:-)
It's broken with drivers using MMIO, I meant to say.
This is a *hardware* mapping on some non-x86 platforms (like PPC 44x or
MIPS Alchemy). The arch/ppc/ and arch/mips/ kernels have special hooks called
from ioremap() which help create an illusion that the PCI memory space on such
platforms (not only it) is mapped below 4 GB; arch/powerpc/ kernel doesn't do
this anymore -- hence this newly encountered issue.
WBR, Sergei
--