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
verboseadditional 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
glXSwapBufferscalls 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_ENUMerror, a corresponding error message indicating where the error occurred, and possibly why, will be printed to stderr. For release builds,MESA_DEBUGdefaults to off (no debug output).MESA_DEBUGaccepts 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_PROGvariable as well. MESA_EXTENSION_OVERRIDE- can be used to enable/disable extensions. A value such as
GL_EXT_foo -GL_EXT_barwill enable theGL_EXT_fooextension and disable theGL_EXT_barextension. MESA_EXTENSION_MAX_YEAR- The
GL_EXTENSIONSstring 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] FCis an optional suffix that indicates a forward compatible context. This is only valid for versions >= 3.0.COMPATis an optional suffix that indicates a compatibility context orGL_ARB_compatibilitysupport. 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_compatibilityextension 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_compatibilityenabled per the driver default. 3.1FC- select GL version 3.1 with forward compatibility and
GL_ARB_compatibilitydisabled. 3.1COMPAT- select GL version 3.1 with
GL_ARB_compatibilityenabled. 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 as130. 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, orGto 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_cachewithin 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_PATHandMESA_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 version as 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
NIR passes enviroment variables
The following are only applicable for drivers that uses NIR, as they modify the behaviour for the common NIR_PASS and NIR_PASS_V macros, that wrap calls to NIR lowering/optimizations.
NIR_PRINT- If defined, the resulting NIR shader will be printed out at each succesful NIR lowering/optimization call.
NIR_TEST_CLONE- If defined, cloning a NIR shader would be tested at each succesful NIR lowering/optimization call.
NIR_TEST_SERIALIZE- If defined, serialize and deserialize a NIR shader would be tested at each succesful NIR lowering/optimization call.
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
pixmaporximage 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
nofc- disable fast clears
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=helpand run e.g.glxgearsfor 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_VISIBLEtofalseandGALLIUM_HUD_TOGGLE_SIGNALto10(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=truefor choosing one of the software rendererssoftpipe,llvmpipeorswr. 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.cfor 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.logfile, such as the OpenGL program's name and command line arguments. SVGA_NO_LOGGING- if set, disables logging to the
vmware.logfile. 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)
RADV driver environment variables
RADV_DEBUG- a comma-separated list of named flags, which do various things:
allbos- force all allocated buffers to be referenced in submissions
allentrypoints- enable all device/instance entrypoints
checkir- validate the LLVM IR before LLVM compiles the shader
errors- display more info about errors
info- show GPU-related information
metashaders- dump internal meta shaders
nobinning- disable primitive binning
nocache- disable shaders cache
nocompute- disable compute queue
nodcc- disable Delta Color Compression (DCC) on images
nodynamicbounds- do not check OOB access for dynamic descriptors
nofastclears- disable fast color/depthstencil clears
nohiz- disable HIZ for depthstencil images
noibs- disable directly recording command buffers in GPU-visible memory
noloadstoreopt- disable LLVM SILoadStoreOptimizer pass
nomemorycache- disable memory shaders cache
nongg- disable NGG for GFX10+
nooutoforder- disable out-of-order rasterization
noshaderballot- disable shader ballot
nosisched- disable LLVM sisched experimental scheduler
nothreadllvm- disable LLVM threaded compilation
preoptir- dump LLVM IR before any optimizations
shaders- dump shaders
shaderstats- dump shader statistics
spirv- dump SPIR-V
startup- display info at startup
syncshaders- synchronize shaders after all draws/dispatches
vmfaults- check for VM memory faults via dmesg
zerovram- initialize all memory allocated in VRAM as zero
RADV_FORCE_FAMILY- force the driver to use a specific family eg. gfx900 (developers only)
RADV_PERFTEST- a comma-separated list of named flags, which do various things:
aco- enable ACO experimental compiler
bolist- enable the global BO list
cswave32- enable wave32 for compute shaders (GFX10+)
dccmsaa- enable DCC for MSAA images
dfsm- enable dfsm
gewave32- enable wave32 for vertex/tess/geometry shaders (GFX10+)
localbos- enable local BOs
nobatchchain- disable chained submissions
pswave32- enable wave32 for pixel shaders (GFX10+)
shader_ballot- enable shader ballot
sisched- enable LLVM sisched experimental scheduler
tccompatcmask- enable TC-compat cmask for MSAA images
RADV_SECURE_COMPILE_THREADS- maximum number of secure compile threads (up to 32)
RADV_TRACE_FILE- generate cmdbuffer tracefiles when a GPU hang is detected
radeonsi driver environment variables
AMD_DEBUG- a comma-separated list of named flags, which do various things:
nodma- Disable SDMA
nodmaclear- Disable SDMA clears
nodmacopyimage- Disable SDMA image copies
zerovram- Clear VRAM allocations.
nodcc- Disable DCC.
nodccclear- Disable DCC fast clear.
nodccfb- Disable separate DCC on the main framebuffer
nodccmsaa- Disable DCC for MSAA
nodpbb- Disable DPBB.
nodfsm- Disable DFSM.
notiling- Disable tiling
nofmask- Disable MSAA compression
nohyperz- Disable Hyper-Z
norbplus- Disable RB+.
no2d- Disable 2D tiling
info- Print driver information
tex- Print texture info
compute- Print compute info
vm- Print virtual addresses when creating resources
vs- Print vertex shaders
ps- Print pixel shaders
gs- Print geometry shaders
tcs- Print tessellation control shaders
tes- Print tessellation evaluation shaders
cs- Print compute shaders
noir- Don't print the LLVM IR
nonir- Don't print NIR when printing shaders
noasm- Don't print disassembled shaders
preoptir- Print the LLVM IR before initial optimizations
sisched- Enable LLVM SI Machine Instruction Scheduler.
gisel- Enable LLVM global instruction selector.
w32ge- Use Wave32 for vertex, tessellation, and geometry shaders.
w32ps- Use Wave32 for pixel shaders.
w32cs- Use Wave32 for computes shaders.
w64ge- Use Wave64 for vertex, tessellation, and geometry shaders.
w64ps- Use Wave64 for pixel shaders.
w64cs- Use Wave64 for computes shaders.
checkir- Enable additional sanity checks on shader IR
mono- Use old-style monolithic shaders compiled on demand
nooptvariant- Disable compiling optimized shader variants.
forcedma- Use SDMA for all operations when possible.
nowc- Disable GTT write combining
check_vm- Check VM faults and dump debug info.
reserve_vmid- Force VMID reservation per context.
nogfx- Disable graphics. Only multimedia compute paths can be used.
nongg- Disable NGG and use the legacy pipeline.
nggc- Always use NGG culling even when it can hurt.
nonggc- Disable NGG culling.
alwayspd- Always enable the primitive discard compute shader.
pd- Enable the primitive discard compute shader for large draw calls.
nopd- Disable the primitive discard compute shader.
switch_on_eop- Program WD/IA to switch on end-of-packet.
nooutoforder- Disable out-of-order rasterization
dpbb- Enable DPBB.
dfsm- Enable DFSM.
Disable features / workaround flags (useful to diagnose an issue):
Info flags:
Print shaders flags:
Shader compilation tuning flags:
Advanced usage flags:
Other Gallium drivers have their own environment variables. These may change frequently so the source code should be consulted for details.