docs/submittingpatches.html

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  11   <h1>The Mesa 3D Graphics Library</h1>
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  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">submitted to 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 </ul>
 108
 109
 110
 111 <h2 id="testing">Testing Patches</h2>
 112
 113 <p>
 114 It should go without saying that patches must be tested.  In general,
 115 do whatever testing is prudent.
 116 </p>
 117
 118 <p>
 119 You should always run the Mesa test suite before submitting patches.
 120 The test suite can be run using the 'make check' command. All tests
 121 must pass before patches will be accepted, this may mean you have
 122 to update the tests themselves.
 123 </p>
 124
 125 <p>
 126 Whenever possible and applicable, test the patch with
 127 <a href="http://piglit.freedesktop.org">Piglit</a> and/or
 128 <a href="https://android.googlesource.com/platform/external/deqp/">dEQP</a>
 129 to check for regressions.
 130 </p>
 131
 132
 133 <h2 id="mailing">Mailing Patches</h2>
 134
 135 <p>
 136 Patches should be sent to the mesa-dev mailing list for review:
 137 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
 138 mesa-dev@lists.freedesktop.org</a>.
 139 When submitting a patch make sure to use
 140 <a href="https://git-scm.com/docs/git-send-email">git send-email</a>
 141 rather than attaching patches to emails. Sending patches as
 142 attachments prevents people from being able to provide in-line review
 143 comments.
 144 </p>
 145
 146 <p>
 147 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
 148 etc patches show up as replies to the originals. This usually works well
 149 when you're sending out updates to individual patches (as opposed to
 150 re-sending the whole series). Using --in-reply-to makes
 151 it harder for reviewers to accidentally review old patches.
 152 </p>
 153
 154 <p>
 155 When submitting follow-up patches you should also login to
 156 <a href="https://patchwork.freedesktop.org">patchwork</a> and change the
 157 state of your old patches to Superseded.
 158 </p>
 159
 160 <h2 id="reviewing">Reviewing Patches</h2>
 161
 162 <p>
 163 When you've reviewed a patch on the mailing list, please be unambiguous
 164 about your review.  That is, state either
 165 </p>
 166 <pre>
 167     Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 168 </pre>
 169 or
 170 <pre>
 171     Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
 172 </pre>
 173 <p>
 174 Rather than saying just "LGTM" or "Seems OK".
 175 </p>
 176
 177 <p>
 178 If small changes are suggested, it's OK to say something like:
 179 </p>
 180 <pre>
 181    With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
 182 </pre>
 183 <p>
 184 which tells the patch author that the patch can be committed, as long
 185 as the issues are resolved first.
 186 </p>
 187
 188
 189 <h2 id="nominations">Nominating a commit for a stable branch</h2>
 190
 191 <p>
 192 There are three ways to nominate patch for inclusion of the stable branch and
 193 release.
 194 </p>
 195 <ul>
 196 <li> By adding the Cc: mesa-stable@ tag as described below.
 197 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
 198 <li> Forwarding the patch from the mesa-dev@ mailing list.
 199 </li>
 200 </ul>
 201 <p>
 202 Note: resending patch identical to one on mesa-dev@ or one that differs only
 203 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
 204 </p>
 205
 206
 207 <h3 id="thetag">The stable tag</h3>
 208
 209 <p>
 210 If you want a commit to be applied to a stable branch,
 211 you should add an appropriate note to the commit message.
 212 </p>
 213
 214 <p>
 215 Here are some examples of such a note:
 216 </p>
 217 <ul>
 218   <li>CC: &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 219   <li>CC: "9.2 10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 220   <li>CC: "10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 221 </ul>
 222
 223 Simply adding the CC to the mesa-stable list address is adequate to nominate
 224 the commit for the most-recently-created stable branch. It is only necessary
 225 to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the
 226 examples above), if you want to nominate the commit for an older stable
 227 branch. And, as in these examples, you can nominate the commit for the older
 228 branch in addition to the more recent branch, or nominate the commit
 229 exclusively for the older branch.
 230
 231 This "CC" syntax for patch nomination will cause patches to automatically be
 232 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 233 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
 234 won't have any effect negative effect on the patch nomination.
 235
 236 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
 237
 238 Mesa has a designated release manager for each stable branch, and the release
 239 manager is the only developer that should be pushing changes to these
 240 branches. Everyone else should simply nominate patches using the mechanism
 241 described above.
