From: James Simmons <jsimmons@edgeglobal.com>
  To  : ggi-develop@eskimo.com
  Date: Tue, 2 Feb 1999 11:16:47 -0500 (EST)

Re: Support for VGA modes?

On Tue, 2 Feb 1999, Marcus Sundberg wrote:

> Hartmut Niemann wrote:
> > Is there consensus whether these modes should be supported and
> > what price we would be willing to pay?
> > Would it be reasonable to have e.g. one strictly-MMIO Millennium driver,
> > which does support multiheading, and a second legacy-support driver
> > which uses traditional VGA modes as well?
> 
> In case of the Millennium MMIO or not is not an issue. AFAIK all VGA
> registers are mirrored in the MMIO space. It's just a matter of the
> accelerator requiring a minimum virtual x of 512 pixels.

If the driver has the VGA registers mirrored in MMIO space then use them
to support all modes. If a card doesn't support ordinary vga mode
registers in MMIO then don't. The reason is that many platforms don't
support intel sytle io access and this leads to portability issues. Also
MMIO insures multihead support for people how do want it. As for disabling
accels in 320x200 do you really want to do accelerated graphics in 320x200
mode. No you want the highest resolution available with accels.  

James Simmons
Linux System Admin
EdgeNet Inc.
jsimmons@edgeglobal.com
http://www.edgeglobal.com/~jsimmons