Messages in this thread | | | Date | Wed, 5 Aug 1998 15:05:07 +0200 (CEST) | From | Geert Uytterhoeven <> | Subject | Re: FB and MTRR |
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On Wed, 5 Aug 1998, Richard Gooch wrote: > 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?
Right. VGA relies on the legacy I/O stuff.
> 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?
Right.
Greetings,
Geert
-- Geert Uytterhoeven Geert.Uytterhoeven@cs.kuleuven.ac.be Wavelets, Linux/{m68k~Amiga,PPC~CHRP} http://www.cs.kuleuven.ac.be/~geert/ Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium
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