[coreboot] Serengeti VGA

Marc Jones Marc.Jones at amd.com
Mon Oct 20 22:26:03 CEST 2008

Myles Watson wrote:
> On Mon, Oct 20, 2008 at 1:48 PM, Marc Jones <Marc.Jones at amd.com 
> <mailto:Marc.Jones at amd.com>> wrote:
>     Myles Watson wrote:
>         I've been trying to make the configuration spaces match between
>         v2 and v3.
>         The biggest difference left is the disabled/hidden devices which
>         are not
>         hidden in v3.
>         Any chance that's causing the problem?
>         I've also been trying to figure out where the legacy IO space
>         (e.g. 0x3d4)
>         gets routed to the card.  Does this happen automatically because
>         the VGA bit
>         is set in the bridge?
>     Yes, The vga bit on the subtractive bridge routes the graphics io.
>     How did you work around the vm86 problem? Did the graphics command
>     register get re-enabled?
> I made the interrupts self contained, with no output.  The VGA ROM 
> initialization returns, but there is no output to the screen.  At least 
> the screen turns black on an int10 now, though.
> The only differences between the PCI configuration registers now is that 
> v3 has a little larger space for VGA and SERR is set.

Ok, That should be fine. Black usually means all FF in the vga memory. 
Check A000-BFFFF are getting to the controller. VGA enable in the bridge 
control register (3e) and VGA pallet snoop in the command register (04) 
should be set in the bridge.


Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com

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