I was able to solve the problem by enabling
the guest to directly access an external usb cdrom device.
Therefore dom0 has control of the internal
cdrom device and 3 domains get one usb port each. 
 
1) Change /boot/grub/menu.lst in dom0 and
reboot 
 
title Xen2
    kernel (hd0,4)/xen.gz
dom0_mem=417972 physdev_dom0_hide='(00:03.0)(00:03.1)(00:03.2)'
    module
(hd0,4)/vmlinuz-2.6.8-24.14-xen
    module
(hd0,4)/initrd-2.6.8-24.14-xen
 
2) add pci device line in domU config
file:
 
    pci = [ '00,03,00' ]
 
 
Thanks,
 
    
From:
xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Utsav Agarwal
Sent: Wednesday, July 27, 2005
1:27 PM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] error
accessing cdrom in domU
 
 
The following 2 error messages found in
dom0 system log:
 
kernel: hdc: cdrom_read_intr: data
underrun (2 blocks)
kernel: end_request: I/O error, dev hdc,
sector 64
 
when I try to mount the cdrom from domU
 
 
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Utsav Agarwal
Sent: Wednesday, July 27, 2005
11:48 AM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] cdrom access
in domU
 
 
I am currently having to nfs export cdrom from dom0 to domU
and that is cumbersome. 
Is there a way to do it at the device level?
 
 
------------------------------------------------------------------------------------
Utsav Agarwal
Systems Analyst
eXcellence in IS Solutions (X-ISS)
------------------------------------------------------------------------------------