I have been using a xen service for a few weeks. I was using PF and spamd. 
spamd was definitely working according to my logs.

Some upgrade was done by my Xen provider. I know nothing about the domain0 
but I think it is running NetBSD.

I have:

# uname -mrsv
NetBSD 3.0 NetBSD 3.0 (XENU) #0: Mon Dec 19 01:30:48 UTC 2005  
builds@works.netbsd.org:/home/builds/ab/netbsd-3-0-RELEASE/i386/200512182024Z-obj/home/builds/ab/netbsd-3-0-RELEASE/src/sys/arch/i386/compile/XENU 
i386

# ls -l /usr/lkm/pf.o
-r--r--r--  1 root  wheel  176613 Dec 18  2005 /usr/lkm/pf.o

When I attempt to load the module I get:

# /sbin/modload /usr/lkm/pf.o
modload: error initializing module: Program version wrong

And /var/log/messages has:

Jul 19 04:41:09 ca /netbsd: LKM 'pf': environment compile options mismatch 
- LKM '', kernel 'DEBUG,DIAGNOSTIC'

Anyone else have this problem?

I tried using modload -f before, but I think it locked up my system. I 
could not tell at that time because my console IP was changed. And I don't 
want to try again just in case I can't recover.

- Jeremy C. Reed

ps. Please carbon-copy me on replies.