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  11   <h1>The Mesa 3D Graphics Library</h1>
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  16
  17 <h1>Development Notes</h1>
  18
  19
  20 <h2>Adding Extensions</h2>
  21
  22 <p>
  23 To add a new GL extension to Mesa you have to do at least the following.
  24
  25 <ul>
  26 <li>
  27    If glext.h doesn't define the extension, edit include/GL/gl.h and add
  28    code like this:
  29    <pre>
  30      #ifndef GL_EXT_the_extension_name
  31      #define GL_EXT_the_extension_name 1
  32      /* declare the new enum tokens */
  33      /* prototype the new functions */
  34      /* TYPEDEFS for the new functions */
  35      #endif
  36    </pre>
  37 </li>
  38 <li>
  39    In the src/mapi/glapi/gen/ directory, add the new extension functions and
  40    enums to the gl_API.xml file.
  41    Then, a bunch of source files must be regenerated by executing the
  42    corresponding Python scripts.
  43 </li>
  44 <li>
  45    Add a new entry to the <code>gl_extensions</code> struct in mtypes.h
  46 </li>
  47 <li>
  48    Update the <code>extensions.c</code> file.
  49 </li>
  50 <li>
  51    From this point, the best way to proceed is to find another extension,
  52    similar to the new one, that's already implemented in Mesa and use it
  53    as an example.
  54 </li>
  55 <li>
  56    If the new extension adds new GL state, the functions in get.c, enable.c
  57    and attrib.c will most likely require new code.
  58 </li>
  59 <li>
  60    The dispatch tests check_table.cpp and dispatch_sanity.cpp
  61    should be updated with details about the new extensions functions. These
  62    tests are run using 'make check'
  63 </li>
  64 </ul>
  65
  66
  67
  68 <h2>Coding Style</h2>
  69
  70 <p>
  71 Mesa's code style has changed over the years.  Here's the latest.
  72 </p>
  73
  74 <p>
  75 Comment your code!  It's extremely important that open-source code be
  76 well documented.  Also, strive to write clean, easily understandable code.
  77 </p>
  78
  79 <p>
  80 3-space indentation
  81 </p>
  82
  83 <p>
  84 If you use tabs, set them to 8 columns
  85 </p>
  86
  87 <p>
  88 Line width: the preferred width to fill comments and code in Mesa is 78
  89 columns.  Exceptions are sometimes made for clarity (e.g. tabular data is
  90 sometimes filled to a much larger width so that extraneous carriage returns
  91 don't obscure the table).
  92 </p>
  93
  94 <p>
  95 Brace example:
  96 </p>
  97 <pre>
  98         if (condition) {
  99            foo;
 100         }
 101         else {
 102            bar;
 103         }
 104
 105         switch (condition) {
 106         case 0:
 107            foo();
 108            break;
 109
 110         case 1: {
 111            ...
 112            break;
 113         }
 114
 115         default:
 116            ...
 117            break;
 118         }
 119 </pre>
 120
 121 <p>
 122 Here's the GNU indent command which will best approximate my preferred style:
 123 (Note that it won't format switch statements in the preferred way)
 124 </p>
 125 <pre>
 126         indent -br -i3 -npcs --no-tabs infile.c -o outfile.c
 127 </pre>
 128
 129
 130 <p>
 131 Local variable name example:  localVarName (no underscores)
 132 </p>
 133
 134 <p>
 135 Constants and macros are ALL_UPPERCASE, with _ between words
 136 </p>
 137
 138 <p>
 139 Global variables are not allowed.
 140 </p>
 141
 142 <p>
 143 Function name examples:
 144 </p>
 145 <pre>
 146         glFooBar()       - a public GL entry point (in glapi_dispatch.c)
 147         _mesa_FooBar()   - the internal immediate mode function
 148         save_FooBar()    - retained mode (display list) function in dlist.c
 149         foo_bar()        - a static (private) function
 150         _mesa_foo_bar()  - an internal non-static Mesa function
 151 </pre>
 152
 153 <p>
 154 Places that are not directly visible to the GL API should prefer the use
 155 of <tt>bool</tt>, <tt>true</tt>, and
 156 <tt>false</tt> over <tt>GLboolean</tt>, <tt>GL_TRUE</tt>, and
 157 <tt>GL_FALSE</tt>.  In C code, this may mean that
 158 <tt>#include &lt;stdbool.h&gt;</tt> needs to be added.  The
 159 <tt>try_emit_</tt>* methods in src/mesa/program/ir_to_mesa.cpp and
 160 src/mesa/state_tracker/st_glsl_to_tgsi.cpp can serve as examples.
 161 </p>
 162
 163 <h2>Submitting patches</h2>
 164
 165 <p>
 166 You should always run the Mesa Testsuite before submitting patches.
 167 The Testsuite can be run using the 'make check' command. All tests
 168 must pass before patches will be accepted, this may mean you have
 169 to update the tests themselves.
