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.
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
- if set to
true
, forces an indirect rendering context/connection. LIBGL_ALWAYS_SOFTWARE
- if set to
true
, always use software rendering LIBGL_NO_DRAWARRAYS
- if set to
true
, do not use DrawArrays GLX protocol (for debugging) LIBGL_SHOW_FPS
- print framerate to stdout based on the number of
glXSwapBuffers
calls per second. LIBGL_DRI3_DISABLE
- disable DRI3 if set to
true
.
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_NO_ERROR
- if set to 1, error checking is disabled as per
KHR_no_error
. This will result in undefined behaviour for invalid use of the api, but can reduce CPU use for apps that are known to be error free. 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. For release builds,MESA_DEBUG
defaults to off (no debug output).MESA_DEBUG
accepts the following comma-separated list of named flags, which adds extra behaviour to just setMESA_DEBUG=1
:silent
- turn off debug messages. Only useful for debug builds.
flush
- flush after each drawing command
incomplete_tex
- extra debug messages when a texture is incomplete
incomplete_fbo
- extra debug messages when a fbo is incomplete
context
- create a debug context (see
GLX_CONTEXT_DEBUG_BIT_ARB
) and print error and performance messages to stderr (orMESA_LOG_FILE
).
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 theGL_EXT_foo
extension and disable theGL_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|COMPAT]
FC
is an optional suffix that indicates a forward compatible context. This is only valid for versions >= 3.0.COMPAT
is an optional suffix that indicates a compatibility context orGL_ARB_compatibility
support. This is only valid for versions >= 3.1.- GL versions <= 3.0 are set to a compatibility (non-Core) profile
- GL versions = 3.1, depending on the driver, it may or may not
have the
ARB_compatibility
extension enabled. - GL versions >= 3.2 are set to a Core profile
- Examples:
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 GL version 3.1 with GL_ARB_compatibility enabled per the driver default.
3.1FC
- select GL version 3.1 with forward compatibility and GL_ARB_compatibility disabled.
3.1COMPAT
- select GL version 3.1 with GL_ARB_compatibility enabled.
X.Y
- override GL version to X.Y without changing the profile.
X.YFC
- select a Core+Forward Compatible profile with GL version X.Y.
X.YCOMPAT
- select a Compatibility profile with GL version X.Y.
- Mesa may not really implement all the features of the given version. (for developers only)
- The format should be
MESA_GLES_VERSION_OVERRIDE
- changes the value returned by
glGetString(GL_VERSION)
for OpenGL ES.- The format should be
MAJOR.MINOR
- Examples:
2.0
,3.0
,3.1
- Mesa may not really implement all the features of the given version. (for developers only)
- The format should be
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_CACHE_DISABLE
- if set to
true
, disables the GLSL shader cache MESA_GLSL_CACHE_MAX_SIZE
- if set, determines the maximum size of the on-disk cache of compiled GLSL
programs. Should be set to a number optionally followed by
K
,M
, orG
to specify a size in kilobytes, megabytes, or gigabytes. By default, gigabytes will be assumed. And if unset, a maximum size of 1GB will be used. Note: A separate cache might be created for each architecture that Mesa is installed for on your system. For example under the default settings you may end up with a 1GB cache for x86_64 and another 1GB cache for i386. MESA_GLSL_CACHE_DIR
- if set, determines the directory to be used for the on-disk cache of
compiled GLSL programs. If this variable is not set, then the cache will
be stored in
$XDG_CACHE_HOME/mesa_shader_cache
(if that variable is set), or else within.cache/mesa_shader_cache
within the user's home directory. MESA_GLSL
- shading language compiler options
MESA_NO_MINMAX_CACHE
- when set, the minmax index cache is globally disabled.
