Isn't there a way to do MMCONF cycles from the NB?
No, I think only newer fam10h cpus can do that.
http://lkml.org/lkml/2007/12/21/134
So, the K8 internal devices are not accessible with the mmconf aperture which is NB dependent anyway. That post says that it may work for newer fam10h cpus. I think this is related: F1x[EC:E0] Configuration Map Registers and DisCohLdtCfg: disable coherent link configuration accesses.
I think linux has some test which test what devices can be accessed through type1 and what it sees on mmconf.
http://www.x86-64.org/pipermail/discuss/2005-December/007371.html
I think the only proper way is to do type1 and maybe some locking is necessary. Rudolf