Hi again,
It would be interesting to test 0x00...300 and 0xff...400 just for completeness.
The 0x00...300 does the same (NMI delivered on all CPUs) and the other one does nothing.
That would be great. I am really curious about the official clarification on the issue. Maybe there is a configuration bit that they forgot to set or something like that.
I try to get someone responsible for this.
I found a really old document about AMD-8131 chipset which seems like something that later morphed into the APIC component of the southbrdiges and in that document they discuss APIC -> HT mapping quite extensively. I wonder what went wrong later on. In this copy of the document it's on page 67 http://www.tautec-electronics.de/Datenblaetter/Schaltkreise/AMD8131.pdf
I think the SB600 series was an ATI design, so perhaps it is just bug.
Thanks Rudolf