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5 <title>Submitting patches</title>
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7</head>
8<body>
9
10<div class="header">
11 <h1>The Mesa 3D Graphics Library</h1>
12</div>
13
14<iframe src="contents.html"></iframe>
15<div class="content">
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>
Timothy Arcerie260bfe2016-11-21 16:30:12 +0000[diff] [blame^]28<li><a href="#gittips">Git tips</a>
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]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,
35perhaps, 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
39components.
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>
45for <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
53displayed in 80-column terminals avoid line wrapping. Note that git
54log uses 4 spaces of indentation (4 + 75 &lt; 80).
55<li>The first line should be a short, concise summary of the change prefixed
56with 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,
65if 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
76patch 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
81process, 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,
102that 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>
114It should go without saying that patches must be tested. In general,
115do whatever testing is prudent.
116</p>
117
118<p>
119You should always run the Mesa test suite before submitting patches.
120The test suite can be run using the 'make check' command. All tests
121must pass before patches will be accepted, this may mean you have
122to update the tests themselves.
123</p>
124
125<p>
126Whenever 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>
129to check for regressions.
130</p>
131
132
133<h2 id="mailing">Mailing Patches</h2>
134
135<p>
136Patches should be sent to the mesa-dev mailing list for review:
137<a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
Emil Velikovb571c072016-11-16 11:54:54 +0000[diff] [blame]138mesa-dev@lists.freedesktop.org</a>.
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]139When submitting a patch make sure to use
140<a href="https://git-scm.com/docs/git-send-email">git send-email</a>
141rather than attaching patches to emails. Sending patches as
142attachments prevents people from being able to provide in-line review
143comments.
144</p>
145
146<p>
147When submitting follow-up patches you can use --in-reply-to to make v2, v3,
148etc patches show up as replies to the originals. This usually works well
149when you're sending out updates to individual patches (as opposed to
150re-sending the whole series). Using --in-reply-to makes
151it harder for reviewers to accidentally review old patches.
152</p>
153
154<p>
155When submitting follow-up patches you should also login to
156<a href="https://patchwork.freedesktop.org">patchwork</a> and change the
157state of your old patches to Superseded.
158</p>
159
160<h2 id="reviewing">Reviewing Patches</h2>
161
162<p>
163When you've reviewed a patch on the mailing list, please be unambiguous
164about your review. That is, state either
Emil Velikovb571c072016-11-16 11:54:54 +0000[diff] [blame]165</p>
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]166<pre>
167 Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
168</pre>
169or
170<pre>
171 Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
172</pre>
Emil Velikovb571c072016-11-16 11:54:54 +0000[diff] [blame]173<p>
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]174Rather than saying just "LGTM" or "Seems OK".
175</p>
176
177<p>
178If small changes are suggested, it's OK to say something like:
Emil Velikovb571c072016-11-16 11:54:54 +0000[diff] [blame]179</p>
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]180<pre>
181 With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
182</pre>
Emil Velikovb571c072016-11-16 11:54:54 +0000[diff] [blame]183<p>
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]184which tells the patch author that the patch can be committed, as long
185as the issues are resolved first.
186</p>
187
188
189<h2 id="nominations">Nominating a commit for a stable branch</h2>
190
191<p>
Emil Velikov07384462016-11-16 11:51:50 +0000[diff] [blame]192There are three ways to nominate patch for inclusion of the stable branch and
193release.
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>
202Note: resending patch identical to one on mesa-dev@ or one that differs only
203by 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>
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]210If you want a commit to be applied to a stable branch,
211you should add an appropriate note to the commit message.
212</p>
213
214<p>
215Here 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
223Simply adding the CC to the mesa-stable list address is adequate to nominate
224the commit for the most-recently-created stable branch. It is only necessary
225to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the
226examples above), if you want to nominate the commit for an older stable
227branch. And, as in these examples, you can nominate the commit for the older
228branch in addition to the more recent branch, or nominate the commit
229exclusively for the older branch.
230
231This "CC" syntax for patch nomination will cause patches to automatically be
232copied to the mesa-stable@ mailing list when you use "git send-email" to send
Emil Velikov07384462016-11-16 11:51:50 +0000[diff] [blame]233patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
234won't have any effect negative effect on the patch nomination.
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]235
236<h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
237
238Mesa has a designated release manager for each stable branch, and the release
239manager is the only developer that should be pushing changes to these
240branches. Everyone else should simply nominate patches using the mechanism
241described above.
242
243The stable-release manager will work with the list of nominated patches, and
244for 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
246important so that the picked patch references the comit ID of the original
247patch.
248
249The stable-release manager may at times need to force-push changes to the
250stable branches, for example, to drop a previously-picked patch that was later
251identified as causing a regression). These force-pushes may cause changes to
252be lost from the stable branch if developers push things directly. Consider
253yourself warned.
254
255The stable-release manager is also given broad discretion in rejecting patches
256that have been nominated for the stable branch. The most basic rule is that
257the stable branch is for bug fixes only, (no new features, no
258regressions). Here is a non-exhaustive list of some reasons that a patch may
259be 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
Timothy Arcerie260bfe2016-11-21 16:30:12 +0000[diff] [blame^]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
333commits 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
Emil Velikov259e65c2016-11-16 00:20:56 +0000[diff] [blame]340
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