RE: [konrad.wilk@xxxxxxxxxx: [Xen-devel] [PATCH 1 of 1] Intel VT-D: Don't turn x2APIC if there is a missing DRHD entry for the IOAPIC]

["Cui, Dexuan" <dexuan.cui@xxxxxxxxx>]

Hi Konrad,
Thanks for the patch! (Sorry for the late reply --  I was on leave...)
BTW, the same sanity checking code also appears in init_vtd_hw(). Maybe we 
could write a function for the check to remove the duplication in future. :-)

Thanks,
-- Dexuan 

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Konrad Rzeszutek 
Wilk
Sent: 2010年3月10日 23:38
To: Zhang, Xiantao
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [konrad.wilk@xxxxxxxxxx: [Xen-devel] [PATCH 1 of 1] Intel VT-D: 
Don't turn x2APIC if there is a missing DRHD entry for the IOAPIC]

On Wed, Mar 10, 2010 at 04:42:19PM +0800, Zhang, Xiantao wrote:
> Jan Beulich wrote:
> >>>> Konrad Rzeszutek Wilk  03/09/10 6:34 PM >>>
> >> 
> >> What are you guys feeling about this patch?
> > 
> > My main question is whether just disabling x2apic in this case is
> > sufficient (i.e. whether instead we shouldn't disable iommu, or at
> > least interrupt remapping, altogether).  
> 
> iommu_enable is called after this point, and it also has sanity-check to 
> determine whether enable or disable iommu and its related features. This 
> early check is only used to determine whether to enable x2apic because it 
> must  be enabled at very early time if supported.

Exactly. So the x2APIC is turned off here and then later on the
Interrupt Remaping is turned off as well.

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