Re: [Xen-devel] Intel: Overly restrictive test for availablility

Correcting Jun's email which is back-to-front in the Signed-off-by.

On Tue, 2010-03-02 at 14:01 +0000, Ian Campbell wrote:
> Hi,
> 
> http://xenbits.xensource.com/xen-unstable.hg?rev/aab9fbd6ffa0 from
> http://lists.xensource.com/archives/html/xen-devel/2008-07/msg00518.html
> restricts the CPUID masking feature to model 0x1d or model 0x17 with
> stepping >=4:
>         if (!((model == 0x1d) || ((model == 0x17) && ((eax & 0xf) >=
>         4)))) {
>               /* fail ... */
>         
> A Xeon E5520 which is supposed to have FlexMigration has family 6, model
> 26 (0x1a) and stepping 5 fails the existing test and we think it should
> be allowed.
> 
> Is there a more precise way of detecting the presence of this
> capability? I've seen:
>         family > 0x6 || (model > 0x17 || (model = 0x17 && stepping >= 4))
> suggested but this looks like it matches exactly the same set of
> processors as the "eax < 0x00010674" in the code before aab9fbd6ffa0
> which was apparently too lenient?
> 
> Ian.
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



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