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