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  10 <div class="header">
  11   <h1>The Mesa 3D Graphics Library</h1>
  12 </div>
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  15 <div class="content">
  16
  17 <h1>Development Notes</h1>
  18
  19
  20 <ul>
  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>
  25 </ul>
  26
  27
  28 <h2 id="style">Coding Style</h2>
  29
  30 <p>
  31 Mesa's code style has changed over the years.  Here's the latest.
  32 </p>
  33
  34 <p>
  35 Comment your code!  It's extremely important that open-source code be
  36 well documented.  Also, strive to write clean, easily understandable code.
  37 </p>
  38
  39 <p>
  40 3-space indentation
  41 </p>
  42
  43 <p>
  44 If you use tabs, set them to 8 columns
  45 </p>
  46
  47 <p>
  48 Line width: the preferred width to fill comments and code in Mesa is 78
  49 columns.  Exceptions are sometimes made for clarity (e.g. tabular data is
  50 sometimes filled to a much larger width so that extraneous carriage returns
  51 don't obscure the table).
  52 </p>
  53
  54 <p>
  55 Brace example:
  56 </p>
  57 <pre>
  58         if (condition) {
  59            foo;
  60         }
  61         else {
  62            bar;
  63         }
  64
  65         switch (condition) {
  66         case 0:
  67            foo();
  68            break;
  69
  70         case 1: {
  71            ...
  72            break;
  73         }
  74
  75         default:
  76            ...
  77            break;
  78         }
  79 </pre>
  80
  81 <p>
  82 Here's the GNU indent command which will best approximate my preferred style:
  83 (Note that it won't format switch statements in the preferred way)
  84 </p>
  85 <pre>
  86         indent -br -i3 -npcs --no-tabs infile.c -o outfile.c
  87 </pre>
  88
  89
  90 <p>
  91 Local variable name example:  localVarName (no underscores)
  92 </p>
  93
  94 <p>
  95 Constants and macros are ALL_UPPERCASE, with _ between words
  96 </p>
  97
  98 <p>
  99 Global variables are not allowed.
 100 </p>
 101
 102 <p>
 103 Function name examples:
 104 </p>
 105 <pre>
 106         glFooBar()       - a public GL entry point (in glapi_dispatch.c)
 107         _mesa_FooBar()   - the internal immediate mode function
 108         save_FooBar()    - retained mode (display list) function in dlist.c
 109         foo_bar()        - a static (private) function
 110         _mesa_foo_bar()  - an internal non-static Mesa function
 111 </pre>
 112
 113 <p>
 114 Places that are not directly visible to the GL API should prefer the use
 115 of <tt>bool</tt>, <tt>true</tt>, and
 116 <tt>false</tt> over <tt>GLboolean</tt>, <tt>GL_TRUE</tt>, and
 117 <tt>GL_FALSE</tt>.  In C code, this may mean that
 118 <tt>#include &lt;stdbool.h&gt;</tt> needs to be added.  The
 119 <tt>try_emit_</tt>* methods in src/mesa/program/ir_to_mesa.cpp and
 120 src/mesa/state_tracker/st_glsl_to_tgsi.cpp can serve as examples.
 121 </p>
 122
 123
 124 <h2 id="submitting">Submitting patches</h2>
 125
 126 <p>
 127 You should always run the Mesa Testsuite before submitting patches.
 128 The Testsuite can be run using the 'make check' command. All tests
 129 must pass before patches will be accepted, this may mean you have
 130 to update the tests themselves.
 131 </p>
 132
 133 <p>
 134 Patches should be sent to the Mesa mailing list for review.
 135 When submitting a patch make sure to use git send-email rather than attaching
 136 patches to emails. Sending patches as attachments prevents people from being
 137 able to provide in-line review comments.
