Re: [Qemu-devel] [PATCH 0/3]: QMP: Introduce inject-nmi command

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 6 May 2011 18:36:31 +0300
Blue Swirl <blauwirbel@gmail.com> wrote:

> On Fri, May 6, 2011 at 12:08 PM, Markus Armbruster <armbru@redhat.com> wrote:
> > Blue Swirl <blauwirbel@gmail.com> writes:
> >
> >> On Mon, May 2, 2011 at 6:57 PM, Luiz Capitulino <lcapitulino@redhat.com> wrote:
> >>> On Sat, 30 Apr 2011 09:33:15 +0300
> >>> Blue Swirl <blauwirbel@gmail.com> wrote:
> >>>
> >>>> On Sat, Apr 30, 2011 at 1:40 AM, Luiz Capitulino <lcapitulino@redhat.com> wrote:
> >>>> > This series introduces the inject-nmi command for QMP, which sends an
> >>>> > NMI to _all_ guest's CPUs.
> >>>> >
> >>>> > Also note that this series changes the human monitor nmi command to use
> >>>> > the QMP implementation, which means that it now has a DIFFERENT behavior.
> >>>> > Please, check patch 3/3 for details.
> >>>>
> >>>> As discussed earlier, please change the QMP version for future
> >>>> expandability so that instead of single command 'inject-nmi', 'inject'
> >>>> takes parameter 'nmi'. HMP command 'nmi' can remain for now, but
> >>>> 'inject' should be added.
> >>>
> >>> I'm not sure I agree with this, because we risky overloading 'inject' the
> >>> same way we did with the 'change' command.
> >>>
> >>> What's 'inject' supposed to do in the future?
> >>
> >> Inject other IRQs, for example inject nmi could become an alias to
> >> something like
> >> inject /apic@fee00000:l1int
> >> which would be a shorthand for
> >> raise /apic@fee00000:l1int
> >> lower /apic@fee00000:l1int
> >>
> >> I think we only need a registration framework for IRQs and other signals.
> >
> > Yes, we could use nicer infrastructure for modeling IRQs.  No, we
> > shouldn't reject Lai's work because it doesn't get us there.  Perfect is
> > the enemy of good.
> >
> > Pick one:
> >
> > 1. We take inject-nmi now.  Should we get a more general inject command
> > like the one you envisage later, we can deprecate inject-nmi, and remove
> > it after a suitable grace time.  Big deal.  We get the special problem
> > solved now, without really compromising future solutions for the general
> > problem.
> >
> > 2. We reject inject-nmi now.  The itch Lai tries to scratch remains
> > unscratched until we get a more general inject command.
> >
> > 2a. Rejection "motivates" Lai to solve the general problem[*].  Or maybe
> > it motivates somebody else.  We get the general problem solved sooner.
> > And maybe I get a pony for my birthday, too.
> >
> > 2b. The general problem remains unsolved along with the special problem.
> > We get nothing.
> 
> 2c. Don't add full generic IRQ registration and aliases just now but
> handle 'inject' with only 'nmi'. That way we introduce no legacy
> baggage to the syntax.

Can you give an example on how this is supposed to look like?