Re: VIA Ezra CentaurHauls

[Guennadi Liakhovetski]

On Wed, 18 Jun 2003 [e-mail] wrote:
> Guennadi Liakhovetski wrote:
> > We have a platform with the above processor, and we happened to have 2
> > revisions thereof: stepping 8 and 10. With stepping 8 we are getting
> > "random" application crashes (segfaults), sometimes with kernel-Oopses.
> > The distribution is Debian-Woody.
>
> Interesting, so stepping 10 is OK?

Looks so.

> > I saw some messages on the Debian
> > mailing list about problems with exactly this CPU, however, it was not
> > related to different revisions (stepping), perhaps, the author only had
> >  / tried stepping 8. The fix was to upgrade libc.
>
> so is it a glibc bug or CPU bug?

Good question...

> > I've done this (to version libc6_2.3.1-16, but it didn't help. Any ideas?
>
> You could search for CMOV instructions on your system,
> which could cause wierdness, like:
>
> find / -perm +111 -type f |
> while read bin; do
>      objdump --disassemble $bin 2>/dev/null |
>      grep -q cmov && echo "$bin has cmov"
> done

Yeah, will try. Plus libraries...

> Note C3 Nehemiah do have CMOV (but no 3dnow).

Meanwhile, I've written a micro-program with an assembly-inline with cmov.
I have no idea about the ix86 assembly, so, I've just done

int main(void)
{
	int x=0,y=1;

	__asm__(
	"testl	%0, %0\n"
"	cmovnz	%0, %1":"=r" (x) :"r" (y));
	exit(x);
}

On "10" the exit code is 1, which is correct (?), on "8" the exit code is
76. Funny enough, strace on "8" produces also
semget(2, 1074927648, 0)                = -1 ENOSYS (Function not implemented)
but this, most probably, comes from the new libc6, that I installed there.

Guennadi
---------------------------------
Guennadi Liakhovetski, Ph.D.
DSA Daten- und Systemtechnik GmbH
Pascalstr. 28
D-52076 Aachen
Germany