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>You can produce those fixes lines by running <pre>git config --global pretty.fixes 'Fixes: %h ("%s")'</pre> once and then using <pre>git show -s --pretty=fixes &lt;sha1&gt;</pre>
  89 <li>If there have been several revisions to a patch during the review
  90 process, they should be noted such as in this example:
  91 <pre>
  92     st/mesa: add ARB_texture_stencil8 support (v4)
  93
  94     if we support stencil texturing, enable texture_stencil8
  95     there is no requirement to support native S8 for this,
  96     the texture can be converted to x24s8 fine.
  97
  98     v2: fold fixes from Marek in:
  99        a) put S8 last in the list
 100        b) fix renderable to always test for d/s renderable
 101         fixup the texture case to use a stencil only format
 102         for picking the format for the texture view.
 103     v3: hit fallback for getteximage
 104     v4: put s8 back in front, it shouldn't get picked now (Ilia)
 105 </pre>
 106 <li>If someone tested your patch, document it with a line like this:
 107 <pre>
 108     Tested-by: Joe Hacker &lt;jhacker@foo.com&gt;
 109 </pre>
 110 <li>If the patch was reviewed (usually the case) or acked by someone,
 111 that should be documented with:
 112 <pre>
 113     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 114     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 115 </pre>
 116 <li>If sending later revision of a patch, add all the tags - ack, r-b,
 117 Cc: mesa-stable and/or other. This provides reviewers with quick feedback if the
 118 patch has already been reviewed.
 119 <li>In order for your patch to reach the prospective reviewer easier/faster,
 120 use the script scripts/get_reviewer.pl to get a list of individuals and include
 121 them in the CC list.
 122 <p>
 123 Please use common sense and do <strong>not</strong> blindly add everyone.
 124 </p>
 125 <pre>
 126     $ scripts/get_reviewer.pl --help # to get the help screen
 127     $ scripts/get_reviewer.pl -f src/egl/drivers/dri2/platform_android.c
 128     Rob Herring &lt;robh@kernel.org&gt; (reviewer:ANDROID EGL SUPPORT,added_lines:188/700=27%,removed_lines:58/283=20%)
 129     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%)
 130     Emil Velikov &lt;emil.l.velikov@gmail.com&gt; (authored:13/41=32%,removed_lines:76/283=27%)
 131 </pre>
 132 </ul>
 133
 134
 135
 136 <h2 id="testing">Testing Patches</h2>
 137
 138 <p>
 139 It should go without saying that patches must be tested.  In general,
 140 do whatever testing is prudent.
 141 </p>
 142
 143 <p>
 144 You should always run the Mesa test suite before submitting patches.
 145 The test suite can be run using the 'meson test' command. All tests
 146 must pass before patches will be accepted, this may mean you have
 147 to update the tests themselves.
 148 </p>
 149
 150 <p>
 151 Whenever possible and applicable, test the patch with
 152 <a href="https://piglit.freedesktop.org">Piglit</a> and/or
 153 <a href="https://android.googlesource.com/platform/external/deqp/">dEQP</a>
 154 to check for regressions.
 155 </p>
 156
 157 <p>
 158 As mentioned at the begining, patches should be bisectable.
 159 A good way to test this is to make use of the `git rebase` command,
 160 to run your tests on each commit. Assuming your branch is based off
 161 <code>origin/master</code>, you can run:
 162 </p>
 163 <pre>
 164 $ git rebase --interactive --exec "meson test -C build/" origin/master
 165 </pre>
 166 <p>
 167 replacing <code>"meson test"</code> with whatever other test you want to
 168 run.
 169 </p>
 170
 171
 172 <h2 id="submit">Submitting Patches</h2>
 173
 174 <p>
 175 Patches may be submitted to the Mesa project by
 176 <a href="#mailing">email</a> or with a
 177 GitLab <a href="#merge-request">merge request</a>. To prevent
 178 duplicate code review, only use one method to submit your changes.
