Problems with more than 8 AMD Opteron Cores per System

[Oliver Weihe <o.weihe@deltacomputer.de>]

Hello,

I've two Iwill 8way Opteron equipped with 8 Opteron 875 CPUs each.
(In the past we build some systems with singlecore CPUs and they went
very well)

The Problem now is that the machines crash during boot when maxcpus is
greater than 8.
2.6.12-rc4 works well with maxcpus=8, with 9 or more it freezes after
"Testing NMI Watchdog... OK"

2.6.12-rc5 and above have more problems even with maxcpus=4 or less very
early during booting.

2.6.13-X crashes later during boot (from 2 to 16 cores it's the same
behavior)

The last I can so on the console (kernel 2.6.13-rc2-git4, maxcpus=2..16)
is:

NET: Registered protocol family 1
Using IPI Shortcut mode
int3: 0000 [1] SMP
CPU4
Modules linked in:
Freeing unused kernel memory: 212k freed
Pid: 0, comm: swapper Not tainted 2.6.13-rc2-git4-default
RIP: 0010:[<ffffffff8050fc00>]

After that the machines are totally freezed.

With maxcpus=1 all (tested) versions >=2.6.12-rc3 are able to boot.

Any hints/ideas/what ever?

Regards,
   Oliver Weihe

P.S. if you answer CC me ;)