Mesa 23.3 Adds EGL Explicit Device Support

One of the latest feature additions for next quarter's Mesa 23.3 release of these open-source user-space graphics driver components is adding support for the EGL explicit device extension.

A patch originally authored five years ago by Red Hat's Adam Jackson was merged for exposing the EGL_EXT_explicit_device extension. Robert Foss carried the work forward and got the code merged.

The EGL explicit device extension is around allowing the game/application to specify the desired GPU in cases of multiple GPU devices natively supporting EGL. The Khronos Registry spec describes EGL_EXT_explicit_device as:

A system may support rendering with multiple devices for the same windowing system. In that case, an EGL implementation must select a default device based on the native display.

This extension allows an application to explicitly request a device to use for rendering instead of the implementation's default.

This differs from EGL_EXT_platform_device in that EGL_EXT_platform_device uses an EGLDeviceEXT instead of a native display. Thus, EGL_EXT_platform_device allows offscreen rendering to a pbuffer or FBO, but it does not require or use a windowing system, and thus does not allow pixmap or window surfaces.

Using EGL_EXT_explicit_device with EGL_MESA_platform_surfaceless is functionally identical to EGL_EXT_platform_device.

This EGL extension was originally authored by Adam Jackson along with other open-source developers Nicolai Haehnle and Daniel Stone along with Kyle Brenneman of NVIDIA's Linux graphics team.