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SubjectRe: VMI Interface Proposal Documentation for I386, Part 5
Pavel Machek wrote:
>> from the hypervisor perspective - if the guest enables interrupts, and
>> you have something pending to deliver, for correctness, you have to
>> deliver it, right now. But does the kernel truly require that interrupt
>> deliver immediately - in most cases, no. In particular, on the fast
>>
>
> I'd say PCI hardware can delay interrupts for any arbitrary
> delay... so if driver expects to get them "immediately", I'd say it is
> broken. It should be enough to deliver them "soon enough", like not
> more than 1msec late...
>

I agree. One case we hit that did cause us a bug was local APIC
delivery of self-IPIs. I didn't dig too deep into why Linux was unhappy
without immediate delivery (we deferred delivery here unnecessarily, but
did not stop it). I believe this was in SMP specific code that was
using self-IPIs to regenerate IRQs .

Zach
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