[Xen-devel] Re: AMD IOMMU intremap tables and IOAPICs

[Wei Wang2 <wei.wang2@xxxxxxx>]

On Tuesday 06 September 2011 17:47:59 George Dunlap wrote:
> Wei,
>
> Quick question:  Am I reading the code correctly, that even with
> per-device interrupt remap tables, that GSIs are accounted to the
> intremap table of the corresponding IOAPIC, presumably because the
> IOMMU sees interrupts generated as GSIs as coming from the IOAPIC?  In
> that case, then we need all devices sharing the same IOAPIC must not
> have any vector collisions.  Is that correct?
>
>  -George

That is true.  All legacy devices have to send interrupts to IOMMU via IOAPIC. 
So even we use per-device table. All devices attached to the same IOAPIC will 
use the same interrupt table. There should be no vector collisions. 
Per-device table only makes sense for MSI devices or systems with multiple 
IOAPICs.

Thanks
Wei


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