Re: CHALLENGE!!! =)

Stephen Williams (steve@icarus.com)
Fri, 14 Aug 1998 13:23:50 -0700


Caveat: The PCI systems I work with and BIOSes I write do not support
VGA devices in general, though I have had to deal with the occasional
VGA chip. So...

alex.buell@tahallah.demon.co.uk said:
> Does PCI allows us to plug in say, two Matrox Millenniums, and use as
> an unified X11 display across the two of the monitors?

PCI allows one to map the address of boards from the BIOS, but the
VGA space is a specific exception. A VGA device responds to the VGA
area *in addition to any BAR regions it may support.* So, at least one
of your video cards must support turning this area off. All the linear
frame buffers are not a problem as they are managed through the BARs
and can be separated by normal BIOS behavior.

It's that pesky 0xa0000-0xbFFFF memory range. It is possible for some
boards to have this range jumpered *off*.

-- 
Steve Williams                "The woods are lovely, dark and deep.
steve@icarus.com              But I have promises to keep,
steve@picturel.com            and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."

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