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

[Jan Kiszka]

Paul Brook wrote:
> On Sunday 29 June 2008, Jan Kiszka wrote:
>> 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.
> 
> That's exactly what -icount auto does. It gradually varies the virtual clock 
> rate to keep it in line with the outside world. You get some clock skew, but 
> that true whatever you do (including the proposed patch).

Interesting. This seems to require a closer look, and maybe some
quantification of the potential overhead.

Jan

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