Re: nmi is broken?

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> writes:

> Avi Kivity <avi@redhat.com> writes:
>
>>> This seems to be complex stuff depending on hardware configurations. I'm
>>> not fully understanding though, current state of it is,
>>>
>>> Yes, PIC is in AEOI mode if linux is using IO-APIC. Um.., kvm says
>>> irq == 0 is mp_INT mode in MADT, not mp_ExtINT.
>>
>> That is correct, kvm doesn't connect the master 8259 output to the 
>> IOAPIC.  Instead the 8259 is connected to LINT0 (which is configured for 
>> ExtInt when the IOAPIC is disabled, or for NMI which the NMI watchdog is 
>> enabled).
>>
>> However, now I can't see how it would work. auto EOI works on the INTA 
>> cycle, which would only occur if LINT0 is configured for ExtInt.  If it 
>> is configured for NMI, I don't think it would issue the INTA cycle.  So 
>> the NMI watchdog not working is actually correct for our hardware 
>> configuration!
>>
>> But I may be misunderstanding something here.
>
> I see. If the physical machine was configured as above, I guess (not
> pretty sure, I don't have this configuration machine), IOAPIC test
> (check_timer() in io_apic.c) should fail, and IOAPIC wouldn't have any
> effect. And I think MADT should tell mp_ExtINT.
>
> Yes, I also guess the above configuration wouldn't work NMI watchdog of
> IOAPIC mode, and linux will report as NMI watchdog can't work in
> check_timer().

Hm.., if smp was enabled, what configuration model is used by kvm? I
think this configuration model can't work on smp.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>