Re: [Qemu-devel] [Xen-devel] [XEN][RFC PATCH 14/15] xl-parsing: Parse the new option device_models

[Stefano Stabellini]

On Tue, 3 Apr 2012, Ian Jackson wrote:
> Julien Grall writes ("Re: [Xen-devel] [XEN][RFC PATCH 14/15] xl-parsing: 
> Parse the new option device_models"):
> > On 04/03/2012 02:31 PM, Ian Jackson wrote:
> > > Are the PCI addresses not assigned in a deterministic fashion by code
> > > in qemu-dm, in this case in the qemu-dm which is emulating the pci
> > > bridge ?  If not then that needs to be fixed, surely ?
> > 
> > Indeed but each QEMU emulate a subset of the hardware.
> > So how QEMU can know the available PCI addresses ?
> > I think that toolstack must allocate the BDF, otherwise we need to have
> > communication between each qemu-dm.
> 
> Currently the bdfs are allocated by the single qemu-dm, right ?  Why
> cannot that functionality stay there, with the pci bridge emulation ?
 
Because the allocation of most BDFs in QEMU is done ad-hoc in a first
come first served basis. If the first QEMU is not going to emulate these
devices then it is not going to allocate the BDF for them either.