docs/submittingpatches.html

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  11   <h1>The Mesa 3D Graphics Library</h1>
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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="#mailing">Mailing 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="#gittips">Git tips</a>
  29 </ul>
  30
  31 <h2 id="guidelines">Basic guidelines</h2>
  32
  33 <ul>
  34 <li>Patches should not mix code changes with code formatting changes (except,
  35 perhaps, in very trivial cases.)
  36 <li>Code patches should follow Mesa
  37 <a href="codingstyle.html" target="_parent">coding conventions</a>.
  38 <li>Whenever possible, patches should only effect individual Mesa/Gallium
  39 components.
  40 <li>Patches should never introduce build breaks and should be bisectable (see
  41 <code>git bisect</code>.)
  42 <li>Patches should be properly <a href="#formatting">formatted</a>.
  43 <li>Patches should be sufficiently <a href="#testing">tested</a> before submitting.
  44 <li>Patches should be submitted to <a href="#mailing">mesa-dev</a>
  45 for <a href="#reviewing">review</a> using <code>git send-email</code>.
  46
  47 </ul>
  48
  49 <h2 id="formatting">Patch formatting</h2>
  50
  51 <ul>
  52 <li>Lines should be limited to 75 characters or less so that git logs
  53 displayed in 80-column terminals avoid line wrapping.  Note that git
  54 log uses 4 spaces of indentation (4 + 75 &lt; 80).
  55 <li>The first line should be a short, concise summary of the change prefixed
  56 with a module name.  Examples:
  57 <pre>
  58     mesa: Add support for querying GL_VERTEX_ATTRIB_ARRAY_LONG
  59
  60     gallium: add PIPE_CAP_DEVICE_RESET_STATUS_QUERY
  61
  62     i965: Fix missing type in local variable declaration.
  63 </pre>
  64 <li>Subsequent patch comments should describe the change in more detail,
  65 if needed.  For example:
  66 <pre>
  67     i965: Remove end-of-thread SEND alignment code.
  68
  69     This was present in Eric's initial implementation of the compaction code
  70     for Sandybridge (commit 077d01b6). There is no documentation saying this
  71     is necessary, and removing it causes no regressions in piglit on any
  72     platform.
  73 </pre>
  74 <li>A "Signed-off-by:" line is not required, but not discouraged either.
  75 <li>If a patch address a bugzilla issue, that should be noted in the
  76 patch comment.  For example:
  77 <pre>
  78    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89689
  79 </pre>
  80 <li>If there have been several revisions to a patch during the review
  81 process, they should be noted such as in this example:
  82 <pre>
  83     st/mesa: add ARB_texture_stencil8 support (v4)
  84
  85     if we support stencil texturing, enable texture_stencil8
  86     there is no requirement to support native S8 for this,
  87     the texture can be converted to x24s8 fine.
  88
  89     v2: fold fixes from Marek in:
  90        a) put S8 last in the list
  91        b) fix renderable to always test for d/s renderable
  92         fixup the texture case to use a stencil only format
  93         for picking the format for the texture view.
  94     v3: hit fallback for getteximage
  95     v4: put s8 back in front, it shouldn't get picked now (Ilia)
  96 </pre>
  97 <li>If someone tested your patch, document it with a line like this:
  98 <pre>
  99     Tested-by: Joe Hacker &lt;jhacker@foo.com&gt;
 100 </pre>
 101 <li>If the patch was reviewed (usually the case) or acked by someone,
 102 that should be documented with:
 103 <pre>
 104     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 105     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 106 </pre>
 107 <li>In order for your patch to reach the prospective reviewer easier/faster,
 108 use the script scripts/get_reviewer.pl to get a list of individuals and include
 109 them in the CC list.
 110 <br>
 111 Please use common sense and do <strong>not</strong> blindly add everyone.
 112 <br>
 113 <pre>
 114     $ scripts/get_reviewer.pl --help # to get the the help screen
 115     $ scripts/get_reviewer.pl -f src/egl/drivers/dri2/platform_android.c
 116     Rob Herring <robh@kernel.org> (reviewer:ANDROID EGL SUPPORT,added_lines:188/700=27%,removed_lines:58/283=20%)
 117     Tomasz Figa <tfiga@chromium.org> (reviewer:ANDROID EGL SUPPORT,authored:12/41=29%,added_lines:308/700=44%,removed_lines:115/283=41%)
 118     Emil Velikov <emil.l.velikov@gmail.com> (authored:13/41=32%,removed_lines:76/283=27%)
 119 </pre>
 120 </ul>
 121
 122
 123
 124 <h2 id="testing">Testing Patches</h2>
 125
 126 <p>
 127 It should go without saying that patches must be tested.  In general,
 128 do whatever testing is prudent.
