Re: pci in arch/powerpc vs arch/ppc

It means the bus on which legacy I/O ports can be found.  It's a fairly
broken concept; each host bridge should really be treated as a
completely separate entity, and if something like a VGA card has legacy
I/O ports that need to be used, they should be looked for on the same
PCI bus as the card itself.  Legacy ISA ports should be discovered
through the device tree (or platform devices, or whatever) that
explicitly state which PCI-to-ISA bridge they're under.

Currently, Linux does not allow multiple PCI domains to use
overlapping legacy I/O ranges.  Yeah it's a pain.

Yes, apparently -- according to a recent thread here, recent versions 
of
the PCI spec removed the wording that prohibited a zero BAR (is there
then no way to disable a BAR?).

I couldn't find that prohibition even in ancient versions of
the PCI specification, for what it's worth.  Maybe I'm just
blind.

Still, it'd be better to avoid it.

Yeah, many drivers go bonkers otherwise.  Some devices might
misbehave, too.


Segher