Re: [Qemu-devel] [PATCH] pc_piix: enable legacy hotplug for Xen

[Stefano Stabellini]

On Wed, 5 Feb 2014, Paolo Bonzini wrote:
> Il 05/02/2014 17:41, Stefano Stabellini ha scritto:
> > > Yeah, especially because nowadays "-M pc" works with Xen.  It would be
> > nice if
> > > fw_cfg could be enabled even for Xen on all machines except the legacy "-M
> > > xenfv".
> > >
> > > Stefano, could you give it a shot now that you'll be soon done with 4.4?
> > 
> > It might not be that straightforward as Xen emulates some devices in the
> > hypervisor and patches have been recently posted to support multiple
> > device models for a single VM.
> 
> I'm not sure how this is related to fw_cfg?  fw_cfg is just a simple key-value
> store.  If hvmloader doesn't use it, it should be a burden.

I was referring to the fact that QEMU might not have all the info that
need to be written to fw_cfg when running on Xen: some of the info might
be in the hypervisor and some other in another QEMU instance.
Or do you think that fw_cfg could be written by multiple entities
simultaneously?