[Qemu-devel] Re: [PATCH 11/11] QMP: Command-line flag to enable control mode

[Avi Kivity]

On 06/23/2009 01:54 PM, Jan Kiszka wrote:
> > It would be a nightmare, consider both libvirt and a user hotplugging
> > something into the same pci slot, or a user starting migration, or
> > quitting, or ...
> >      
>
> Migration, yes, but hot-plugging is resolvable - given config update events.
>    

I'm not saying it's impossible, just that we don't want to do it.

> > Having -monitor readonly makes sense.
> >      
>
> But not for all features, only those libvirt is capable to handle (I
> think there are quite a few qemu specifics libvirt does not bother
> about) and only as long as there is no proper synchronization. Again,
> migration and save/restore will continue to require exclusive access,
> but the rest is just a question of proper synchronization IMHO.
>    

If libvirt "doesn't bother" about something useful, that's a libvirt 
bug.  It's wierd to have something controlled by two parallel management 
channels.

> See, I don't want to kill my management app just because I attached to a
> guest via gdb and start injecting reconfiguration events for testing
> purposes (e.g. attach/detach a USB device for which I develop a driver).
>    

You're talking about a usb developer, not a qemu developer, working in 
some virtual lab environment?  In that case, libvirt and the management 
app should certainly support usb.  A random usb developer shouldn't need 
to ever talk to the qemu monitor.

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