[Xen-devel] Re: FW: about VIRQ & PIRQ

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> > >To understand better, have a look at .../xen/arch/x86/irq.c, and in
> > >particular the function __do_IRQ_guest().
> >
> > But do hvm guests use event channels as used in
> > /xen/arch/x86/irq.c. My thinking was they use emulated pic/apic.
>
> That is correct - the HVM guests use a different principle - although
> there's still an event-channel for the QEMU to signal to the hypervisor
> that there's an interrupt pending so that the hypervisor will "look" at
> the emulated pic/apic.

Additionally, HVM guests can make use of Xen event channels if paravirtualised 
driver support is added to them.  I'm not sure how they actually interface 
with the event channels.

For "normal" HVM guests that don't have any Xen-aware software installed in 
them this is irrelevant.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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