Re: [Qemu-devel] [PATCH v3 1/5] hpet 'driftfix': add hooks required to detect coalesced interrupts (x86 apic only)

[Ulrich Obergfell]

> On 2011-04-28 20:51, Blue Swirl wrote:
>> On Thu, Apr 28, 2011 at 5:24 PM, Ulrich Obergfell wrote:
>>> 'target_get_irq_delivered' and 'target_reset_irq_delivered' contain
>>> entry addresses of functions that are utilized by update_irq() to
>>> detect coalesced interrupts. apic code loads these pointers during
>>> initialization.
>>
>> I'm not so happy with this approach, but probably then the i386
>> dependencies can be removed from RTC and it can be compiled only once
>> for all targets.
> 
> This whole series is really the minimalistic approach. The callbacks
> defined here must remain a temporary "shortcut". Just like proper
> abstraction of periodic tick compensation for reuse in other timers has
> to be added later on. And the limitation to edge-triggered legacy HPET
> INTs has to be removed.

Since QEMU doesn't have a generic infrastructure to track interrupt
delivery, I decided to reuse something that is currently available.
The only mechanism that I'm aware of is the one that is utilized by
RTC code ('rtc_td_hack'), i.e. apic_get_irq_delivered() etc.

The changes that would be introduced by part 1/5 and part 4/5 of
this patch series could be replaced if a generic infrastructure
to track interrupt delivery becomes available.

Regards,

Uli