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11 <h1>The Mesa
3D Graphics Library
</h1>
14 <iframe src=
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17 <h1>Development Notes
</h1>
21 <li><a href=
"#style">Coding Style
</a>
22 <li><a href=
"#submitting">Submitting Patches
</a>
23 <li><a href=
"#release">Making a New Mesa Release
</a>
24 <li><a href=
"#extensions">Adding Extensions
</a>
28 <h2 id=
"style">Coding Style
</h2>
31 Mesa is over
20 years old and the coding style has evolved over time.
32 Some old parts use a style that's a bit out of date.
33 If the guidelines below don't cover something, try following the format of
34 existing, neighboring code.
38 Basic formatting guidelines
42 <li>3-space indentation, no tabs.
43 <li>Limit lines to
78 or fewer characters. The idea is to prevent line
44 wrapping in
80-column editors and terminals. There are exceptions, such
45 as if you're defining a large, static table of information.
46 <li>Opening braces go on the same line as the if/for/while statement.
56 <li>Put a space before/after operators. For example,
<tt>a = b + c;
</tt>
57 and not
<tt>a=b+c;
</tt>
59 <li>This GNU indent command generally does the right thing for formatting:
61 indent -br -i3 -npcs --no-tabs infile.c -o outfile.c
64 <li>Use comments wherever you think it would be helpful for other developers.
65 Several specific cases and style examples follow. Note that we roughly
66 follow
<a href=
"http://www.stack.nl/~dimitri/doxygen/">Doxygen
</a> conventions.
71 /* null-out pointer to prevent dangling reference below */
76 bufferObj = NULL; /* prevent dangling reference below */
80 /* If this is a new buffer object id, or one which was generated but
81 * never used before, allocate a buffer object now.
84 We try to quote the OpenGL specification where prudent:
86 /* Page
38 of the PDF of the OpenGL ES
3.0 spec says:
88 *
"An INVALID_OPERATION error is generated for any of the following
91 * * <length> is zero."
93 * Additionally, page
94 of the PDF of the OpenGL
4.5 core spec
94 * (
30.10.2014) also says this, so it's no longer allowed for desktop GL,
98 Function comment example:
101 * Create and initialize a new buffer object. Called via the
102 * ctx-
>Driver.CreateObject() driver callback function.
103 * \param name integer name of the object
104 * \param type one of GL_FOO, GL_BAR, etc.
105 * \return pointer to new object or NULL if error
108 _mesa_create_object(GLuint name, GLenum type)
114 <li>Put the function return type and qualifiers on one line and the function
115 name and parameters on the next, as seen above. This makes it easy to use
116 <code>grep ^function_name dir/*
</code> to find function definitions. Also,
117 the opening brace goes on the next line by itself (see above.)
119 <li>Function names follow various conventions depending on the type of function:
121 glFooBar() - a public GL entry point (in glapi_dispatch.c)
122 _mesa_FooBar() - the internal immediate mode function
123 save_FooBar() - retained mode (display list) function in dlist.c
124 foo_bar() - a static (private) function
125 _mesa_foo_bar() - an internal non-static Mesa function
128 <li>Constants, macros and enumerant names are ALL_UPPERCASE, with _ between
130 <li>Mesa usually uses camel case for local variables (Ex:
"localVarname")
131 while gallium typically uses underscores (Ex:
"local_var_name").
132 <li>Global variables are almost never used because Mesa should be thread-safe.
134 <li>Booleans. Places that are not directly visible to the GL API
135 should prefer the use of
<tt>bool
</tt>,
<tt>true
</tt>, and
136 <tt>false
</tt> over
<tt>GLboolean
</tt>,
<tt>GL_TRUE
</tt>, and
137 <tt>GL_FALSE
</tt>. In C code, this may mean that
138 <tt>#include
<stdbool.h
></tt> needs to be added. The
139 <tt>try_emit_
</tt>* methods in src/mesa/program/ir_to_mesa.cpp and
140 src/mesa/state_tracker/st_glsl_to_tgsi.cpp can serve as examples.
145 <h2 id=
"submitting">Submitting patches
</h2>
148 The basic guidelines for submitting patches are:
152 <li>Patches should be sufficiently tested before submitting.
