Re: [Qemu-devel] [PATCH 2/2 V7] qemu, qmp: add inject-nmi qmp command

[Daniel P. Berrange]

On Wed, Apr 13, 2011 at 10:56:21PM +0300, Blue Swirl wrote:
> On Wed, Apr 13, 2011 at 4:08 PM, Luiz Capitulino <address@hidden> wrote:
> > On Tue, 12 Apr 2011 21:31:18 +0300
> > Blue Swirl <address@hidden> wrote:
> >
> >> On Tue, Apr 12, 2011 at 10:52 AM, Avi Kivity <address@hidden> wrote:
> >> > On 04/11/2011 08:15 PM, Blue Swirl wrote:
> >> >>
> >> >> On Mon, Apr 11, 2011 at 10:01 AM, Markus Armbruster<address@hidden>
> >> >>  wrote:
> >> >> >  Avi Kivity<address@hidden>  writes:
> >> >> >
> >> >> >>  On 04/08/2011 12:41 AM, Anthony Liguori wrote:
> >> >> >>>
> >> >> >>>  And it's a good thing to have, but exposing this as the only API to
> >> >> >>>  do something as simple as generating a guest crash dump is not the
> >> >> >>>  friendliest thing in the world to do to users.
> >> >> >>
> >> >> >>  nmi is a fine name for something that corresponds to a real-life nmi
> >> >> >>  button (often labeled "NMI").
> >> >> >
> >> >> >  Agree.
> >> >>
> >> >> We could also introduce an alias mechanism for user friendly names, so
> >> >> nmi could be used in addition of full path. Aliases could be useful
> >> >> for device paths as well.
> >> >
> >> > Yes.  Perhaps limited to the human monitor.
> >>
> >> I'd limit all debugging commands (including NMI) to the human monitor.
> >
> > Why?
> 
> Do they have any real use in production environment? Also, we should
> have the freedom to change the debugging facilities (for example, to
> improve some internal implementation) as we want without regard to
> compatibility to previous versions.

We have users of libvirt requesting that we add an API for triggering
a NMI. They want this for support in a production environment, to be
able to initiate Windows crash dumps.  We really don't want to have to
use HMP passthrough for this, instead of a proper QMP command.

More generally I don't want to see stuff in HMP, that isn't in the QMP.
We already have far too much that we have to do via HMP passthrough in
libvirt due to lack of QMP commands, to the extent that we might as
well have just ignored QMP and continued with HMP for everything.

If we want the flexibility to change the debugging commands between
releases then we should come up with a plan to do this within the
scope of QMP, not restrict them to HMP only.

Regards,
Daniel
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