Re: [Qemu-devel] [PATCH v4 5/7] RTC:Add RTC update-ended interrupt support

[Paolo Bonzini]

Il 22/03/2012 11:29, Stefano Stabellini ha scritto:
>> The purpose of using two timer is trying to keep the UF, AF and UIP
>> synchronous. User can poll UIP to check UF and AF bit. If we use
>> timer for UF/AF bit track and check UIP by another way, since the
>> timer will be fired with delay, then the problem is encountered:
>> the UIP is cleared, but due to the delay of timer, the UF/AF bit is
>> not set. So we need to check them on a same level. Although we can
>> update UF/AF when reading it, the logic is too complicated,
>> especially for AF bit.

FWIW, the solution I used when I removed the second timer from the
current code (not yet posted, I do hope your patches can be fixed!) was
to set UIP when reading A, and clear it in the timer.  You have
something like that, but keep the two timers.

Paolo