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.
LibGL environment variables
- LIBGL_DEBUG - If defined debug information will be printed to stderr. If set to 'verbose' additional information will be printed.
- LIBGL_DRIVERS_PATH - colon-separated list of paths to search for DRI drivers
- LIBGL_ALWAYS_INDIRECT - forces an indirect rendering context/connection.
- LIBGL_ALWAYS_SOFTWARE - if set, always use software rendering
- LIBGL_NO_DRAWARRAYS - if set do not use DrawArrays GLX protocol (for debugging)
- LIBGL_SHOW_FPS - print framerate to stdout based on the number of glXSwapBuffers calls per second.
Core Mesa environment variables
- MESA_NO_ASM - if set, disables all assembly language optimizations
- MESA_NO_MMX - if set, disables Intel MMX optimizations
- MESA_NO_3DNOW - if set, disables AMD 3DNow! optimizations
- MESA_NO_SSE - if set, disables Intel SSE optimizations
- 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 occurred, and possibly why, will be
printed to stderr.
If the value of MESA_DEBUG is 'FP' floating point arithmetic errors will generate exceptions.
- MESA_LOG_FILE - specifies a file name for logging all errors, warnings, etc., rather than stderr
- MESA_TEX_PROG - if set, implement conventional texture env modes with fragment programs (intended for developers only)
- 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.
- 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.
- 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.
- MESA_GL_VERSION_OVERRIDE - changes the value returned by
glGetString(GL_VERSION) and possibly the GL API type.
- The format should be MAJOR.MINOR[FC]
- FC is an optional suffix that indicates a forward compatible context. This is only valid for versions >= 3.0.
- GL versions < 3.0 are set to a compatibility (non-Core) profile
- GL versions = 3.0, see below
- GL versions > 3.0 are set to a Core profile
- Examples: 2.1, 3.0, 3.0FC, 3.1, 3.1FC
- 2.1 - select a compatibility (non-Core) profile with GL version 2.1
- 3.0 - select a compatibility (non-Core) profile with GL version 3.0
- 3.0FC - select a Core+Forward Compatible profile with GL version 3.0
- 3.1 - select a Core profile with GL version 3.1
- 3.1FC - select a Core+Forward Compatible profile with GL version 3.1
- Mesa may not really implement all the features of the given version. (for developers only)
- 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)
- MESA_GLSL - shading language compiler options
Mesa Xlib driver environment variables
The following are only applicable to the Mesa Xlib software driver. See the Xlib software driver page for details.
- MESA_RGB_VISUAL - specifies the X visual and depth for RGB mode
- MESA_CI_VISUAL - specifies the X visual and depth for CI mode
- MESA_BACK_BUFFER - specifies how to implement the back color buffer, either "pixmap" or "ximage"
- MESA_GAMMA - gamma correction coefficients for red, green, blue channels
- MESA_XSYNC - enable synchronous X behavior (for debugging only)
- MESA_GLX_FORCE_CI - if set, force GLX to treat 8bpp visuals as CI visuals
- MESA_GLX_FORCE_ALPHA - if set, forces RGB windows to have an alpha channel.
- MESA_GLX_DEPTH_BITS - specifies default number of bits for depth buffer.
- MESA_GLX_ALPHA_BITS - specifies default number of bits for alpha channel.
i945/i965 driver environment variables (non-Gallium)
- INTEL_NO_HW - if set to 1, prevents batches from being submitted to the hardware. This is useful for debugging hangs, etc.
- INTEL_DEBUG - a comma-separated list of named flags, which do various things:
- tex - emit messages about textures.
- state - emit messages about state flag tracking
- blit - emit messages about blit operations
- miptree - emit messages about miptrees
- perf - emit messages about performance issues
- perfmon - emit messages about AMD_performance_monitor
- bat - emit batch information
- pix - emit messages about pixel operations
- buf - emit messages about buffer objects
- reg - emit messages about regions
- fbo - emit messages about framebuffers
- fs - dump shader assembly for fragment shaders
- gs - dump shader assembly for geometry shaders
- sync - emit messages about synchronization
- prim - emit messages about drawing primitives
- vert - emit messages about vertex assembly
- dri - emit messages about the DRI interface
- sf - emit messages about the strips & fans unit (for old gens, includes the SF program)
- stats - enable statistics counters. you probably actually want perfmon or intel_gpu_top instead.
- urb - emit messages about URB setup
- vs - dump shader assembly for vertex shaders
- clip - emit messages about the clip unit (for old gens, includes the CLIP program)
- aub - dump batches into an AUB trace for use with simulation tools
- shader_time - record how much GPU time is spent in each shader
- no16 - suppress generation of 16-wide fragment shaders. useful for debugging broken shaders
- blorp - emit messages about the blorp operations (blits & clears)
- nodualobj - suppress generation of dual-object geometry shader code
Radeon driver environment variables (radeon, r200, and r300g)
- RADEON_NO_TCL - if set, disable hardware-accelerated Transform/Clip/Lighting.
EGL environment variables
Mesa EGL supports different sets of environment variables. See the Mesa EGL page for the details.
Gallium environment variables
- 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.
- GALLIUM_LOG_FILE - specifies a file for logging all errors, warnings, etc. rather than stderr.
- GALLIUM_PRINT_OPTIONS - if non-zero, print all the Gallium environment variables which are used, and their current values.
- GALLIUM_DUMP_CPU - if non-zero, print information about the CPU on start-up
- TGSI_PRINT_SANITY - if set, do extra sanity checking on TGSI shaders and print any errors to stderr.
- DRAW_FSE - ???
- DRAW_NO_FSE - ???
- DRAW_USE_LLVM - if set to zero, the draw module will not use LLVM to execute shaders, vertex fetch, etc.
- 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.
Softpipe driver environment variables
- SOFTPIPE_DUMP_FS - if set, the softpipe driver will print fragment shaders to stderr
- SOFTPIPE_DUMP_GS - if set, the softpipe driver will print geometry shaders to stderr
- SOFTPIPE_NO_RAST - if set, rasterization is no-op'd. For profiling purposes.
- SOFTPIPE_USE_LLVM - if set, the softpipe driver will try to use LLVM JIT for vertex shading processing.
LLVMpipe driver environment variables
- LP_NO_RAST - if set LLVMpipe will no-op rasterization
- LP_DEBUG - a comma-separated list of debug options is accepted. See the source code for details.
- LP_PERF - a comma-separated list of options to selectively no-op various parts of the driver. See the source code for details.
- 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.
VMware SVGA driver environment variables
- SVGA_FORCE_SWTNL - force use of software vertex transformation
- SVGA_NO_SWTNL - don't allow software vertex transformation fallbacks (will often result in incorrect rendering).
- SVGA_DEBUG - for dumping shaders, constant buffers, etc. See the code for details.
- 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.