docs/envvars.html

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  11   <h1>The Mesa 3D Graphics Library</h1>
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  16
  17 <h1>Environment Variables</h1>
  18
  19 <p>
  20 Normally, no environment variables need to be set.  Most of the environment
  21 variables used by Mesa/Gallium are for debugging purposes, but they can
  22 sometimes be useful for debugging end-user issues.
  23 </p>
  24
  25
  26 <h2>LibGL environment variables</h2>
  27
  28 <ul>
  29 <li>LIBGL_DEBUG - If defined debug information will be printed to stderr.
  30    If set to 'verbose' additional information will be printed.
  31 <li>LIBGL_DRIVERS_PATH - colon-separated list of paths to search for DRI drivers
  32 <li>LIBGL_ALWAYS_INDIRECT - if set to `true`, forces an indirect rendering context/connection.
  33 <li>LIBGL_ALWAYS_SOFTWARE - if set to `true`, always use software rendering
  34 <li>LIBGL_NO_DRAWARRAYS - if set to `true`, do not use DrawArrays GLX protocol (for debugging)
  35 <li>LIBGL_SHOW_FPS - print framerate to stdout based on the number of glXSwapBuffers
  36     calls per second.
  37 <li>LIBGL_DRI3_DISABLE - disable DRI3 if set to `true`.
  38 </ul>
  39
  40
  41
  42 <h2>Core Mesa environment variables</h2>
  43
  44 <ul>
  45 <li>MESA_NO_ASM - if set, disables all assembly language optimizations
  46 <li>MESA_NO_MMX - if set, disables Intel MMX optimizations
  47 <li>MESA_NO_3DNOW - if set, disables AMD 3DNow! optimizations
  48 <li>MESA_NO_SSE - if set, disables Intel SSE optimizations
  49 <li>MESA_NO_ERROR - if set to 1, error checking is disabled as per KHR_no_error.
  50    This will result in undefined behaviour for invalid use of the api, but
  51    can reduce CPU use for apps that are known to be error free.</li>
  52 <li>MESA_DEBUG - if set, error messages are printed to stderr.  For example,
  53    if the application generates a GL_INVALID_ENUM error, a corresponding error
  54    message indicating where the error occurred, and possibly why, will be
  55    printed to stderr.<br>
  56
  57    For release builds, MESA_DEBUG defaults to off (no debug output).
  58
  59    MESA_DEBUG accepts the following comma-separated list of named
  60    flags, which adds extra behaviour to just set MESA_DEBUG=1:
  61    <ul>
  62      <li>silent - turn off debug messages. Only useful for debug builds.</li>
  63      <li>flush - flush after each drawing command</li>
  64      <li>incomplete_tex - extra debug messages when a texture is incomplete</li>
  65      <li>incomplete_fbo - extra debug messages when a fbo is incomplete</li>
  66      <li>context - create a debug context (see GLX_CONTEXT_DEBUG_BIT_ARB) and
  67          print error and performance messages to stderr (or MESA_LOG_FILE).</li>
  68    </ul>
  69 <li>MESA_LOG_FILE - specifies a file name for logging all errors, warnings,
  70 etc., rather than stderr
  71 <li>MESA_TEX_PROG - if set, implement conventional texture env modes with
  72 fragment programs (intended for developers only)
  73 <li>MESA_TNL_PROG - if set, implement conventional vertex transformation
  74 operations with vertex programs (intended for developers only).
  75 Setting this variable automatically sets the MESA_TEX_PROG variable as well.
  76 <li>MESA_EXTENSION_OVERRIDE - can be used to enable/disable extensions.
  77 A value such as "GL_EXT_foo -GL_EXT_bar" will enable the GL_EXT_foo extension
  78 and disable the GL_EXT_bar extension.
  79 <li>MESA_EXTENSION_MAX_YEAR - The GL_EXTENSIONS string returned by Mesa is sorted
  80 by extension year.
  81 If this variable is set to year X, only extensions defined on or before year
  82 X will be reported.
  83 This is to work-around a bug in some games where the extension string is
  84 copied into a fixed-size buffer without truncating.
  85 If the extension string is too long, the buffer overrun can cause the game
  86 to crash.
