docs/submittingpatches: flesh out "how to nominate" methods
[mesa.git] / docs / submittingpatches.html
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2 <html lang="en">
3 <head>
4 <meta http-equiv="content-type" content="text/html; charset=utf-8">
5 <title>Submitting patches</title>
6 <link rel="stylesheet" type="text/css" href="mesa.css">
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>
28 </ul>
29
30 <h2 id="guidelines">Basic guidelines</h2>
31
32 <ul>
33 <li>Patches should not mix code changes with code formatting changes (except,
34 perhaps, in very trivial cases.)
35 <li>Code patches should follow Mesa
36 <a href="codingstyle.html" target="_parent">coding conventions</a>.
37 <li>Whenever possible, patches should only effect individual Mesa/Gallium
38 components.
39 <li>Patches should never introduce build breaks and should be bisectable (see
40 <code>git bisect</code>.)
41 <li>Patches should be properly <a href="#formatting">formatted</a>.
42 <li>Patches should be sufficiently <a href="#testing">tested</a> before submitting.
43 <li>Patches should be submitted to <a href="#mailing">submitted to mesa-dev</a>
44 for <a href="#reviewing">review</a> using <code>git send-email</code>.
45
46 </ul>
47
48 <h2 id="formatting">Patch formatting</h2>
49
50 <ul>
51 <li>Lines should be limited to 75 characters or less so that git logs
52 displayed in 80-column terminals avoid line wrapping. Note that git
53 log uses 4 spaces of indentation (4 + 75 &lt; 80).
54 <li>The first line should be a short, concise summary of the change prefixed
55 with a module name. Examples:
56 <pre>
57 mesa: Add support for querying GL_VERTEX_ATTRIB_ARRAY_LONG
58
59 gallium: add PIPE_CAP_DEVICE_RESET_STATUS_QUERY
60
61 i965: Fix missing type in local variable declaration.
62 </pre>
63 <li>Subsequent patch comments should describe the change in more detail,
64 if needed. For example:
65 <pre>
66 i965: Remove end-of-thread SEND alignment code.
67
68 This was present in Eric's initial implementation of the compaction code
69 for Sandybridge (commit 077d01b6). There is no documentation saying this
70 is necessary, and removing it causes no regressions in piglit on any
71 platform.
72 </pre>
73 <li>A "Signed-off-by:" line is not required, but not discouraged either.
74 <li>If a patch address a bugzilla issue, that should be noted in the
75 patch comment. For example:
76 <pre>
77 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89689
78 </pre>
79 <li>If there have been several revisions to a patch during the review
80 process, they should be noted such as in this example:
81 <pre>
82 st/mesa: add ARB_texture_stencil8 support (v4)
83
84 if we support stencil texturing, enable texture_stencil8
85 there is no requirement to support native S8 for this,
86 the texture can be converted to x24s8 fine.
87
88 v2: fold fixes from Marek in:
89 a) put S8 last in the list
90 b) fix renderable to always test for d/s renderable
91 fixup the texture case to use a stencil only format
92 for picking the format for the texture view.
93 v3: hit fallback for getteximage
94 v4: put s8 back in front, it shouldn't get picked now (Ilia)
95 </pre>
96 <li>If someone tested your patch, document it with a line like this:
97 <pre>
98 Tested-by: Joe Hacker &lt;jhacker@foo.com&gt;
99 </pre>
100 <li>If the patch was reviewed (usually the case) or acked by someone,
101 that should be documented with:
102 <pre>
103 Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
104 Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
105 </pre>
106 </ul>
107
108
109
110 <h2 id="testing">Testing Patches</h2>
111
112 <p>
113 It should go without saying that patches must be tested. In general,
114 do whatever testing is prudent.
115 </p>
116
117 <p>
118 You should always run the Mesa test suite before submitting patches.
119 The test suite can be run using the 'make check' command. All tests
120 must pass before patches will be accepted, this may mean you have
121 to update the tests themselves.
