Re: kill -9 <pid of X>

Kragen (kragen@pobox.com)
Wed, 12 Aug 1998 13:14:39 -0400 (EDT)

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On Wed, 12 Aug 1998, Jon M. Taylor wrote:
> On 12 Aug 1998, Linus Torvalds wrote:
> > So "that's not the kernel's job" is correct.
>
> I stand by my claim. If userspace cannot, by its nature, properly
> guarantee the atomicity of those critical sections, video card programming
> cannot be done properly in userspace. Thus, it *is* the kernel's job.

Remember, we're talking about defending against signals from a hostile
root who wants to crash the video card. In this scenario, not even the
kernel can do it -- root can install a kernel module which overwrites
the CLI instruction in the "atomic" code with a NOP. It's a little
more work than "killall -9 XF86_SVGA".

> Sorry> trusting the X server, you convinced me of that. I will NOT buy the X
> server being unable to handle signal 9 correctly.

Boy, it's no wonder Linus is grumpy these days.

Kragen

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