Re: FB and MTRR
Richard Gooch (Richard.Gooch@atnf.CSIRO.AU)
Wed, 5 Aug 1998 21:54:23 +1000
Geert Uytterhoeven writes:
> On Wed, 5 Aug 1998, Richard Gooch wrote:
> > Martin Mares writes:
> > > > Isn't it a bad idea to touch the old VGA registers? I thought it was
> > > > better to use the new PCI space registers (so you can support multiple
> > > > heads)?
> > >
> > > Unfortunately, different PCI video cards have different register
> > > addressing :(
> >
> > Sorry, I'm missing the significance of that. My point was that the old
> > VGA registers mapped to < 1 MByte limit you to one card, so would it
> > not be better to have the FB code access the registers mapped to the
> > PCI space?
>
> Martin is right about this: mirros of the VGA registers in PCI
> memory space are nonstandard and differ between different video
> chipsets.
Is this a problem because you couldn't then have a plain VGA driver?
If so now I finally understand the point. That then imples that the
plain VGA/VESA driver can only ever support one card, whereas a
chipset-specific driver can support multiple cards?
Regards,
Richard....
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