<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html lang="en"> <head> <meta http-equiv="content-type" content="text/html; charset=utf-8"> <title>Environment Variables</title> <link rel="stylesheet" type="text/css" href="mesa.css"> </head> <body> <div class="header"> <h1>The Mesa 3D Graphics Library</h1> </div> <iframe src="contents.html"></iframe> <div class="content"> <h1>Environment Variables</h1> <p> 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. </p> <h2>LibGL environment variables</h2> <ul> <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 - if set to `true`, forces an indirect rendering context/connection. <li>LIBGL_ALWAYS_SOFTWARE - if set to `true`, always use software rendering <li>LIBGL_NO_DRAWARRAYS - if set to `true`, 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. <li>LIBGL_DRI3_DISABLE - disable DRI3 if set to `true`. </ul> <h2>Core Mesa environment variables</h2> <ul> <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_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.</li> <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 occurred, and possibly why, will be printed to stderr.<br> 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 set MESA_DEBUG=1: <ul> <li>silent - turn off debug messages. Only useful for debug builds.</li> <li>flush - flush after each drawing command</li> <li>incomplete_tex - extra debug messages when a texture is incomplete</li> <li>incomplete_fbo - extra debug messages when a fbo is incomplete</li> <li>context - create a debug context (see GLX_CONTEXT_DEBUG_BIT_ARB) and print error and performance messages to stderr (or MESA_LOG_FILE).</li> </ul> <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. <ul> <li>The format should be MAJOR.MINOR[FC|COMPAT] <li>FC is an optional suffix that indicates a forward compatible context. This is only valid for versions >= 3.0. <li>COMPAT is an optional suffix that indicates a compatibility context or GL_ARB_compatibility support. This is only valid for versions >= 3.1. <li>GL versions <= 3.0 are set to a compatibility (non-Core) profile <li>GL versions = 3.1, depending on the driver, it may or may not have the ARB_compatibility extension enabled. <li>GL versions >= 3.2 are set to a Core profile <li>Examples: 2.1, 3.0, 3.0FC, 3.1, 3.1FC, 3.1COMPAT, X.Y, X.YFC, X.YCOMPAT. <ul> <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 GL version 3.1 with GL_ARB_compatibility enabled per the driver default. <li>3.1FC - select GL version 3.1 with forward compatibility and GL_ARB_compatibility disabled. <li>3.1COMPAT - select GL version 3.1 with GL_ARB_compatibility enabled. <li>X.Y - override GL version to X.Y without changing the profile. <li>X.YFC - select a Core+Forward Compatible profile with GL version X.Y. <li>X.YCOMPAT - select a Compatibility profile with GL version X.Y. </ul> <li>Mesa may not really implement all the features of the given version. (for developers only) </ul> <li>MESA_GLES_VERSION_OVERRIDE - changes the value returned by glGetString(GL_VERSION) for OpenGL ES. <ul> <li> The format should be MAJOR.MINOR <li> Examples: 2.0, 3.0, 3.1 <li> Mesa may not really implement all the features of the given version. (for developers only) </ul> <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_CACHE_DISABLE - if set to `true`, disables the GLSL shader cache <li>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', 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. <li>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 (if that variable is set), or else within .cache/mesa within the user's home directory. <li>MESA_GLSL - <a href="shading.html#envvars">shading language compiler options</a> <li>MESA_NO_MINMAX_CACHE - when set, the minmax index cache is globally disabled. <li>MESA_SHADER_CAPTURE_PATH - see <a href="shading.html#capture">Capturing Shaders</a></li> <li>MESA_SHADER_DUMP_PATH and MESA_SHADER_READ_PATH - see <a href="shading.html#replacement">Experimenting with Shader Replacements</a></li> <li>MESA_VK_VERSION_OVERRIDE - changes the Vulkan physical device version as returned in VkPhysicalDeviceProperties::apiVersion. <ul> <li>The format should be MAJOR.MINOR[.PATCH]</li> <li>This will not let you force a version higher than the driver's instance versionas advertised by vkEnumerateInstanceVersion</li> <li>This can be very useful for debugging but some features may not be implemented correctly. (For developers only)</li> </ul> </li> </ul> <h2>Mesa Xlib driver environment variables</h2> <p> The following are only applicable to the Mesa Xlib software driver. See the <a href="xlibdriver.html">Xlib software driver page</a> for details. </p> <ul> <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. </ul> <h2>i945/i965 driver environment variables (non-Gallium)</h2> <ul> <li>INTEL_NO_HW - if set to 1, prevents batches from being submitted to the hardware. This is useful for debugging hangs, etc.