  87 This is a work-around for that.
  88 <li>MESA_GL_VERSION_OVERRIDE - changes the value returned by
  89 glGetString(GL_VERSION) and possibly the GL API type.
  90 <ul>
  91   <li>The format should be MAJOR.MINOR[FC|COMPAT]
  92   <li>FC is an optional suffix that indicates a forward compatible
  93       context. This is only valid for versions &gt;= 3.0.
  94   <li>COMPAT is an optional suffix that indicates a compatibility
  95       context or GL_ARB_compatibility support. This is only valid for
  96       versions &gt;= 3.1.
  97   <li>GL versions &lt;= 3.0 are set to a compatibility (non-Core)
  98       profile
  99   <li>GL versions = 3.1, depending on the driver, it may or may not
 100       have the ARB_compatibility extension enabled.
 101   <li>GL versions &gt;= 3.2 are set to a Core profile
 102   <li>Examples: 2.1, 3.0, 3.0FC, 3.1, 3.1FC, 3.1COMPAT, X.Y, X.YFC,
 103       X.YCOMPAT.
 104   <ul>
 105     <li>2.1 - select a compatibility (non-Core) profile with GL
 106         version 2.1.
 107     <li>3.0 - select a compatibility (non-Core) profile with GL
 108         version 3.0.
 109     <li>3.0FC - select a Core+Forward Compatible profile with GL
 110         version 3.0.
 111     <li>3.1 - select GL version 3.1 with GL_ARB_compatibility enabled
 112         per the driver default.
 113     <li>3.1FC - select GL version 3.1 with forward compatibility and
 114         GL_ARB_compatibility disabled.
 115     <li>3.1COMPAT - select GL version 3.1 with GL_ARB_compatibility
 116         enabled.
 117     <li>X.Y - override GL version to X.Y without changing the profile.
 118     <li>X.YFC - select a Core+Forward Compatible profile with GL
 119         version X.Y.
 120     <li>X.YCOMPAT - select a Compatibility profile with GL version
 121         X.Y.
 122   </ul>
 123   <li>Mesa may not really implement all the features of the given
 124       version. (for developers only)
 125 </ul>
 126 <li>MESA_GLES_VERSION_OVERRIDE - changes the value returned by
 127 glGetString(GL_VERSION) for OpenGL ES.
 128 <ul>
 129 <li> The format should be MAJOR.MINOR
 130 <li> Examples: 2.0, 3.0, 3.1
 131 <li> Mesa may not really implement all the features of the given version.
 132 (for developers only)
 133 </ul>
 134 <li>MESA_GLSL_VERSION_OVERRIDE - changes the value returned by
 135 glGetString(GL_SHADING_LANGUAGE_VERSION). Valid values are integers, such as
 136 "130".  Mesa will not really implement all the features of the given language version
 137 if it's higher than what's normally reported. (for developers only)
 138 <li>MESA_GLSL_CACHE_DISABLE - if set to `true`, disables the GLSL shader cache
 139 <li>MESA_GLSL_CACHE_MAX_SIZE - if set, determines the maximum size of
 140 the on-disk cache of compiled GLSL programs. Should be set to a number
 141 optionally followed by 'K', 'M', or 'G' to specify a size in
 142 kilobytes, megabytes, or gigabytes. By default, gigabytes will be
 143 assumed. And if unset, a maximum size of 1GB will be used. Note: A separate
 144 cache might be created for each architecture that Mesa is installed for on
 145 your system. For example under the default settings you may end up with a 1GB
 146 cache for x86_64 and another 1GB cache for i386.
 147 <li>MESA_GLSL_CACHE_DIR - if set, determines the directory to be used
 148 for the on-disk cache of compiled GLSL programs. If this variable is
 149 not set, then the cache will be stored in $XDG_CACHE_HOME/mesa (if
 150 that variable is set), or else within .cache/mesa within the user's
 151 home directory.
 152 <li>MESA_GLSL - <a href="shading.html#envvars">shading language compiler options</a>
 153 <li>MESA_NO_MINMAX_CACHE - when set, the minmax index cache is globally disabled.
