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SubjectRe: Next round of console patches
On Wed, 2 Sep 1998, Vojtech Pavlik wrote:

> On Wed, Sep 02, 1998 at 08:20:32AM +0200, Gerd Knorr wrote:
>
> > There is. The VESA BIOS will tell you (a) how much video memory the board
> > has installed and (b) where the linear framebuffer starts. vesafb (well,
> > the real mode boot code) asks the BIOS for these values and uses this for
> > the framebuffer device. And for exactly this area the mtrr entry is added.
> >
> > Assuming legal framebuffer space and MMIO don't overlap, this works fine.
>
> As far as I know, this assumption is not true at least for Mach64 based VGA
> cards - they map their MMIO over the last kilobyte of video RAM in the
> aperture.
^^^^^^^^
Could you explain this? My dictionary has'nt conputer-speak translation
for this...

Does it really mean the video memory and mmio overlap? Or is this some
larger area (say 16 MB space) for graphics I/O with the framebuffer (say 4
MB) at the start and 1k MMIO at the end and some unused space inbetween?

Gerd


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