3 <title>Mesa EGL
</title>
5 <head><link rel=
"stylesheet" type=
"text/css" href=
"mesa.css"></head>
11 <p>The current version of EGL in Mesa implements EGL
1.4. More information
12 about EGL can be found at
13 <a href=
"http://www.khronos.org/egl/" target=
"_parent">
14 http://www.khronos.org/egl/
</a>.
</p>
16 <p>The Mesa's implementation of EGL uses a driver architecture. The main
17 library (
<code>libEGL
</code>) is window system neutral. It provides the EGL
18 API entry points and helper functions for use by the drivers. Drivers are
19 dynamically loaded by the main library and most of the EGL API calls are
20 directly dispatched to the drivers.
</p>
22 <p>The driver in use decides the window system to support. For drivers that
23 support hardware rendering, there are usually multiple drivers supporting the
24 same window system. Each one of of them supports a certain range of graphics
31 <p>Run
<code>configure
</code> with the desired state trackers and and enable
32 the Gallium driver for your hardware. For example
</p>
35 $ ./configure --with-state-trackers=egl,es,vega --enable-gallium-intel
38 <p>The main library will be enabled by default. The
<code>egl
</code> state
39 tracker is needed by a number of EGL drivers. EGL drivers will be covered
40 later. The
<a href=
"opengles.html">es state tracker
</a> provides OpenGL ES
1.x
41 and
2.x and the
<a href=
"openvg.html">vega state tracker
</a> provides OpenVG
45 <li>Build and install Mesa as usual.
</li>
48 <p>In the given example, it will build and install
<code>libEGL
</code>,
49 <code>libGLESv1_CM
</code>,
<code>libGLESv2
</code>,
<code>libOpenVG
</code>, and
50 one or more EGL drivers.
</p>
52 <h3>Configure Options
</h3>
54 <p>There are several options that control the build of EGL at configuration
58 <li><code>--enable-egl
</code>
60 <p>By default, EGL is enabled. When disabled, the main library and the drivers
61 will not be built.
</p>
65 <li><code>--with-egl-displays
</code>
67 <p>List the window system(s) to support. It is by default
<code>x11
</code>,
68 which supports the X Window System. Its argument is a comma separated string
69 like, for example,
<code>--with-egl-displays=x11,kms
</code>. Because an EGL
70 driver decides which window system to support, this example will enable two
71 (sets of) EGL drivers. One supports the X window system and the other supports
72 bare KMS (kernel modesetting).
</p>
76 <li><code>--with-state-trackers
</code>
78 <p>The argument is a comma separated string. It is usually used to specify the
79 rendering APIs, like OpenGL ES or OpenVG, to build. But it should be noted
80 that a number of EGL drivers depend on the
<code>egl
</code> state tracker.
81 They will
<em>not
</em> be built without the
<code>egl
</code> state tracker.
</p>
85 <li><code>--enable-gallium-swrast
</code>
87 <p>This option is not specific to EGL. But if there is no driver for your
88 hardware, or you are experiencing problems with the hardware driver, you can
89 enable the swrast DRM driver. It is a dummy driver and EGL will fallback to
90 software rendering automatically.
</p>
97 <p>The OpenGL state tracker is not built in the above example. It should be
98 noted that the classic
<code>libGL
</code> is not a state tracker and cannot be
99 used with EGL (unless the EGL driver in use is
<code>egl_glx
</code>). To build
100 the OpenGL state tracker, one may append
<code>glx
</code> to
101 <code>--with-state-trackers
</code> and manually build
102 <code>src/gallium/winsys/xlib/
</code>.
</p>
106 <p> The demos for OpenGL ES and OpenVG can be found in
<code>progs/es1/
</code>,
107 <code>progs/es2/
</code> and
<code>progs/openvg/
</code>. You can use them to
108 test your build. For example,
</p>
116 <h3>Environment Variables
</h3>
118 <p>There are several environment variables that control the behavior of EGL at
122 <li><code>EGL_DRIVER
</code>
124 <p>This variable forces the specified EGL driver to be loaded. It comes in
125 handy when one wants to test a specific driver.
