[Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information.

[Jan Kiszka <jan.kiszka@web.de>]

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Paul Brook wrote:
>> The model takes into account that not all interrupt controller are
>> capable to detect missed interrupt (it is possible that there is no
>> interrupt controller at all). In this case irq function should
>> return one and everything will fall back to how it works now.
> 
> On a related note the correct way to fix this is "-icount auto".
> You should make sure that your hacks are not enabled when we have a realistic 
> virtual timebase.

Virtual timebases don't help if the guest has to interact with the real
life - ie. clocks you cannot tweak. In the end, you will have to bring
them in sync again, so this approach basically points in the right
direction.

However, I started to wonder if this model is already enough to handle
the case where QEMU itself looses ticks. At least the PIT should
currently not be able to deal with such issues, so you also won't see
coalesce counters increase. Or am I missing something?

Jan


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