--- Vladimir Dergachev <[EMAIL PROTECTED]> wrote:
> As far as acceleration - either 2d or 3d - it makes sense for it to stay
> in userspace.
X and everything else needs to stop mapping the registers to user space and
instead start using an IOCTL interface to a driver. The problem is that X or
whatever sets a bunch of register values. Then a VT swap happens and something
else writes all over those register values. The kernel driver is needed to track
this state and restore it on VT swap.
Simple example, DRM starts GPU coprocessor running. VT swap happens. New user
stops coprocessor. VT swap back to DRM. Now DRM thinks it left the coprocessor
running but that's not true now. DRM and FB conflict when FB is using the
coprocessor for accelerated text.
We can tell everyone to implement save/restore functions for VT swap. But the
save/restore function for DRM is going to have to save all of the registers,
VRAM, AGP space, coprocessor state, etc. This is a huge amount of state to save.
It is much better to have a common driver. With a common driver the state
save/restore problem goes away. Timesharing device drivers on the graphics
hardware at VT swap is a very broken design.
=====
Jon Smirl
[EMAIL PROTECTED]
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