[lkml]   [2003]   [Sep]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata
On Tue, 16 Sep 2003, Dave Jones wrote:

> On Tue, Sep 16, 2003 at 12:46:36PM +0100, Jamie Lokier wrote:
> > > The user space problem worries me more, because the expectation
> > > is that if CPUID says the program can use perfetch, it could
> > > and should regardless of what the kernel decided to do here.
> >
> > If the workaround isn't compiled in, "prefetch" should be removed from
> > /proc/cpuinfo on the buggy chips.
> prefetch isn't a cpuid feature flag. The only way you could do
> what you suggest is by removing '3dnow' or 'sse', which cripples
> things more than necessary.

Good point, and even if it were a separate feature, any code which was
clever enough to use prefetch is likely to check the CPU bits rather
than the /proc anyway. That's a guess, I suspect most programs do
whatever gcc/glibc choose.

If the fixup were not in place, would it be useful to emit a warning
like "you have booted a non-Athlon kernel on an Athlon process, user
programs may get unexpected page faults." That's in init code, hopefully
there is no critical size issue there, I assume, other than how large a
kernel can be booted by the boot loader.

bill davidsen <>
CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:48    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean