[Open-graphics] From PCI to VGA registers

[Fredrik Tolf]

On Sat, 2007-08-11 at 21:04 +0200, Fredrik Tolf wrote:
> On Sat, 2007-08-11 at 19:23 +0200, Michael Meeuwisse wrote:
> > On 11 Aug 2007, at 16:02, Fredrik Tolf wrote:
> > > On Fri, 2007-08-10 at 00:35 +0200, Michael Meeuwisse wrote:
> > >> I found the appropriate second in the PCI Specification, I'll read up
> > >> on it.
> > > Might I ask how you found the PCI Specification? Surely, you did  
> > > not pay
> > > $3000 to join the PCI-SIG?
> > And I've got "The PC-hardware book" by Hans-Peter Messmer (translated  
> > to Dutch from German I believe) which explains a boatload of details.  
> > Really nice book.
> 
> Thanks for the tips, both of you! If have actually already ordered the
> book that Timothy linked to.

The book arrived today, and I now understand a *lot* more about PCI than
I did previously. Thanks again!

This might not be the place for these things, but if you don't mind
spending a little time on me, there's still something I don't quite
understand in relation to VGA legacy address decoding. Namely, how does
the system select which card is supposed to do legacy decode?

Since it is usually selectable in the system BIOS UI which card should
be initialized as _the_ VGA card in the presence of multiple
VGA-compatible cards, there has to be some standardized way of enabling
legacy decode on a card, right? I just can't find what that way is. My
naive guess is that it might be that the system BIOS only calls the VGA
BIOS code for the selected card, and it sets up legacy decode in a
card-specific way, but I can just find no way to confirm that, and I've
been googling for quite some time now.

Fredrik Tolf