FreeBSD DomU: Upgrade from 7.2 to 8.0

[Alexander Johannes]

Hello,

i'm running a small FreeBSD-Box as XEN-DomU.

	# uname -a
	FreeBSD box.nirgal.de 7.2-RELEASE-p8 FreeBSD 7.2-RELEASE-p8 #0: Wed  
May 26 03:08:50 UTC 2010     root at i386-builder.daemonology.net:/usr/ 
obj/usr/src/sys/GENERIC  i386

The Dom0 is run by my provider with the following System (this is some  
Ubuntu-Flavor):

	Linux 2.6.18.8-xen #3 SMP Sat Sep 20 11:15:30 UTC 2008 x86_64
	xen-shell 1.2.83 running on Xen version 3.3.1

As FreeBSD 7.2 has reached EOL, i'm forced to update my System sooner  
or later to the current version.

Unfortunately neither FreeBSD 7.3 nor 8.0 will even boot, and are  
stopping with

	panic: vm_fault: fault on nofault entry, addr: c32ef000

after printing real and avaliable memory.

After reading the archives of this list, this seems to be a common  
problem, which /may/ be solved by building a custom kernel.

So i figure, that i have to check out the sources for FreeBSD 8  
(RELENG_8) and build a new Kernel with the configuration from /usr/src/ 
sys/i386/conf/XEN. Is the result sufficient or do i have to do more  
than that?

Any advise would be appreciated.

Alex