[Xen-devel] Re: [PATCH] [RFC] More fp instructions for realmode emulation (Enables booting OS/2 as a HVM guest on Intel/VT hardware)

[Andi Kleen <andi@xxxxxxxxxxxxxx>]

On Mon, Mar 03, 2008 at 03:00:52PM +0000, Keir Fraser wrote:
> On 3/3/08 14:52, "Andi Kleen" <andi@xxxxxxxxxxxxxx> wrote:
> 
> >> Intel SDM Volume 1 Section 8.6 (?X87 FPU Exception Synchronization?) is 
> >> very
> >> helpful in this regard. It confirms my suspicions, that we will need to 
> >> wrap
> >> the FPU inline asms in some fixup glue. The only exceptions to this rule 
> >> are
> > 
> > Yes you definitely need to. That was a kernel crash bug on native Linux
> > some time ago...
> > 
> > Also you need to do the same for any FXSAVEs/FXRSTORs if you haven't 
> > already.
> 
> FXSAVE/FXRSTOR do not flush pending FPU exceptions, right?

Yes they do not, but there are other ways to make them #GP

-Andi

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