 179 </p>
 180
 181 <h3 id="mailing">Mailing Patches</h3>
 182
 183 <p>
 184 Patches may be sent to the mesa-dev mailing list for review:
 185 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 186 mesa-dev@lists.freedesktop.org</a>.
 187 When submitting a patch make sure to use
 188 <a href="https://git-scm.com/docs/git-send-email">git send-email</a>
 189 rather than attaching patches to emails. Sending patches as
 190 attachments prevents people from being able to provide in-line review
 191 comments.
 192 </p>
 193
 194 <p>
 195 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
 196 etc patches show up as replies to the originals. This usually works well
 197 when you're sending out updates to individual patches (as opposed to
 198 re-sending the whole series). Using --in-reply-to makes
 199 it harder for reviewers to accidentally review old patches.
 200 </p>
 201
 202 <p>
 203 When submitting follow-up patches you should also login to
 204 <a href="https://patchwork.freedesktop.org">patchwork</a> and change the
 205 state of your old patches to Superseded.
 206 </p>
 207
 208 <p>
 209 Some companies' mail server automatically append a legal disclaimer,
 210 usually containing something along the lines of "The information in this
 211 email is confidential" and "distribution is strictly prohibited".
 212 </p>
 213 <p>
 214 These legal notices prevent us from being able to accept your patch,
 215 rendering the whole process pointless. Please make sure these are
 216 disabled before sending your patches. (Note that you may need to contact
 217 your email administrator for this.)
 218 </p>
 219
 220 <h3 id="merge-request">GitLab Merge Requests</h3>
 221
 222 <p>
 223   <a href="https://gitlab.freedesktop.org/mesa/mesa">GitLab</a> Merge
 224   Requests (MR) can also be used to submit patches for Mesa.
 225 </p>
 226
 227 <p>
 228   If the MR may have interest for most of the Mesa community, you can
 229   send an email to the mesa-dev email list including a link to the MR.
 230   Don't send the patch to mesa-dev, just the MR link.
 231 </p>
 232 <p>
 233   Add labels to your MR to help reviewers find it. For example:
 234 </p>
 235 <ul>
 236   <li>Mesa changes affecting all drivers: mesa
 237   <li>Hardware vendor specific code: amd, intel, nvidia, ...
 238   <li>Driver specific code: anvil, freedreno, i965, iris, radeonsi,
 239     radv, vc4, ...
 240   <li>Other tag examples: gallium, util
 241 </ul>
 242 <p>
 243   Tick the following when creating the MR. It allows developers to
 244   rebase your work on top of master.
 245 </p>
 246 <pre>Allow commits from members who can merge to the target branch</pre>
 247 <p>
 248   If you revise your patches based on code review and push an update
 249   to your branch, you should maintain a <strong>clean</strong> history
 250   in your patches. There should not be "fixup" patches in the history.
 251   The series should be buildable and functional after every commit
 252   whenever you push the branch.
 253 </p>
 254 <p>
 255   It is your responsibility to keep the MR alive and making progress,
 256   as there are no guarantees that a Mesa dev will independently take
 257   interest in it.
 258 </p>
 259 <p>
 260   Some other notes:
 261 </p>
 262 <ul>
 263   <li>Make changes and update your branch based on feedback
 264   <li>After an update, for the feedback you handled, close the
 265     feedback discussion with the "Resolve Discussion" button. This way
 266     the reviewers know which feedback got handled and which didn't.
 267   <li>Old, stale MR may be closed, but you can reopen it if you
 268     still want to pursue the changes
 269   <li>You should periodically check to see if your MR needs to be
 270     rebased
 271   <li>Make sure your MR is closed if your patches get pushed outside
 272     of GitLab
 273   <li>Please send MRs from a personal fork rather than from the main
 274     Mesa repository, as it clutters it unnecessarily.
 275 </ul>
 276
 277 <h2 id="reviewing">Reviewing Patches</h2>
 278
 279 <p>
 280   To participate in code review, you should monitor the
 281   <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 282   mesa-dev</a> email list and the GitLab
