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 <br>
 122 Please use common sense and do <strong>not</strong> blindly add everyone.
 123 <br>
 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".<br/>
 211 These legal notices prevent us from being able to accept your patch,
 212 rendering the whole process pointless. Please make sure these are
 213 disabled before sending your patches. (Note that you may need to contact
 214 your email administrator for this.)
 215 </p>
 216
 217 <h3 id="merge-request">GitLab Merge Requests</h3>
 218
 219 <p>
 220   <a href="https://gitlab.freedesktop.org/mesa/mesa">GitLab</a> Merge
 221   Requests (MR) can also be used to submit patches for Mesa.
 222 </p>
 223
 224 <p>
 225   If the MR may have interest for most of the Mesa community, you can
 226   send an email to the mesa-dev email list including a link to the MR.
 227   Don't send the patch to mesa-dev, just the MR link.
 228 </p>
 229 <p>
 230   Add labels to your MR to help reviewers find it. For example:
 231 </p>
 232 <ul>
 233   <li>Mesa changes affecting all drivers: mesa
 234   <li>Hardware vendor specific code: amd, intel, nvidia, ...
 235   <li>Driver specific code: anvil, freedreno, i965, iris, radeonsi,
 236     radv, vc4, ...
 237   <li>Other tag examples: gallium, util
 238 </ul>
 239 <p>
 240   Tick the following when creating the MR. It allows developers to
 241   rebase your work on top of master.
 242 </p>
 243 <pre>Allow commits from members who can merge to the target branch</pre>
 244 <p>
 245   If you revise your patches based on code review and push an update
 246   to your branch, you should maintain a <strong>clean</strong> history
 247   in your patches. There should not be "fixup" patches in the history.
 248   The series should be buildable and functional after every commit
 249   whenever you push the branch.
 250 </p>
 251 <p>
 252   It is your responsibility to keep the MR alive and making progress,
 253   as there are no guarantees that a Mesa dev will independently take
 254   interest in it.
 255 </p>
 256 <p>
 257   Some other notes:
 258 </p>
 259 <ul>
 260   <li>Make changes and update your branch based on feedback
 261   <li>After an update, for the feedback you handled, close the
 262     feedback discussion with the "Resolve Discussion" button. This way
 263     the reviewers know which feedback got handled and which didn't.
 264   <li>Old, stale MR may be closed, but you can reopen it if you
 265     still want to pursue the changes
 266   <li>You should periodically check to see if your MR needs to be
 267     rebased
 268   <li>Make sure your MR is closed if your patches get pushed outside
 269     of GitLab
 270   <li>Please send MRs from a personal fork rather than from the main
 271     Mesa repository, as it clutters it unnecessarily.
 272 </ul>
 273
 274 <h2 id="reviewing">Reviewing Patches</h2>
 275
 276 <p>
 277   To participate in code review, you should monitor the
 278   <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 279   mesa-dev</a> email list and the GitLab
 280   Mesa <a href="https://gitlab.freedesktop.org/mesa/mesa/merge_requests">Merge
 281   Requests</a> page.
 282 </p>
 283
 284 <p>
 285 When you've reviewed a patch on the mailing list, please be unambiguous
 286 about your review.  That is, state either
 287 </p>
 288 <pre>
 289     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 290 </pre>
 291 or
 292 <pre>
 293     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 294 </pre>
 295 <p>
 296 Rather than saying just "LGTM" or "Seems OK".
 297 </p>
 298
 299 <p>
 300 If small changes are suggested, it's OK to say something like:
 301 </p>
 302 <pre>
 303    With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 304 </pre>
 305 <p>
 306 which tells the patch author that the patch can be committed, as long
 307 as the issues are resolved first.
 308 </p>
 309
 310 <p>
 311 These Reviewed-by, Acked-by, and Tested-by tags should also be amended
 312 into commits in a MR before it is merged.
 313 </p>
 314
 315 <p>
 316 When providing a Reviewed-by, Acked-by, or Tested-by tag in a gitlab MR,
 317 enclose the tag in backticks:
 318 </p>
 319 <pre>
 320   `Reviewed-by: Joe Hacker &lt;jhacker@example.com&gt;`</pre>
 321 <p>
 322 This is the markdown format for literal, and will prevent gitlab from hiding
 323 the &lt; and &gt; symbols.
 324 </p>
 325
 326 <p>
 327 Review by non-experts is encouraged.  Understanding how someone else
 328 goes about solving a problem is a great way to learn your way around
 329 the project.  The submitter is expected to evaluate whether they have
 330 an appropriate amount of review feedback from people who also
 331 understand the code before merging their patches.
 332 </p>
 333
 334 <h2 id="nominations">Nominating a commit for a stable branch</h2>
 335
 336 <p>
 337 There are three ways to nominate a patch for inclusion in the stable branch and
 338 release.
 339 </p>
 340 <ul>
 341 <li> By adding the Cc: mesa-stable@ tag as described below.
 342 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
 343 <li> Forwarding the patch from the mesa-dev@ mailing list.
 344 </li>
 345 </ul>
 346 <p>
 347 Note: resending patch identical to one on mesa-dev@ or one that differs only
 348 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
 349 </p>
 350 <p>
 351 If you are not the author of the original patch, please Cc: them in your
 352 nomination request.
