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 --------------------------- .. envvar:: LIBGL_DEBUG If defined debug information will be printed to stderr. If set to ``verbose`` additional information will be printed. .. envvar:: LIBGL_DRIVERS_PATH colon-separated list of paths to search for DRI drivers .. envvar:: LIBGL_ALWAYS_INDIRECT if set to ``true``, forces an indirect rendering context/connection. .. envvar:: LIBGL_ALWAYS_SOFTWARE if set to ``true``, always use software rendering .. envvar:: LIBGL_NO_DRAWARRAYS if set to ``true``, do not use DrawArrays GLX protocol (for debugging) .. envvar:: LIBGL_SHOW_FPS print framerate to stdout based on the number of ``glXSwapBuffers`` calls per second. .. envvar:: LIBGL_DRI2_DISABLE disable DRI2 if set to ``true``. .. envvar:: LIBGL_DRI3_DISABLE disable DRI3 if set to ``true``. Core Mesa environment variables ------------------------------- .. envvar:: MESA_NO_ASM if set, disables all assembly language optimizations .. envvar:: MESA_NO_MMX if set, disables Intel MMX optimizations .. envvar:: MESA_NO_3DNOW if set, disables AMD 3DNow! optimizations .. envvar:: MESA_NO_SSE if set, disables Intel SSE optimizations .. envvar:: MESA_NO_ERROR if set to 1, error checking is disabled as per :ext:`GL_KHR_no_error`. This will result in undefined behavior for invalid use of the API, but can reduce CPU use for apps that are known to be error free. .. envvar:: 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, :envvar:`MESA_DEBUG` defaults to off (no debug output). :envvar:`MESA_DEBUG` accepts the following comma-separated list of named flags, which adds extra behavior to just set :envvar:`MESA_DEBUG` to ``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 (or ``MESA_LOG_FILE``). .. envvar:: MESA_LOG_FILE specifies a file name for logging all errors, warnings, etc., rather than stderr .. envvar:: 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. Note that this will override extensions override configured using driconf. .. envvar:: 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. .. envvar:: 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 or :ext:`GL_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 :ext:`GL_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 :ext:`GL_ARB_compatibility` enabled per the driver default. ``3.1FC`` select GL version 3.1 with forward compatibility and :ext:`GL_ARB_compatibility` disabled. ``3.1COMPAT`` select GL version 3.1 with :ext:`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) .. envvar:: 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) .. envvar:: 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) .. envvar:: MESA_SHADER_CACHE_DISABLE if set to ``true``, disables the on-disk shader cache. If set to ``false``, enables the on-disk shader cache when it is disabled by default. .. envvar:: MESA_SHADER_CACHE_MAX_SIZE if set, determines the maximum size of the on-disk cache of compiled shader programs. Should be set to a number optionally followed by ``K``, ``M``, or ``G`` 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. .. envvar:: MESA_SHADER_CACHE_DIR if set, determines the directory to be used for the on-disk cache of compiled shader 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. .. envvar:: MESA_SHADER_CACHE_SHOW_STATS if set to ``true``, keeps hit/miss statistics for the shader cache. These statistics are printed when the app terminates. .. envvar:: MESA_GLSL :ref:`shading language compiler options ` .. envvar:: MESA_NO_MINMAX_CACHE when set, the minmax index cache is globally disabled. .. envvar:: MESA_SHADER_CAPTURE_PATH see :ref:`Capturing Shaders ` .. envvar:: MESA_SHADER_DUMP_PATH see :ref:`Experimenting with Shader Replacements ` .. envvar:: MESA_SHADER_READ_PATH see :ref:`Experimenting with Shader Replacements ` .. envvar:: 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) .. envvar:: MESA_VK_WSI_PRESENT_MODE overrides the WSI present mode clients specify in ``VkSwapchainCreateInfoKHR::presentMode``. Values can be ``fifo``, ``relaxed``, ``mailbox`` or ``immediate``. .. envvar:: MESA_VK_ABORT_ON_DEVICE_LOSS causes the Vulkan driver to call abort() immediately after detecting a lost device. This is extremely useful when testing as it prevents the test suite from continuing on with a lost device. .. envvar:: MESA_VK_ENABLE_SUBMIT_THREAD