</p>
129 <li><code>EGL_DISPLAY
</code>
131 <p>When
<code>EGL_DRIVER
</code> is not set, the main library loads
<em>all
</em>
132 EGL drivers that support a certain window system.
<code>EGL_DISPLAY
</code> can
133 be used to specify the window system and the valid values are, for example,
134 <code>x11
</code> or
<code>kms
</code>. When the variable is not set, the main
135 library defaults the value to the first window system listed in
136 <code>--with-egl-displays
</code> at configuration time.
140 <li><code>EGL_LOG_LEVEL
</code>
142 <p>This changes the log level of the main library and the drivers. The valid
143 values are:
<code>debug
</code>,
<code>info
</code>,
<code>warning
</code>, and
144 <code>fatal
</code>.
</p>
148 <li><code>EGL_SOFTWARE
</code>
150 <p>For drivers that support both hardware and software rendering, setting this
151 variable to true forces the use of software rendering.
</p>
158 <p>There are two categories of EGL drivers: Gallium and classic.
</p>
160 <p>Gallium EGL drivers supports all rendering APIs specified in EGL
1.4. The
161 support for optional EGL functions and EGL extensions is usually more complete
162 than the classic ones. These drivers depend on the
<code>egl
</code> state
163 tracker to build. The available drivers are
</p>
166 <li><code>egl_
<dpy
>_i915
</code></li>
167 <li><code>egl_
<dpy
>_i965
</code></li>
168 <li><code>egl_
<dpy
>_radeon
</code></li>
169 <li><code>egl_
<dpy
>_nouveau
</code></li>
170 <li><code>egl_
<dpy
>_swrast
</code></li>
171 <li><code>egl_
<dpy
>_vmwgfx
</code></li>
174 <p><code><dpy
></code> is given by
<code>--with-egl-displays
</code> at
175 configuration time. There will be one EGL driver for each combination of the
176 displays listed and the hardware drivers enabled.
</p>
178 <p>Classic EGL drivers, on the other hand, supports only OpenGL as its
179 rendering API. They can be found under
<code>src/egl/drivers/
</code>. There
183 <li><code>egl_glx
</code>
185 <p>This driver provides a wrapper to GLX. It uses exclusively GLX to implement
186 the EGL API. It supports both direct and indirect rendering when the GLX does.
187 It is accelerated when the GLX is. As such, it cannot provide functions that
188 is not available in GLX or GLX extensions.
</p>
191 <li><code>egl_xdri
</code>
193 <p>This driver supports the X Window System as its window system. It functions
194 as a DRI driver loader and can load DRI/DRI2/DRISW drivers. Unlike
195 <code>egl_glx
</code>, it has no dependency on
<code>libGL
</code>. It talks to
196 the X server directly using DRI or DRI2 protocols. It also talks minimal GLX
197 protocol for things like available visuals or fbconfigs. With direct access to
198 the DRI drivers, it has the potential to support more EGL functions that are
199 not possible with
<code>egl_glx
</code>.
</p>
202 <li><code>egl_dri
</code>
204 <p>This driver lacks maintenance and does
<em>not
</em> build. It is similiar
205 to
<code>egl_xdri
</code> in that it functions as a DRI driver loader. But
206 unlike
<code>egl_xdri
</code>, it supports Linux framebuffer devices as its
207 window system and supports EGL_MESA_screen_surface extension. It loads only
208 DRI1 drivers. As DRI1 drivers is phasing out, it might be better to rewrite
209 the driver to support KMS and DRI2.
</p>
214 <p>To use the classic drivers, one must manually set
<code>EGL_DRIVER
</code> at
219 The sources of the main library and the classic drivers can be found at
220 <code>src/egl/
</code>. The sources of the
<code>egl
</code> state tracker can
221 be found at
<code>src/gallium/state_trackers/egl/
</code>.
226 <li>Thread safety
</li>
227 <li>Pass the conformance tests
</li>
228 <li>Better automatic driver selection:
<code>EGL_DISPLAY
</code> loads all
229 drivers and might eat too much memory.
</li>