Hyper-V virtual DVD not detected

[xenophon\+freebsd]

Hi everybody!

Is anyone else running FreeBSD-current under Hyper-V?  I can boot
10.0-ALPHA4 under Hyper-V Server 2012 using the installation CD image,
but once running FreeBSD doesn't detect the virtual DVD drive - or at
least the cd0 device is missing.  Virtual hard disks attached to the
same storage controller work just fine, IDE or SCSI.  Conversely,
everything works as expected under FreeBSD 9.2.  I was able to install
10.0-ALPHA4 by attaching a second hard drive and copying the ISO image
over the top of it.  (The installer had no problems locating the
FREEBSD_INSTALL volume on the second hard drive.)

I'm not sure how to go about troubleshooting this.  To start I am
upgrading to r256072 in case any commits since ALPHA4 have fixed this
problem.  I'm also going to take a look at the source to the Hyper-V
drivers.  Beyond that, I'm open to any suggestions.

Best wishes,
Matthew

-- 
I FIGHT FOR THE USERS