It's easier with a compositor. And you could even support the non-composited case by emulating a composited environment in the driver. In that case you could store the backing pixmaps wherever it makes the most sense (vram or system ram) and then use the GPU to composite the final image. For CPU rendered buffers you'd still need to migrate them to pinned memory for the GPU to access them, but you could keep the shadow front buffer in pinned memory. There are also some tricky corner cases to deal with. It's possible, but it basically comes down to writing a new acceleration architecture which would take time to write and mature. Before going down that road I think it makes sense to see what can be done with an existing acceleration architecture like glamor.
No announcement yet.
GLAMOR Radeon Shows 2D Acceleration Promise