I know that X runs suid root, but I think that processes even when suid
root have to call an ioperm system call for these io-addresses which
they want to use. So when X has access only to the addresses of the
graphics card, it should receive SIGSEGV when trying to write to the
timer. Maybe I am wrong. But I think even a root process shouldn't have
the rights to write to anywhere by default until it has asked the kernel
for permissions to do that for a specified adress space.
Greetings, Michael
PS: After fixing the bug in my X-server, my system runs OK now. Thank
you all for your help.
Steve Dodd wrote:
>
> On Wed, Apr 21, 1999 at 02:48:54PM +0200, Michael Mess wrote:
>
> > I still don't understand how X can make the clock running slow. I think
> > that the kernel should not allow programs to mess up the system timings.
>
> X has to run setuid root to allow it to access the graphics card. So it can
> do anything. Presumably the framebuffer X server doesn't need to be setuid
> root, as long as it has permissions on the framebuffer device?
>
> --
> There was a young man of St. John's / Who wanted to bugger the swans. /
> But the loyal hall porter / Said, "Pray take my daughter! /
> Those birds are reserved for the dons."
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