Shared kernel graphics buffers in main or memory mapped framebuffer device memory are one thing (common in the early 80's, i.e. 1982 SunView using /dev/fb), but

Shared kernel graphics buffers in main or memory mapped framebuffer device memory are one thing (common in the early 80's, i.e. 1982 SunView using /dev/fb), but does it expose modern shared GPU texture buffers to multiple processes, which are a whole other ball game, and orders of magnitude more efficient, by not requiring ping-ponging pixels back and forth between the CPU and GPU when drawing and compositing or crossing process boundaries?