 283   Mesa <a href="https://gitlab.freedesktop.org/mesa/mesa/merge_requests">Merge
 284   Requests</a> page.
 285 </p>
 286
 287 <p>
 288 When you've reviewed a patch on the mailing list, please be unambiguous
 289 about your review.  That is, state either
 290 </p>
 291 <pre>
 292     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 293 </pre>
 294 or
 295 <pre>
 296     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 297 </pre>
 298 <p>
 299 Rather than saying just "LGTM" or "Seems OK".
 300 </p>
 301
 302 <p>
 303 If small changes are suggested, it's OK to say something like:
 304 </p>
 305 <pre>
 306    With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 307 </pre>
 308 <p>
 309 which tells the patch author that the patch can be committed, as long
 310 as the issues are resolved first.
 311 </p>
 312
 313 <p>
 314 These Reviewed-by, Acked-by, and Tested-by tags should also be amended
 315 into commits in a MR before it is merged.
 316 </p>
 317
 318 <p>
 319 When providing a Reviewed-by, Acked-by, or Tested-by tag in a gitlab MR,
 320 enclose the tag in backticks:
 321 </p>
 322 <pre>
 323   `Reviewed-by: Joe Hacker &lt;jhacker@example.com&gt;`</pre>
 324 <p>
 325 This is the markdown format for literal, and will prevent gitlab from hiding
 326 the &lt; and &gt; symbols.
 327 </p>
 328
 329 <p>
 330 Review by non-experts is encouraged.  Understanding how someone else
 331 goes about solving a problem is a great way to learn your way around
 332 the project.  The submitter is expected to evaluate whether they have
 333 an appropriate amount of review feedback from people who also
 334 understand the code before merging their patches.
 335 </p>
 336
 337 <h2 id="nominations">Nominating a commit for a stable branch</h2>
 338
 339 <p>
 340 There are three ways to nominate a patch for inclusion in the stable branch and
 341 release.
 342 </p>
 343 <ul>
 344 <li> By adding the Cc: mesa-stable@ tag as described below.
 345 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
 346 <li> Forwarding the patch from the mesa-dev@ mailing list.
 347 </li>
 348 </ul>
 349 <p>
 350 Note: resending patch identical to one on mesa-dev@ or one that differs only
 351 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
 352 </p>
 353 <p>
 354 If you are not the author of the original patch, please Cc: them in your
 355 nomination request.
 356 </p>
 357
 358 <p>
 359 The current patch status can be observed in the <a href="releasing.html#stagingbranch">staging branch</a>.
 360 </p>
 361
 362 <h3 id="thetag">The stable tag</h3>
 363
 364 <p>
 365 If you want a commit to be applied to a stable branch,
 366 you should add an appropriate note to the commit message.
 367 </p>
 368
 369 <p>
 370 Here are some examples of such a note:
 371 </p>
 372 <pre>
 373 CC: &lt;mesa-stable@lists.freedesktop.org&gt;
 374 </pre>
 375
 376 Simply adding the CC to the mesa-stable list address is adequate to nominate
 377 the commit for all the active stable branches. If the commit is not applicable
 378 for said branch the stable-release manager will reply stating so.
 379
 380 This "CC" syntax for patch nomination will cause patches to automatically be
 381 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 382 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
 383 won't have any negative effect on the patch nomination.
 384
 385 <p>
 386 Note: by removing the tag [as the commit is pushed] the patch is
 387 <strong>explicitly</strong> rejected from inclusion in the stable branch(es).
 388 Thus, drop the line <strong>only</strong> if you want to cancel the nomination.
 389 </p>
 390
 391 Alternatively, if one uses the "Fixes" tag as described in the "Patch formatting"
 392 section, it nominates a commit for all active stable branches that include the
 393 commit that is referred to.
 394
 395 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
 396
 397 Mesa has a designated release manager for each stable branch, and the release
 398 manager is the only developer that should be pushing changes to these branches.
 399 Everyone else should nominate patches using the mechanism described above.
 400
 401 The following rules define which patches are accepted and which are not. The
 402 stable-release manager is also given broad discretion in rejecting patches
 403 that have been nominated.
