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10<h1>Environment Variables</h1>
11
12<p>
13Normally, no environment variables need to be set.  Most of the environment
14variables used by Mesa/Gallium are for debugging purposes, but they can
15sometimes be useful for debugging end-user issues.
16</p>
17
18
19<h2>LibGL environment variables</h2>
20
21<ul>
22<li>LIBGL_DEBUG - If defined debug information will be printed to stderr.
23   If set to 'verbose' additional information will be printed.
24<li>LIBGL_DRIVERS_PATH - colon-separated list of paths to search for DRI drivers
25<li>LIBGL_ALWAYS_INDIRECT - forces an indirect rendering context/connection.
26<li>LIBGL_ALWAYS_SOFTWARE - if set, always use software rendering
27<li>LIBGL_NO_DRAWARRAYS - if set do not use DrawArrays GLX protocol (for debugging)
28</ul>
29
30
31
32<h2>Core Mesa environment variables</h2>
33
34<ul>
35<li>MESA_NO_ASM - if set, disables all assembly language optimizations
36<li>MESA_NO_MMX - if set, disables Intel MMX optimizations
37<li>MESA_NO_3DNOW - if set, disables AMD 3DNow! optimizations
38<li>MESA_NO_SSE - if set, disables Intel SSE optimizations
39<li>MESA_DEBUG - if set, error messages are printed to stderr.  For example,
40   if the application generates a GL_INVALID_ENUM error, a corresponding error
41   message indicating where the error occured, and possibly why, will be
42   printed to stderr.<br>
43   If the value of MESA_DEBUG is 'FP' floating point arithmetic errors will
44   generate exceptions.
45<li>MESA_LOG_FILE - specifies a file name for logging all errors, warnings,
46etc., rather than stderr
47<li>MESA_TEX_PROG - if set, implement conventional texture env modes with
48fragment programs (intended for developers only)
49<li>MESA_TNL_PROG - if set, implement conventional vertex transformation
50operations with vertex programs (intended for developers only).
51Setting this variable automatically sets the MESA_TEX_PROG variable as well.
52<li>MESA_EXTENSION_OVERRIDE - can be used to enable/disable extensions.
53A value such as "GL_EXT_foo -GL_EXT_bar" will enable the GL_EXT_foo extension
54and disable the GL_EXT_bar extension.
55<li>MESA_EXTENSION_MAX_YEAR - The GL_EXTENSIONS string returned by Mesa is sorted
56by extension year.
57If this variable is set to year X, only extensions defined on or before year
58X will be reported.
59This is to work-around a bug in some games where the extension string is
60copied into a fixed-size buffer without truncating.
61If the extension string is too long, the buffer overrun can cause the game
62to crash.
63This is a work-around for that.
64<li>MESA_GL_VERSION_OVERRIDE - changes the value returned by
65glGetString(GL_VERSION). Valid values are point-separated version numbers,
66such as "3.0". Mesa will not really implement all the features of the given
67version if it's higher than what's normally reported.
68<li>MESA_GLSL_VERSION_OVERRIDE - changes the value returned by
69glGetString(GL_SHADING_LANGUAGE_VERSION). Valid values are integers, such as
70"130".  Mesa will not really implement all the features of the given language version
71if it's higher than what's normally reported. (for developers only)
72<li>MESA_GLSL - <a href="shading.html#envvars">shading language compiler options</a>
73</ul>
74
75
76<h2>Mesa Xlib driver environment variables</h2>
77
78<p>
79The following are only applicable to the Mesa Xlib software driver.
80See the <a href="xlibdriver.html">Xlib software driver page</a> for details.
81</p>
82<ul>
83<li>MESA_RGB_VISUAL - specifies the X visual and depth for RGB mode
84<li>MESA_CI_VISUAL - specifies the X visual and depth for CI mode
85<li>MESA_BACK_BUFFER - specifies how to implement the back color buffer,
86    either "pixmap" or "ximage"
87<li>MESA_GAMMA - gamma correction coefficients for red, green, blue channels
88<li>MESA_XSYNC - enable synchronous X behavior (for debugging only)
89<li>MESA_GLX_FORCE_CI - if set, force GLX to treat 8bpp visuals as CI visuals
90<li>MESA_GLX_FORCE_ALPHA - if set, forces RGB windows to have an alpha channel.
91<li>MESA_GLX_DEPTH_BITS - specifies default number of bits for depth buffer.
92<li>MESA_GLX_ALPHA_BITS - specifies default number of bits for alpha channel.
93</ul>
94
95
96<h2>i945/i965 driver environment variables (non-Gallium)</h2>
97
98<ul>
99<li>INTEL_STRICT_CONFORMANCE - if set to 1, enable sw fallbacks to improve
100    OpenGL conformance.  If set to 2, always use software rendering.
101<li>INTEL_NO_BLIT - if set, disable hardware-accelerated glBitmap,
102    glCopyPixels, glDrawPixels.
103</ul>
104
105
106<h2>Radeon driver environment variables (radeon, r200, and r300g)</h2>
107
108<ul>
109<li>RADEON_NO_TCL - if set, disable hardware-accelerated Transform/Clip/Lighting.
110</ul>
111
112
113<h2>EGL environment variables</h2>
114
115<p>
116Mesa EGL supports different sets of environment variables.  See the
117<a href="egl.html">Mesa EGL</a> page for the details.
118</p>
119
120
121<h2>Gallium environment variables</h2>
122
123<ul>
124<li>GALLIUM_LOG_FILE - specifies a file for logging all errors, warnings, etc.
125    rather than stderr.
126<li>GALLIUM_PRINT_OPTIONS - if non-zero, print all the Gallium environment
127    variables which are used, and their current values.
128<li>GALLIUM_NOSSE - if non-zero, do not use SSE runtime code generation for
129    shader execution
130<li>GALLIUM_NOPPC - if non-zero, do not use PPC runtime code generation for
131    shader execution
132<li>GALLIUM_DUMP_CPU - if non-zero, print information about the CPU on start-up
133<li>TGSI_PRINT_SANITY - if set, do extra sanity checking on TGSI shaders and
134    print any errors to stderr.
135<LI>DRAW_FSE - ???
136<LI>DRAW_NO_FSE - ???
137<li>DRAW_USE_LLVM - if set to zero, the draw module will not use LLVM to execute
138    shaders, vertex fetch, etc.
139</ul>
140
141<h3>Softpipe driver environment variables</h3>
142<ul>
143<li>SOFTPIPE_DUMP_FS - if set, the softpipe driver will print fragment shaders
144    to stderr
145<li>SOFTPIPE_DUMP_GS - if set, the softpipe driver will print geometry shaders
146    to stderr
147<li>SOFTPIPE_NO_RAST - if set, rasterization is no-op'd.  For profiling purposes.
148<li>SOFTPIPE_USE_LLVM - if set, the softpipe driver will try to use LLVM JIT for
149    vertex shading procesing.
150</ul>
151
152
153<h3>LLVMpipe driver environment variables</h3>
154<ul>
155<li>LP_NO_RAST - if set LLVMpipe will no-op rasterization
156<li>LP_DEBUG - a comma-separated list of debug options is acceptec.  See the
157    source code for details.
158<li>LP_PERF - a comma-separated list of options to selectively no-op various
159    parts of the driver.  See the source code for details.
160<li>LP_NUM_THREADS - an integer indicating how many threads to use for rendering.
161    Zero turns of threading completely.  The default value is the number of CPU
162    cores present.
163</ul>
164
165
166<p>
167Other Gallium drivers have their own environment variables.  These may change
168frequently so the source code should be consulted for details.
169</p>
170
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