Re: [Xen-devel] [PATCH 0/3] x2APIC improvement

[Weidong Han <weidong.han@xxxxxxxxx>]

Konrad Rzeszutek Wilk wrote:
> On Wed, Jul 07, 2010 at 01:09:08PM +0800, Weidong Han wrote:
>   
> > Konrad Rzeszutek Wilk wrote:
> >     
> > > On Mon, Jul 05, 2010 at 03:07:58PM +0800, Han, Weidong wrote:
> > >       
> > > > The patchset improves Xen x2APIC support.
> > > >
> > > > Patch 1/3: allocate iommu when create a drhd
> > > >         A drhd is created when parse ACPI DMAR table, but drhd->iommu is not 
> > > > allocated until iommu setup. But iommu is needed by x2APIC which will enable interrupt 
> > > > remapping before iommu setup. This patch allocates iommu when create drhd. And then 
> > > > drhd->ecap can be removed because it's the same as iommu->ecap.
> > > >
> > > >         
> > > Have these patches been tested on a machine where the number of DRHD !=
> > > number of IOAPICs?
> > >
> > >       
> > Why need to care about number of DRHD != number of IOAPICs? One DRHD
> > may cover more than one IOAPICs. And there is already check if all
> >     
> And the inverse might be true as well - in which case we should disable
> x2APIC.
>
>   
Each IOAPIC must have a corresponding DRHD, but a DRHD maybe don't have 
a IOAPIC in its device scope. So it won't enable x2APIC if there is any 
IOAPIC which doesn't have corresponding DRHD.
> > IOAPICs have corresponding DRHD.
> >     
> I understand. I am asking whether these patches have not changed that
> behavior and whether you have tested for that.
>   
These patches don't change that behavior.

Regards,
Weidong


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