+
+<h2>Gallium environment variables</h2>
+
+<ul>
+<li>GALLIUM_PRINT_OPTIONS - if non-zero, print all the Gallium environment
+ variables which are used, and their current values.
+<li>GALLIUM_NOSSE - if non-zero, do not use SSE runtime code generation for
+ shader execution
+<li>GALLIUM_NOPPC - if non-zero, do not use PPC runtime code generation for
+ shader execution
+<li>GALLIUM_DUMP_CPU - if non-zero, print information about the CPU on start-up
+<li>TGSI_PRINT_SANITY - if set, do extra sanity checking on TGSI shaders and
+ print any errors to stderr.
+<LI>DRAW_FSE - ???
+<LI>DRAW_NO_FSE - ???
+<li>DRAW_USE_LLVM - if set to zero, the draw module will not use LLVM to execute
+ shaders, vertex fetch, etc.
+</ul>
+
+<h3>Softpipe driver environment variables</h3>
+<ul>
+<li>SOFTPIPE_DUMP_FS - if set, the softpipe driver will print fragment shaders
+ to stderr
+<li>SOFTPIPE_DUMP_GS - if set, the softpipe driver will print geometry shaders
+ to stderr
+<li>SOFTPIPE_NO_RAST - if set, rasterization is no-op'd. For profiling purposes.
+</ul>
+
+
+<h3>LLVMpipe driver environment variables</h3>
+<ul>
+<li>LP_NO_RAST - if set LLVMpipe will no-op rasterization
+<li>LP_DEBUG - a comma-separated list of debug options is acceptec. See the
+ source code for details.
+<li>LP_PERF - a comma-separated list of options to selectively no-op various
+ parts of the driver. See the source code for details.
+<li>LP_NUM_THREADS - an integer indicating how many threads to use for rendering.
+ Zero turns of threading completely. The default value is the number of CPU
+ cores present.
+</ul>
+
+
+<p>
+Other Gallium drivers have their own environment variables. These may change
+frequently so the source code should be consulted for details.
+</p>
+
+
+<br>
+<br>
+
+