From: Keith W. <ke...@tu...> - 2003-11-06 10:03:09
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Jon Smirl wrote: > --- Eric Anholt <et...@lc...> wrote: > >>This makes me wonder how difficult it would be to get two >>servers to cooperatively share a DRM instance (both of them >>holding the DRM open, rather than the reinit thing done >>before). > > > I'd find this useful. It would let me run X on one VT and the new Mesa-solo > stuff on another while sharing the same DRM. But wouldn't you need a lot more > info, like how memory is getting allocated and which buffer the hardware is > displaying? There is alread a need to notice VT switches and restore state on those switches - this would just be some more state to fix up at that point. In particular, all of the info in the DRM initialization struct could potentially change on VT switches. Currently, the DRI-aware X server grabs the lock and holds it while the VT is switched away, effectively putting the 3d clients to sleep and preventing them om trying to direct-render until the VT is returned. Some new mechanism for this would be required if the X server were to release the lock when releasing the VT. There are problems with releasing the lock: - While existing clients can cope with most video/agp memory being pulled out from under their feet (ie texture memory), some memory is expected to be preserved even while the lock is not held. In particular, DMA buffers and glXAllocateMemoryNV() memory are expected to not be clobbered. Both of these are AGP only at the moment. - ? Any others ? If the drm continues to respect its existing allocations on VT switches, I don't see what is stopping us from running multiple 3D X servers or Mesa-solo's on different VT's with a single card. > For example a windowing system based on pbuffers could make a window full > screen just by telling the video hardware to use a different buffer. The other > DRM client is going to need to know about this. > > A future client could also be a DRI-console that knows how to talk to the DRM. > One solution to the FB/DRM problem is to make an fbconsole equivalent for DRM. Yes, or for the cutdown drm as advocated recently by Linus. Keith |