Greg,
The problem with Arjan's patch, if I understand it correctly, is that it
requires drivers to make a call to access extended PCI config space.
And, IIRC, Arjan's patch encumbers drivers for all arch's, even those
that have no MMCONFIG problems.
The patches proposed by Loic, Ivan, Matthew, and myself, all address the
problem in an x86-specific manner that is transparent to the drivers.
--