Xen users - Oct 2012 - Booting Xen 4.1.3 Dom0 hangs with PANIC on CPU 6: Xen BUG at io_apic.c:129

Hi all,

I have searched the net and haven''t found a good answer so I hope
perhaps someone here can help.

I have an IBM x3850 (8863) that I am upgrading from SLES11SP1 to SLES11SP2, and
at the same time XEN is being upgraded as part of the distro.   The server is
used as a Xen host for up to 6 guests.

  Anyway, the server boots fine with the SLES11SP2 default kernel, and the trace
kernel, but, fails on booting to the Xen kernel and exits with:

(XEN) ****************************************
(XEN) Panic on CPU 6:
(XEN) Xen BUG at io_apic.c:129
(XEN) ****************************************

There are only 4 cpu''s in the system, but, xen seems to always report
2x more since I have started using xen 3x.


Prior to this message I was receiving "waiting for drive to appear" ,
but, I changed the initrd to remove some old kernel module, and reinstalled the
xen kernel.

I have added most of the APIC related lines from the log below.

Any suggestions?
Thanks,
Brent
=====================================
Serial Con log:

[    0.131484] ACPI: Core revision 20110413
[    0.131484] ACPI: Core revision 20110413
(XEN) io_apic.c:2538: 
(XEN) ioapic_guest_write: apic=1, pin=1, irq=4
(XEN) ioapic_guest_write: new_entry=000000f1
(XEN) ioapic_guest_write: old_entry=00000030 pirq=1
(XEN) ioapic_guest_write: Attempt to modify IO-APIC pin for in-use IRQ!
(XEN) allocated vector e5 for irq 5
(XEN) irq.c:1630: dom0: pirq 0 or irq 5 already mapped
(XEN) allocated vector ea for irq 10
(XEN) irq.c:1630: dom0: pirq 7 or irq 10 already mapped
(XEN) allocated vector eb for irq 11
(XEN) irq.c:1630: dom0: pirq 8 or irq 11 already mapped
(XEN) allocated vector 88 for irq 16
(XEN) allocated vector 90 for irq 17
(XEN) allocated vector 98 for irq 18
[    0.168754] SMP alternatives: switching to SMP code
[    0.168754] SMP alternatives: switching to SMP code
[    0.222020] Brought up 8 CPUs
[    0.222020] Brought up 8 CPUs
[    0.222243] devtmpfs: initialized
[    0.222243] devtmpfs: initialized
[    0.222243] print_constraints: dummy: 
[    0.222243] print_constraints: dummy: 
[    0.222243] Time: 19:50:22  Date: 10/01/12
[    0.222243] Time: 19:50:22  Date: 10/01/12
[    0.222243] NET: Registered protocol family 16
[    0.222243] NET: Registered protocol family 16
[    0.222243] ACPI: bus type pci registered
[    0.222243] ACPI: bus type pci registered
[    0.222243] PCI: Using configuration type 1 for base access
[    0.222243] PCI: Using configuration type 1 for base access
[    0.222243] PCI: IBM System x3850 detected, can skip ISA alignment
[    0.222243] PCI: IBM System x3850 detected, can skip ISA alignment
[    0.224666] bio: create slab <bio-0> at 0
[    0.224666] bio: create slab <bio-0> at 0
[    0.440315] swapper:1 conflicting memory types bff75000-bff77000
uncached-minus<->write-back
[    0.440315] swapper:1 conflicting memory types bff75000-bff77000
uncached-minus<->write-back
[    0.440326] reserve_me(XEN) 
(XEN) ****************************************
(XEN) Panic on CPU 6:
(XEN) Xen BUG at io_apic.c:129
(XEN) ****************************************
(XEN) 
(XEN) Reboot in five seconds...