Thomas,

Is this failure specific to NO_HZ, and that is why the "nolapic_timer" fix is i386 only?
I'm running 2.6.21-rc5 an nx6325 here in 64-bit mode and I don't see the dramatic
boot failure described earlier in this thread.

However, I have observed that when running on battery,
the LOC falls behind the irq0 timer to the tune of about
2 interrupt/minute.  eg. when i booted my machine, LOC was
behind irq0 by 50, and now about a 20 minutes later it is behind
irq0 by 99.  However, the LOC for each processor remain at
a constant offset with respect to each other.

I do not see these this drift when running on AC.
Yes, the system exports just C1 in both cases.

Other oddities is the IRQ name on irq0 is garbled:

lenb@nx6325:~> uname -a; cat /proc/interrupts; sleep 100; cat /proc/interrupts
Linux nx6325 2.6.21-rc5 #37 SMP Tue Mar 27 22:26:00 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
           CPU0       CPU1
  0:     723812          0    <NULL>-edge      timer
  1:        716          0   IO-APIC-edge      i8042
  8:          0          0   IO-APIC-edge      rtc
 12:      30719          0   IO-APIC-edge      i8042
 14:      24318          0   IO-APIC-edge      ide0
 16:      18316          0   IO-APIC-fasteoi   libata
 19:         21          0   IO-APIC-fasteoi   ehci_hcd:usb1, ohci_hcd:usb2, ohci_hcd:usb3
 20:          1          0   IO-APIC-fasteoi   ohci1394
 21:       6736          0   IO-APIC-fasteoi   acpi
 23:      30358          0   IO-APIC-fasteoi   eth0
NMI:          0          0
LOC:     723675     723651
ERR:          0
           CPU0       CPU1
  0:     748812          0    <NULL>-edge      timer
  1:        716          0   IO-APIC-edge      i8042
  8:          0          0   IO-APIC-edge      rtc
 12:      30719          0   IO-APIC-edge      i8042
 14:      25164          0   IO-APIC-edge      ide0
 16:      18361          0   IO-APIC-fasteoi   libata
 19:         21          0   IO-APIC-fasteoi   ehci_hcd:usb1, ohci_hcd:usb2, ohci_hcd:usb3
 20:          1          0   IO-APIC-fasteoi   ohci1394
 21:       6960          0   IO-APIC-fasteoi   acpi
 23:      31385          0   IO-APIC-fasteoi   eth0
NMI:          0          0
LOC:     748673     748649
ERR:          0
lenb@nx6325:~> bc -l
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.
748812-723812
25000
748673-723675
24998
723812-723675
137
748812-748673
139
lenb@nx6325:~> 

Further, in dmesg:
ATI board detected. Disabling timer routing over 8254.

..MP-BIOS bug: 8254 timer not connected to IO-APIC

-Len