Hi,
Linus really wants the extended (4Kb) PCI configuration space (using MCFG acpi table etc) to be opt-in, since there's many issues with it and most drivers don't even use/need it. The idea behind opt-in is that if you don't use it, you don't get to suffer the bugs...
Booted on my 64 bit test machine; sadly it has a defunct BIOS that doesn't have a working MCFG.
From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Subject: Make MMCONFIG space a driver opt-in
There are many issues with using the extended PCI configuration space (CPU, Chipset and most of all BIOS bugs). This while the vast majority of drivers
and devices don't even use/need to use the memory mapped access methods since they
don't use the config space beyond the traditional 256 bytes.
This patch makes accessing the extended config space a driver choice, via the
pci_enable_ext_config(pdev)