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

[Markus Armbruster]

Luiz Capitulino <address@hidden> writes:

> On Fri, 6 May 2011 18:36:31 +0300
> Blue Swirl <address@hidden> wrote:
>
>> On Fri, May 6, 2011 at 12:08 PM, Markus Armbruster <address@hidden> wrote:
>> > Blue Swirl <address@hidden> writes:
>> >
>> >> On Mon, May 2, 2011 at 6:57 PM, Luiz Capitulino <address@hidden> wrote:
>> >>> On Sat, 30 Apr 2011 09:33:15 +0300
>> >>> Blue Swirl <address@hidden> wrote:
>> >>>
>> >>>> On Sat, Apr 30, 2011 at 1:40 AM, Luiz Capitulino <address@hidden> 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 /address@hidden:l1int
>> >> which would be a shorthand for
>> >> raise /address@hidden:l1int
>> >> lower /address@hidden: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?

No reply.  When you demand a redesign to generalize a simple feature to
something only you envisage, please explain what exactly you want.
Documentation to stick into qmp-commands.hx would be a start.  Here's
the baseline from Luiz, for your editing convenience.


inject-nmi
----------

Inject an NMI on guest's CPUs.

Arguments: None.

Example:

-> { "execute": "inject-nmi" }
<- { "return": {} }

Note: inject-nmi is only supported for x86 guest currently, it will
      returns "Unsupported" error for non-x86 guest.