Here's the issue, as I understand it...
To get reasonable graphics performance, you can't afford system calls.
So the X server has, from the beginning, mapped the graphics hardware
into its address space, and directly manipulated them itself. Trust us,
this is really true.... X does *MILLIONS* of operations/second on current
hardware.
Ok, in principle this isn't a killer: sanely designed graphics and computer
hardware would (and has on occasion) no way to touch memory except that
of the processes using it.
Unfortunatly, most PC graphics hardware is not sane: the AGP bus gives
you the opportunity (if you are hardware) to do just about anything you
like to any byte of your physical RAM.
So if you have access to the graphics hardware, you have license to
write any byte in physical memory, and therefore are the moral equivalent
of the kernel (i.e. root).
Now, we can have a discussion (best on LKML), whether something other
UID than root might have merit, but don't kid yourself, on the hardware
you have, it would have the same effect in reality.
So this is an artifact of PC hardware, not X (X would be happy to have
a UID of its own, so long as it can get at the hardware).
- Jim
--
Jim Gettys
Cambridge Research Laboratory
Compaq Computer Corporation
[EMAIL PROTECTED]
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