 138 </p>
 139
 140 <p>
 141 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
 142 etc patches show up as replies to the originals. This usually works well
 143 when you're sending out updates to individual patches (as opposed to
 144 re-sending the whole series). Using --in-reply-to makes
 145 it harder for reviewers to accidentally review old patches.
 146 </p>
 147
 148 <h3>Marking a commit as a candidate for a stable branch</h3>
 149
 150 <p>
 151 If you want a commit to be applied to a stable branch,
 152 you should add an appropriate note to the commit message.
 153 </p>
 154
 155 <p>
 156 Here are some examples of such a note:
 157 </p>
 158 <ul>
 159   <li>CC: &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 160   <li>CC: "9.2 10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 161   <li>CC: "10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 162 </ul>
 163
 164 Simply adding the CC to the mesa-stable list address is adequate to nominate
 165 the commit for the most-recently-created stable branch. It is only necessary
 166 to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the
 167 examples above), if you want to nominate the commit for an older stable
 168 branch. And, as in these examples, you can nominate the commit for the older
 169 branch in addition to the more recent branch, or nominate the commit
 170 exclusively for the older branch.
 171
 172 This "CC" syntax for patch nomination will cause patches to automatically be
 173 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 174 patches to the mesa-dev@ mailing list. Also, if you realize that a commit
 175 should be nominated for the stable branch after it has already been committed,
 176 you can send a note directly to the mesa-stable@lists.freedesktop.org where
 177 the Mesa stable-branch maintainers will receive it. Be sure to mention the
 178 commit ID of the commit of interest (as it appears in the mesa master branch).
 179
 180 The latest set of patches that have been nominated, accepted, or rejected for
 181 the upcoming stable release can always be seen on the
 182 <a href="http://cworth.org/~cworth/mesa-stable-queue/">Mesa Stable Queue</a>
 183 page.
 184
 185 <h3>Criteria for accepting patches to the stable branch</h3>
 186
 187 Mesa has a designated release manager for each stable branch, and the release
 188 manager is the only developer that should be pushing changes to these
 189 branches. Everyone else should simply nominate patches using the mechanism
 190 described above.
 191
 192 The stable-release manager will work with the list of nominated patches, and
 193 for each patch that meets the crtieria below will cherry-pick the patch with:
 194 <code>git cherry-pick -x &lt;commit&gt;</code>. The <code>-x</code> option is
 195 important so that the picked patch references the comit ID of the original
 196 patch.
 197
 198 The stable-release manager may at times need to force-push changes to the
 199 stable branches, for example, to drop a previously-picked patch that was later
 200 identified as causing a regression). These force-pushes may cause changes to
 201 be lost from the stable branch if developers push things directly. Consider
 202 yourself warned.
 203
 204 The stable-release manager is also given broad discretion in rejecting patches
 205 that have been nominated for the stable branch. The most basic rule is that
 206 the stable branch is for bug fixes only, (no new features, no
 207 regressions). Here is a non-exhaustive list of some reasons that a patch may
 208 be rejected:
 209
 210 <ul>
 211   <li>Patch introduces a regression. Any reported build breakage or other
 212   regression caused by a particular patch, (game no longer work, piglit test
 213   changes from PASS to FAIL), is justification for rejecting a patch.</li>
 214
 215   <li>Patch is too large, (say, larger than 100 lines)</li>
 216
 217   <li>Patch is not a fix. For example, a commit that moves code around with no
 218   functional change should be rejected.</li>
 219
 220   <li>Patch fix is not clearly described. For example, a commit message
 221   of only a single line, no description of the bug, no mention of bugzilla,
 222   etc.</li>
 223
 224   <li>Patch has not obviously been reviewed, For example, the commit message
 225   has no Reviewed-by, Signed-off-by, nor Tested-by tags from anyone but the
 226   author.</li>
 227
 228   <li>Patch has not already been merged to the master branch. As a rule, bug
 229   fixes should never be applied first to a stable branch. Patches should land
 230   first on the master branch and then be cherry-picked to a stable
 231   branch. (This is to avoid future releases causing regressions if the patch
 232   is not also applied to master.) The only things that might look like
 233   exceptions would be backports of patches from master that happen to look
 234   significantly different.</li>
 235
 236   <li>Patch depends on too many other patches. Ideally, all stable-branch
 237   patches should be self-contained. It sometimes occurs that a single, logical
 238   bug-fix occurs as two separate patches on master, (such as an original
 239   patch, then a subsequent fix-up to that patch). In such a case, these two
 240   patches should be squashed into a single, self-contained patch for the
 241   stable branch. (Of course, if the squashing makes the patch too large, then
 242   that could be a reason to reject the patch.)</li>
 243
 244   <li>Patch includes new feature development, not bug fixes. New OpenGL
 245   features, extensions, etc. should be applied to Mesa master and included in
 246   the next major release. Stable releases are intended only for bug fixes.
