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Re: [Xen-devel] ARM Generic Timer interrupt

On Tue, 27 May 2014, Julien Grall wrote:
> On 05/27/2014 01:11 PM, Stefano Stabellini wrote:
> > Given that 1) didn't sound right to me, I tried 2) first but I had
> > issues with the ARM emulator at the time.  And as an ulterior
> > confirmation that deactivating it is not how ARM thought that the vtimer
> > should be used, Linux and KVM do 1) too.
> I suspect you had issue on the emulator because VCPU can EOI the timer
> IRQ on another CPU.
> If so, you will disable the vtimer interrupt forever on this CPU.

I don't think so (unless the vcpu is migrated).
Keep in mind that the vtimer is a PPI.

> > But I don't like the idea of having to modify the vtimer handler in QNX,
> > so I have hacked together this patch, that would do 2) on top of my
> > maintenance interrupt series. Unfortunately it needs to ask for a
> > maintenance interrupt for the vtimer interrupt, so I can't say I am
> > completely convinced that it is the right thing to do.
> > 
> > What do people think about this?
> The solution 2) seems very hackish. Hence, this IRQ will be fired very
> often.
> It may be better to let either QNX use physical timer (AFAIK it's
> working out-of-box), or modifying to support virtual timer.

I agree.

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