Re: enable sysenter on 32bit guests

[Avi Kivity <avi@redhat.com>]

On 06/18/2009 08:38 PM, Andrea Arcangeli wrote:
> From: Andrea Arcangeli<aarcange@redhat.com>
>
> model=2 is not existent when vendor is intel and an errata of P6 says
> that any model<= 2 when family is 6 lack sap feature, so windows and
> linux 32bit guests disable sap in software and slowdown for no good
> reason when running inside kvm on intel CPU.
>
> Fix is to set model = 3 so it'll be the duron cpu when kvm runs on amd bare
> metal (not anymore athlon but userland doesn't see the difference) and it'll be
> PII that has sysenter functional like all cpus that run KVM have too when on
> intel bare metal.
>
> Patch will follow, workaround without this fix is -cpu qemu64,model=3.
>
> There is a bug in skype that it checks if the sep feature is set to
> run sysenter on intel chip inside its binary without passing through
> ntdll, without verifying the model was<= 2 like windows does, so
> windows forbids sysenter but skype calls it anyway. This is skype bug
> and it would trigger on real P6 hardware too (but nobody tests skype
> on P6). qemu64,-sep fixed skype. But because every time we have an
> intel cpu running kvm, we also have sysenter functioning, we boots the
> model to 3 so windows 32bit (and linux32bit) gets a boost with
> sysenter too.
>
>    

Please post to qemu-devel since it affects upstream too.

> -        .model = 2,
> +	/* AMD Duron || PII Intel with sep capbility - P6 has no sep */
> +        .model = 3,
>    


But detab it first...

-- 
error compiling committee.c: too many arguments to function