But you don't need SurfaceFlinger to get multicontext GL out of Android GPU drivers... You only need to use the "gralloc" buffer allocator and give EGL an address from there and you can start rendering to the framebuffer or offscreen.

SurfaceFlinger does handle some things like allowing windows to draw directly to the framebuffer when they're unoccluded, but the Linux guys don't care about that (or they would unredirect frontmost windows in their X compositors, which still nobody does, ugh!).

SurfaceFlinger is also pretty immature and featureless for a desktop surface compositor: 1. Only handles 2x2 transforms (+translation) which it expands internally to 4x4 GL matrices. 2. Written entirely around GLESv1 -- no shaders, no complex geometry: no "genie effect" or anything like that. 3. Immature multi-display support. It was literally just added in Android 4.2. Try taking a screenshot of anything that's not display 0. 4. No IPC system, unless you count Binder which has it's own set of problems ("lets make every message be synchronous").

I haven't kept up with Wayland, but I imagine it has a lot of these problems addressed (except for allowing unoccluded windows direct framebuffer access -- almost nobody bothers with that one, even though it's a big win).

Also, someone at Canonical wrote a library, "libhybris" which supposedly could load GL implementations compiled against bionic on a glibc system -- this seems a much more sensible approach to me...