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Bridge/BIOS issue



All,

I've got a PCI bus master device that wants 256MB of memory space
allocated to it.  If I plug it directly into the motherboard (in this
case, a Gigabyte 6VXD7, PIII, VIA chipset, AMI BIOS), everything comes
up normally.  However, if I place it behind an Intel 21150 bridge chip,
when plugged into the same motherboard, something weird happens:

- BIOS programs my part to a base address of 0xC0000000
- BIOS programs the 21150's base address to 0xD9A00000
- BIOS programs the 21150's limit address to 0xD9AFFFFF

I would expect the base/limit registers in the 21150 to be set to
0xC0000000/0xCFFFFFFF but that's not what the BIOS does.  Obviously this
won't work.  Is 256MB of space too much to ask to sit behind the
bridge?  Could this be a problem with the 21150 or is it more likely the
BIOS running on the motherboard?  Anything I overlooked?

Thanks in advance for your help.

Andrew Krenz
Aristos Logic Corp.