 129 </p>
 130
 131 <p>
 132 You should always run the Mesa test suite before submitting patches.
 133 The test suite can be run using the 'make check' command. All tests
 134 must pass before patches will be accepted, this may mean you have
 135 to update the tests themselves.
 136 </p>
 137
 138 <p>
 139 Whenever possible and applicable, test the patch with
 140 <a href="http://piglit.freedesktop.org">Piglit</a> and/or
 141 <a href="https://android.googlesource.com/platform/external/deqp/">dEQP</a>
 142 to check for regressions.
 143 </p>
 144
 145
 146 <h2 id="mailing">Mailing Patches</h2>
 147
 148 <p>
 149 Patches should be sent to the mesa-dev mailing list for review:
 150 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 151 mesa-dev@lists.freedesktop.org</a>.
 152 When submitting a patch make sure to use
 153 <a href="https://git-scm.com/docs/git-send-email">git send-email</a>
 154 rather than attaching patches to emails. Sending patches as
 155 attachments prevents people from being able to provide in-line review
 156 comments.
 157 </p>
 158
 159 <p>
 160 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
 161 etc patches show up as replies to the originals. This usually works well
 162 when you're sending out updates to individual patches (as opposed to
 163 re-sending the whole series). Using --in-reply-to makes
 164 it harder for reviewers to accidentally review old patches.
 165 </p>
 166
 167 <p>
 168 When submitting follow-up patches you should also login to
 169 <a href="https://patchwork.freedesktop.org">patchwork</a> and change the
 170 state of your old patches to Superseded.
 171 </p>
 172
 173 <h2 id="reviewing">Reviewing Patches</h2>
 174
 175 <p>
 176 When you've reviewed a patch on the mailing list, please be unambiguous
 177 about your review.  That is, state either
 178 </p>
 179 <pre>
 180     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 181 </pre>
 182 or
 183 <pre>
 184     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 185 </pre>
 186 <p>
 187 Rather than saying just "LGTM" or "Seems OK".
 188 </p>
 189
 190 <p>
 191 If small changes are suggested, it's OK to say something like:
 192 </p>
 193 <pre>
 194    With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 195 </pre>
 196 <p>
 197 which tells the patch author that the patch can be committed, as long
 198 as the issues are resolved first.
 199 </p>
 200
 201
 202 <h2 id="nominations">Nominating a commit for a stable branch</h2>
 203
 204 <p>
 205 There are three ways to nominate patch for inclusion of the stable branch and
 206 release.
 207 </p>
 208 <ul>
 209 <li> By adding the Cc: mesa-stable@ tag as described below.
 210 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
 211 <li> Forwarding the patch from the mesa-dev@ mailing list.
 212 </li>
 213 </ul>
 214 <p>
 215 Note: resending patch identical to one on mesa-dev@ or one that differs only
 216 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
 217 </p>
 218
 219
 220 <h3 id="thetag">The stable tag</h3>
 221
 222 <p>
 223 If you want a commit to be applied to a stable branch,
 224 you should add an appropriate note to the commit message.
 225 </p>
 226
 227 <p>
 228 Here are some examples of such a note:
 229 </p>
 230 <ul>
 231   <li>CC: &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 232   <li>CC: "9.2 10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 233   <li>CC: "10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 234 </ul>
 235
 236 Simply adding the CC to the mesa-stable list address is adequate to nominate
 237 the commit for the most-recently-created stable branch. It is only necessary
 238 to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the
 239 examples above), if you want to nominate the commit for an older stable
 240 branch. And, as in these examples, you can nominate the commit for the older
 241 branch in addition to the more recent branch, or nominate the commit
 242 exclusively for the older branch.
 243
 244 This "CC" syntax for patch nomination will cause patches to automatically be
 245 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 246 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
 247 won't have any effect negative effect on the patch nomination.
 248
 249 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
 250
 251 Mesa has a designated release manager for each stable branch, and the release
 252 manager is the only developer that should be pushing changes to these
 253 branches. Everyone else should simply nominate patches using the mechanism
 254 described above.
 255
 256 The stable-release manager will work with the list of nominated patches, and
 257 for each patch that meets the criteria below will cherry-pick the patch with:
 258 <code>git cherry-pick -x &lt;commit&gt;</code>. The <code>-x</code> option is
 259 important so that the picked patch references the commit ID of the original
 260 patch.