153 <li>Code patches should follow Mesa coding conventions.
154 <li>Whenever possible, patches should only effect individual Mesa/Gallium
156 <li>Patches should never introduce build breaks and should be bisectable (see
157 <code>git bisect
</code>.)
158 <li>Patches should be properly formatted (see below).
159 <li>Patches should be submitted to mesa-dev for review using
160 <code>git send-email
</code>.
161 <li>Patches should not mix code changes with code formatting changes (except,
162 perhaps, in very trivial cases.)
165 <h3>Patch formatting
</h3>
168 The basic rules for patch formatting are:
172 <li>Lines should be limited to
75 characters or less so that git logs
173 displayed in
80-column terminals avoid line wrapping. Note that git
174 log uses
4 spaces of indentation (
4 +
75 < 80).
175 <li>The first line should be a short, concise summary of the change prefixed
176 with a module name. Examples:
178 mesa: Add support for querying GL_VERTEX_ATTRIB_ARRAY_LONG
180 gallium: add PIPE_CAP_DEVICE_RESET_STATUS_QUERY
182 i965: Fix missing type in local variable declaration.
184 <li>Subsequent patch comments should describe the change in more detail,
185 if needed. For example:
187 i965: Remove end-of-thread SEND alignment code.
189 This was present in Eric's initial implementation of the compaction code
190 for Sandybridge (commit
077d01b6). There is no documentation saying this
191 is necessary, and removing it causes no regressions in piglit on any
194 <li>A
"Signed-off-by:" line is not required, but not discouraged either.
195 <li>If a patch address a bugzilla issue, that should be noted in the
196 patch comment. For example:
198 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=
89689
200 <li>If there have been several revisions to a patch during the review
201 process, they should be noted such as in this example:
203 st/mesa: add ARB_texture_stencil8 support (v4)
205 if we support stencil texturing, enable texture_stencil8
206 there is no requirement to support native S8 for this,
207 the texture can be converted to x24s8 fine.
209 v2: fold fixes from Marek in:
210 a) put S8 last in the list
211 b) fix renderable to always test for d/s renderable
212 fixup the texture case to use a stencil only format
213 for picking the format for the texture view.
214 v3: hit fallback for getteximage
215 v4: put s8 back in front, it shouldn't get picked now (Ilia)
217 <li>If someone tested your patch, document it with a line like this:
219 Tested-by: Joe Hacker
<jhacker@foo.com
>
221 <li>If the patch was reviewed (usually the case) or acked by someone,
222 that should be documented with:
224 Reviewed-by: Joe Hacker
<jhacker@foo.com
>
225 Acked-by: Joe Hacker
<jhacker@foo.com
>
231 <h3>Testing Patches
</h3>
234 It should go without saying that patches must be tested. In general,
235 do whatever testing is prudent.
239 You should always run the Mesa test suite before submitting patches.
240 The test suite can be run using the 'make check' command. All tests
241 must pass before patches will be accepted, this may mean you have
242 to update the tests themselves.
246 Whenever possible and applicable, test the patch with
247 <a href=
"http://piglit.freedesktop.org">Piglit
</a> to
248 check for regressions.
252 <h3>Mailing Patches
</h3>
255 Patches should be sent to the Mesa mailing list for review.
256 When submitting a patch make sure to use git send-email rather than attaching
257 patches to emails. Sending patches as attachments prevents people from being
258 able to provide in-line review comments.
262 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
263 etc patches show up as replies to the originals. This usually works well
264 when you're sending out updates to individual patches (as opposed to
265 re-sending the whole series). Using --in-reply-to makes
266 it harder for reviewers to accidentally review old patches.
270 When submitting follow-up patches you should also login to
271 <a href=
"https://patchwork.freedesktop.org">patchwork
</a> and change the
272 state of your old patches to Superseded.
275 <h3>Reviewing Patches
</h3>
278 When you've reviewed a patch on the mailing list, please be unambiguous
279 about your review. That is, state either
281 Reviewed-by: Joe Hacker
<jhacker@foo.com
>
285 Acked-by: Joe Hacker
<jhacker@foo.com
>
287 Rather than saying just
"LGTM" or
"Seems OK".
