Btw, looking at that bogus BAR#3 some more: I don't actually think it's
even an MCFG resource.
I think it's literally the resource that describes the HT window for the
host bridge. So it's literally like the "root" resource - all external
MMIO resources that go over HT have to be in that window.
IOW, I'm starting to think that it's not even broken. It is probably
perfectly real. It's not a "PCI bridge" in the sense that it doesn't
bridge one PCI bus to another, but it's a host bridge, and it bridges the
CPU memory accesses to another bus.
The fact that the MCFG area happens to be at the start of that window is
probably just a random detail.
Does anybody know how to find chipset docs for AMD/ATI chipsets? I find
CPU docs, and the GPU docs, but not the 790 chipset docs anywhere (yeah,
it looks promising with a link that says "AMD 790FX Chipset
Specifications", but the link just takes you to some trivial overview, not
any actual specs.