for Vulkan drivers which support real timeline semaphores, this forces them to use a submit thread from the beginning, regardless of whether or not they ever see a wait-before-signal condition. .. envvar:: MESA_LOADER_DRIVER_OVERRIDE chooses a different driver binary such as ``etnaviv`` or ``zink``. .. envvar:: DRI_PRIME the default GPU is the one used by Wayland/Xorg or the one connected to a display. This variable allows to select a different GPU. It applies to OpenGL and Vulkan (in this case "select" means the GPU will be first in the reported physical devices list). The supported syntaxes are: - ``DRI_PRIME=1``: selects the first non-default GPU. - ``DRI_PRIME=pci-0000_02_00_0``: selects the GPU connected to this PCIe bus - ``DRI_PRIME=vendor_id:device_id``: selects the first GPU matching these ids .. note:: ``lspci -nn | grep VGA`` can be used to know the PCIe bus or ids to use. NIR passes environment variables -------------------------------- The following are only applicable for drivers that uses NIR, as they modify the behavior for the common ``NIR_PASS`` and ``NIR_PASS_V`` macros, that wrap calls to NIR lowering/optimizations. .. envvar:: NIR_DEBUG a comma-separated list of debug options to apply to NIR shaders. Use ``NIR_DEBUG=help`` to print a list of available options. .. envvar:: NIR_SKIP a comma-separated list of optimization/lowering passes to skip. Mesa Xlib driver environment variables -------------------------------------- The following are only applicable to the Mesa Xlib software driver. See the :doc:`Xlib software driver page ` for details. .. envvar:: MESA_RGB_VISUAL specifies the X visual and depth for RGB mode .. envvar:: MESA_BACK_BUFFER specifies how to implement the back color buffer, either ``pixmap`` or ``ximage`` .. envvar:: MESA_XSYNC enable synchronous X behavior (for debugging only) .. envvar:: MESA_GLX_FORCE_ALPHA if set, forces RGB windows to have an alpha channel. .. envvar:: MESA_GLX_DEPTH_BITS specifies default number of bits for depth buffer. .. envvar:: MESA_GLX_ALPHA_BITS specifies default number of bits for alpha channel. Mesa WGL driver environment variables ------------------------------------- The following are only applicable to the Mesa WGL driver, which is in use on Windows. .. envvar:: WGL_FORCE_MSAA if set to a positive value, specifies the number of MSAA samples to force when choosing the display configuration. .. envvar:: WGL_DISABLE_ERROR_DIALOGS if set to 1, true or yes, disables Win32 error dialogs. Useful for automated test-runs. Intel driver environment variables ---------------------------------------------------- .. envvar:: INTEL_BLACKHOLE_DEFAULT if set to 1, true or yes, then the OpenGL implementation will default ``GL_BLACKHOLE_RENDER_INTEL`` to true, thus disabling any rendering. .. envvar:: INTEL_COMPUTE_CLASS If set to 1, true or yes, then I915_ENGINE_CLASS_COMPUTE will be supported. For OpenGL, iris will attempt to use a compute engine for compute dispatches if one is detected. For Vulkan, anvil will advertise support for a compute queue if a compute engine is detected. .. envvar:: INTEL_DEBUG a comma-separated list of named flags, which do various things: ``ann`` annotate IR in assembly dumps ``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 ``bt`` emit messages binding tables ``capture-all`` flag all buffers to be captured by the kernel driver when generating an error stage after a GPU hang ``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 ``fall`` emit messages about performance issues (same as ``perf``) ``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 ``mesh`` dump shader assembly for mesh shaders ``no8`` don't generate SIMD8 fragment shader ``no16`` suppress generation of 16-wide fragment shaders. useful for debugging broken shaders ``no32`` suppress generation of 32-wide fragment shaders. useful for debugging broken shaders ``no-oaconfig`` disable HW performance metric configuration, and anything related to i915-perf (useful when running on simulation) ``nocompact`` disable instruction compaction ``nodualobj`` suppress generation of dual-object geometry shader code ``nofc`` disable fast clears ``noccs`` disable lossless color compression ``optimizer`` dump shader assembly to files at each optimization pass and iteration that make progress ``pc`` emit messages