 lines.</li>
 418
 419   <li>Patches that move code around with no functional change should be
 420   rejected.</li>
 421
 422   <li>Patch must be a bug fix and not a new feature.
 423
 424   Note: An exception to this rule, are hardware-enabling "features". For
 425   example, <a href="#backports">backports</a> of new code to support a
 426   newly-developed hardware product can be accepted if they can be reasonably
 427   determined not to have effects on other hardware.</li>
 428
 429   <li>Patch must be reviewed, For example, the commit message has Reviewed-by,
 430   Signed-off-by, or Tested-by tags from someone but the author.</li>
 431
 432   <li>Performance patches are considered only if they provide information
 433   about the hardware, program in question and observed improvement. Use numbers
 434   to represent your measurements.</li>
 435 </ul>
 436
 437 If the patch complies with the rules it will be
 438 <a href="releasing.html#pickntest">cherry-picked</a>. Alternatively the release
 439 manager will reply to the patch in question stating why the patch has been
 440 rejected or would request a backport.
 441
 442 A summary of all the picked/rejected patches will be presented in the
 443 <a href="releasing.html#prerelease">pre-release</a> announcement.
 444
 445 The stable-release manager may at times need to force-push changes to the
 446 stable branches, for example, to drop a previously-picked patch that was later
 447 identified as causing a regression). These force-pushes may cause changes to
 448 be lost from the stable branch if developers push things directly. Consider
 449 yourself warned.
 450
 451 <h2 id="backports">Sending backports for the stable branch</h2>
 452 <p>
 453 By default merge conflicts are resolved by the stable-release manager. In which
 454 case he/she should provide a comment about the changes required, alongside the
 455 <code>Conflicts</code> section. Summary of which will be provided in the
 456 <a href="releasing.html#prerelease">pre-release</a> announcement.
 457 </p>
 458
 459 <p>
 460 Developers are interested in sending backports are recommended to use either a
 461 <code>[BACKPORT #branch]</code> subject prefix or provides similar information
 462 within the commit summary.
 463 </p>
 464
 465 <h2 id="gittips">Git tips</h2>
 466
 467 <ul>
 468 <li><code>git rebase -i ...</code> is your friend. Don't be afraid to use it.
 469 <li>Apply a fixup to commit FOO.
 470 <pre>
 471     git add ...
 472     git commit --fixup=FOO
 473     git rebase -i --autosquash ...
 474 </pre>
 475 <li>Test for build breakage between patches e.g last 8 commits.
 476 <pre>
 477     git rebase -i --exec="ninja -C build/" HEAD~8
 478 </pre>
 479 <li>Sets the default mailing address for your repo.
 480 <pre>
 481     git config --local sendemail.to mesa-dev@lists.freedesktop.org
 482 </pre>
 483 <li> Add version to subject line of patch series in this case for the last 8
 484 commits before sending.
 485 <pre>
 486     git send-email --subject-prefix="PATCH v4" HEAD~8
 487     git send-email -v4 @~8 # shorter version, inherited from git format-patch
 488 </pre>
 489 <li> Configure git to use the get_reviewer.pl script interactively. Thus you
 490 can avoid adding the world to the CC list.
 491 <pre>
 492     git config sendemail.cccmd "./scripts/get_reviewer.pl -i"
 493 </pre>
 494 </ul>
 495
 496
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