[Libvir] what is virt-install doing differently?

I'm looking at a problem where HVM xen/ia64 domains hang on boot using virt-install, specifically at this point: ACPI: Core revision 20060707 Boot processor id 0x0/0x0 Given VT-I capable hardware, this can be demonstrated with: virt-install -n rhel5hvm1 -v -r 1024 --vcpus=2 -c \ /root/RHEL5-Server-20070112.3-ia64-DVD.iso -f \ /var/lib/xen/images/rhel5hvm1 -s 20 --vnc The really strange thing is that the boot works fine, using the same configuration, if virt-install is not involved. Actually, I modify the configuration slightly to include the CD-ROM, but otherwise it is the same: # cat /etc/xen/rhel5rc1s7hvm2 # Automatically generated xen config file name = "rhel5rc1s7hvm2" builder = "hvm" memory = "1024" disk = [ 'phy:/dev/cciss/c0d1p1,hda,w', 'file:/root/RHEL5-Server-20070112.3-ia64-DVD.iso,hdc:cdrom,r' ] vif = [ 'type=ioemu, mac=00:16:3e:50:4c:95, bridge=xenbr1', ] uuid = "c228739b-9e6c-bb11-47d8-281ca2edf750" device_model = "/usr/lib/xen/bin/qemu-dm" kernel = "/usr/lib/xen/boot/hvmloader" vnc=1 vncunused=1 apic=1 acpi=1 vcpus=2 serial = "pty" # enable serial console on_reboot = 'restart' on_crash = 'restart' I don't understand what would be different about the virt-install boot vs. booting straight from the generated configuration. Can somebody shed some light on this? Thanks, Aron