Re: [Xen-devel] [query] gic_set_lr always uses maintenance Interrupt

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Please don't top post as it makes it harder to follow the conversation.

On Thu, 7 Nov 2013, Mj Embd wrote:
> A few thoughts are circling around my mind, don't know how much
> interrupt latency would it have.
> 
> Rather than the hypervisor entry when guest does EOI, a late / lazy
> checkin on LR's can be done
>  on next hypervisor entry by
> a) guest doing something and trapping to hypervisor
> b) schedular timer in hypervisor
> 
> What do you think on this...

It might work.
One key issue is how to identify that the guest EOIed a particular irq
and henceforth the corresponding LR can be reused.
I hope that the status bits in the LR register reflect this condition.
Maybe the status becomes 00 invalid after the guest does EOI? Otherwise
I can't really see how we could make it work.

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