 353 </p>
 354
 355 <p>
 356 The current patch status can be observed in the <a href="releasing.html#stagingbranch">staging branch</a>.
 357 </p>
 358
 359 <h3 id="thetag">The stable tag</h3>
 360
 361 <p>
 362 If you want a commit to be applied to a stable branch,
 363 you should add an appropriate note to the commit message.
 364 </p>
 365
 366 <p>
 367 Here are some examples of such a note:
 368 </p>
 369 <ul>
 370   <li>CC: &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 371 </ul>
 372
 373 Simply adding the CC to the mesa-stable list address is adequate to nominate
 374 the commit for all the active stable branches. If the commit is not applicable
 375 for said branch the stable-release manager will reply stating so.
 376
 377 This "CC" syntax for patch nomination will cause patches to automatically be
 378 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 379 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
 380 won't have any negative effect on the patch nomination.
 381
 382 <p>
 383 Note: by removing the tag [as the commit is pushed] the patch is
 384 <strong>explicitly</strong> rejected from inclusion in the stable branch(es).
 385 <br>
 386 Thus, drop the line <strong>only</strong> if you want to cancel the nomination.
 387 </p>
 388
 389 Alternatively, if one uses the "Fixes" tag as described in the "Patch formatting"
 390 section, it nominates a commit for all active stable branches that include the
 391 commit that is referred to.
 392
 393 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
 394
 395 Mesa has a designated release manager for each stable branch, and the release
 396 manager is the only developer that should be pushing changes to these branches.
 397 Everyone else should nominate patches using the mechanism described above.
 398
 399 The following rules define which patches are accepted and which are not. The
 400 stable-release manager is also given broad discretion in rejecting patches
 401 that have been nominated.
 402
 403 <ul>
 404   <li>Patch must conform with the <a href="#guidelines">Basic guidelines</a></li>
 405
 406   <li>Patch must have landed in master first. In case where the original
 407   patch is too large and/or otherwise contradicts with the rules set within, a
 408   backport is appropriate.</li>
 409
 410   <li>It must not introduce a regression - be that build or runtime wise.
 411
 412   Note:  If the regression is due to faulty piglit/dEQP/CTS/other test the
 413   latter must be fixed first. A reference to the offending test(s) and
 414   respective fix(es) should be provided in the nominated patch.</li>
 415
 416   <li>Patch cannot be larger than 100 lines.</li>
 417
 418   <li>Patches that move code around with no functional change should be
 419   rejected.</li>
 420
 421   <li>Patch must be a bug fix and not a new feature.
 422
 423   Note: An exception to this rule, are hardware-enabling "features". For
 424   example, <a href="#backports">backports</a> of new code to support a
 425   newly-developed hardware product can be accepted if they can be reasonably
 426   determined not to have effects on other hardware.</li>
 427
 428   <li>Patch must be reviewed, For example, the commit message has Reviewed-by,
 429   Signed-off-by, or Tested-by tags from someone but the author.</li>
 430
 431   <li>Performance patches are considered only if they provide information
 432   about the hardware, program in question and observed improvement. Use numbers
 433   to represent your measurements.</li>
 434 </ul>
 435
 436 If the patch complies with the rules it will be
 437 <a href="releasing.html#pickntest">cherry-picked</a>. Alternatively the release
 438 manager will reply to the patch in question stating why the patch has been
 439 rejected or would request a backport.
 440
 441 A summary of all the picked/rejected patches will be presented in the
 442 <a href="releasing.html#prerelease">pre-release</a> announcement.
 443
 444 The stable-release manager may at times need to force-push changes to the
 445 stable branches, for example, to drop a previously-picked patch that was later
 446 identified as causing a regression). These force-pushes may cause changes to
 447 be lost from the stable branch if developers push things directly. Consider
 448 yourself warned.
 449
 450 <h2 id="backports">Sending backports for the stable branch</h2>
 451 By default merge conflicts are resolved by the stable-release manager. In which
 452 case he/she should provide a comment about the changes required, alongside the
 453 <code>Conflicts</code> section. Summary of which will be provided in the
 454 <a href="releasing.html#prerelease">pre-release</a> announcement.
 455 <br>
 456 Developers are interested in sending backports are recommended to use either a
 457 <code>[BACKPORT #branch]</code> subject prefix or provides similar information
 458 within the commit summary.
 459
 460 <h2 id="gittips">Git tips</h2>
 461
 462 <ul>
 463 <li><code>git rebase -i ...</code> is your friend. Don't be afraid to use it.
 464 <li>Apply a fixup to commit FOO.
 465 <pre>
 466     git add ...
 467     git commit --fixup=FOO
 468     git rebase -i --autosquash ...
 469 </pre>
 470 <li>Test for build breakage between patches e.g last 8 commits.
 471 <pre>
 472     git rebase -i --exec="ninja -C build/" HEAD~8
 473 </pre>
 474 <li>Sets the default mailing address for your repo.
 475 <pre>
 476     git config --local sendemail.to mesa-dev@lists.freedesktop.org
 477 </pre>
 478 <li> Add version to subject line of patch series in this case for the last 8
 479 commits before sending.
 480 <pre>
 481     git send-email --subject-prefix="PATCH v4" HEAD~8
 482     git send-email -v4 @~8 # shorter version, inherited from git format-patch
 483 </pre>
 484 <li> Configure git to use the get_reviewer.pl script interactively. Thus you
 485 can avoid adding the world to the CC list.
 486 <pre>
 487     git config sendemail.cccmd "./scripts/get_reviewer.pl -i"
 488 </pre>
 489 </ul>
 490
 491
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