 154 <li>MESA_SHADER_CAPTURE_PATH - see <a href="shading.html#capture">Capturing Shaders</a></li>
 155 <li>MESA_SHADER_DUMP_PATH and MESA_SHADER_READ_PATH - see <a href="shading.html#replacement">Experimenting with Shader Replacements</a></li>
 156 <li>MESA_VK_VERSION_OVERRIDE - changes the Vulkan physical device version
 157     as returned in VkPhysicalDeviceProperties::apiVersion.
 158   <ul>
 159     <li>The format should be MAJOR.MINOR[.PATCH]</li>
 160     <li>This will not let you force a version higher than the driver's
 161         instance versionas advertised by vkEnumerateInstanceVersion</li>
 162     <li>This can be very useful for debugging but some features may not be
 163         implemented correctly. (For developers only)</li>
 164   </ul>
 165 </li>
 166 </ul>
 167
 168
 169 <h2>Mesa Xlib driver environment variables</h2>
 170
 171 <p>
 172 The following are only applicable to the Mesa Xlib software driver.
 173 See the <a href="xlibdriver.html">Xlib software driver page</a> for details.
 174 </p>
 175 <ul>
 176 <li>MESA_RGB_VISUAL - specifies the X visual and depth for RGB mode
 177 <li>MESA_CI_VISUAL - specifies the X visual and depth for CI mode
 178 <li>MESA_BACK_BUFFER - specifies how to implement the back color buffer,
 179     either "pixmap" or "ximage"
 180 <li>MESA_GAMMA - gamma correction coefficients for red, green, blue channels
 181 <li>MESA_XSYNC - enable synchronous X behavior (for debugging only)
 182 <li>MESA_GLX_FORCE_CI - if set, force GLX to treat 8bpp visuals as CI visuals
 183 <li>MESA_GLX_FORCE_ALPHA - if set, forces RGB windows to have an alpha channel.
 184 <li>MESA_GLX_DEPTH_BITS - specifies default number of bits for depth buffer.
 185 <li>MESA_GLX_ALPHA_BITS - specifies default number of bits for alpha channel.
 186 </ul>
 187
 188
 189 <h2>i945/i965 driver environment variables (non-Gallium)</h2>
 190
 191 <ul>
 192 <li>INTEL_NO_HW - if set to 1, prevents batches from being submitted to the hardware.
 193    This is useful for debugging hangs, etc.</li>
 194 <li>INTEL_DEBUG - a comma-separated list of named flags, which do various things:
 195 <ul>
 196    <li>ann - annotate IR in assembly dumps</li>
 197    <li>aub - dump batches into an AUB trace for use with simulation tools</li>
 198    <li>bat - emit batch information</li>
 199    <li>blit - emit messages about blit operations</li>
 200    <li>blorp - emit messages about the blorp operations (blits &amp; clears)</li>
 201    <li>buf - emit messages about buffer objects</li>
 202    <li>clip - emit messages about the clip unit (for old gens, includes the CLIP program)</li>
 203    <li>color - use color in output</li>
 204    <li>cs - dump shader assembly for compute shaders</li>
 205    <li>do32 - generate compute shader SIMD32 programs even if workgroup size doesn't exceed the SIMD16 limit</li>
 206    <li>dri - emit messages about the DRI interface</li>
 207    <li>fbo - emit messages about framebuffers</li>
 208    <li>fs - dump shader assembly for fragment shaders</li>
 209    <li>gs - dump shader assembly for geometry shaders</li>
 210    <li>hex - print instruction hex dump with the disassembly</li>
 211    <li>l3 - emit messages about the new L3 state during transitions</li>
 212    <li>miptree - emit messages about miptrees</li>
 213    <li>no8 - don't generate SIMD8 fragment shader</li>
 214    <li>no16 - suppress generation of 16-wide fragment shaders. useful for debugging broken shaders</li>
 215    <li>nocompact - disable instruction compaction</li>
 216    <li>nodualobj - suppress generation of dual-object geometry shader code</li>
 217    <li>norbc - disable single sampled render buffer compression</li>
 218    <li>optimizer - dump shader assembly to files at each optimization pass and iteration that make progress</li>
 219    <li>perf - emit messages about performance issues</li>
