Re: [Qemu-devel] Re: [PATCH 0/4] Machine config files

[Michael S. Tsirkin]

On Mon, Jul 06, 2009 at 04:56:16PM +0300, Michael S. Tsirkin wrote:
> On Mon, Jul 06, 2009 at 03:43:23PM +0200, Gerd Hoffmann wrote:
> > On 07/06/09 14:49, Michael S. Tsirkin wrote:
> >> On Fri, Jun 12, 2009 at 06:11:24PM +0200, Jan Kiszka wrote:
> >> Can't we extend loadvm/savevm format to support machine config? It is
> >> already supported by all devices, it seems that we just need to add some
> >> detail such as pci addresses, and qemu flags to save/load this config.
> >> No?
> >
> > No.  Adding some info to the devices doesn't cut it as you also need to  
> > know which devices are present in the first place.
> 
> Actually at least for pci devices you have the devid/vendor id
> register - from this you can know which devices are present.
> 
> > Current savevm  
> > doesn't do that, thats why you have to start the virtual machine with  
> > the complete set of command line arguments even when resuming /  
> > migrating.

It seems that it'd be trivial to solve this just by adding a fixed size header
telling you which load function to call. No?

> >  Once we have a working device tree implementation we can fix  
> > that too though.  Rough plan is:
> >
> >   (1) convert drivers to qdev.
> >   (2) create qdev device tree from config file (probably fdt).
> >
> > With this in place it is just a little step to also carry this in the  
> > savevm format:  We just need a to do a qdev->fdt conversion, then we can  
> > send the device tree as one savevm section and rebuild the vm from that.
> >
> > cheers,
> >   Gerd