Re: [Qemu-devel] Re: [PATCH] Split machine creation from the main loop

[Anthony Liguori]

On 02/23/2011 05:38 PM, Juan Quintela wrote:
> Anthony Liguori<address@hidden>  wrote:
>    
> > On 02/23/2011 05:00 PM, Juan Quintela wrote:
> >      
> > > Anthony Liguori<address@hidden>   wrote:
> > >
> > >        
> > > > The goal is to enable the monitor to run independently of whether the machine
> > > > has been created such that the monitor can be used to specify all of the
> > > > parameters for machine initialization.
> > > >
> > > > Signed-off-by: Anthony Liguori<address@hidden>
> > > >
> > > >          
> > > I agree that it is one step in the right direction, but we are still
> > > calling qemu_machine_init() before calling the main_loop().
> > >
> > > What is the plan from here?
> > >
> > >        
> > 1) Decouple QMP from qemu_machine_init().  This really requires the
> > introduction of the new QAPI server that exists outside of the chardev
> > infrastructure since chardevs are currently initialized in
> > qemu_machine_init().
> >
> > 2) Make qemu_machine_init() take no parameters and just reference
> > global state.
> >      
> Any good idea how that global state is going to be stored?
>
> I just want to be able to launch a qemu on a different machine and
> migrate the "configuration" to it, for doing that, I really need what
> values are different from default or anything like that.  So as you can
> see, I am very interested on that work.
>    

First step is to have everything go through QMP.  If everything flows 
through QMP, we have a gateway that we can focus on.

What I'd like to do next is introduce the notion of a stateful config 
file.  This config file is essentially a global database that can be 
used to store information about the guest from within QEMU.

So -name would become:

case QEMU_OPTION_name:
    qmp_set_name(optarg, NULL);
    break;
}

And qmp_set_name woudl be implemented as:

static const char *qemu_name;

void qmp_set_name(const char *name, Error **errp)
{
      qemu_name = name;
}

char *qmp_query_name(Error **errp)
{
     return qemu_strdup(qemu_name);
}

Now, to integrate this into the stateful config file, we would do 
something like:

void qmp_set_name(const char *name, Error **errp)
{
     qemu_set_config("global", "name", name);
}

char *qmp_query_name(Error **errp)
{
     return qemu_strdup(qemu_get_config("global", "name"));
}

This is a simplistic example and more complex examples have not been 
totally thought out, but this is where I'm looking to go.

Regards,

Anthony Liguori

> Later, Juan.
>
>