root NFS causes solid lockup, serial console no help, watchdog NMI won't function on Dual AMD system

[Brad Barnett <lists@l8r.net>]

Hello,

I have a couple of dual AMD Opteron system with differing motherboards. 
On both of these differing pieces of hardware, I can not enable the NMI
watchdog timer, with nmi_watchdog=1.  I constantly get:

testing NMI watchdog ... CPU#0: NMI appears to be stuck (0->0)!

This happens when booting with both Debian's packaged kernels, 2.6.17-2
and 2.6.18-2.  According to this page:

http://www.mjmwired.net/kernel/Documentation/nmi_watchdog.txt

nmi_watchdog=2 does not work with AMD systems at this time.

Both boxes, aside from this, boot fine.  They use nfsroot, booting the
kernel off of a local drive, and switching to nfsroot during the bootup. 
They work flawlessly for anywhere from a week to a few days, then lock up
solid.  I can not seem to reproduce this problem unless I am using
nfsroot, and the above kernels seem fine without issue when booting and
running off of a local drive.

I can not get any information from a serial console, and just for fun I
redirected syslog to another box, yet I did not see anything about the
impending doom to come.  The console itself is simply a blank screen, and
the keyboard is dead... 

Does anyone have any suggestions for tracking this bug down?

Thanks