Dom0 CLI
========
[root@xen-home ~]# cat /etc/modprobe.d/pciback.conf
install e1000 /sbin/modprobe xen_pciback ; /sbin/modprobe --first-time --ignore-install e1000
options xen-pciback hide=(01:0a.*)

[root@xen-home ~]# lspci -k | tail -6
01:0a.0 Ethernet controller: Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) (rev 01)
	Subsystem: Compaq Computer Corporation NC7170 Gigabit Server Adapter
	Kernel driver in use: pciback
01:0a.1 Ethernet controller: Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) (rev 01)
	Subsystem: Compaq Computer Corporation NC7170 Gigabit Server Adapter
	Kernel driver in use: pciback

[root@xen-home ~]# xl pci-assignable-list
0000:01:0a.0
0000:01:0a.1

[root@xen-home ~]# cat /etc/libvirt/libxl/ubuntu.xml
...
  <hostdev type='pci' managed='yes' mode='subsystem'>
    <source>
      <address domain='0x0000' bus='0x01' slot='0x0a' function='0x0' />
    </source>
  </hostdev>
...