[coreboot] vga not working

Kevin O'Connor kevin at koconnor.net
Sun Aug 2 10:57:55 CEST 2009

On Thu, Jul 30, 2009 at 09:56:20AM -0600, Myles Watson wrote:
> On Wed, Jul 29, 2009 at 2:31 AM, Arnaud Maye <arnaud.maye at 4dsp.com> wrote:
> > We are talking about the GFX cards legacy ranges, right? I think
> > Myles looked at the PCI allocation already it seems everything is
> > fine there.
> Actually I said that it wouldn't be related to the allocator because the
> legacy VGA ranges are not aren't allocated there.  This is the place to
> start to look for that:
> 1. Make sure that that's the path to your graphics card.
> 2. Make sure that the correct bits get set in each device so that the I/O to
> the graphics card gets there.
>   - The PCI_BRIDGE_CTL_VGA bit is in the device structure, so it doesn't
> affect hardware
>   - Many bridges need some bit set to decode those ranges

In addition to making sure the legacy IO ranges are correct, you also
need to verify the legacy vga memory range (0xa0000 - 0xc0000) is
properly configured in the bridges.  Also, the chipset needs to have
this range be a pci hole - it must not have memory mapped there.


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