Re: pci in arch/powerpc vs arch/ppc

On Thu, 2007-08-09 at 17:56 +0200, Segher Boessenkool wrote:

quoted

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.

I have a plan I exposed a little while ago to handle that. We need that
for VGA cards among others anyway.

The idea is basically a call around the lines of
pci_convert_legacy_resource(struct resource *r);

You fill up the resource with flags = MEM/IO and start/end being your
legacy range, and it returns a "fixed" resource that you can use with
inX/outX, or whatever else.

Haven't had time to code something up, and we need to provide a default
impl. for all archs too ... but feel free to volunteer and beat me to
it :-)

Ben.