docs: updated environment variable list

docs/envvars.html

@@ -9,17 +9,38 @@
 <H1>Environment Variables</H1>
 
 <p>
-Mesa supports the following environment variables:
+Normally, no environment variables need to be set.  Most of the environment
+variables used by Mesa/Gallium are for debugging purposes, but they can
+sometimes be useful for debugging end-user issues.
 </p>
+
+
+<H2>LibGL environment variables</H2>
+
+<ul>
+<li>LIBGL_DEBUG - If defined debug information will be printed to stderr.
+   If set to 'verbose' additional information will be printed.
+<li>LIBGL_DRIVERS_PATH - colon-separated list of paths to search for DRI drivers
+<li>LIBGL_ALWAYS_INDIRECT - forces an indirect rendering context/connection.
+<li>LIBGL_ALWAYS_SOFTWARE - if set, always use software rendering
+<li>LIBGL_NO_DRAWARRAYS - if set do not use DrawArrays GLX protocol (for debugging)
+</ul>
+
+
+
+<H2>Core Mesa environment variables</H2>
+
 <ul>
 <li>MESA_NO_ASM - if set, disables all assembly language optimizations
 <li>MESA_NO_MMX - if set, disables Intel MMX optimizations
 <li>MESA_NO_3DNOW - if set, disables AMD 3DNow! optimizations
 <li>MESA_NO_SSE - if set, disables Intel SSE optimizations
-<li>MESA_DEBUG - if set, error messages are printed to stderr.
-If the value of MESA_DEBUG is "FP" floating point arithmetic errors will
-generate exceptions.
-<li>MESA_NO_DITHER - if set, disables dithering, overriding glEnable(GL_DITHER)
+<li>MESA_DEBUG - if set, error messages are printed to stderr.  For example,
+   if the application generates a GL_INVALID_ENUM error, a corresponding error
+   message indicating where the error occured, and possibly why, will be
+   printed to stderr.<br>
+   If the value of MESA_DEBUG is 'FP' floating point arithmetic errors will
+   generate exceptions.
 <li>MESA_TEX_PROG - if set, implement conventional texture env modes with
 fragment programs (intended for developers only)
 <li>MESA_TNL_PROG - if set, implement conventional vertex transformation
@@ -28,11 +49,14 @@ Setting this variable automatically sets the MESA_TEX_PROG variable as well.
 <li>MESA_EXTENSION_OVERRIDE - can be used to enable/disable extensions.
 A value such as "GL_EXT_foo -GL_EXT_bar" will enable the GL_EXT_foo extension
 and disable the GL_EXT_bar extension.
-<li>MESA_GLSL - <a href="shading.html#envvars">shading language options</a>
+<li>MESA_GLSL - <a href="shading.html#envvars">shading language compiler options</a>
 </ul>
 
+
+<H2>Mesa Xlib driver environment variables</H2>
+
 <p>
-The following are only applicable to the Xlib software driver.
+The following are only applicable to the Mesa Xlib software driver.
 See the <A HREF="xlibdriver.html">Xlib software driver page</A> for details.
 </p>
 <ul>
@@ -51,9 +75,8 @@ See the <A HREF="xlibdriver.html">Xlib software driver page</A> for details.
 </ul>
 
 
-<p>
-These environment variables are for the Intel i945/i965 drivers:
-</p>
+<h2>i945/i965 driver environment variables (non-Gallium)</h2>
+
 <ul>
 <li>INTEL_STRICT_CONFORMANCE - if set to 1, enable sw fallbacks to improve
     OpenGL conformance.  If set to 2, always use software rendering.
@@ -62,17 +85,71 @@ These environment variables are for the Intel i945/i965 drivers:
 </ul>
 
 
-<p>
-These environment variables are for the Radeon R300 driver:
-</p>
+<h2>Radeon R300 driver environment variables (non-Gallium)</h2>
+
 <ul>
 <li>R300_NO_TCL - if set, disable hardware-accelerated Transform/Clip/Lighting.
 </ul>
 
+
+<h2>EGL environment variables</h2>
+
 <p>
 Mesa EGL supports different sets of environment variables.  See the
 <a href="egl.html">Mesa EGL</a> page for the details.
 </p>
 
+
+<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>
+
+
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