Re: [Qemu-devel] ANN: QEMU Monitor Protocol git tree

[Luiz Capitulino <lcapitulino@redhat.com>]

On Wed, 23 Sep 2009 18:08:16 +0100
"Daniel P. Berrange" <berrange@redhat.com> wrote:

> On Wed, Sep 23, 2009 at 10:57:01AM +0100, Daniel P. Berrange wrote:
> > On Tue, Sep 22, 2009 at 08:56:04PM -0500, Anthony Liguori wrote:
> > > Luiz Capitulino wrote:
> > > >Now the controversial part: it's json based. ;)
> > > >
> > > >I have chosen json because of the reasons already explained by others in
> > > >the original QMP thread. Basically, json is so simple that if we design
> > > >a small protocol from scratch, chances are it will look like json.
> > > >  
> > > 
> > > json is not a deal break.  My main concern was our ability to extend 
> > > json and whether supporting stock json libraries was a hard 
> > > requirement.  I also would like to see a C client library since our 
> > > biggest consumer (libvirt) is based in C.
> > 
> > I've googled around quickly and there are at least 5 pieces of C code
> > and/or C libraries that can parse JSON. Hopefully one of them will be
> > sufficient / suitable for libvirt's needs. We'll just need to try it
> > out and see what happens....
> 
> I'm in the process of re-factoring the libvirt monitor handling code to
> make it possible for us to add in support for QMP in parallel to the 
> legacy monitor support. Once the Luiz'  QMP branch progresses a little
> further I'll aim to make available a libvirt branch which supports QMP.

 Great!

> To help priortization, the one critical command we need implemented
> which isn't there yet is 'cont', since all our VMs are launched with
> CPUs initially stopped. 

 I will convert 'cont' as soon as the new error handling code is
finished, as 'cont' can fail.

> The next priorities would be 'stop', 'info cpus', 'balloon' and 
> 'info balloon'  (all except info cpus are there in Luiz tree already
> I believe).

 That's right.

> With those we could do some useful testing & validation of the QMP work
> in libvirt.

 Yeah, would be very nice.

 I was also considering writing kvm-autotest tests, will look at it.

> Then in no particular order of preference the other commands we
> currently make use of are
> 
>  - migrate / migrate_set_speed / info migrate
>  - pci_add / pci_del
>  - host_net_add / host_net_del / getfd / closefd
>  - eject / change
>  - usb_add / usb_del
>  - info block     (desirable to allow query of a single device at a time)
>  - memsave / pmemsave
> 
> 
> Figuring out how to handle password prompts for 'cont' for encrypted
> qcow is probably another unusal area. Perhaps we should have explicit
> commands to set the decryption passwords ahead of time, rather than
> having QEMU prompt in response to 'cont'

 Hmm, yes, forgot about this.