Re: [Qemu-devel] Re: [RFT][PATCH 07/15] qemu_irq: Add IRQ handlers with delivery feedback

[Gleb Natapov]

On Sat, May 29, 2010 at 09:35:30AM +0000, Blue Swirl wrote:
> > I still don't see how the alternative is supposed to simplify our life
> > or improve the efficiency of the de-coalescing workaround. It's rather
> > problematic like Gleb pointed out: The de-coalescing logic needs to be
> > informed about periodicity changes that can only be delivered along
> > IRQs. So what to do with the backlog when the timer is stopped?
> 
> What happens with the current design? Gleb only mentioned the
> frequency change, I thought that was not so big problem. But I don't
> think this case should be allowed happen at all, it can't exist on
> real HW.
> 
Hm, why it can't exist on real HW? Do simple exercise. Run WindowsXP
inside QEMU, connect with gdb to QEMU process and check what frequency
RTC configured with (hint: it will be 64Hz), now run video inside the
guest and check frequency again (hint: it will be 1Khz).

--
                        Gleb.