 247
 248   Note: As an exception to this rule, the stable-release manager may accept
 249   hardware-enabling "features". For example, backports of new code to support
 250   a newly-developed hardware product can be accepted if they can be reasonably
 251   determined to not have effects on other hardware.</li>
 252
 253   <li>Patch is a performance optimization. As a rule, performance patches are
 254   not candidates for the stable branch. The only exception might be a case
 255   where an application's performance was recently severely impacted so as to
 256   become unusable. The fix for this performance regression could then be
 257   considered for a stable branch. The optimization must also be
 258   non-controversial and the patches still need to meet the other criteria of
 259   being simple and self-contained</li>
 260
 261   <li>Patch introduces a new failure mode (such as an assert). While the new
 262   assert might technically be correct, for example to make Mesa more
 263   conformant, this is not the kind of "bug fix" we want in a stable
 264   release. The potential problem here is that an OpenGL program that was
 265   previously working, (even if technically non-compliant with the
 266   specification), could stop working after this patch. So that would be a
 267   regression that is unaacceptable for the stable branch.</li>
 268 </ul>
 269
 270
 271 <h2 id="release">Making a New Mesa Release</h2>
 272
 273 <p>
 274 These are the instructions for making a new Mesa release.
 275 </p>
 276
 277 <h3>Get latest source files</h3>
 278 <p>
 279 Use git to get the latest Mesa files from the git repository, from whatever
 280 branch is relevant. This document uses the convention X.Y.Z for the release
 281 being created, which should be created from a branch named X.Y.
 282 </p>
 283
 284 <h3>Perform basic testing</h3>
 285 <p>
 286 The release manager should, at the very least, test the code by compiling it,
 287 installing it, and running the latest piglit to ensure that no piglit tests
 288 have regressed since the previous release.
 289 </p>
 290
 291 <p>
 292 The release manager should do this testing with at least one hardware driver,
 293 (say, whatever is contained in the local development machine), as well as on
 294 both Gallium and non-Gallium software drivers. The software testing can be
 295 performed by running piglit with the following environment-variable set:
 296 </p>
 297
 298 <pre>
 299 LIBGL_ALWAYS_SOFTWARE=1
 300 </pre>
 301
 302 And Gallium vs. non-Gallium software drivers can be obtained by using the
 303 following configure flags on separate builds:
 304
 305 <pre>
 306 --with-dri-drivers=swrast
 307 --with-gallium-drivers=swrast
 308 </pre>
 309
 310 <p>
 311 Note: If both options are given in one build, both swrast_dri.so drivers will
 312 be compiled, but only one will be installed. The following command can be used
 313 to ensure the correct driver is being tested:
 314 </p>
 315
 316 <pre>
 317 LIBGL_ALWAYS_SOFTWARE=1 glxinfo | grep "renderer string"
 318 </pre>
 319
 320 If any regressions are found in this testing with piglit, stop here, and do
 321 not perform a release until regressions are fixed.
 322
 323 <h3>Update version in file VERSION</h3>
 324
 325 <p>
 326 Increment the version contained in the file VERSION at Mesa's top-level, then
 327 commit this change.
 328 </p>
 329
 330 <h3>Create release notes for the new release</h3>
 331
 332 <p>
 333 Create a new file docs/relnotes/X.Y.Z.html, (follow the style of the previous
 334 release notes). Note that the sha256sums section of the release notes should
 335 be empty at this point.
 336 </p>
 337
 338 <p>
 339 Two scripts are available to help generate portions of the release notes:
 340
 341 <pre>
 342         ./bin/bugzilla_mesa.sh
 343         ./bin/shortlog_mesa.sh
 344 </pre>
 345
 346 <p>
 347 The first script identifies commits that reference bugzilla bugs and obtains
 348 the descriptions of those bugs from bugzilla. The second script generates a
 349 log of all commits. In both cases, HTML-formatted lists are printed to stdout
 350 to be included in the release notes.
 351 </p>
 352
 353 <p>
 354 Commit these changes
 355 </p>
 356
 357 <h3>Make the release archives, signatures, and the release tag</h3>
 358 <p>
 359 From inside the Mesa directory:
 360 <pre>
 361         ./autogen.sh
 362         make -j1 tarballs
 363 </pre>
 364
 365 <p>
 366 After the tarballs are created, the sha256 checksums for the files will
 367 be computed and printed. These will be used in a step below.
 368 </p>
 369
 370 <p>
 371 It's important at this point to also verify that the constructed tar file
 372 actually builds:
 373 </p>
 374
 375 <pre>
 376         tar xjf MesaLib-X.Y.Z.tar.bz2
 377         cd Mesa-X.Y.Z
 378         ./configure --enable-gallium-llvm
 379         make -j6
 380         make install
 381 </pre>
 382
 383 <p>
 384 Some touch testing should also be performed at this point, (run glxgears or
 385 more involved OpenGL programs against the installed Mesa).
 386 </p>
 387
 388 <p>
 389 Create detached GPG signatures for each of the archive files created above:
 390 </p>
 391
 392 <pre>
 393         gpg --sign --detach MesaLib-X.Y.Z.tar.gz
 394         gpg --sign --detach MesaLib-X.Y.Z.tar.bz2
 395         gpg --sign --detach MesaLib-X.Y.Z.zip
 396 </pre>
 397
 398 <p>
 399 Tag the commit used for the build:
 400 </p>
 401
 402 <pre>
 403         git tag -s mesa-X.Y.X -m "Mesa X.Y.Z release"
 404 </pre>
 405
 406 <p>
 407 Note: It would be nice to investigate and fix the issue that causes the
 408 tarballs target to fail with multiple build process, such as with "-j4". It
 409 would also be nice to incorporate all of the above commands into a single
 410 makefile target. And instead of a custom "tarballs" target, we should
 411 incorporate things into the standard "make dist" and "make distcheck" targets.
 412 </p>
 413
 414 <h3>Add the sha256sums to the release notes</h3>
 415
 416 <p>
 417 Edit docs/relnotes/X.Y.Z.html to add the sha256sums printed as part of "make
 418 tarballs" in the previous step. Commit this change.
 419 </p>
 420
 421 <h3>Push all commits and the tag creates above</h3>
 422
 423 <p>
 424 This is the first step that cannot easily be undone. The release is going
 425 forward from this point:
 426 </p>
 427
 428 <pre>
 429         git push origin X.Y --tags
 430 </pre>
 431
 432 <h3>Install the release files and signatures on the distribution server</h3>
 433
 434 <p>
 435 The following commands can be used to copy the release archive files and
 436 signatures to the freedesktop.org server:
 437 </p>
 438
 439 <pre>
 440         scp MesaLib-X.Y.Z* people.freedesktop.org:
 441         ssh people.freedesktop.org
 442         cd /srv/ftp.freedesktop.org/pub/mesa
 443         mkdir X.Y.Z
 444         cd X.Y.Z
 445         mv ~/MesaLib-X.Y.Z* .
