Timothy Normand Miller wrote:
On Fri, Aug 1, 2008 at 5:05 AM, Mark Marshall
<[EMAIL PROTECTED]> wrote:
Ti
I'll hopefully have a basic framework checked in this weekend, it's nearly
there. The code doesn't do anything yet, but it installs handlers, can
change the PCI config registers and do other dull housekeeping things.
Very nice!
So, I'm wondering something. Say we have two OGD1 boards in, and one
gets picked as the console and setup by the BIOS. So our BIOS code is
running... how does it tell which card was picked? I think I saw
somewhere that there are int calls to the system BIOS that handle
config space and also can tell you which device you are.
I think that you are aloud to have multiple VGA cards installed at any
one time. When the motherboard BIOS calls the VGA BIOS it passes in the
Bus, Device and Function numbers, which I think are enough to identify
the card. The VGA BIOS can then store these numbers and use them later
when it wants to talk to the configuration space or the BAR's. There
are also collection of INT 0x10 calls that are to do with switching
display adapter, but I'm not really sure that I fully understand them yet.
The best reference that I've found of this is Ralf Browns dual monitor
code, which is ancient, but enabled a DOS program to switch between two
PCI VGA's.
Another question with this sort of setup is to do with the motherboard
copying the VGA BIOS from ROM into RAM and calling the initialization
function - does this happen for each VGA separately? What does it do
with the memory from the first when it calls the second?
I'm not sure where this sort of stuff is specified, any ideas?
MM
http://www.cs.cmu.edu/~ralf/files.html
RBdualVGA
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