Re: [Qemu-devel] How to reliably start a bare QEMU target to query capabilities via QMP

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Aug 22, 2012 at 03:25:38PM -0500, Anthony Liguori wrote:
> "Daniel P. Berrange" <berrange@redhat.com> writes:
> 
> > I've been adapting libvirt to use to the various new QMP commands to
> > query QEMU's capabilities, instead of the hated -help parsing. Obviously
> > the critical part of this is being able to reliably start a bare QEMU
> > process with no actual guest OS configured (no disks, no kernel, etc)
> > and talk to its monitor. I hadn't anticipated problems since I only
> > tested with x86_64 / i386 most of the time, which work well in this
> > respect. Currently I am doing
> >
> >   # $QEMU_BINARY -S \
> >          -no-user-config \
> >          -nodefconfig \
> >          -nodefaults \
> >          -nographic \
> >          -qmp stdio
> >
> >
> > This works for about 50% of the QEMU targets:


> > Do we have to go down the route of adding some sort of "-no-vm" flag to
> > explicitly say we don't care about any of the VM setup parts ? This would
> > be more like what my old patches did which mapped monitors commands
> > onto '-query-XXXXX' command line args, bypassing VM setup, but still
> > using normal QMP monitor interaction.
> >
> > Any other suggestions on how to reliably get a QMP monitor to a target,
> > without any VM config. ?
> 
> -M none.  See the patch I just sent out.  I think we can include this in
> 1.2 as it poses no real risk.

Great, that's an nice elegant solution to the problem :-)


Daniel
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