 446 </pre>
 447
 448 <h3>Back on mesa master, andd the new release notes into the tree</h3>
 449
 450 <p>
 451 Something like the following steps will do the trick:
 452 </p>
 453
 454 <pre>
 455         cp docs/relnotes/X.Y.Z.html /tmp
 456         git checkout master
 457         cp /tmp/X.Y.Z.html docs/relnotes
 458         git add docs/relnotes/X.Y.Z.html
 459 </pre>
 460
 461 <p>
 462 Also, edit docs/relnotes.html to add a link to the new release notes, and edit
 463 docs/index.html to add a news entry. Then commit and push:
 464 </p>
 465
 466 <pre>
 467         git commit -a -m "docs: Import X.Y.Z release notes, add news item."
 468         git push origin
 469 </pre>
 470
 471 <h3>Update the mesa3d.org website</h3>
 472
 473 <p>
 474 NOTE: The recent release managers have not been performing this step
 475 themselves, but leaving this to Brian Paul, (who has access to the
 476 sourceforge.net hosting for mesa3d.org). Brian is more than willing to grant
 477 the permission necessary to future release managers to do this step on their
 478 own.
 479 </p>
 480
 481 <p>
 482 Update the web site by copying the docs/ directory's files to
 483 /home/users/b/br/brianp/mesa-www/htdocs/ with:
 484 <br>
 485 <code>
 486 sftp USERNAME,mesa3d@web.sourceforge.net
 487 </code>
 488 </p>
 489
 490
 491 <h3>Announce the release</h3>
 492 <p>
 493 Make an announcement on the mailing lists:
 494
 495 <em>mesa-dev@lists.freedesktop.org</em>,
 496 and
 497 <em>mesa-announce@lists.freedesktop.org</em>
 498
 499 Follow the template of previously-sent release announcements. The following
 500 command can be used to generate the log of changes to be included in the
 501 release announcement:
 502
 503 <pre>
 504         git shortlog mesa-X.Y.Z-1..mesa-X.Y.Z
 505 </pre>
 506 </p>
 507
 508
 509 <h2 id="extensions">Adding Extensions</h2>
 510
 511 <p>
 512 To add a new GL extension to Mesa you have to do at least the following.
 513
 514 <ul>
 515 <li>
 516    If glext.h doesn't define the extension, edit include/GL/gl.h and add
 517    code like this:
 518    <pre>
 519      #ifndef GL_EXT_the_extension_name
 520      #define GL_EXT_the_extension_name 1
 521      /* declare the new enum tokens */
 522      /* prototype the new functions */
 523      /* TYPEDEFS for the new functions */
 524      #endif
 525    </pre>
 526 </li>
 527 <li>
 528    In the src/mapi/glapi/gen/ directory, add the new extension functions and
 529    enums to the gl_API.xml file.
 530    Then, a bunch of source files must be regenerated by executing the
 531    corresponding Python scripts.
 532 </li>
 533 <li>
 534    Add a new entry to the <code>gl_extensions</code> struct in mtypes.h
 535 </li>
 536 <li>
 537    Update the <code>extensions.c</code> file.
 538 </li>
 539 <li>
 540    From this point, the best way to proceed is to find another extension,
 541    similar to the new one, that's already implemented in Mesa and use it
 542    as an example.
 543 </li>
 544 <li>
 545    If the new extension adds new GL state, the functions in get.c, enable.c
 546    and attrib.c will most likely require new code.
 547 </li>
 548 <li>
 549    The dispatch tests check_table.cpp and dispatch_sanity.cpp
 550    should be updated with details about the new extensions functions. These
 551    tests are run using 'make check'
 552 </li>
 553 </ul>
 554
 555
 556
 557
 558 </div>
 559 </body>
 560 </html>