 220    <li>perfmon - emit messages about AMD_performance_monitor</li>
 221    <li>pix - emit messages about pixel operations</li>
 222    <li>prim - emit messages about drawing primitives</li>
 223    <li>reemit - mark all state dirty on each draw call</li>
 224    <li>sf - emit messages about the strips &amp; fans unit (for old gens, includes the SF program)</li>
 225    <li>shader_time - record how much GPU time is spent in each shader</li>
 226    <li>spill_fs - force spilling of all registers in the scalar backend (useful to debug spilling code)</li>
 227    <li>spill_vec4 - force spilling of all registers in the vec4 backend (useful to debug spilling code)</li>
 228    <li>state - emit messages about state flag tracking</li>
 229    <li>submit - emit batchbuffer usage statistics</li>
 230    <li>sync - after sending each batch, emit a message and wait for that batch to finish rendering</li>
 231    <li>tcs - dump shader assembly for tessellation control shaders</li>
 232    <li>tes - dump shader assembly for tessellation evaluation shaders</li>
 233    <li>tex - emit messages about textures.</li>
 234    <li>urb - emit messages about URB setup</li>
 235    <li>vert - emit messages about vertex assembly</li>
 236    <li>vs - dump shader assembly for vertex shaders</li>
 237 </ul>
 238 <li>INTEL_SCALAR_VS (or TCS, TES, GS) - force scalar/vec4 mode for a shader stage (Gen8-9 only)</li>
 239 <li>INTEL_PRECISE_TRIG - if set to 1, true or yes, then the driver prefers
 240    accuracy over performance in trig functions.</li>
 241 </ul>
 242
 243
 244 <h2>Radeon driver environment variables (radeon, r200, and r300g)</h2>
 245
 246 <ul>
 247 <li>RADEON_NO_TCL - if set, disable hardware-accelerated Transform/Clip/Lighting.
 248 </ul>
 249
 250
 251 <h2>EGL environment variables</h2>
 252
 253 <p>
 254 Mesa EGL supports different sets of environment variables.  See the
 255 <a href="egl.html">Mesa EGL</a> page for the details.
 256 </p>
 257
 258
 259 <h2>Gallium environment variables</h2>
 260
 261 <ul>
 262 <li>GALLIUM_HUD - draws various information on the screen, like framerate,
 263     cpu load, driver statistics, performance counters, etc.
 264     Set GALLIUM_HUD=help and run e.g. glxgears for more info.
 265 <li>GALLIUM_HUD_PERIOD - sets the hud update rate in seconds (float). Use zero
 266     to update every frame. The default period is 1/2 second.
 267 <li>GALLIUM_HUD_VISIBLE - control default visibility, defaults to true.
 268 <li>GALLIUM_HUD_TOGGLE_SIGNAL - toggle visibility via user specified signal.
 269     Especially useful to toggle hud at specific points of application and
 270     disable for unencumbered viewing the rest of the time. For example, set
 271     GALLIUM_HUD_VISIBLE to false and GALLIUM_HUD_TOGGLE_SIGNAL to 10 (SIGUSR1).
 272     Use kill -10 &lt;pid&gt; to toggle the hud as desired.
 273 <li>GALLIUM_HUD_DUMP_DIR - specifies a directory for writing the displayed
 274     hud values into files.
 275 <li>GALLIUM_DRIVER - useful in combination with LIBGL_ALWAYS_SOFTWARE=true for
 276     choosing one of the software renderers "softpipe", "llvmpipe" or "swr".
 277 <li>GALLIUM_LOG_FILE - specifies a file for logging all errors, warnings, etc.
 278     rather than stderr.
 279 <li>GALLIUM_PRINT_OPTIONS - if non-zero, print all the Gallium environment
 280     variables which are used, and their current values.
 281 <li>GALLIUM_DUMP_CPU - if non-zero, print information about the CPU on start-up
 282 <li>TGSI_PRINT_SANITY - if set, do extra sanity checking on TGSI shaders and
 283     print any errors to stderr.
 284 <LI>DRAW_FSE - ???
 285 <LI>DRAW_NO_FSE - ???
 286 <li>DRAW_USE_LLVM - if set to zero, the draw module will not use LLVM to execute
 287     shaders, vertex fetch, etc.
 288 <li>ST_DEBUG - controls debug output from the Mesa/Gallium state tracker.
