Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos

[Paolo Bonzini]

On 14/12/2015 14:27, Gonglei (Arei) wrote:
> 
>>
>> On 14/12/2015 13:49, Gonglei (Arei) wrote:
>>>>>>> This patch introduce nmi disable bit handler to fix the problem
>>>>>>> and make the emulated CMOS like the real hardware.
>>>>>
>>>>> I think that this only works with -machine kernel_irqchip=off, however.
>>> IIRCC, the kernel_irqchip is disabled by default, and we used the default
>> value.
>>
>> No, it's enabled by default.
>>
> 
> Okay, yes, I saw the source code again. That means kmod finish the NMI 
> injection
> wrok, and the NMI will not pass Qemu side. So, you thought this patch cannot 
> block
> NMI injection when kernel_irqchip=on ?

I am not sure.  It depends on which NMIs are blocked by the bit.  For
example, the IOAPIC can deliver NMIs, and they wouldn't be blocked.

Do you have any documentation, to see whether they can actually happen
on emulated hardware?  I guess we support the TCO watchdog, so yes.

> Maybe we should pass the nmi_disable bit to Kmod when kernel_irqchip=on , 
> right?

Yes, that's the idea.

But first of all, I've read the thread you linked, and I couldn't find
the place where it says that the root cause is NMIs.

Paolo