Re: [Qemu-devel] [PATCH v3 1/4] cpus: Define NMI callback

[Alexander Graf]

On 11.06.14 10:37, Paolo Bonzini wrote:
> Il 11/06/2014 10:29, Alexander Graf ha scritto:
> > > But right now inject-nmi was a CPU-specific interface and whoever
> > > needs something different will have to find a way.
> > >
> > > You could argue that Alexey does need something different thanks to
> > > his need to inject the NMI on all CPUs.
> > >
> > > What about an NMIMonitorHandler interface that takes a Monitor*, and
> > > then you iterate on all of /machine looking for implementors of the
> > > interface?  Then -M mac99 can add it to the MPIC, -M spapr can just
> > > ignore the Monitor*, and i386/s390 can look at the current CPU.
> >
> > I think modeling a button is easier and closer to what you'd actually
> > get on real hardware.
>
> What is a button?  It certainly doesn't have any evdev support in Linux.

It's a device that links a qemu_irq line and implements an interface to 
call it.

> The NMI button is just something that closes a circuit.  Whoever is 
> attached to that circuit reacts, in QEMU that's whoever implements an 
> NMIMonitorHandler.  The Monitor* is just for backwards HMP compatibility.

I think the only major difference in thinking we have here is that I 
don't think it's necessary to maintain HMP compatibility for this debug 
feature that maybe 2 people in the world ever used ;).


Alex