Re: [Qemu-devel] Re: [RFC][PATCH v1 00/11] QEMU Guest Agent: QMP-based host/guest communication (virtagent)

[Anthony Liguori]

On 03/25/2011 03:42 PM, Michael Roth wrote:
> On 03/25/2011 02:47 PM, Michael Roth wrote:
> > These apply on top of Anthony's glib tree, commit 
> > 03d5927deb5e6baebaade1b4c8ff2428a85e125c currently, and can also be 
> > obtained from:
> > git://repo.or.cz/qemu/mdroth.git qga_v1
> >
> > The QGA-specific patches are in pretty rough shape, and there are 
> > some outstanding issues that I'll note below. I just wanted to put 
> > the general approach out there for consideration. Patch-level 
> > comments/review are still much-appreciated though.
> >
> > However, patches 1-5 are general json/QAPI-related fixes. Anthony, 
> > please consider pulling these into your glib tree. The json fix-ups 
> > may need further evaluation, but I'm confident they're at least an 
> > improvement. The QAPI ones are trivial fix-ups.
> >
> > ISSUES/TODOS:
> >
> >   - QMP's async callbacks expect the command results to be 
> > de-marshalled beforehand. This is completely infeasible to attempt 
> > outside of the code generator, so this is a big area that needs to be 
> > addressed. So for now, only the 'guest-ping' command works, since it 
> > has no return value. The dummy "guest-view-file" command will cause 
> > an error to be reported to the client.
>
> Well, not completely de-marshalled. 

I don't follow.  Are you talking about async callbacks within QEMU?  
Because that should be totally transparent to you.  You'll receive a 
qobject and you can do whatever you need with it.

> Basically just need a way to pull whatever is stored in the response 
> qdict's "return" field out without specifying the QTYPE in advance... 
> which exists in qdict.c:qdict_get_obj(), it's just not currently 
> exposed to outside callers.

Just use qdict_get()--but I still don't understand what the problem is.

Regards,

Anthony Liguori


> Alternatively, the callback function can take in the entire response's 
> qdict and pull the value out using knowledge from the schema. Will 
> look into this more, but not nearly involved as I first thought.
>
> >   - qemu-ga guest daemon is currently not working over virtio-serial 
> > or isa-serial. This is probably an issue with how I'm using glib's io 
> > channel interfaces, still investigating. This means the only way to 
> > currently test is by invocing qemu-ga with "-c unix-listen 
> > -p<sockpath>", then doing something like `socat /dev/ttyS0,raw,echo=0 
> > unix-connect:<sockpath>`.
> >   - guest-view-file is a stub, and will be broken out into an 
> > open/read/close set of RPCs, possibly with a high-level interface 
> > built around those.