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

[Blue Swirl]

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.