122 </p>
123
124 <p>
125 Whenever possible and applicable, test the patch with
126 <a href="http://piglit.freedesktop.org">Piglit</a> and/or
127 <a href="https://android.googlesource.com/platform/external/deqp/">dEQP</a>
128 to check for regressions.
129 </p>
130
131
132 <h2 id="mailing">Mailing Patches</h2>
133
134 <p>
135 Patches should be sent to the mesa-dev mailing list for review:
136 <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev">
137 mesa-dev@lists.freedesktop.org<a/>.
138 When submitting a patch make sure to use
139 <a href="https://git-scm.com/docs/git-send-email">git send-email</a>
140 rather than attaching patches to emails. Sending patches as
141 attachments prevents people from being able to provide in-line review
142 comments.
143 </p>
144
145 <p>
146 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
147 etc patches show up as replies to the originals. This usually works well
148 when you're sending out updates to individual patches (as opposed to
149 re-sending the whole series). Using --in-reply-to makes
150 it harder for reviewers to accidentally review old patches.
151 </p>
152
153 <p>
154 When submitting follow-up patches you should also login to
155 <a href="https://patchwork.freedesktop.org">patchwork</a> and change the
156 state of your old patches to Superseded.
157 </p>
158
159 <h2 id="reviewing">Reviewing Patches</h2>
160
161 <p>
162 When you've reviewed a patch on the mailing list, please be unambiguous
163 about your review. That is, state either
164 <pre>
165 Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
166 </pre>
167 or
168 <pre>
169 Acked-by: Joe Hacker &lt;jhacker@foo.com&gt;
170 </pre>
171 Rather than saying just "LGTM" or "Seems OK".
172 </p>
173
174 <p>
175 If small changes are suggested, it's OK to say something like:
176 <pre>
177 With the above fixes, Reviewed-by: Joe Hacker &lt;jhacker@foo.com&gt;
178 </pre>
179 which tells the patch author that the patch can be committed, as long
180 as the issues are resolved first.
181 </p>
182
183
184 <h2 id="nominations">Nominating a commit for a stable branch</h2>
185
186 <p>
187 There are three ways to nominate patch for inclusion of the stable branch and
188 release.
189 </p>
190 <ul>
191 <li> By adding the Cc: mesa-stable@ tag as described below.
192 <li> Sending the commit ID (as seen in master branch) to the mesa-stable@ mailing list.
193 <li> Forwarding the patch from the mesa-dev@ mailing list.
194 </li>
195 </ul>
196 <p>
197 Note: resending patch identical to one on mesa-dev@ or one that differs only
198 by the extra mesa-stable@ tag is <strong>not</strong> recommended.
199 </p>
200
201
202 <h3 id="thetag">The stable tag</h3>
203
204 <p>
205 If you want a commit to be applied to a stable branch,
206 you should add an appropriate note to the commit message.
207 </p>
208
209 <p>
210 Here are some examples of such a note:
211 </p>
212 <ul>
213 <li>CC: &lt;mesa-stable@lists.freedesktop.org&gt;</li>
214 <li>CC: "9.2 10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
215 <li>CC: "10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
216 </ul>
217
218 Simply adding the CC to the mesa-stable list address is adequate to nominate
219 the commit for the most-recently-created stable branch. It is only necessary
220 to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the
221 examples above), if you want to nominate the commit for an older stable
222 branch. And, as in these examples, you can nominate the commit for the older
223 branch in addition to the more recent branch, or nominate the commit
224 exclusively for the older branch.
225
226 This "CC" syntax for patch nomination will cause patches to automatically be
227 copied to the mesa-stable@ mailing list when you use "git send-email" to send
228 patches to the mesa-dev@ mailing list. If you prefer using --suppress-cc that
229 won't have any effect negative effect on the patch nomination.
