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h1>The Mesa 3D Graphics Library<
/h1>
<
h1>Environment Variables<
/h1>
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.
<
h2>LibGL environment variables<
/h2>
<
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
)
<
li>LIBGL_SHOW_FPS - print framerate to stdout based on the number of glXSwapBuffers
calls per second.
<
h2>Core Mesa environment variables<
/h2>
<
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.
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
If the value of MESA_DEBUG is 'FP' floating point arithmetic errors will
generate exceptions.
<
li>MESA_LOG_FILE - specifies a file
name for logging all errors, warnings,
etc., rather than stderr
<
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
operations with vertex programs (intended for developers only).
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_EXTENSION_MAX_YEAR - The GL_EXTENSIONS string returned by Mesa is sorted
by extension year.
If this variable is set to year X, only extensions defined on or before year
X will be reported.
This is to work-around a bug in some games where the extension string is
copied into a fixed-size buffer without truncating.
If the extension string is too long, the buffer overrun can cause the game
to crash.
This is a work-around for that.
<
li>MESA_GL_VERSION_OVERRIDE - changes the
value returned by
glGetString(GL_VERSION) and possibly the GL API type.
<
li> The format should be MAJOR.MINOR
[FC
]
<
li> FC is an optional suffix that indicates a forward compatible context.
This is only valid for versions >= 3.0.
<
li> GL versions <
3.0 are set to a compatibility
(non-Core
) profile
<
li> GL versions
= 3.0, see below
<
li> GL versions >
3.0 are set to a Core
profile
<
li> Examples:
2.1,
3.0, 3.0FC,
3.1, 3.1FC
<
li>
2.1 - select a compatibility
(non-Core
) profile with GL
version 2.1
<
li>
3.0 - select a compatibility
(non-Core
) profile with GL
version 3.0
<
li> 3.0FC - select a Core+Forward Compatible
profile with GL
version 3.0
<
li>
3.1 - select a Core
profile with GL
version 3.1
<
li> 3.1FC - select a Core+Forward Compatible
profile with GL
version 3.1
<
li> Mesa may not really implement all the features of the given
version.
(for developers only)
<
li>MESA_GLSL_VERSION_OVERRIDE - changes the
value returned by
glGetString(GL_SHADING_LANGUAGE_VERSION). Valid values are integers, such as
"130". Mesa will not really implement all the features of the given language version
if it's higher than what's normally reported. (for developers only)
<
li>MESA_GLSL - <
a href="shading.html#envvars">shading
language compiler options<
/a>
<
h2>Mesa Xlib driver environment variables<
/h2>
The following are only applicable to the Mesa Xlib software driver.
See the <
a href="xlibdriver.html">Xlib software driver page<
/a>
for details.
<
li>MESA_RGB_VISUAL - specifies the X visual and depth
for RGB mode
<
li>MESA_CI_VISUAL - specifies the X visual and depth
for CI mode
<
li>MESA_BACK_BUFFER - specifies how to implement the back
color buffer,
either "pixmap" or "ximage"
<
li>MESA_GAMMA - gamma correction coefficients
for red, green, blue channels
<
li>MESA_XSYNC - enable synchronous X behavior
(for debugging only
)
<
li>MESA_GLX_FORCE_CI - if set, force GLX to treat 8bpp visuals as CI visuals
<
li>MESA_GLX_FORCE_ALPHA - if set, forces RGB windows to have an alpha channel.
<
li>MESA_GLX_DEPTH_BITS - specifies default number of bits
for depth buffer.
<
li>MESA_GLX_ALPHA_BITS - specifies default number of bits
for alpha channel.
<
h2>i945
/i965 driver environment variables
(non-Gallium
)<
/h2>
<
li>INTEL_STRICT_CONFORMANCE - if set to
1, enable sw fallbacks to improve
OpenGL conformance. If set to 2, always use software rendering.
<
li>INTEL_NO_BLIT - if set, disable hardware-accelerated glBitmap,
glCopyPixels, glDrawPixels.
<
h2>Radeon driver environment variables
(radeon, r200, and r300g
)<
/h2>
<
li>RADEON_NO_TCL - if set, disable hardware-accelerated Transform
/Clip
/Lighting.
<
h2>EGL environment variables<
/h2>
Mesa EGL supports different sets of environment variables. See the
<
a href="egl.html">Mesa EGL<
/a> page
for the details.
<
h2>Gallium environment variables<
/h2>
<
li>GALLIUM_HUD - draws various information on the screen, like framerate,
cpu load, driver statistics, performance counters, etc.
Set GALLIUM_HUD=help and run e.g. glxgears for more info.
<
li>GALLIUM_LOG_FILE - specifies a file
for logging all errors, warnings, etc.
rather than stderr.
<
li>GALLIUM_PRINT_OPTIONS - if non-zero, print all the Gallium environment
variables which are used, and their current values.
<
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_USE_LLVM - if set to zero, the draw module will not use LLVM to execute
shaders, vertex fetch, etc.
<
li>ST_DEBUG - controls debug output from the Mesa
/Gallium state tracker.
Setting to "tgsi", for example, will print all the TGSI shaders.
See src/mesa/state_tracker/st_debug.c for other options.
<
h3>Softpipe driver environment variables<
/h3>
<
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.
<li>SOFTPIPE_USE_LLVM - if set, the softpipe driver will try to use LLVM JIT for
vertex shading procesing.
</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>
<h3>VMware SVGA driver environment variables</h3>
<ul>
<li>SVGA_FORCE_SWTNL - force use of software vertex transformation
<li>SVGA_NO_SWTNL - don't allow software vertex transformation fallbacks
(will often result in incorrect rendering).
<
li>SVGA_DEBUG -
for dumping shaders, constant buffers, etc. See the
code
for details.
<
li>See the driver
code for other, lesser-used variables.
Other Gallium drivers have their own environment variables. These may change
frequently so the source code should be consulted for details.