about PIPE_CONTROL instruction usage ``perf`` emit messages about performance issues ``perfmon`` emit messages about :ext:`GL_AMD_performance_monitor` ``reemit`` mark all state dirty on each draw call ``rt`` dump shader assembly for ray tracing shaders ``sf`` emit messages about the strips & fans unit (for old gens, includes the SF program) ``soft64`` enable implementation of software 64bit floating point support ``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) ``stall`` inserts a stall on the GPU after each draw/dispatch command to wait for it to finish before starting any new work. ``submit`` emit batchbuffer usage statistics ``sync`` after sending each batch, wait on the CPU for that batch to finish rendering ``task`` dump shader assembly for task shaders ``tcs`` dump shader assembly for tessellation control shaders ``tcs8`` force usage of 8-patches tessellation control shaders (only for gfx 9-11) ``tes`` dump shader assembly for tessellation evaluation shaders ``tex`` emit messages about textures. ``urb`` emit messages about URB setup ``vs`` dump shader assembly for vertex shaders ``wm`` dump shader assembly for fragment shaders (same as ``fs``) .. envvar:: INTEL_MEASURE Collects GPU timestamps over common intervals, and generates a CSV report to show how long rendering took. The overhead of collection is limited to the flushing that is required at the interval boundaries for accurate timestamps. By default, timing data is sent to ``stderr``. To direct output to a file: ``INTEL_MEASURE=file=/tmp/measure.csv {workload}`` To begin capturing timestamps at a particular frame: ``INTEL_MEASURE=file=/tmp/measure.csv,start=15 {workload}`` To capture only 23 frames: ``INTEL_MEASURE=count=23 {workload}`` To capture frames 15-37, stopping before frame 38: ``INTEL_MEASURE=start=15,count=23 {workload}`` Designate an asynchronous control file with: ``INTEL_MEASURE=control=path/to/control.fifo {workload}`` As the workload runs, enable capture for 5 frames with: ``$ echo 5 > path/to/control.fifo`` Enable unbounded capture: ``$ echo -1 > path/to/control.fifo`` and disable with: ``$ echo 0 > path/to/control.fifo`` Select the boundaries of each snapshot with: ``INTEL_MEASURE=draw`` Collects timings for every render (DEFAULT) ``INTEL_MEASURE=rt`` Collects timings when the render target changes ``INTEL_MEASURE=batch`` Collects timings when batches are submitted ``INTEL_MEASURE=frame`` Collects timings at frame boundaries With ``INTEL_MEASURE=interval=5``, the duration of 5 events will be combined into a single record in the output. When possible, a single start and end event will be submitted to the GPU to minimize stalling. Combined events will not span batches, except in the case of ``INTEL_MEASURE=frame``. .. envvar:: INTEL_NO_HW if set to 1, true or yes, prevents batches from being submitted to the hardware. This is useful for debugging hangs, etc. .. envvar:: INTEL_PRECISE_TRIG if set to 1, true or yes, then the driver prefers accuracy over performance in trig functions. .. envvar:: INTEL_SHADER_ASM_READ_PATH if set, determines the directory to be used for overriding shader assembly. The binaries with custom assembly should be placed in this folder and have a name formatted as ``sha1_of_assembly.bin``. The SHA-1 of a shader assembly is printed when assembly is dumped via corresponding :envvar:`INTEL_DEBUG` flag (e.g. ``vs`` for vertex shader). A binary could be generated from a dumped assembly by ``i965_asm``. For :envvar:`INTEL_SHADER_ASM_READ_PATH` to work it is necessary to enable dumping of corresponding shader stages via :envvar:`INTEL_DEBUG`. It is advised to use ``nocompact`` flag of :envvar:`INTEL_DEBUG` when dumping and overriding shader assemblies. The success of assembly override would be signified by "Successfully overrode shader with sha1 " in stderr replacing the original assembly. DRI environment variables ------------------------- .. envvar:: DRI_NO_MSAA disable MSAA for GLX/EGL MSAA visuals Vulkan mesa device select layer environment variables ----------------------------------------------------- .. envvar:: MESA_VK_DEVICE_SELECT when set to "list" prints the list of devices. when set to "vid:did" number from PCI device. That PCI device is selected as default. The default device is returned as the first device in vkEnumeratePhysicalDevices