Re: [Qemu-devel] [SeaBIOS] [PATCH v3] pciinit: Enable default VGA device

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

On Wed, 2013-03-20 at 19:05 +0100, Paul Menzel wrote:
> Dear Alex,
> 
> 
> Am Mittwoch, den 20.03.2013, 10:58 -0600 schrieb Alex Williamson:
> > As QEMU gains PCI bridge and PCIe root port support,
> 
> could you give a commit or version for QEMU please.

This would be targeted towards QEMU 1.5.  Michael recently sent a pull
request with this patch to enable VGA routing in bridges:

https://git.kernel.org/cgit/virt/kvm/mst/qemu.git/commit/?h=pci&id=e475aeac3e2e7f6632c3ea7e83f4431c0ba3a467

It's difficult to make use of without an assigned VGA device, which I
plan to start posting soon.

> > we won't always find the VGA device on the root bus.  We therefore
> > need to add support to find and enable a VGA device and the path to it
> > through the VGA Enable support in the PCI bridge control register.
> 
> Just to be sure, did you test this with older QEMU too?

Yes, it works with the QEMU 1.2.x shipped in F18.  Any existing QEMU
configuration is going to have the VGA device on the host bridge and
therefore bail out on the first loop, having done nothing other than add
a debug print.

> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> > 
> > v3: use pci_config_maskw() to trim out some code
> > v2: move to qemu specific pciinit.c
> > 
> >  src/optionroms.c |    2 +-
> >  src/pciinit.c    |   40 ++++++++++++++++++++++++++++++++++++++++
> >  src/util.h       |    1 +
> >  3 files changed, 42 insertions(+), 1 deletion(-)
> > 
> > diff --git a/src/optionroms.c b/src/optionroms.c
> > index caa2151..ac92613 100644
> > --- a/src/optionroms.c
> > +++ b/src/optionroms.c
> > @@ -213,7 +213,7 @@ run_file_roms(const char *prefix, int isvga, u64 *sources)
> >   ****************************************************************/
> >  
> >  // Verify device is a vga device with legacy address decoding enabled.
> > -static int
> > +int
> >  is_pci_vga(struct pci_device *pci)
> >  {
> >      if (pci->class != PCI_CLASS_DISPLAY_VGA)
> > diff --git a/src/pciinit.c b/src/pciinit.c
> > index ce0a4cc..bb9355f 100644
> > --- a/src/pciinit.c
> > +++ b/src/pciinit.c
> > @@ -316,6 +316,44 @@ static void pci_bios_init_devices(void)
> >      }
> >  }
> >  
> > +static void pci_enable_default_vga(void)
> > +{
> > +    struct pci_device *pci;
> > +
> > +    foreachpci(pci) {
> > +        if (is_pci_vga(pci)) {
> > +            dprintf(1, "PCI: Using %02x:%02x.%x for primary VGA\n",
> > +                    pci_bdf_to_bus(pci->bdf), pci_bdf_to_dev(pci->bdf),
> > +                    pci_bdf_to_fn(pci->bdf));
> 
> As this is used several times, a function returning a string with %02x:%
> 02x.%x would be handy.
> 
> > +            return;
> > +        }
> > +    }
> 
> […]
> 
> Acked-by: Paul Menzel <paulepanter@users.sourceforge.net>

Thanks!

Alex