 242
 243 The stable-release manager will work with the list of nominated patches, and
 244 for each patch that meets the crtieria below will cherry-pick the patch with:
 245 <code>git cherry-pick -x &lt;commit&gt;</code>. The <code>-x</code> option is
 246 important so that the picked patch references the comit ID of the original
 247 patch.
 248
 249 The stable-release manager may at times need to force-push changes to the
 250 stable branches, for example, to drop a previously-picked patch that was later
 251 identified as causing a regression). These force-pushes may cause changes to
 252 be lost from the stable branch if developers push things directly. Consider
 253 yourself warned.
 254
 255 The stable-release manager is also given broad discretion in rejecting patches
 256 that have been nominated for the stable branch. The most basic rule is that
 257 the stable branch is for bug fixes only, (no new features, no
 258 regressions). Here is a non-exhaustive list of some reasons that a patch may
 259 be rejected:
 260
 261 <ul>
 262   <li>Patch introduces a regression. Any reported build breakage or other
 263   regression caused by a particular patch, (game no longer work, piglit test
 264   changes from PASS to FAIL), is justification for rejecting a patch.</li>
 265
 266   <li>Patch is too large, (say, larger than 100 lines)</li>
 267
 268   <li>Patch is not a fix. For example, a commit that moves code around with no
 269   functional change should be rejected.</li>
 270
 271   <li>Patch fix is not clearly described. For example, a commit message
 272   of only a single line, no description of the bug, no mention of bugzilla,
 273   etc.</li>
 274
 275   <li>Patch has not obviously been reviewed, For example, the commit message
 276   has no Reviewed-by, Signed-off-by, nor Tested-by tags from anyone but the
 277   author.</li>
 278
 279   <li>Patch has not already been merged to the master branch. As a rule, bug
 280   fixes should never be applied first to a stable branch. Patches should land
 281   first on the master branch and then be cherry-picked to a stable
 282   branch. (This is to avoid future releases causing regressions if the patch
 283   is not also applied to master.) The only things that might look like
 284   exceptions would be backports of patches from master that happen to look
 285   significantly different.</li>
 286
 287   <li>Patch depends on too many other patches. Ideally, all stable-branch
 288   patches should be self-contained. It sometimes occurs that a single, logical
 289   bug-fix occurs as two separate patches on master, (such as an original
 290   patch, then a subsequent fix-up to that patch). In such a case, these two
 291   patches should be squashed into a single, self-contained patch for the
 292   stable branch. (Of course, if the squashing makes the patch too large, then
 293   that could be a reason to reject the patch.)</li>
 294
 295   <li>Patch includes new feature development, not bug fixes. New OpenGL
 296   features, extensions, etc. should be applied to Mesa master and included in
 297   the next major release. Stable releases are intended only for bug fixes.
 298
 299   Note: As an exception to this rule, the stable-release manager may accept
 300   hardware-enabling "features". For example, backports of new code to support
 301   a newly-developed hardware product can be accepted if they can be reasonably
 302   determined to not have effects on other hardware.</li>
 303
 304   <li>Patch is a performance optimization. As a rule, performance patches are
 305   not candidates for the stable branch. The only exception might be a case
 306   where an application's performance was recently severely impacted so as to
 307   become unusable. The fix for this performance regression could then be
 308   considered for a stable branch. The optimization must also be
 309   non-controversial and the patches still need to meet the other criteria of
 310   being simple and self-contained</li>
 311
 312   <li>Patch introduces a new failure mode (such as an assert). While the new
 313   assert might technically be correct, for example to make Mesa more
 314   conformant, this is not the kind of "bug fix" we want in a stable
 315   release. The potential problem here is that an OpenGL program that was
 316   previously working, (even if technically non-compliant with the
 317   specification), could stop working after this patch. So that would be a
 318   regression that is unaacceptable for the stable branch.</li>
 319 </ul>
 320
 321 <h2 id="gittips">Git tips</h2>
 322
 323 <ul>
 324 <li>Test for build breakage between patches e.g last 8 commits.
 325 <pre>
 326     git rebase -i --exec="make -j4" HEAD~8
 327 </pre>
 328 <li>Sets the default mailing address for your repo.
 329 <pre>
 330     git config --local sendemail.to mesa-dev@lists.freedesktop.org
 331 </pre>
 332 <li> Add version to subject line of patch series in this case for the last 8
 333 commits before sending.
 334 <pre>
 335     git send-email --subject-prefix="PATCH v4" HEAD~8
 336     git send-email -v4 @~8 # shorter version, inherited from git format-patch
 337 </pre>
 338 </ul>
 339
 340
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