 289 Setting to "tgsi", for example, will print all the TGSI shaders.
 290 See src/mesa/state_tracker/st_debug.c for other options.
 291 </ul>
 292
 293 <h3>Clover state tracker environment variables</h3>
 294
 295 <ul>
 296 <li>CLOVER_EXTRA_BUILD_OPTIONS - allows specifying additional compiler and linker
 297     options. Specified options are appended after the options set by the OpenCL
 298     program in clBuildProgram.
 299 <li>CLOVER_EXTRA_COMPILE_OPTIONS - allows specifying additional compiler
 300     options. Specified options are appended after the options set by the OpenCL
 301     program in clCompileProgram.
 302 <li>CLOVER_EXTRA_LINK_OPTIONS - allows specifying additional linker
 303     options. Specified options are appended after the options set by the OpenCL
 304     program in clLinkProgram.
 305 </ul>
 306
 307
 308 <h3>Softpipe driver environment variables</h3>
 309 <ul>
 310 <li>SOFTPIPE_DUMP_FS - if set, the softpipe driver will print fragment shaders
 311     to stderr
 312 <li>SOFTPIPE_DUMP_GS - if set, the softpipe driver will print geometry shaders
 313     to stderr
 314 <li>SOFTPIPE_NO_RAST - if set, rasterization is no-op'd.  For profiling purposes.
 315 <li>SOFTPIPE_USE_LLVM - if set, the softpipe driver will try to use LLVM JIT for
 316     vertex shading processing.
 317 </ul>
 318
 319
 320 <h3>LLVMpipe driver environment variables</h3>
 321 <ul>
 322 <li>LP_NO_RAST - if set LLVMpipe will no-op rasterization
 323 <li>LP_DEBUG - a comma-separated list of debug options is accepted.  See the
 324     source code for details.
 325 <li>LP_PERF - a comma-separated list of options to selectively no-op various
 326     parts of the driver.  See the source code for details.
 327 <li>LP_NUM_THREADS - an integer indicating how many threads to use for rendering.
 328     Zero turns off threading completely.  The default value is the number of CPU
 329     cores present.
 330 </ul>
 331
 332 <h3>VMware SVGA driver environment variables</h3>
 333 <ul>
 334 <li>SVGA_FORCE_SWTNL - force use of software vertex transformation
 335 <li>SVGA_NO_SWTNL - don't allow software vertex transformation fallbacks
 336 (will often result in incorrect rendering).
 337 <li>SVGA_DEBUG - for dumping shaders, constant buffers, etc.  See the code
 338 for details.
 339 <li>SVGA_EXTRA_LOGGING - if set, enables extra logging to the vmware.log file,
 340 such as the OpenGL program's name and command line arguments.
 341 <li>See the driver code for other, lesser-used variables.
 342 </ul>
 343
 344 <h3>WGL environment variables</h3>
 345 <ul>
 346 <li>WGL_SWAP_INTERVAL - to set a swap interval, equivalent to calling
 347 wglSwapIntervalEXT() in an application.  If this environment variable
 348 is set, application calls to wglSwapIntervalEXT() will have no effect.
 349 </ul>
 350
 351 <h3>VA-API state tracker environment variables</h3>
 352 <ul>
 353 <li>VAAPI_MPEG4_ENABLED - enable MPEG4 for VA-API, disabled by default.
 354 </ul>
 355
 356
 357 <h3>VC4 driver environment variables</h3>
 358 <ul>
 359 <li>VC4_DEBUG - a comma-separated list of named flags, which do various things:
 360 <ul>
 361    <li>cl - dump command list during creation</li>
 362    <li>qpu - dump generated QPU instructions</li>
 363    <li>qir - dump QPU IR during program compile</li>
 364    <li>nir - dump NIR during program compile</li>
 365    <li>tgsi - dump TGSI during program compile</li>
 366    <li>shaderdb - dump program compile information for shader-db analysis</li>
 367    <li>perf - print during performance-related events</li>
 368    <li>norast - skip actual hardware execution of commands</li>
 369    <li>always_flush - flush after each draw call</li>
 370    <li>always_sync - wait for finish after each flush</li>
 371    <li>dump - write a GPU command stream trace file (VC4 simulator only)</li>
 372 </ul>
 373 </ul>
 374
 375
 376 <p>
 377 Other Gallium drivers have their own environment variables.  These may change
 378 frequently so the source code should be consulted for details.
 379 </p>
 380
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