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

[Markus Armbruster]

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.


[*] He's been trying to give us NMI injection via QMP for five months,
so what's a few months more to him.