The current version of EGL in Mesa implements EGL 1.4. More information +about EGL can be found at +http://www.khronos.org/egl/.
+ +The Mesa's implementation of EGL uses a driver architecture. The main
+library (libEGL) is window system neutral. It provides the EGL
+API entry points and helper functions for use by the drivers. Drivers are
+dynamically loaded by the main library and most of the EGL API calls are
+directly dispatched to the drivers.
The driver in use decides the window system to support. For drivers that +support hardware rendering, there are usually multiple drivers supporting the +same window system. Each one of of them supports a certain range of graphics +cards.
+ +Run configure with the desired state trackers and and enable
+the Gallium driver for your hardware. For example
+ $ ./configure --with-state-trackers=egl_g3d,es,vega --enable-gallium-intel ++ +
The main library will be enabled by default. The egl_g3d state
+tracker is needed by a number of EGL drivers. EGL drivers will be covered
+later. The es state tracker provides OpenGL ES 1.x
+and 2.x and the vega state tracker provides OpenVG
+1.x.
In the given example, it will build and install libEGL,
+libGLESv1_CM, libGLESv2, libOpenVG, and
+one or more EGL drivers.
There are several options that control the build of EGL at configuration +time
+ +--enable-egl
+
+By default, EGL is enabled. When disabled, the main library and the drivers +will not be built.
+ +--with-egl-displays
+
+List the window system(s) to support. It is by default x11,
+which supports the X Window System. Its argument is a comma separated string
+like, for example, --with-egl-displays=x11,kms. Because an EGL
+driver decides which window system to support, this example will enable two
+(sets of) EGL drivers. One supports the X window system and the other supports
+bare KMS (kernel modesetting).
--with-state-trackers
+
+The argument is a comma separated string. It is usually used to specify the
+rendering APIs, like OpenGL ES or OpenVG, to build. But it should be noted
+that a number of EGL drivers depend on the egl_g3d state tracker.
+They will not be built without the egl_g3d state
+tracker.
The OpenGL state tracker is not built in the above example. It should be
+noted that the classic libGL is not a state tracker and cannot be
+used with EGL (unless the EGL driver in use is egl_glx). To build
+the OpenGL state tracker, one may append glx to
+--with-state-trackers and manually build
+src/gallium/winsys/xlib/.
The demos for OpenGL ES and OpenVG can be found in progs/es1/,
+progs/es2/ and progs/openvg/. You can use them to
+test your build. For example,
+ $ cd progs/es1/xegl + $ make + $ ./torus ++ +
There are several environment variables that control the behavior of EGL at +runtime
+ +EGL_DRIVER
+
+This variable forces the specified EGL driver to be loaded. It comes in +handy when one wants to test a specific driver.
+ +EGL_DISPLAY
+
+When EGL_DRIVER is not set, the main library loads all
+EGL drivers that support a certain window system. EGL_DISPLAY can
+be used to specify the window system and the valid values are, for example,
+x11 or kms. When the variable is not set, the main
+library defaults the value to the first window system listed in
+--with-egl-displays at configuration time.
+
+
EGL_LOG_LEVEL
+
+This changes the log level of the main library and the drivers. The valid
+values are: debug, info, warning, and
+fatal.
EGL_SOFTWARE
+
+For drivers that support both hardware and software rendering, setting this +variable to true forces the use of software rendering.
+ +There are two categories of EGL drivers: Gallium and classic.
+ +Gallium EGL drivers supports all rendering APIs specified in EGL 1.4. The
+support for optional EGL functions and EGL extensions is usually more complete
+than the classic ones. These drivers depend on the egl_g3d state
+tracker to build. The available drivers are
egl_<dpy>_i915egl_<dpy>_i965egl_<dpy>_radeonegl_<dpy>_nouveauegl_<dpy>_vmwgfx<dpy> is given by --with-egl-displays at
+configuration time. There will be one EGL driver for each combination of the
+displays listed and the hardware drivers enabled.
Classic EGL drivers, on the other hand, supports only OpenGL as its
+rendering API. They can be found under src/egl/drivers/. There
+are 3 of them
egl_glx
+
+This driver provides a wrapper to GLX. It uses exclusively GLX to implement +the EGL API. It supports both direct and indirect rendering when the GLX does. +It is accelerated when the GLX is. As such, it cannot provide functions that +is not available in GLX or GLX extensions.
+egl_xdri
+
+This driver supports the X Window System as its window system. It functions
+as a DRI driver loader. Unlike egl_glx, it has no dependency on
+libGL. It talks to the X server directly using DRI or DRI2
+protocols. It also talks minimal GLX protocol for things like available
+visuals or fbconfigs. With direct access to the DRI drivers, it has the
+potential to support more EGL functions that are not possible with
+egl_glx
egl_dri
+
+This driver lacks maintenance and does not build. It is similiar
+to egl_xdri in that it functions as a DRI driver loader. But
+unlike egl_xdri, it supports Linux framebuffer devices as its
+window system and supports EGL_MESA_screen_surface extension. It loads only
+DRI1 drivers. As DRI1 drivers is phasing out, it might be better to rewrite
+the driver to support KMS and DRI2.
To use the classic drivers, one must manually set EGL_DRIVER at
+runtime.
src/egl/. The sources of the egl_g3d state tracker
+can be found at src/gallium/state_trackers/egl_g3d/.
+
+EGL_DISPLAY loads all
+drivers and might eat too much memory.