</li> <li>INTEL_DEBUG - a comma-separated list of named flags, which do various things: <ul> <li>ann - annotate IR in assembly dumps</li> <li>aub - dump batches into an AUB trace for use with simulation tools</li> <li>bat - emit batch information</li> <li>blit - emit messages about blit operations</li> <li>blorp - emit messages about the blorp operations (blits & clears)</li> <li>buf - emit messages about buffer objects</li> <li>clip - emit messages about the clip unit (for old gens, includes the CLIP program)</li> <li>color - use color in output</li> <li>cs - dump shader assembly for compute shaders</li> <li>do32 - generate compute shader SIMD32 programs even if workgroup size doesn't exceed the SIMD16 limit</li> <li>dri - emit messages about the DRI interface</li> <li>fbo - emit messages about framebuffers</li> <li>fs - dump shader assembly for fragment shaders</li> <li>gs - dump shader assembly for geometry shaders</li> <li>hex - print instruction hex dump with the disassembly</li> <li>l3 - emit messages about the new L3 state during transitions</li> <li>miptree - emit messages about miptrees</li> <li>no8 - don't generate SIMD8 fragment shader</li> <li>no16 - suppress generation of 16-wide fragment shaders. useful for debugging broken shaders</li> <li>nocompact - disable instruction compaction</li> <li>nodualobj - suppress generation of dual-object geometry shader code</li> <li>norbc - disable single sampled render buffer compression</li> <li>optimizer - dump shader assembly to files at each optimization pass and iteration that make progress</li> <li>perf - emit messages about performance issues</li> <li>perfmon - emit messages about AMD_performance_monitor</li> <li>pix - emit messages about pixel operations</li> <li>prim - emit messages about drawing primitives</li> <li>reemit - mark all state dirty on each draw call</li> <li>sf - emit messages about the strips & fans unit (for old gens, includes the SF program)</li> <li>shader_time - record how much GPU time is spent in each shader</li> <li>spill_fs - force spilling of all registers in the scalar backend (useful to debug spilling code)</li> <li>spill_vec4 - force spilling of all registers in the vec4 backend (useful to debug spilling code)</li> <li>state - emit messages about state flag tracking</li> <li>submit - emit batchbuffer usage statistics</li> <li>sync - after sending each batch, emit a message and wait for that batch to finish rendering</li> <li>tcs - dump shader assembly for tessellation control shaders</li> <li>tes - dump shader assembly for tessellation evaluation shaders</li> <li>tex - emit messages about textures.</li> <li>urb - emit messages about URB setup</li> <li>vert - emit messages about vertex assembly</li> <li>vs - dump shader assembly for vertex shaders</li> </ul> <li>INTEL_SCALAR_VS (or TCS, TES, GS) - force scalar/vec4 mode for a shader stage (Gen8-9 only)</li> <li>INTEL_PRECISE_TRIG - if set to 1, true or yes, then the driver prefers accuracy over performance in trig functions.</li> </ul> <h2>Radeon driver environment variables (radeon, r200, and r300g)</h2> <ul> <li>RADEON_NO_TCL - if set, disable hardware-accelerated Transform/Clip/Lighting. </ul> <h2>EGL environment variables</h2> <p> Mesa EGL supports different sets of environment variables. See the <a href="egl.html">Mesa EGL</a> page for the details. </p> <h2>Gallium environment variables</h2> <ul> <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_HUD_PERIOD - sets the hud update rate in seconds (float). Use zero to update every frame. The default period is 1/2 second. <li>GALLIUM_HUD_VISIBLE - control default visibility, defaults to true. <li>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 to false and GALLIUM_HUD_TOGGLE_SIGNAL to 10 (SIGUSR1). Use kill -10 <pid> to toggle the hud as desired. <li>GALLIUM_HUD_DUMP_DIR - specifies a directory for writing the displayed hud values into files. <li>GALLIUM_DRIVER - useful in combination with LIBGL_ALWAYS_SOFTWARE=true for choosing one of the software renderers "softpipe", "llvmpipe" or "swr". <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_FSE - ??? <LI>DRAW_NO_FSE - ??? <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. </ul> <h3>Clover state tracker environment variables</h3> <ul> <li>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. <li>CLOVER_EXTRA_COMPILE_OPTIONS - allows specifying additional compiler options. Specified options are appended after the options set by the OpenCL program in clCompileProgram. <li>CLOVER_EXTRA_LINK_OPTIONS - allows specifying additional linker options. Specified options are appended after the options set by the OpenCL program in clLinkProgram. </ul> <h3>Softpipe driver environment variables</h3> <ul> <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 processing. </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 accepted. 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 off 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>SVGA_EXTRA_LOGGING - if set, enables extra logging to the vmware.log file, such as the OpenGL program's name and command line arguments. <li>See the driver code for other, lesser-used variables. </ul> <h3>WGL environment variables</h3> <ul> <li>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. </ul> <h3>VA-API state tracker environment variables</h3> <ul> <li>VAAPI_MPEG4_ENABLED - enable MPEG4 for VA-API, disabled by default. </ul> <h3>VC4 driver environment variables</h3> <ul> <li>VC4_DEBUG - a comma-separated list of named flags, which do various things: <ul> <li>cl - dump command list during creation</li> <li>qpu - dump generated QPU instructions</li> <li>qir - dump QPU IR during program compile</li> <li>nir - dump NIR during program compile</li> <li>tgsi - dump TGSI during program compile</li> <li>shaderdb - dump program compile information for shader-db analysis</li> <li>perf - print during performance-related events</li> <li>norast - skip actual hardware execution of commands</li> <li>always_flush - flush after each draw call</li> <li>always_sync - wait for finish after each flush</li> <li>dump - write a GPU command stream trace file (VC4 simulator only)</li> </ul> </ul> <p> Other Gallium drivers have their own environment variables. These may change frequently so the source code should be consulted for details. </p> </div> </body> </html>