Mark Marshall wrote:
Timothy Normand Miller wrote:
On Fri, Aug 1, 2008 at 3:25 PM, Mark Marshall
<[EMAIL PROTECTED]> wrote:
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?
Somehow, I had gotten the impression that the VGA BIOS goes in a fixed
location in the lower 1 meg, and that only the BIOS from the main
console gets shadowed there. Other VGA cards are treated like generic
PCI devices, having their BARs assigned space (if that's enabled in
the BIOS config), but with memory space decode disabled, and the PROM
is pretty-much ignored.
This is explained in section 6.3 of the PCI spec.
Sorry for jumping in like this but I read this overview a couple of days
ago (memory layout for a 32-bit "intel" pc - which may or may not be
helpful):
http://duartes.org/gustavo/blog/post/motherboard-chipsets-memory-map
There's also a link on that page to very interesting "deep dive" into
how memory works (which probably won't help much in this case):
http://people.redhat.com/drepper/cpumemory.pdf
Best regards
Peter K
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