trouble with pygrub after upgrade

[John Hayward <john.hayward%wheaton.edu@localhost>]

Dear NetBSD-Xeners,
Yesterday I did an upgrade to NetBSD-5.1.2 and had a few issues along the way:

The netbsd-XEN3_DOM0 kernel did not automatically find the wd0a disk as root - 
I had to build a kernel with root on wd0a.

My bigger problem is that some of my linux vms did not come up - those which 
did not have pygrub specified came up fine.  Those which used pygrub did not 
come up.

The error in terminal was:
xm create bio-Ubuntu64-10.04
Using config file "./bio-Ubuntu64-10.04".
Error: Boot loader didn't return any data!

The errorr in xend.log was:
[2012-07-09 12:13:58 213] DEBUG (XendDomain:449) Adding Domain: 14
[2012-07-09 12:13:58 213] DEBUG (XendDomainInfo:2149) 
XendDomainInfo.initDomain: 14 2
56
[2012-07-09 12:13:58 1764] DEBUG (XendBootloader:113) Launching bootloader as 
['/usr/
pkg/bin/pygrub', '--args=root=/dev/hda1 ro ip=:127.0.255.255::::eth0:dhcp 
fastboot ra
id=noautodetect', '--output=/var/run/xend/boot/xenbl.5941', '-q', 
'/BioXen/fs/BioRoot
64.fs'].
[2012-07-09 12:13:58 213] ERROR (XendBootloader:213) Boot loader didn't return 
any da
ta!
[2012-07-09 12:13:58 213] ERROR (XendDomainInfo:467) VM start failed
Traceback (most recent call last):
  File "/usr/pkg/lib/python2.7/site-packages/xen/xend/XendDomainInfo.py", line 
447, i
n start
    XendTask.log_progress(31, 60, self._initDomain)
  File "/usr/pkg/lib/python2.7/site-packages/xen/xend/XendTask.py", line 209, 
in log_
progress
    retval = func(*args, **kwds)
  File "/usr/pkg/lib/python2.7/site-packages/xen/xend/XendDomainInfo.py", line 
2151,
in _initDomain
    self._configureBootloader()
  File "/usr/pkg/lib/python2.7/site-packages/xen/xend/XendDomainInfo.py", line 
2604,
in _configureBootloader
    bootloader_args, kernel, ramdisk, args)
  File "/usr/pkg/lib/python2.7/site-packages/xen/xend/XendBootloader.py", line 
214, i
n bootloader
    raise VmError, msg
VmError: Boot loader didn't return any data!

Any hints on how to proceed would be appreciated.

johnh...