VGA arbitration: API proposal

[Jon Smirl]

On Sat, 05 Mar 2005 10:44:25 +1100, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
>    This one would inform the arbitrer that your card is decoding VGA
> accesses or not. It should be called by the driver, by default, the
> arbitrer assumes all cards are decoding VGA addresses. I need to double
> check what is needed for radeon to stop decoding VGA accesses, I'm not
> 100% sure about that. CRTC_EXT_DISP_EN plus some other bit in DAC_CNTL
> may be enough, but we should make sure of that. I think nVidia's can
> remap the VGA IOs to some other place in PCI space with real decoding,
> so they become a non-issue.

Doesn't VGA support both a primary and secondary address range? If we
can't figure out how to completely shut off VGA could we map all of
cards we aren't going to use on top of each other in the secondary
address range and then ignore them?

-- 
Jon Smirl
jonsmirl at gmail.com