I mentioned this yesterday,
but it was buried in another thread:
 
When I try to reboot dom0,
it switches to runlevel 6 and the xen init.d script attempts to stop a domU
containing an Asterisk installation.  It's at that point I get an
"hda: interrupt lost" on the physical console.  SSH become
inaccessible and eventually the system pukes up a bunch of ext3 and RAID
controller related errors and freezes.  I have to physically power cycle
the box to get it back up.
 
I suspect that a PCIe telephony
card that I’m passing to the domU using pciback is the source of the
problem.  The card is a Digium AEX800 (which is actually a PCIe version of
Digium's PCI-based TDM800P). Based on some preliminary testing, the card seems
to function just fine in the domU.  lspci output is:
 
0b:08.0 Ethernet controller:
Digium, Inc. Unknown device 8002 (rev 11)
       
Subsystem: Digium, Inc. Unknown device 8002
       
Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping-
SERR- FastB2B-
       
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort-
<MAbort- >SERR- <PERR-
       
Interrupt: pin A routed to IRQ 16
       
Region 0: I/O ports at dc00 [disabled] [size=256]
       
Region 1: Memory at fc7dfc00 (32-bit, non-prefetchable) [disabled] [size=1K]
       
Expansion ROM at fc7e0000 [disabled] [size=128K]
       
Capabilities: [c0] Power Management version 2
               
Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold-)
               
Status: D0 PME-Enable- DSel=0 DScale=0 PME-
 
Any suggestions?  This
is a new Dell PowerEdge 1950 with a PERC SATA RAID 1 array, running CentOS 5.1
(2.6.18-53.1.14.el5xen) in both the dom0 and domU.