USB on DomU

[Martin Hargreaves <m.l.hargreaves@xxxxxxxxx>]

Dear Xen Community,

I have recently created an Ubuntu 16.04 Guest DomU which seems to run 
okay but I’m struggling for it to see USBs.
On my host Dom0 system, a ‘lsusb’  shows my device as..
Bus 002 Device 005: ID 058f:6387 Alcor Micro Corp. Flash Drive

In my config file I use the settings…

usbctrl=[ 'type=auto,version=2' ]
usbdev=[ 'hostbus=2,hostaddr=5' ]

As I issue the xl create command, the USB mounted on Dom0 is unmounted 
(I don’t know if this is expected) and my DomU seems to start ok. 
However, when I do an ‘lsusb’ I can’t see it when in my DomU.
On Dom0 (ID=3), if I issue the following command,  it seems like it has 
worked.
root@Dell-e6400-2:~# xl usb-list 3
Devid  Type         BE  state usb-ver ports
0      qusb         0   1     2       8
  Port 1: Bus 002 Device 005
  Port 2:
  Port 3:
  Port 4:
  Port 5:
  Port 6:
  Port 7:
  Port 8:

Am I missing a further step to see the USB device in my DomU?

  Thank you for any insights that anyone may have.

    Martin...