1 <HTML> 2 3 <TITLE>Cell Driver</TITLE> 4 5 <link rel="stylesheet" type="text/css" href="mesa.css"></head> 6 7 <BODY> 8 9 <H1>Mesa/Gallium Cell Driver</H1> 10 11 <p> 12 The Mesa 13 <a href="http://en.wikipedia.org/wiki/Cell_%28microprocessor%29" target="_parent">Cell</a> 14 driver is part of the 15 <a href="http://wiki.freedesktop.org/wiki/Software/gallium" target="_parent">Gallium3D</a> 16 architecture. 17 Tungsten Graphics did the original implementation of the Cell driver. 18 </p> 19 20 21 <H2>Source Code</H2> 22 23 <p> 24 The latest Cell driver source code is on the master branch of the Mesa 25 git repository. 26 </p> 27 <p> 28 To build the driver you'll need the IBM Cell SDK (version 2.1 or 3.0). 29 To use the driver you'll need a Cell system, such as a PS3 running Linux, 30 or the Cell Simulator (untested, though). 31 </p> 32 33 <p> 34 If using Cell SDK 2.1, see the configs/linux-cell file for some 35 special changes. 36 </p> 37 38 <p> 39 To compile the code, run <code>make linux-cell</code>. 40 Or to build in debug mode, run <code>make linux-cell-debug</code>. 41 </p> 42 43 <p> 44 To use the library, make sure your current directory is the top of the 45 Mesa tree, then set <code>LD_LIBRARY_PATH</code> like this: 46 <pre> 47 export LD_LIBRARY_PATH=$PWD/lib/gallium:$PWD/lib/ 48 </pre> 49 50 <p> 51 Verify that the Cell driver is being used by running 52 <code>progs/xdemos/glxinfo</code> and looking for: 53 <pre> 54 OpenGL renderer string: Gallium 0.3, Cell on Xlib 55 </pre> 56 57 58 <H2>Driver Implementation Summary</H2> 59 60 <p> 61 Rasterization is parallelized across the SPUs in a tiled-based manner. 62 Batches of transformed triangles are sent to the SPUs (actually, pulled by from 63 main memory by the SPUs). 64 Each SPU loops over a set of 32x32-pixel screen tiles, rendering the triangles 65 into each tile. 66 Because of the limited SPU memory, framebuffer tiles are paged in/out of 67 SPU local store as needed. 68 Similarly, textures are tiled and brought into local store as needed. 69 </p> 70 71 72 <H2>Status</H2> 73 74 <p> 75 As of October 2008, the driver runs quite a few OpenGL demos. 76 Features that work include: 77 </p> 78 <ul> 79 <li>Point/line/triangle rendering, glDrawPixels 80 <li>2D, NPOT and cube texture maps with nearest/linear/mipmap filtering 81 <li>Dynamic SPU code generation for fragment shaders, but not complete 82 <li>Dynamic SPU code generation for fragment ops (blend, Z-test, etc), but not complete 83 <li>Dynamic PPU/PPC code generation for vertex shaders, but not complete 84 </ul> 85 <p> 86 Performance has recently improved with the addition of PPC code generation 87 for vertex shaders, but the code quality isn't too great yet. 88 </p> 89 <p> 90 Another bottleneck is SwapBuffers. It may be the limiting factor for 91 many simple GL tests. 92 </p> 93 94 95 96 <H2>Debug Options</H2> 97 98 <p> 99 The CELL_DEBUG env var can be set to a comma-separated list of one or 100 more of the following debug options: 101 </p> 102 <ul> 103 <li><b>checker</b> - use a different background clear color for each SPU. 104 This lets you see which SPU is rendering which screen tiles. 105 <li><b>sync</b> - wait/synchronize after each DMA transfer 106 <li><b>asm</b> - print generated SPU assembly code to stdout 107 <li><b>fragops</b> - emit fragment ops debug messages 108 <li><b>fragopfallback</b> - don't use codegen for fragment ops 109 <li><b>cmd</b> - print SPU commands as their received 110 <li><b>cache</b> - print texture cache statistics when program exits 111 </ul> 112 <p> 113 Note that some of these options may only work for linux-cell-debug builds. 114 </p> 115 116 <p> 117 If the GALLIUM_NOPPC env var is set, PPC code generation will not be used 118 and vertex shaders will be run with the TGSI interpreter. 119 </p> 120 <p> 121 If the GALLIUM_NOCELL env var is set, the softpipe driver will be used 122 intead of the Cell driver. 123 This is useful for comparison/validation. 124 </p> 125 126 127 128 <H2>Contributing</H2> 129 130 <p> 131 If you're interested in contributing to the effort, familiarize yourself 132 with the code, join the <a href="lists.html">mesa3d-dev mailing list</a>, 133 and describe what you'd like to do. 134 </p> 135 136 137 </BODY> 138 </HTML> 139