291 If small changes are suggested, it's OK to say something like:
293 With the above fixes, Reviewed-by: Joe Hacker
<jhacker@foo.com
>
295 which tells the patch author that the patch can be committed, as long
296 as the issues are resolved first.
300 <h3>Marking a commit as a candidate for a stable branch
</h3>
303 If you want a commit to be applied to a stable branch,
304 you should add an appropriate note to the commit message.
308 Here are some examples of such a note:
311 <li>CC:
<mesa-stable@lists.freedesktop.org
></li>
312 <li>CC:
"9.2 10.0" <mesa-stable@lists.freedesktop.org
></li>
313 <li>CC:
"10.0" <mesa-stable@lists.freedesktop.org
></li>
316 Simply adding the CC to the mesa-stable list address is adequate to nominate
317 the commit for the most-recently-created stable branch. It is only necessary
318 to specify a specific branch name, (such as
"9.2 10.0" or
"10.0" in the
319 examples above), if you want to nominate the commit for an older stable
320 branch. And, as in these examples, you can nominate the commit for the older
321 branch in addition to the more recent branch, or nominate the commit
322 exclusively for the older branch.
324 This
"CC" syntax for patch nomination will cause patches to automatically be
325 copied to the mesa-stable@ mailing list when you use
"git send-email" to send
326 patches to the mesa-dev@ mailing list. Also, if you realize that a commit
327 should be nominated for the stable branch after it has already been committed,
328 you can send a note directly to the mesa-stable@lists.freedesktop.org where
329 the Mesa stable-branch maintainers will receive it. Be sure to mention the
330 commit ID of the commit of interest (as it appears in the mesa master branch).
332 The latest set of patches that have been nominated, accepted, or rejected for
333 the upcoming stable release can always be seen on the
334 <a href=
"http://cworth.org/~cworth/mesa-stable-queue/">Mesa Stable Queue
</a>
337 <h3>Criteria for accepting patches to the stable branch
</h3>
339 Mesa has a designated release manager for each stable branch, and the release
340 manager is the only developer that should be pushing changes to these
341 branches. Everyone else should simply nominate patches using the mechanism
344 The stable-release manager will work with the list of nominated patches, and
345 for each patch that meets the crtieria below will cherry-pick the patch with:
346 <code>git cherry-pick -x
<commit
></code>. The
<code>-x
</code> option is
347 important so that the picked patch references the comit ID of the original
350 The stable-release manager may at times need to force-push changes to the
351 stable branches, for example, to drop a previously-picked patch that was later
352 identified as causing a regression). These force-pushes may cause changes to
353 be lost from the stable branch if developers push things directly. Consider
356 The stable-release manager is also given broad discretion in rejecting patches
357 that have been nominated for the stable branch. The most basic rule is that
358 the stable branch is for bug fixes only, (no new features, no
359 regressions). Here is a non-exhaustive list of some reasons that a patch may
363 <li>Patch introduces a regression. Any reported build breakage or other
364 regression caused by a particular patch, (game no longer work, piglit test
365 changes from PASS to FAIL), is justification for rejecting a patch.
</li>
367 <li>Patch is too large, (say, larger than
100 lines)
</li>
369 <li>Patch is not a fix. For example, a commit that moves code around with no
370 functional change should be rejected.
</li>
372 <li>Patch fix is not clearly described. For example, a commit message
373 of only a single line, no description of the bug, no mention of bugzilla,
376 <li>Patch has not obviously been reviewed, For example, the commit message
377 has no Reviewed-by, Signed-off-by, nor Tested-by tags from anyone but the
380 <li>Patch has not already been merged to the master branch. As a rule, bug
381 fixes should never be applied first to a stable branch. Patches should land
382 first on the master branch and then be cherry-picked to a stable
383 branch. (This is to avoid future releases causing regressions if the patch
384 is not also applied to master.) The only things that might look like
385 exceptions would be backports of patches from master that happen to look
386 significantly different.
