Re: [Qemu-devel] Re: [Bug 599958] Re: Timedrift problems with Win7: hpet missing time drift fixups

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

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Avi Kivity wrote:
> On 07/05/2010 10:36 AM, Jan Kiszka wrote:
>>
>>> Assumes that CPU with
>>> lowest index is BSP (that one we can actually guaranty if we want
>>> to).
>>>      
>> Well, the generic solution would be returning a bitmap of the CPUs that
>> were affected, but this is impractical. However, at least x86 should be
>> fine with the information "state change also on BSP", e.g. like this:
>>   0 - state change on one or more CPUs, none of them is the BSP
>>   1 - state change on BSP (and possible more CPUs)
>>    
> 
> What about ack notifiers?  Ask the APIC to notify you when an interrupt
> is acked.  That allows you to track the BSP, all cpus, or some subset. 
> Masking can be seen at the irq controller level.

So, if I understand you correctly, an IRQ state change that is ignored
due to masking would invoke the ack notifier chain as well?

> 
> It's more involved, but provides more information.

Well, it requires to establish ack notifier chains in parallel to the
existing IRQ delivery routes. Definitely more invasive.

Jan


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