230
231 <h2 id="criteria">Criteria for accepting patches to the stable branch</h2>
232
233 Mesa has a designated release manager for each stable branch, and the release
234 manager is the only developer that should be pushing changes to these
235 branches. Everyone else should simply nominate patches using the mechanism
236 described above.
237
238 The stable-release manager will work with the list of nominated patches, and
239 for each patch that meets the crtieria below will cherry-pick the patch with:
240 <code>git cherry-pick -x &lt;commit&gt;</code>. The <code>-x</code> option is
241 important so that the picked patch references the comit ID of the original
242 patch.
243
244 The stable-release manager may at times need to force-push changes to the
245 stable branches, for example, to drop a previously-picked patch that was later
246 identified as causing a regression). These force-pushes may cause changes to
247 be lost from the stable branch if developers push things directly. Consider
248 yourself warned.
249
250 The stable-release manager is also given broad discretion in rejecting patches
251 that have been nominated for the stable branch. The most basic rule is that
252 the stable branch is for bug fixes only, (no new features, no
253 regressions). Here is a non-exhaustive list of some reasons that a patch may
254 be rejected:
255
256 <ul>
257 <li>Patch introduces a regression. Any reported build breakage or other
258 regression caused by a particular patch, (game no longer work, piglit test
259 changes from PASS to FAIL), is justification for rejecting a patch.</li>
260
261 <li>Patch is too large, (say, larger than 100 lines)</li>
262
263 <li>Patch is not a fix. For example, a commit that moves code around with no
264 functional change should be rejected.</li>
265
266 <li>Patch fix is not clearly described. For example, a commit message
267 of only a single line, no description of the bug, no mention of bugzilla,
268 etc.</li>
269
270 <li>Patch has not obviously been reviewed, For example, the commit message
271 has no Reviewed-by, Signed-off-by, nor Tested-by tags from anyone but the
272 author.</li>
273
274 <li>Patch has not already been merged to the master branch. As a rule, bug
275 fixes should never be applied first to a stable branch. Patches should land
276 first on the master branch and then be cherry-picked to a stable
277 branch. (This is to avoid future releases causing regressions if the patch
278 is not also applied to master.) The only things that might look like
279 exceptions would be backports of patches from master that happen to look
280 significantly different.</li>
281
282 <li>Patch depends on too many other patches. Ideally, all stable-branch
283 patches should be self-contained. It sometimes occurs that a single, logical
284 bug-fix occurs as two separate patches on master, (such as an original
285 patch, then a subsequent fix-up to that patch). In such a case, these two
286 patches should be squashed into a single, self-contained patch for the
287 stable branch. (Of course, if the squashing makes the patch too large, then
288 that could be a reason to reject the patch.)</li>
289
290 <li>Patch includes new feature development, not bug fixes. New OpenGL
291 features, extensions, etc. should be applied to Mesa master and included in
292 the next major release. Stable releases are intended only for bug fixes.
293
294 Note: As an exception to this rule, the stable-release manager may accept
295 hardware-enabling "features". For example, backports of new code to support
296 a newly-developed hardware product can be accepted if they can be reasonably
297 determined to not have effects on other hardware.</li>
298
299 <li>Patch is a performance optimization. As a rule, performance patches are
300 not candidates for the stable branch. The only exception might be a case
301 where an application's performance was recently severely impacted so as to
302 become unusable. The fix for this performance regression could then be
303 considered for a stable branch. The optimization must also be
304 non-controversial and the patches still need to meet the other criteria of
305 being simple and self-contained</li>
306
307 <li>Patch introduces a new failure mode (such as an assert). While the new
308 assert might technically be correct, for example to make Mesa more
309 conformant, this is not the kind of "bug fix" we want in a stable
310 release. The potential problem here is that an OpenGL program that was
311 previously working, (even if technically non-compliant with the
312 specification), could stop working after this patch. So that would be a
313 regression that is unaacceptable for the stable branch.</li>
314 </ul>
315
316
317 </div>
318 </body>
319 </html>