</li>
388 <li>Patch depends on too many other patches. Ideally, all stable-branch
389 patches should be self-contained. It sometimes occurs that a single, logical
390 bug-fix occurs as two separate patches on master, (such as an original
391 patch, then a subsequent fix-up to that patch). In such a case, these two
392 patches should be squashed into a single, self-contained patch for the
393 stable branch. (Of course, if the squashing makes the patch too large, then
394 that could be a reason to reject the patch.)
</li>
396 <li>Patch includes new feature development, not bug fixes. New OpenGL
397 features, extensions, etc. should be applied to Mesa master and included in
398 the next major release. Stable releases are intended only for bug fixes.
400 Note: As an exception to this rule, the stable-release manager may accept
401 hardware-enabling
"features". For example, backports of new code to support
402 a newly-developed hardware product can be accepted if they can be reasonably
403 determined to not have effects on other hardware.
</li>
405 <li>Patch is a performance optimization. As a rule, performance patches are
406 not candidates for the stable branch. The only exception might be a case
407 where an application's performance was recently severely impacted so as to
408 become unusable. The fix for this performance regression could then be
409 considered for a stable branch. The optimization must also be
410 non-controversial and the patches still need to meet the other criteria of
411 being simple and self-contained
</li>
413 <li>Patch introduces a new failure mode (such as an assert). While the new
414 assert might technically be correct, for example to make Mesa more
415 conformant, this is not the kind of
"bug fix" we want in a stable
416 release. The potential problem here is that an OpenGL program that was
417 previously working, (even if technically non-compliant with the
418 specification), could stop working after this patch. So that would be a
419 regression that is unaacceptable for the stable branch.
</li>
423 <h2 id=
"release">Making a New Mesa Release
</h2>
426 These are the instructions for making a new Mesa release.
429 <h3>Get latest source files
</h3>
431 Use git to get the latest Mesa files from the git repository, from whatever
432 branch is relevant. This document uses the convention X.Y.Z for the release
433 being created, which should be created from a branch named X.Y.
436 <h3>Perform basic testing
</h3>
438 The release manager should, at the very least, test the code by compiling it,
439 installing it, and running the latest piglit to ensure that no piglit tests
440 have regressed since the previous release.
444 The release manager should do this testing with at least one hardware driver,
445 (say, whatever is contained in the local development machine), as well as on
446 both Gallium and non-Gallium software drivers. The software testing can be
447 performed by running piglit with the following environment-variable set:
451 LIBGL_ALWAYS_SOFTWARE=
1
454 And Gallium vs. non-Gallium software drivers can be obtained by using the
455 following configure flags on separate builds:
458 --with-dri-drivers=swrast
459 --with-gallium-drivers=swrast
463 Note: If both options are given in one build, both swrast_dri.so drivers will
464 be compiled, but only one will be installed. The following command can be used
465 to ensure the correct driver is being tested:
469 LIBGL_ALWAYS_SOFTWARE=
1 glxinfo | grep
"renderer string"
472 If any regressions are found in this testing with piglit, stop here, and do
473 not perform a release until regressions are fixed.
475 <h3>Update version in file VERSION
</h3>
478 Increment the version contained in the file VERSION at Mesa's top-level, then
482 <h3>Create release notes for the new release
</h3>
485 Create a new file docs/relnotes/X.Y.Z.html, (follow the style of the previous
486 release notes). Note that the sha256sums section of the release notes should
487 be empty at this point.
491 Two scripts are available to help generate portions of the release notes:
494 ./bin/bugzilla_mesa.sh
495 ./bin/shortlog_mesa.sh
499 The first script identifies commits that reference bugzilla bugs and obtains
500 the descriptions of those bugs from bugzilla. The second script generates a
501 log of all commits. In both cases, HTML-formatted lists are printed to stdout
502 to be included in the release notes.
509 <h3>Make the release archives, signatures, and the release tag
</h3>
511 From inside the Mesa directory:
518 After the tarballs are created, the sha256 checksums for the files will
519 be computed and printed. These will be used in a step below.
523 It's important at this point to also verify that the constructed tar file
528 tar xjf MesaLib-X.Y.Z.tar.bz2
530 ./configure --enable-gallium-llvm
536 Some touch testing should also be performed at this point, (run glxgears or
537 more involved OpenGL programs against the installed Mesa).
