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Re: [Xen-devel] ARM Generic Timer interrupt

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.

> 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

It may be better to let either QNX use physical timer (AFAIK it's
working out-of-box), or modifying to support virtual timer.


Julien Grall

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