Re: [Xen-devel] [PATCH 5/5] xen/arm: Only enable physical IRQs when the guest asks

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 25 Jun 2013, Julien Grall wrote:
> On 06/25/2013 05:19 PM, Stefano Stabellini wrote:
> 
> > On Tue, 25 Jun 2013, Julien Grall wrote:
> >> If the guest VCPU receives an interrupts when it's disabled, it will throw
> >                                    ^interrupt
> > 
> >> away the IRQ with EOIed it.
> > 
> > What does this mean? I cannot parse the sentence.
> 
> "it will throw away the IRQ without EOIing".
> 
> > 
> >> This is result to lost IRQ forever.
> >> Directly EOIed the interrupt doesn't help because the IRQ could be fired
> >> again and result to an infinited loop.
> >>
> >> It happens during dom0 boot on the versatile express TC2 with the ethernet
> >> card.
> >>
> >> Let the interrupt disabled when Xen setups the route and enable it when 
> >> Linux
> >> asks to enable it.
> > 
> > Is the problem that Xen keeps the interrupt enabled even when Linux
> > disables it at the gic level? Is this what this patch is trying to
> > address?
> 
> This patch only delays the physical IRQ activation until Linux will
> enable it. This patch avoids to lose IRQ when a VCPU is disabled.
> 
> I tried to also disable the IRQ when Linux asks to disable it but the
> versatile express platform hang.

do you know why? and the arndale?

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