API. .. envvar:: MESA_VK_DEVICE_SELECT_FORCE_DEFAULT_DEVICE when set to 1, the device identified as default will be the only one returned in vkEnumeratePhysicalDevices API. EGL environment variables ------------------------- Mesa EGL supports different sets of environment variables. See the :doc:`Mesa EGL ` page for the details. Gallium environment variables ----------------------------- .. envvar:: GALLIUM_HUD draws various information on the screen, like framerate, CPU load, driver statistics, performance counters, etc. Set :envvar:`GALLIUM_HUD` to ``help`` and run e.g. ``glxgears`` for more info. .. envvar:: GALLIUM_HUD_PERIOD sets the HUD update rate in seconds (float). Use zero to update every frame. The default period is 1/2 second. .. envvar:: GALLIUM_HUD_VISIBLE control default visibility, defaults to true. .. envvar:: 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 :envvar:`GALLIUM_HUD_VISIBLE` to ``false`` and :envvar:`GALLIUM_HUD_TOGGLE_SIGNAL` to ``10`` (``SIGUSR1``). Use ``kill -10 `` to toggle the HUD as desired. .. envvar:: GALLIUM_HUD_SCALE Scale HUD by an integer factor, for high DPI displays. Default is 1. .. envvar:: GALLIUM_HUD_ROTATION Rotate the HUD by an integer number of degrees, the specified value must be a multiple of 90. Default is 0. .. envvar:: GALLIUM_HUD_DUMP_DIR specifies a directory for writing the displayed HUD values into files. .. envvar:: GALLIUM_DRIVER useful in combination with :envvar:`LIBGL_ALWAYS_SOFTWARE` = ``true`` for choosing one of the software renderers ``softpipe`` or ``llvmpipe``. .. envvar:: GALLIUM_LOG_FILE specifies a file for logging all errors, warnings, etc. rather than stderr. .. envvar:: GALLIUM_PIPE_SEARCH_DIR specifies an alternate search directory for pipe-loader which overrides the compile-time path based on the install location. .. envvar:: GALLIUM_PRINT_OPTIONS if non-zero, print all the Gallium environment variables which are used, and their current values. .. envvar:: GALLIUM_TRACE If set, this variable will cause the :ref:`trace` output to be written to the specified file. Paths may be relative or absolute; relative paths are relative to the working directory. For example, setting it to "trace.xml" will cause the trace to be written to a file of the same name in the working directory. .. envvar:: GALLIUM_TRACE_TC If enabled while :ref:`trace` is active, this variable specifies that the threaded context should be traced for drivers which implement it. By default, the driver thread is traced, which will include any reordering of the command stream from threaded context. .. envvar:: GALLIUM_TRACE_TRIGGER If set while :ref:`trace` is active, this variable specifies a filename to monitor. Once the file exists (e.g., from the user running 'touch /path/to/file'), a single frame will be recorded into the trace output. Paths may be relative or absolute; relative paths are relative to the working directory. .. envvar:: GALLIUM_DUMP_CPU if non-zero, print information about the CPU on start-up .. envvar:: TGSI_PRINT_SANITY if set, do extra sanity checking on TGSI shaders and print any errors to stderr. .. envvar:: DRAW_FSE Enable fetch-shade-emit middle-end even though its not correct (e.g. for Softpipe) .. envvar:: DRAW_NO_FSE Disable fetch-shade-emit middle-end even when it is correct .. envvar:: DRAW_USE_LLVM if set to zero, the draw module will not use LLVM to execute shaders, vertex fetch, etc. .. envvar:: ST_DEBUG controls debug output from the Mesa/Gallium state tracker. Setting to ``tgsi``, for example, will print all the TGSI shaders. See :file:`src/mesa/state_tracker/st_debug.c` for other options. .. envvar:: GALLIUM_OVERRIDE_CPU_CAPS Override CPU capabilities for LLVMpipe and Softpipe, possible values for x86: ``nosse`` ``sse`` ``sse2`` ``sse3`` ``ssse3`` ``sse4.1`` ``avx`` Clover environment variables ---------------------------- .. envvar:: 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``. .. envvar:: CLOVER_EXTRA_COMPILE_OPTIONS allows specifying additional compiler options. Specified options are appended after the options set by the OpenCL program in ``clCompileProgram``. .. envvar:: CLOVER_EXTRA_LINK_OPTIONS allows specifying additional linker options. Specified options are appended after the options set by the OpenCL program in ``clLinkProgram``. Rusticl environment variables ----------------------------- .. envvar:: RUSTICL_DEVICE_TYPE allows to overwrite the device type of devices. Possible values are ``accelerator``, ``cpu``, ``custom`` and ``gpu`` .. envvar:: RUSTICL_CL_VERSION overwrites the auto detected OpenCL version of all devices. Specified as ``major.minor``. .. envvar:: RUSTICL_ENABLE a comma-separated list of drivers to enable CL on. An optional list of comma-separated integers can be passed per driver to specify which devices to enable. Examples: - ``RUSTICL_ENABLE=iris`` (enables all iris devices) - ``RUSTICL_ENABLE=iris:1,radeonsi:0,2`` (enables second iris and first and third radeonsi device) Nine frontend environment variables ----------------------------------- .. envvar:: D3D_ALWAYS_SOFTWARE an integer, which forces Nine to use the CPU instead of GPU acceleration. .. envvar:: NINE_DEBUG a comma-separated list of named flags that do debugging things. Use ``NINE_DEBUG=help`` to print a list of available options. .. envvar:: NINE_FF_DUMP a boolean, which dumps shaders generated by a fixed function (FF). .. envvar:: NINE_SHADER a comma-separated list of named flags, which do alternate shader handling. Use ``NINE_SHADER=help`` to print a list of available options. .. envvar:: NINE_QUIRKS a comma-separated list of named flags that do various things. Use ``NINE_DEBUG=help`` to print a list of available options. Softpipe driver environment variables ------------------------------------- .. envvar:: SOFTPIPE_DEBUG a comma-separated list of named flags, which do various things: ``vs`` Dump vertex shader assembly to stderr ``fs`` Dump fragment shader assembly to stderr ``gs`` Dump geometry shader assembly to stderr ``cs`` Dump compute shader assembly to stderr ``no_rast`` rasterization is disabled. For profiling purposes. ``use_llvm`` the Softpipe driver will try to use LLVM JIT for vertex shading processing. ``use_tgsi`` if set, the Softpipe driver will ask to directly consume TGSI, instead of NIR. LLVMpipe driver environment variables ------------------------------------- .. envvar:: LP_NO_RAST if set LLVMpipe will no-op rasterization .. envvar:: LP_DEBUG a comma-separated list of debug options is accepted. See the source code for details. .. envvar:: LP_PERF a comma-separated list of options to selectively no-op various parts of the driver. See the source code for details. .. envvar:: 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 ---------------------------------------- .. envvar:: SVGA_FORCE_SWTNL force use of software vertex transformation .. envvar:: SVGA_NO_SWTNL don't allow software vertex transformation fallbacks (will often result in incorrect rendering). .. envvar:: SVGA_DEBUG for dumping shaders, constant buffers, etc. See the code for details. .. envvar:: SVGA_EXTRA_LOGGING if set, enables extra logging to the ``vmware.log`` file, such as the OpenGL program's name and command line arguments. .. envvar:: 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 ------------------------- .. envvar:: WGL_SWAP_INTERVAL to set a swap interval, equivalent to calling ``wglSwapIntervalEXT()`` in an application. If this environment variable is set, application calls to ``wglSwapIntervalEXT()`` will have no effect. VA-API environment variables ---------------------------- .. envvar:: VAAPI_MPEG4_ENABLED enable MPEG4 for VA-API, disabled by default. VC4 driver environment variables -------------------------------- .. envvar:: VC4_DEBUG a comma-separated list of named flags, which do various things. Use ``VC4_DEBUG=help`` to print a list of available options. V3D/V3DV driver environment variables ------------------------------------- .. envvar:: V3D_DEBUG a comma-separated list of debug options. Use ``V3D_DEBUG=help`` to print a list of available options. .. _radv env-vars: RADV driver environment variables --------------------------------- .. envvar:: RADV_DEBUG a comma-separated list of named flags, which do various things: ``llvm`` enable LLVM compiler backend ``allbos`` force all allocated buffers to be referenced in submissions ``checkir`` validate the LLVM IR before LLVM compiles the shader ``epilogs`` dump fragment shader epilogs ``forcecompress`` Enables DCC,FMASK,CMASK,HTILE in situations where the driver supports it but normally does not deem it beneficial. ``hang`` enable GPU hangs detection and dump a report to $HOME/radv_dumps__