>> When it comes to talking to the framebuffer, I disagree with you.  I
>> do not believe it would be acceptable to pay a syscall price for
>> every framebuffer operation.

> I don't know which side of the board you're looking at here, but I
> didn't say anything about requiring syscalls for all operations...  :-)

Not explicitly, but you espoused a viewpoint that requires it.

> With a proper device driver interface there's no reason why the
> high-volume I/O's can't be done through mapped addresses and that DMA
> can't happen to/from that memory directly without needing syscalls
> for every operation.

That *is* just giving the user process direct access to the hardware,
which is what I thought you were arguing against.  (I'm not sure what
you're going on about DMA for, though.)  It exposes practically
everything about the device to userland, with the possible exception of
exactly where it lives in the machine's physical address space.

> The point of using a proper device driver instead of just opening
> all/much/most of the hardware and memory up to the Xserver is to
> provide proper control over what process(es) get access to the device
> registers and whatever memory space is used for DMA operations.

If you're arguing against letting the X server at _other_ devices, I
agree with you - and if the XFree86 design demands that, I'm glad I
never went near it, because I'd never stand for anything that
hair-raisingly insecure.

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