[coreboot] SeaBIOS and the Geode LX framebuffer

Kevin O'Connor kevin at koconnor.net
Thu Oct 9 02:11:29 CEST 2008

On Mon, Oct 06, 2008 at 08:32:15AM -0600, Jordan Crouse wrote:
> On 04/10/08 21:59 -0400, Kevin O'Connor wrote:
> > I'm not an expert on VGA, but I think it may be possible to implement
> > a bare bones vgabios with only a couple of chip specific functions
> Not just a possibility - but a certainty.  Geode could be ported in a
> matter of hours. 

Hi Jordan,

I've spent some time taking a closer look at this.  The bochs vgabios
has a large number of in/out calls.  If the geode vga doesn't natively
emulate the legacy in/out ports then I think there is a fair amount of
work to port bochs vgabios to geode.

Also, I have a couple of questions that I'm hoping you might know the
answers to.  Do you know if the geode vga can map its control
registers and part of its framebuffer into the space between 0xa0000 -
0xc0000?  A 16bit vga bios can't reliably access high memory, so key
registers need to be mapped below 1Meg.  Also, do you know if the
geode vga can support CGA text mode natively?  That is, can it be
configured in a mode where if one writes an 'X' character to 0xb8000
it will automatically display the 'X' font on the screen?


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