uname -a
Linux 2.6.16-11.1-amd64-generic #2 SMP Tue Sep 12 19:11:38 UTC 2006 x86_64 GNU/Linux
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Intel(R) Xeon(TM) CPU 2.80GHz (EMT/AMD64 instruction set)
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Ubuntu Edgy updated to latest
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Hitachi SATA drive
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During bootup of domU:
...
XENBUS: Device with no driver: device/vbd/2049
....
Begin: Waiting for root file system...
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It hangs for a while, then punts into busybox/initramfs:

ALERT! /dev/sda1 does not exist. Dropping to a shell!
BusyBox v1.1.3 (Debian 1:1.1.3-2ubuntu3) Built-in shell (ash)
Enter 'help' for a list of built-in commands.

/bin/sh: can't access tty; job control turned off
(initramfs)