Re: [Xen-devel] Enabling VT-d PI by default

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.04.17 at 02:59, <chao.gao@xxxxxxxxx> wrote:
> As you know, with VT-d PI enabled, hardware can directly deliver external
> interrupts to guest without any VMM intervention. It will reduces overall
> interrupt latency to guest and reduces overheads otherwise incurred by the
> VMM for virtualizing interrupts. In my mind, it's an important feature to
> interrupt virtualization.
> 
> But VT-d PI feature is disabled by default on Xen for some corner
> cases and bugs. Based on Feng's work, we have fixed those corner
> cases related to VT-d PI. Do you think it is a time to enable VT-d PI by
> default. If no, could you list your concerns so that we can resolve them?

I don't recall you addressing the main issue (blocked vCPU-s list
length; see the comment next to the iommu_intpost definition).

Jan


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