Re: [Qemu-devel] [PATCH v3 5/7] hmp: Add info commands for preconfig

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Markus Armbruster (armbru@redhat.com) wrote:
> "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> writes:
> 
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > Allow a bunch of the info commands to be used in preconfig.
> >
> > version, chardev, name, uuid,memdev, iothreads
> >   Were enabled in QMP in the previous patch from Igor
> 
> Yes, these are okay together with PATCH 4.
> 
> > status, hotpluggable_cpus
> >   Was enabled in the original allow-preconfig series
> 
> query-status looks okay to me.
> 
> > history
> >   is HMP specific
> 
> Yes.
> 
> > usbhost, qom-tree, numa
> >   Don't have a QMP equivalent
> 
> HMP commands without a QMP equivalent are okay if their functionality
> makes no sense in QMP, or is of use only for human users.
> 
> Example for "makes no sense in QMP": setting the current CPU, because a
> QMP monitor doesn't have a current CPU.
> 
> Examples for "is of use only for human users": HMP command "help", the
> integrated pocket calculator.

Right, but they do already exist; it's possible we may want to fix/add
QMP versions - but this series isn't about going through and fixing
existing stuff up.

> Now let's review the three commands:
> 
> * Gerd, why does "info usbhost" have no QMP equivalent?
> 
> * Eduardo, why does "info numa" have no QMP equivalent?
> 
> * "info qom-tree" is a recursive variant of qom-list that skips anything
>   but children.  This convenience command exists so you don't have to
>   filter and string together output from many qom-list.
> 
>   I think it stands to reason that if providing "info qom-tree" makes
>   sense, then so does qom-list (HMP and QMP).  If qom-list, then
>   qom-list-types, qom-list-properties, qom-get, and probably even
>   qom-set (I've always been suspicious of qom-set, but that has nothing
>   to do with preconfig state).
> 
>   It might make sense to split off the whole QOM shebang into a separate
>   patch.

People have been trying to add qom-get etc for quite a while (I tried a
couple of years ago); it gets stuck in type display issues.  I've not
directly seen a need for those other variants, but qom-get is something
I'd love to have, still that's a job for another patch.

'info qom-tree' is very very useful when debugging qemu to see what the
basic state we're building is; it's primarily for debugging.

Dave

> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK