X.Org Server Change Allows GLAMOR To Fallback To Software Rendering For Obsolete GPUs

For those trying to use the X.Org Server's GLAMOR accelerated 2D rendering on legacy/obsolete GPUs, there's now a fallback in place to allow software rendering to work when encountering crippled hardware.

The existing behavior for GLAMOR was to throw a fatal error when there is a GLSL linking failure but the change merged today allows for falling back to software rendering with GLAMOR.

Independent contributor Balló György has been pursuing the change for the past half-year to be able to use GLAMOR via software rendering for old systems with limited hardware resources. Namely this can benefit systems with very old graphics like the Intel i915 chipset era (not to be confused with the i915 DRM driver that also supports much newer GPUs) or using the ATI R300 driver.

Basically for old graphics processors / drivers not able to handle GLAMOR correctly, now at least the X.Org Server GLAMOR code will allow falling back to software rendering rather than just a fatal error. György commented on the performance when using this patch on old hardware:

"I'd love to see it merged as it allows Glamor to be used with the i915 Mesa driver and possibly on other legacy hardware with limited shader support. Performance is similar to the Intel DDX driver and I haven't experienced any issues."

Another user also chimed in during the code review:

"I tested it at mesa 23.3.5 and ran it at mesa 24 for a long time, without any problems with i915 Gallium and a fast glamor. At i915 Gallium GL 2.1 again is available. Without this patch glamor still is not activated at this driver!!"

Today the code was finally merged with X.Org developer Matt Turner commenting, "I guess let's merge it and see what happens."