> So you end up with a module that creates a /dev/Xgraphics device
> [using the gift of dev_fs (-: ] which does all your mode switches.
> The X server opens this device and instructs it to change modes,
> do some acceleration, whatever.
Yes, that's stable[1] and secure, but the overhead of a kernel trap for
each acceleration command would make it very slow compared with the
current XFrees.
And allowing userspace access to mmio registers is not an option, because
for many, if not most, PC (and - thanks to the wonders of PCI - Alpha,
PPC, etc) video cards, unless the kernel traps and emulates all of these
accesses (even worse), there is no way that it can restore a sane state.
Only on low-end (dumb framebuffer) or high-end (context-enabled card)
hardware is this an option, and those cases are the ones which the
current situation works well for...
Matthew.
[1] As stable as the driver is, anyway.
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