 170 </p>
 171
 172 <p>
 173 Patches should be sent to the Mesa mailing list for review.
 174 When submitting a patch make sure to use git send-email rather than attaching
 175 patches to emails. Sending patches as attachments prevents people from being
 176 able to provide in-line review comments.
 177 </p>
 178
 179 <p>
 180 When submitting follow-up patches you can use --in-reply-to to make v2, v3,
 181 etc patches show up as replies to the originals. This usually works well
 182 when you're sending out updates to individual patches (as opposed to
 183 re-sending the whole series). Using --in-reply-to makes
 184 it harder for reviewers to accidentally review old patches.
 185 </p>
 186
 187 <h2>Marking a commit as a candidate for a stable branch</h2>
 188
 189 <p>
 190 If you want a commit to be applied to a stable branch,
 191 you should add an appropriate note to the commit message.
 192 </p>
 193
 194 <p>
 195 Here are some examples of such a note:
 196 </p>
 197 <ul>
 198   <li>CC: &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 199   <li>CC: "9.2 10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 200   <li>CC: "10.0" &lt;mesa-stable@lists.freedesktop.org&gt;</li>
 201 </ul>
 202
 203 Simply adding the CC to the mesa-stable list address is adequate to nominate
 204 the commit for the most-recently-created stable branch. It is only necessary
 205 to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the
 206 examples above), if you want to nominate the commit for an older stable
 207 branch. And, as in these examples, you can nominate the commit for the older
 208 branch in addition to the more recent branch, or nominate the commit
 209 exclusively for the older branch.
 210
 211 This "CC" syntax for patch nomination will cause patches to automatically be
 212 copied to the mesa-stable@ mailing list when you use "git send-email" to send
 213 patches to the mesa-dev@ mailing list. Also, if you realize that a commit
 214 should be nominated for the stable branch after it has already been committed,
 215 you can send a note directly to the mesa-stable@lists.freedesktop.org where
 216 the Mesa stable-branch maintainers will receive it. Be sure to mention the
 217 commit ID of the commit of interest (as it appears in the mesa master branch).
 218
 219 The latest set of patches that have been nominated, accepted, or rejected for
 220 the upcoming stable release can always be seen on the
 221 <a href="http://cworth.org/~cworth/mesa-stable-queue/">Mesa Stable Queue</a>
 222 page.
 223
 224 <h2>Criteria for accepting patches to the stable branch</h2>
 225
 226 Mesa has a designated release manager for each stable branch, and the release
 227 manager is the only developer that should be pushing changes to these
 228 branches. Everyone else should simply nominate patches using the mechanism
 229 described above.
 230
 231 The stable-release manager will work with the list of nominated patches, and
 232 for each patch that meets the crtieria below will cherry-pick the patch with:
 233 <code>git cherry-pick -x &lt;commit&gt;</code>. The <code>-x</code> option is
 234 important so that the picked patch references the comit ID of the original
 235 patch.
 236
 237 The stable-release manager may at times need to force-push changes to the
 238 stable branches, for example, to drop a previously-picked patch that was later
 239 identified as causing a regression). These force-pushes may cause changes to
 240 be lost from the stable branch if developers push things directly. Consider
 241 yourself warned.
 242
 243 The stable-release manager is also given broad discretion in rejecting patches
 244 that have been nominated for the stable branch. The most basic rule is that
 245 the stable branch is for bug fixes only, (no new features, no
 246 regressions). Here is a non-exhaustive list of some reasons that a patch may
 247 be rejected:
 248
 249 <ul>
 250   <li>Patch introduces a regression. Any reported build breakage or other
 251   regression caused by a particular patch, (game no longer work, piglit test
 252   changes from PASS to FAIL), is justification for rejecting a patch.</li>
 253
 254   <li>Patch is too large, (say, larger than 100 lines)</li>
 255
 256   <li>Patch is not a fix. For example, a commit that moves code around with no
 257   functional change should be rejected.</li>
 258
 259   <li>Patch fix is not clearly described. For example, a commit message
 260   of only a single line, no description of the bug, no mention of bugzilla,
 261   etc.</li>
 262
 263   <li>Patch has not obviously been reviewed, For example, the commit message
 264   has no Reviewed-by, Signed-off-by, nor Tested-by tags from anyone but the
 265   author.</li>
 266
 267   <li>Patch has not already been merged to the master branch. As a rule, bug
 268   fixes should never be applied first to a stable branch. Patches should land
 269   first on the master branch and then be cherry-picked to a stable
 270   branch. (This is to avoid future releases causing regressions if the patch
 271   is not also applied to master.) The only things that might look like
 272   exceptions would be backports of patches from master that happen to look
 273   significantly different.</li>
 274
 275   <li>Patch depends on too many other patches. Ideally, all stable-branch
 276   patches should be self-contained. It sometimes occurs that a single, logical
 277   bug-fix occurs as two separate patches on master, (such as an original
 278   patch, then a subsequent fix-up to that patch). In such a case, these two
 279   patches should be squashed into a single, self-contained patch for the
 280   stable branch. (Of course, if the squashing makes the patch too large, then
 281   that could be a reason to reject the patch.)</li>
 282
 283   <li>Patch includes new feature development, not bug fixes. New OpenGL
 284   features, extensions, etc. should be applied to Mesa master and included in
 285   the next major release. Stable releases are intended only for bug fixes.
