Re: [Qemu-devel] [PATCH V7 23/24] apci: fix PXB behaviour if used with unsupported BIOS

[Michael S. Tsirkin]

On Mon, Jun 01, 2015 at 02:24:02PM +0200, Gerd Hoffmann wrote:
> On Mo, 2015-06-01 at 14:17 +0200, Michael S. Tsirkin wrote:
> > On Mon, Jun 01, 2015 at 01:40:19PM +0200, Gerd Hoffmann wrote:
> > > On Mo, 2015-06-01 at 12:44 +0300, Marcel Apfelbaum wrote:
> > > > On 05/31/2015 09:12 PM, Michael S. Tsirkin wrote:
> > > > > On Mon, May 25, 2015 at 06:34:01PM +0300, Marcel Apfelbaum wrote:
> > > > >> PXB does not work with unsupported bioses, but should
> > > > >> not interfere with normal OS operation.
> > > > >> We don't ship them anymore, but it's reasonable
> > > > >> to keep the work-around until we update the bios in qemu.
> > > > >
> > > > > We already did, did we not?
> > > > Yes, we did, but Gerd preferred to keep this patch around.
> > > > Adding him to thread.
> > > 
> > > seabios bundled with qemu isn't the only possible firmware.
> > > 
> > > We have ovmf, coreboot, qboot.
> > 
> > ovmf is especially interesting. Marcel, did you look at what
> > happens with pxb and ovmf?
> > 
> > > You might boot with old seabios for
> > > whatever reasons (say bisecting down something).
> > 
> > But then you won't have pxb, will you?
> 
> Devices behind pxb wouldn't be working because they didn't got resources
> assigned, yes.

I mean that there's no way to get old seabios+pxb when bisecting.

>  But at least the resources for the primary root bus
> devices would not be screwed up like they are without this patch (IIRC).
> 
> cheers,
>   Gerd
>