freebsd-update mounted system

[rhlampe]

I have a FreeBSD 8.0 Live FS and want to run freebsd-update on different versions of FreeBSD mounted to /tmp/mnt without using chroot.

I thought this would be possible running:

# freebsd-update -b /tmp/mnt/ -d /tmp/mnt/var/db/freebsd-update fetch
# freebsd-update -b /tmp/mnt/ -d /tmp/mnt/var/db/freebsd-update install

However, this just tries to run freebsd-update on the live fs.

Am I doing something wrong or is this even possible?