PCI IO range limitation

[Benjamin Herrenschmidt]

> Define "legacy device"? What should that entail? You mean like mapping
> most of those registers to the first couple of kilobytes of "IO"?

Anything that hard-decodes IOs in the low ISA range yes. That includes
VGA video cards.

> If they're just left as their own on their own as PCI devices, why would
> it matter what the window was?

Because quite a few of those things hard decodes (can't be moved around,
so -have- to be able to generate cycles to those low addresses to hit
them) and sometimes don't even fully decode the 32 bits addresses
(though that's more rare).

For example, a VGA video card in text mode hard decodes both IO and
Memory at the legacy VGA ranges.

Ben.