 286
 287   Note: As an exception to this rule, the stable-release manager may accept
 288   hardware-enabling "features". For example, backports of new code to support
 289   a newly-developed hardware product can be accepted if they can be reasonably
 290   determined to not have effects on other hardware.</li>
 291
 292   <li>Patch is a performance optimization. As a rule, performance patches are
 293   not candidates for the stable branch. The only exception might be a case
 294   where an application's performance was recently severely impacted so as to
 295   become unusable. The fix for this performance regression could then be
 296   considered for a stable branch. The optimization must also be
 297   non-controversial and the patches still need to meet the other criteria of
 298   being simple and self-contained</li>
 299
 300   <li>Patch introduces a new failure mode (such as an assert). While the new
 301   assert might technically be correct, for example to make Mesa more
 302   conformant, this is not the kind of "bug fix" we want in a stable
 303   release. The potential problem here is that an OpenGL program that was
 304   previously working, (even if technically non-compliant with the
 305   specification), could stop working after this patch. So that would be a
 306   regression that is unaacceptable for the stable branch.</li>
 307 </ul>
 308
 309 <h2>Making a New Mesa Release</h2>
 310
 311 <p>
 312 These are the instructions for making a new Mesa release.
 313 </p>
 314
 315 <h3>Get latest source files</h3>
 316 <p>
 317 Use git to get the latest Mesa files from the git repository, from whatever
 318 branch is relevant.
 319 </p>
 320
 321
 322 <h3>Verify and update version info in VERSION</h3>
 323
 324 <p>
 325 Create a docs/relnotes/x.y.z.html file.
 326 The bin/bugzilla_mesa.sh and bin/shortlog_mesa.sh scripts can be used to
 327 create the HTML-formatted lists of bugfixes and changes to include in the file.
 328 Link the new docs/relnotes/x.y.z.html file into the main <a href="relnotes.html">relnotes.html</a> file.
 329 </p>
 330
 331 <p>
 332 Update <a href="index.html">docs/index.html</a>.
 333 </p>
 334
 335 <p>
 336 Tag the files with the release name (in the form <b>mesa-x.y</b>)
 337 with: <code>git tag -s mesa-x.y -m "Mesa x.y Release"</code>
 338 Then: <code>git push origin mesa-x.y</code>
 339 </p>
 340
 341
 342 <h3>Make the tarballs</h3>
 343 <p>
 344 Make the distribution files.  From inside the Mesa directory:
 345 <pre>
 346         ./autogen.sh
 347         make tarballs
 348 </pre>
 349
 350 <p>
 351 After the tarballs are created, the md5 checksums for the files will
 352 be computed.
 353 Add them to the docs/relnotes/x.y.html file.
 354 </p>
 355
 356 <p>
 357 Copy the distribution files to a temporary directory, unpack them,
 358 compile everything, and run some demos to be sure everything works.
 359 </p>
 360
 361 <h3>Update the website and announce the release</h3>
 362 <p>
 363 Make a new directory for the release on annarchy.freedesktop.org with:
 364 <br>
 365 <code>
 366 mkdir /srv/ftp.freedesktop.org/pub/mesa/x.y
 367 </code>
 368 </p>
 369
 370 <p>
 371 Basically, to upload the tarball files with:
 372 <br>
 373 <code>
 374 rsync -avP -e ssh MesaLib-x.y.* USERNAME@annarchy.freedesktop.org:/srv/ftp.freedesktop.org/pub/mesa/x.y/
 375 </code>
 376 </p>
 377
 378 <p>
 379 Update the web site by copying the docs/ directory's files to
 380 /home/users/b/br/brianp/mesa-www/htdocs/ with:
 381 <br>
 382 <code>
 383 sftp USERNAME,mesa3d@web.sourceforge.net
 384 </code>
 385 </p>
 386
 387 <p>
 388 Make an announcement on the mailing lists:
 389
 390 <em>mesa-dev@lists.freedesktop.org</em>,
 391 <em>mesa-users@lists.freedesktop.org</em>
 392 and
 393 <em>mesa-announce@lists.freedesktop.org</em>
 394 </p>
 395
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