 261
 262 The stable-release manager may at times need to force-push changes to the
 263 stable branches, for example, to drop a previously-picked patch that was later
 264 identified as causing a regression). These force-pushes may cause changes to
 265 be lost from the stable branch if developers push things directly. Consider
 266 yourself warned.
 267
 268 The stable-release manager is also given broad discretion in rejecting patches
 269 that have been nominated for the stable branch. The most basic rule is that
 270 the stable branch is for bug fixes only, (no new features, no
 271 regressions). Here is a non-exhaustive list of some reasons that a patch may
 272 be rejected:
 273
 274 <ul>
 275   <li>Patch introduces a regression. Any reported build breakage or other
 276   regression caused by a particular patch, (game no longer work, piglit test
 277   changes from PASS to FAIL), is justification for rejecting a patch.</li>
 278
 279   <li>Patch is too large, (say, larger than 100 lines)</li>
 280
 281   <li>Patch is not a fix. For example, a commit that moves code around with no
 282   functional change should be rejected.</li>
 283
 284   <li>Patch fix is not clearly described. For example, a commit message
 285   of only a single line, no description of the bug, no mention of bugzilla,
 286   etc.</li>
 287
 288   <li>Patch has not obviously been reviewed, For example, the commit message
 289   has no Reviewed-by, Signed-off-by, nor Tested-by tags from anyone but the
 290   author.</li>
 291
 292   <li>Patch has not already been merged to the master branch. As a rule, bug
 293   fixes should never be applied first to a stable branch. Patches should land
 294   first on the master branch and then be cherry-picked to a stable
 295   branch. (This is to avoid future releases causing regressions if the patch
 296   is not also applied to master.) The only things that might look like
 297   exceptions would be backports of patches from master that happen to look
 298   significantly different.</li>
 299
 300   <li>Patch depends on too many other patches. Ideally, all stable-branch
 301   patches should be self-contained. It sometimes occurs that a single, logical
 302   bug-fix occurs as two separate patches on master, (such as an original
 303   patch, then a subsequent fix-up to that patch). In such a case, these two
 304   patches should be squashed into a single, self-contained patch for the
 305   stable branch. (Of course, if the squashing makes the patch too large, then
 306   that could be a reason to reject the patch.)</li>
 307
 308   <li>Patch includes new feature development, not bug fixes. New OpenGL
 309   features, extensions, etc. should be applied to Mesa master and included in
 310   the next major release. Stable releases are intended only for bug fixes.
 311
 312   Note: As an exception to this rule, the stable-release manager may accept
 313   hardware-enabling "features". For example, backports of new code to support
 314   a newly-developed hardware product can be accepted if they can be reasonably
 315   determined to not have effects on other hardware.</li>
 316
 317   <li>Patch is a performance optimization. As a rule, performance patches are
 318   not candidates for the stable branch. The only exception might be a case
 319   where an application's performance was recently severely impacted so as to
 320   become unusable. The fix for this performance regression could then be
 321   considered for a stable branch. The optimization must also be
 322   non-controversial and the patches still need to meet the other criteria of
 323   being simple and self-contained</li>
 324
 325   <li>Patch introduces a new failure mode (such as an assert). While the new
 326   assert might technically be correct, for example to make Mesa more
 327   conformant, this is not the kind of "bug fix" we want in a stable
 328   release. The potential problem here is that an OpenGL program that was
 329   previously working, (even if technically non-compliant with the
 330   specification), could stop working after this patch. So that would be a
 331   regression that is unacceptable for the stable branch.</li>
 332 </ul>
 333
 334 <h2 id="gittips">Git tips</h2>
 335
 336 <ul>
 337 <li>Test for build breakage between patches e.g last 8 commits.
 338 <pre>
 339     git rebase -i --exec="make -j4" HEAD~8
 340 </pre>
 341 <li>Sets the default mailing address for your repo.
 342 <pre>
 343     git config --local sendemail.to mesa-dev@lists.freedesktop.org
 344 </pre>
 345 <li> Add version to subject line of patch series in this case for the last 8
 346 commits before sending.
 347 <pre>
 348     git send-email --subject-prefix="PATCH v4" HEAD~8
 349     git send-email -v4 @~8 # shorter version, inherited from git format-patch
 350 </pre>
 351 <li> Configure git to use the get_reviewer.pl script interactively. Thus you
 352 can avoid adding the world to the CC list.
 353 <pre>
 354     git config sendemail.cccmd "./scripts/get_reviewer.pl -i"
 355 </pre>
 356 </ul>
 357
 358
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