Re: [Qemu-devel] [PATCH] pci vga: Support VGA behind bridges

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 2013-02-28 at 23:03 -0500, Kevin O'Connor wrote:
> On Thu, Feb 28, 2013 at 10:52:49AM -0700, Alex Williamson wrote:
> > We currently expect to find VGA devices on the root bus but we will
> > also support them below bridges iff the VGA routing across the bridges
> > is pre-configured.  This patch maintains that behavior, but also
> > enables SeaBIOS to enable VGA routing to the first VGA class device it
> > finds when there is no preconfigured device.  This allows us to
> > support VGA devices behind root ports and bridges without special
> > setup from QEMU.
> [...]
> > --- a/src/optionroms.c
> > +++ b/src/optionroms.c
> > @@ -439,13 +439,47 @@ vgarom_setup(void)
> 
> I don't think that optionroms.c is the right place for this logic.  On
> coreboot, Xen, and CSM, SeaBIOS shouldn't be touching the PCI config.
> It's only QEMU that would need this logic, so something like pciinit.c
> is where this logic should go.

Ok, I can look at finding a spot for it in pciinit.  Note though that
there's nothing QEMU specific about this, if other platforms are already
enabling a route to a VGA device, there's no change.  If something
sneaks through without a VGA device enabled, this should generically
enable the first device.  Thanks,

Alex