<BODY>
-<H1>Mesa Cell Driver</H1>
+<H1>Mesa/Gallium Cell Driver</H1>
<p>
The Mesa
<a href="http://en.wikipedia.org/wiki/Cell_%28microprocessor%29" target="_parent">Cell</a>
driver is part of the
-<a href="http://www.tungstengraphics.com/wiki/index.php/Gallium3D" target="_parent">Gallium3D</a>
+<a href="http://wiki.freedesktop.org/wiki/Software/gallium" target="_parent">Gallium3D</a>
architecture.
-</p>
-
-<p>
-<a href="http://www.tungstengraphics.com/" target="_parent">Tungsten Graphics</a>
-is leading the project.
-Two phases are planned.
-First, to implement the framework for parallel rasterization using the Cell
-SPEs, including texture mapping.
-Second, to implement a full-featured OpenGL driver with support for GLSL, etc.
+Tungsten Graphics did the original implementation of the Cell driver.
</p>
<H2>Source Code</H2>
<p>
-The Cell driver source code is on the <code>gallium-0.1</code> branch of the
+The latest Cell driver source code is on the master branch of the Mesa
git repository.
+</p>
+<p>
To build the driver you'll need the IBM Cell SDK (version 2.1 or 3.0).
To use the driver you'll need a Cell system, such as a PS3 running Linux,
or the Cell Simulator (untested, though).
</p>
<p>
-To compile the code, run <code>make linux-cell</code>.
+If using Cell SDK 2.1, see the configs/linux-cell file for some
+special changes.
</p>
<p>
-To use the library, make sure <code>LD_LIBRARY_PATH</code> points the Mesa/lib/
-directory that contains <code>libGL.so</code>.
+To compile the code, run <code>make linux-cell</code>.
+Or to build in debug mode, run <code>make linux-cell-debug</code>.
</p>
<p>
-Verify that the Cell driver is being used by running <code>glxinfo</code>
-and looking for:
+To use the library, make sure your current directory is the top of the
+Mesa tree, then set <code>LD_LIBRARY_PATH</code> like this:
<pre>
- OpenGL renderer string: Gallium 0.1, Cell on Xlib
+ export LD_LIBRARY_PATH=$PWD/lib/gallium:$PWD/lib/
</pre>
+<p>
+Verify that the Cell driver is being used by running
+<code>progs/xdemos/glxinfo</code> and looking for:
+<pre>
+ OpenGL renderer string: Gallium 0.3, Cell on Xlib
+</pre>
+
+
+<H2>Driver Implementation Summary</H2>
+
+<p>
+Rasterization is parallelized across the SPUs in a tiled-based manner.
+Batches of transformed triangles are sent to the SPUs (actually, pulled by from
+main memory by the SPUs).
+Each SPU loops over a set of 32x32-pixel screen tiles, rendering the triangles
+into each tile.
+Because of the limited SPU memory, framebuffer tiles are paged in/out of
+SPU local store as needed.
+Similarly, textures are tiled and brought into local store as needed.
+</p>
+
<H2>Status</H2>
<p>
-As of January 2008 the driver supports smooth/flat shaded triangle rendering
-with Z testing.
-Simple demos like gears run successfully.
-Basic texture mapping should be working within a month.
-There's still unfinished work in the PPU-to-SPU communication facilities.
+As of October 2008, the driver runs quite a few OpenGL demos.
+Features that work include:
+</p>
+<ul>
+<li>Point/line/triangle rendering, glDrawPixels
+<li>2D, NPOT and cube texture maps with nearest/linear/mipmap filtering
+<li>Dynamic SPU code generation for fragment shaders, but not complete
+<li>Dynamic SPU code generation for fragment ops (blend, Z-test, etc), but not complete
+<li>Dynamic PPU/PPC code generation for vertex shaders, but not complete
+</ul>
+<p>
+Performance has recently improved with the addition of PPC code generation
+for vertex shaders, but the code quality isn't too great yet.
+</p>
+<p>
+Another bottleneck is SwapBuffers. It may be the limiting factor for
+many simple GL tests.
+</p>
+
+
+
+<H2>Debug Options</H2>
+
+<p>
+The CELL_DEBUG env var can be set to a comma-separated list of one or
+more of the following debug options:
</p>
+<ul>
+<li><b>checker</b> - use a different background clear color for each SPU.
+ This lets you see which SPU is rendering which screen tiles.
+<li><b>sync</b> - wait/synchronize after each DMA transfer
+<li><b>asm</b> - print generated SPU assembly code to stdout
+<li><b>fragops</b> - emit fragment ops debug messages
+<li><b>fragopfallback</b> - don't use codegen for fragment ops
+<li><b>cmd</b> - print SPU commands as their received
+<li><b>cache</b> - print texture cache statistics when program exits
+</ul>
+<p>
+Note that some of these options may only work for linux-cell-debug builds.
+</p>
+
+<p>
+If the GALLIUM_NOPPC env var is set, PPC code generation will not be used
+and vertex shaders will be run with the TGSI interpreter.
+</p>
+<p>
+If the GALLIUM_NOCELL env var is set, the softpipe driver will be used
+intead of the Cell driver.
+This is useful for comparison/validation.
+</p>
+
<H2>Contributing</H2>
projects / mesa.git / blobdiff