MESA_SHADER_CAPTURE_PATH
- see Capturing Shaders
MESA_SHADER_DUMP_PATH
andMESA_SHADER_READ_PATH
- see Experimenting with Shader Replacements
MESA_VK_VERSION_OVERRIDE
- changes the Vulkan physical device version
as returned in
VkPhysicalDeviceProperties::apiVersion
.- The format should be
MAJOR.MINOR[.PATCH]
- This will not let you force a version higher than the driver's
instance versionas advertised by
vkEnumerateInstanceVersion
- This can be very useful for debugging but some features may not be implemented correctly. (For developers only)
- The format should be
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
orximage
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:
ann
- annotate IR in assembly dumps
aub
- dump batches into an AUB trace for use with simulation tools
bat
- emit batch information
blit
- emit messages about blit operations
blorp
- emit messages about the blorp operations (blits & clears)
buf
- emit messages about buffer objects
clip
- emit messages about the clip unit (for old gens, includes the CLIP program)
color
- use color in output
cs
- dump shader assembly for compute shaders
do32
- generate compute shader SIMD32 programs even if workgroup size doesn't exceed the SIMD16 limit
dri
- emit messages about the DRI interface
fbo
- emit messages about framebuffers
fs
- dump shader assembly for fragment shaders
gs
- dump shader assembly for geometry shaders
hex
- print instruction hex dump with the disassembly
l3
- emit messages about the new L3 state during transitions
miptree
- emit messages about miptrees
no8
- don't generate SIMD8 fragment shader
no16
- suppress generation of 16-wide fragment shaders. useful for debugging broken shaders
nocompact
- disable instruction compaction
nodualobj
- suppress generation of dual-object geometry shader code
norbc
- disable single sampled render buffer compression
optimizer
- dump shader assembly to files at each optimization pass and iteration that make progress
perf
- emit messages about performance issues
perfmon
- emit messages about
AMD_performance_monitor
pix
- emit messages about pixel operations
prim
- emit messages about drawing primitives
reemit
- mark all state dirty on each draw call
sf
- emit messages about the strips & fans unit (for old gens, includes the SF program)
shader_time
- record how much GPU time is spent in each shader
spill_fs
- force spilling of all registers in the scalar backend (useful to debug spilling code)
spill_vec4
- force spilling of all registers in the vec4 backend (useful to debug spilling code)
state
- emit messages about state flag tracking
submit
- emit batchbuffer usage statistics
sync
- after sending each batch, emit a message and wait for that batch to finish rendering
tcs
- dump shader assembly for tessellation control shaders
tes
- dump shader assembly for tessellation evaluation shaders
tex
- emit messages about textures.
urb
- emit messages about URB setup
vert
- emit messages about vertex assembly
vs
- dump shader assembly for vertex shaders
INTEL_SCALAR_VS
(orTCS
,TES
,GS
)- force scalar/vec4 mode for a shader stage (Gen8-9 only)
INTEL_PRECISE_TRIG
- if set to 1, true or yes, then the driver prefers accuracy over performance in trig functions.
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_HUD_PERIOD
- sets the hud update rate in seconds (float). Use zero to update every frame. The default period is 1/2 second.
GALLIUM_HUD_VISIBLE
- control default visibility, defaults to true.
GALLIUM_HUD_TOGGLE_SIGNAL
- toggle visibility via user specified signal.
Especially useful to toggle hud at specific points of application and
disable for unencumbered viewing the rest of the time. For example, set
GALLIUM_HUD_VISIBLE
tofalse
andGALLIUM_HUD_TOGGLE_SIGNAL
to10
(SIGUSR1
). Usekill -10 <pid>
to toggle the hud as desired. GALLIUM_HUD_DUMP_DIR
- specifies a directory for writing the displayed hud values into files.
GALLIUM_DRIVER
- useful in combination with
LIBGL_ALWAYS_SOFTWARE=true
for choosing one of the software rendererssoftpipe
,llvmpipe
orswr
. 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. Seesrc/mesa/state_tracker/st_debug.c
for other options.
Clover state tracker environment variables
CLOVER_EXTRA_BUILD_OPTIONS
- allows specifying additional compiler and linker
options. Specified options are appended after the options set by the OpenCL
program in
clBuildProgram
. CLOVER_EXTRA_COMPILE_OPTIONS
- allows specifying additional compiler
options. Specified options are appended after the options set by the OpenCL
program in
clCompileProgram
. CLOVER_EXTRA_LINK_OPTIONS
- allows specifying additional linker
options. Specified options are appended after the options set by the OpenCL
program in
clLinkProgram
.
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 off 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.
SVGA_EXTRA_LOGGING
- if set, enables extra logging to the vmware.log file, such as the OpenGL program's name and command line arguments.
SVGA_NO_LOGGING
- if set, disables logging to the vmware.log file. This is useful when using Valgrind because it otherwise crashes when initializing the host log feature.
See the driver code for other, lesser-used variables.
WGL environment variables
WGL_SWAP_INTERVAL
- to set a swap interval, equivalent to calling
wglSwapIntervalEXT()
in an application. If this environment variable is set, application calls towglSwapIntervalEXT()
will have no effect.
VA-API state tracker environment variables
VAAPI_MPEG4_ENABLED
- enable MPEG4 for VA-API, disabled by default.
VC4 driver environment variables
VC4_DEBUG
- a comma-separated list of named flags, which do various things:
cl
- dump command list during creation
qpu
- dump generated QPU instructions
qir
- dump QPU IR during program compile
nir
- dump NIR during program compile
tgsi
- dump TGSI during program compile
shaderdb
- dump program compile information for shader-db analysis
perf
- print during performance-related events
norast
- skip actual hardware execution of commands
always_flush
- flush after each draw call
always_sync
- wait for finish after each flush
dump
- write a GPU command stream trace file (VC4 simulator only)
Other Gallium drivers have their own environment variables. These may change frequently so the source code should be consulted for details.