Re: [Qemu-devel] [v4][PATCH 4/5] xen, gfx passthrough: create host bridge to passthrough

[Chen, Tiejun]

> -----Original Message-----
> From: Michael S. Tsirkin [mailto:address@hidden
> Sent: Tuesday, June 03, 2014 4:37 AM
> To: Chen, Tiejun
> Cc: address@hidden; address@hidden;
> address@hidden; address@hidden;
> address@hidden; address@hidden;
> address@hidden; Kay, Allen M; Zhang, Yang Z
> Subject: Re: [v4][PATCH 4/5] xen, gfx passthrough: create host bridge to
> passthrough
> 
> On Fri, May 30, 2014 at 04:59:28PM +0800, Tiejun Chen wrote:
> > Implement that pci host bridge to specific to passthrough. Actually
> > this just inherit the standard one.
> >
> > Signed-off-by: Tiejun Chen <address@hidden>
> 
> Can this actually inherit TYPE_I440FX_PCI_DEVICE?

Yes, but

> The parent is TYPE_PCI_DEVICE, but if it was TYPE_I440FX_PCI_DEVICE then
> you could re-use i440fx_initfn.
> And you could do *pi440fx_state = I440FX_PCI_DEVICE(d) unconditionally.
> 

one of reasons to implement our own pci host bridge which just inherit that 
standard one, please refer to some comments from v1:

http://patchwork.ozlabs.org/patch/322443/

And I also think this separation may be flexible to extend more in the future.  

Thanks
Tiejun