541 Create detached GPG signatures for each of the archive files created above:
545 gpg --sign --detach MesaLib-X.Y.Z.tar.gz
546 gpg --sign --detach MesaLib-X.Y.Z.tar.bz2
547 gpg --sign --detach MesaLib-X.Y.Z.zip
551 Tag the commit used for the build:
555 git tag -s mesa-X.Y.X -m
"Mesa X.Y.Z release"
559 Note: It would be nice to investigate and fix the issue that causes the
560 tarballs target to fail with multiple build process, such as with
"-j4". It
561 would also be nice to incorporate all of the above commands into a single
562 makefile target. And instead of a custom
"tarballs" target, we should
563 incorporate things into the standard
"make dist" and
"make distcheck" targets.
566 <h3>Add the sha256sums to the release notes
</h3>
569 Edit docs/relnotes/X.Y.Z.html to add the sha256sums printed as part of
"make
570 tarballs" in the previous step. Commit this change.
573 <h3>Push all commits and the tag created above
</h3>
576 This is the first step that cannot easily be undone. The release is going
577 forward from this point:
581 git push origin X.Y --tags
584 <h3>Install the release files and signatures on the distribution server
</h3>
587 The following commands can be used to copy the release archive files and
588 signatures to the freedesktop.org server:
592 scp MesaLib-X.Y.Z* people.freedesktop.org:
593 ssh people.freedesktop.org
594 cd /srv/ftp.freedesktop.org/pub/mesa
597 mv ~/MesaLib-X.Y.Z* .
600 <h3>Back on mesa master, add the new release notes into the tree
</h3>
603 Something like the following steps will do the trick:
607 cp docs/relnotes/X.Y.Z.html /tmp
609 cp /tmp/X.Y.Z.html docs/relnotes
610 git add docs/relnotes/X.Y.Z.html
614 Also, edit docs/relnotes.html to add a link to the new release notes, and edit
615 docs/index.html to add a news entry. Then commit and push:
619 git commit -a -m
"docs: Import X.Y.Z release notes, add news item."
623 <h3>Update the mesa3d.org website
</h3>
626 NOTE: The recent release managers have not been performing this step
627 themselves, but leaving this to Brian Paul, (who has access to the
628 sourceforge.net hosting for mesa3d.org). Brian is more than willing to grant
629 the permission necessary to future release managers to do this step on their
634 Update the web site by copying the docs/ directory's files to
635 /home/users/b/br/brianp/mesa-www/htdocs/ with:
638 sftp USERNAME,mesa3d@web.sourceforge.net
643 <h3>Announce the release
</h3>
645 Make an announcement on the mailing lists:
647 <em>mesa-dev@lists.freedesktop.org
</em>,
649 <em>mesa-announce@lists.freedesktop.org
</em>
651 Follow the template of previously-sent release announcements. The following
652 command can be used to generate the log of changes to be included in the
653 release announcement:
656 git shortlog mesa-X.Y.Z-
1..mesa-X.Y.Z
661 <h2 id=
"extensions">Adding Extensions
</h2>
664 To add a new GL extension to Mesa you have to do at least the following.
668 If glext.h doesn't define the extension, edit include/GL/gl.h and add
671 #ifndef GL_EXT_the_extension_name
672 #define GL_EXT_the_extension_name
1
673 /* declare the new enum tokens */
674 /* prototype the new functions */
675 /* TYPEDEFS for the new functions */
680 In the src/mapi/glapi/gen/ directory, add the new extension functions and
681 enums to the gl_API.xml file.
682 Then, a bunch of source files must be regenerated by executing the
683 corresponding Python scripts.
686 Add a new entry to the
<code>gl_extensions
</code> struct in mtypes.h
689 Add a new entry to the src/mesa/main/extensions_table.h file.
692 From this point, the best way to proceed is to find another extension,
693 similar to the new one, that's already implemented in Mesa and use it
697 If the new extension adds new GL state, the functions in get.c, enable.c
698 and attrib.c will most likely require new code.
701 The dispatch tests check_table.cpp and dispatch_sanity.cpp
702 should be updated with details about the new extensions functions. These
703 tests are run using 'make check'