RE: [Xen-devel] [PATCH] Fix hvm vcpu hotplug bug

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Ian Jackson wrote:
> Liu, Jinsong writes ("RE: [Xen-devel] [PATCH] Fix hvm vcpu hotplug
> bug"): 
>> I think qemu-xen should add this logic level, so that it can support
>> more gpe events in the future.
> 
> Yes.  But what clears the interrupt ?  Is it edge or level triggered ?
> 

SCI is a shareable level interrupt.
Per my understanding, sci-gpe logic is like

                                                  |------- gpe_sts x
                                        |-----AND
                                        |         |------- gpe_en x
sci int                               |
------------------------------------ OR    ......
(wired to i8259[9] etc)         |
                                        |         |------- gpe_sts y
                                        |-----AND
                                                  |------- gpe_en y

Currently qemu-xen didn't have 'gep event x OR gpe event y --> sci' logic, it 
should add this logic level.

To clear the interrupt:
1). gpe_sts x & gpe_en x --> low gpe event x
2). all gpe events low --> low sci
(low is of logic meaning here, not real electric value)

Thanks,
Jinsong



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