Xen HVM's on raw disk partitions

[eric%cirr.com@localhost (Eric Schnoebelen)]

Emperical evidence suggests that it is impossible to put an Xen
HVM on a raw disk (r?d?*) partition.  Only a file backed disk image will
work.

Having had success with running NetBSD DomU's on a raw disk
partition (marked as type CCD in the disklabel), I'd like to do
the same for HVM systems.

My software:

        NetBSD egsner.cirr.com 5.99.27 NetBSD 5.99.27 (XEN3_DOM0) #0: Tue Apr 
13 00:12:10 CDT 2010  
eric%bob-the-builder.cirr.com@localhost:/work/eric/NetBSD-current/obj/amd64/sys/arch/amd64/compile/XEN3_DOM0
 amd64

        xentools33-3.3.2nb5
        xenkernel33-3.3.2nb1

Is there a way to use raw partitions for HVM's?  Is it a bug in
the qemu back end driver, or somewhere else?

Thanks,
        Eric

--
Eric Schnoebelen                eric%cirr.com@localhost         
http://www.cirr.com
  "I came out of it dead broke, without a house, without anything except a
   girlfriend and a knowledge of Unix." "Well, that's something. Normally
     those two are mutually exclusive" - Neal Stephenson, Cryptonomicon