How it works:
- after successful execution of /etc/rc, check the value of "init.root"
sysctl node, if it's different than "/", chroot() into its value and run
/etc/rc inside the chroot(),
- in single-user, return back to the original / file system.
Allows running with / file system on e.g., cgd(4), vnd(4) or ccd(4) volumes.
Idea first discussed with Matt Thomas, implemented by Jachym Holecek <freza
(at) liberouter.org> with some nitpicks by me. Successfully used by me for
almost a year with / on a cgd(4) volume (for more information about the setup
check ftp://ftp.NetBSD.org/pub/NetBSD/misc/salo/init-chroot/ ).
salo