 404
 405 <ul>
 406   <li>Patch must conform with the <a href="#guidelines">Basic guidelines</a></li>
 407
 408   <li>Patch must have landed in master first. In case where the original
 409   patch is too large and/or otherwise contradicts with the rules set within, a
 410   backport is appropriate.</li>
 411
 412   <li>It must not introduce a regression - be that build or runtime wise.
 413
 414   Note:  If the regression is due to faulty piglit/dEQP/CTS/other test the
 415   latter must be fixed first. A reference to the offending test(s) and
 416   respective fix(es) should be provided in the nominated patch.</li>
 417
 418   <li>Patch cannot be larger than 100 lines.</li>
 419
 420   <li>Patches that move code around with no functional change should be
 421   rejected.</li>
 422
 423   <li>Patch must be a bug fix and not a new feature.
 424
 425   Note: An exception to this rule, are hardware-enabling "features". For
 426   example, <a href="#backports">backports</a> of new code to support a
 427   newly-developed hardware product can be accepted if they can be reasonably
 428   determined not to have effects on other hardware.</li>
 429
 430   <li>Patch must be reviewed, For example, the commit message has Reviewed-by,
 431   Signed-off-by, or Tested-by tags from someone but the author.</li>
 432
 433   <li>Performance patches are considered only if they provide information
 434   about the hardware, program in question and observed improvement. Use numbers
 435   to represent your measurements.</li>
 436 </ul>
 437
 438 If the patch complies with the rules it will be
 439 <a href="releasing.html#pickntest">cherry-picked</a>. Alternatively the release
 440 manager will reply to the patch in question stating why the patch has been
 441 rejected or would request a backport.
 442
 443 A summary of all the picked/rejected patches will be presented in the
 444 <a href="releasing.html#prerelease">pre-release</a> announcement.
 445
 446 The stable-release manager may at times need to force-push changes to the
 447 stable branches, for example, to drop a previously-picked patch that was later
 448 identified as causing a regression). These force-pushes may cause changes to
 449 be lost from the stable branch if developers push things directly. Consider
 450 yourself warned.
 451
 452 <h2 id="backports">Sending backports for the stable branch</h2>
 453 <p>
 454 By default merge conflicts are resolved by the stable-release manager. In which
 455 case he/she should provide a comment about the changes required, alongside the
 456 <code>Conflicts</code> section. Summary of which will be provided in the
 457 <a href="releasing.html#prerelease">pre-release</a> announcement.
 458 </p>
 459
 460 <p>
 461 Developers are interested in sending backports are recommended to use either a
 462 <code>[BACKPORT #branch]</code> subject prefix or provides similar information
 463 within the commit summary.
 464 </p>
 465
 466 <h2 id="gittips">Git tips</h2>
 467
 468 <ul>
 469 <li><code>git rebase -i ...</code> is your friend. Don't be afraid to use it.
 470 <li>Apply a fixup to commit FOO.
 471 <pre>
 472     git add ...
 473     git commit --fixup=FOO
 474     git rebase -i --autosquash ...
 475 </pre>
 476 <li>Test for build breakage between patches e.g last 8 commits.
 477 <pre>
 478     git rebase -i --exec="ninja -C build/" HEAD~8
 479 </pre>
 480 <li>Sets the default mailing address for your repo.
 481 <pre>
 482     git config --local sendemail.to mesa-dev@lists.freedesktop.org
 483 </pre>
 484 <li> Add version to subject line of patch series in this case for the last 8
 485 commits before sending.
 486 <pre>
 487     git send-email --subject-prefix="PATCH v4" HEAD~8
 488     git send-email -v4 @~8 # shorter version, inherited from git format-patch
 489 </pre>
 490 <li> Configure git to use the get_reviewer.pl script interactively. Thus you
 491 can avoid adding the world to the CC list.
 492 <pre>
 493     git config sendemail.cccmd "./scripts/get_reviewer.pl -i"
 494 </pre>
 495 </ul>
 496
 497
 498 </div>
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