making /dev/cd0a available to linux domu

[John.C.Hayward%wheaton.edu@localhost]

Dear NetBSD Xen fans,
   I have an old NetBSD dom0 (NetBSD 5.0BETA XEN3_DOM0 amd64 from 200811)
and a domu Ubuntu.  I am attempting to make /dev/cd0a on the backend
available to the Ubuntu.
   In the config file I have:
====
disk = [
....
dev:/dev/cd0a,0xb00,w
]
====
    If I do a xm list --long <domaiID> I don't see the cdrom listed.
    If I do a:
====
prompt> xm block-attach 4 /dev/rcd0a 0xb00 r
Error: Block device must have physical details specified
Usage: xm block-attach <Domain> <BackDev> <FrontDev> <Mode> [BackDomain]

Create a new virtual block device.
====
I am attempting to create a device with major 11 and minor 0 for linux
domu.

The comment in the distributed configuration file seems to indicate that
if I use a name I would need to create a /dev/name in dom0 with the 
correct major/minor for linux so xm could stat it but could put in
the major/minor values.

What do I need to do to be able to access the cd/dvd drive from domu
under Linux?

I would also like to be able to make a usb port available to a linux
domu as well - but that is a lower priority.

johnh...