Re: Bugs aren't features: X86_FEATURE_FXSAVE_LEAK

[Andi Kleen <ak@suse.de>]

On Friday 05 May 2006 20:18, H. Peter Anvin wrote:
> Andi Kleen wrote:
> > "H. Peter Anvin" <hpa@zytor.com> writes:
> > 
> >> The recent fix for the AMD FXSAVE information leak had a problematic
> >> side effect.  It introduced an entry in the x86 features vector which
> >> is a bug, not a feature.
> > 
> > It's a non issue because it affects all AMD CPUs (except K5/K6).
> > You'll never find a system where only some CPUs have this problem.
> > 
> 
> It's still wrong architecturally, and we should have a sane way to deal with this as well 
> as other bugs.  This isn't the only bug -- we're getting a decent-size collection of them 
> already -- and not all of them is going to have that particular property.

I'm not very worried because mixing steppings is generally unsupported anyways
and in Linux also doesn't work well with it.

(e.g. my old rig with one CPU FXSAVE capable, one CPU not never worked without
kernel hacks) 

It's probably not worth the effort anyways. The people who build such strange
systems can tweak their kernels for it too.

-Andi