Re: [Qemu-devel] converging around a single guest agent

[Anthony Liguori]

On 11/15/2011 04:39 PM, Ayal Baron wrote:
> ----- Original Message -----
> > On 11/15/2011 11:24 AM, Barak Azulay wrote:
> > > Hi,
> > >
> > > One of the breakout sessions during the ovirt workshop [1] was
> > > about the guest
> > > tools, and focused mainly on the ovirt-guest-agent [2].
> > >
> > > One of the issues discussed there, was the various existing guest
> > > agents out
> > > there, and the need to converge the efforts to a single agent that
> > > will serve
> > > all.
> > >
> > > while 4 agents were mentioned (Matahari, vdagent, qemu-ga&
> > >   ovirt-guest-agent)
> > > during that discussion, we narrowed it down to 2 candidates:
> > >
> > > qemu-ga (aka virt-agent):
> > > -------------------------
> > > - Qemu specific - it was aimed for specific qemu needs (mainly
> > > quiesce guest
> > > I/O)
> > > - Communicates directly with qemu  (not implemented yet)
> > > - Supports ?
> > > - So far linux only
> >
> > But very easy to port.  It also should work on just about any Unix
> > since its
> > only dependency is glib.  Also:
> >
> >    - exists in the QEMU repository
> >
> > > - written in C
> > >
> > > Ovirt-guest-agent:
> > > ------------------
> > > - Has been around for a long time (~5 years) - considered stable
> > > - Started as rhevm specific but evolved a lot since then
> > > - Currently the only fully functional guest agent available for
> > > ovirt
> > > - Written in python
> > > - Some VDI related sub components are written in C&   C++
> > > - Supports a well defined list of message types / protocol [3]
> > > - Supports the folowing guest OSs
> > >     Linux: RHEL5, RHEL6 F15, F16(soon)
> > >     Windows: xp, 2k3 (32/64), w7 (32/64), 2k8 (32/64/R2)
> >
> > The guest agent we use in QEMU exists to implement QEMU specific
> > functionality.
> >    I think one challenge that comes up here is that the ovirt guest
> >    agent has a
> > very different scope than the QEMU agent.  The ovirt guest agent has
> > a very
> > ovirt-engine centric scope.
> >
> > > The need to converge is obvious, and now that ovirt-guest-agent is
> > > opensourced
> > > under the ovirt stack, and since it already produces value for
> > > enterprise
> > > installations, and is cross platform, I offer to join hands around
> > > ovirt-
> > > guest-agent and formalize a single code base that will serve us
> > > all.
> >
> > You are basically saying, stop what you guys are doing and work on
> > our code
> > because it's better.  That's not really convergence.
> >
> > If you want to talk about convergence, the discussion should start
> > around
> > collecting requirements.  We can then figure out if the two sets of
> > requirements
> > are strictly overlapping or if there are any requirements that are
> > fundamentally
> > in opposition.
>
> Agreed.
>
> So vdsm guest agent goal is to ease administration of VMs.  This is not saying 
> much as it is quite broad so I will list what is provided today and some things 
> we need to add:

Is there a spec for the guest agent protocol?

What's the current policy on compatibility?  How does the guest agent protocol 
handle feature negotiation?

Regards,

Anthony Liguori