RCng

I have finally got skeljail implemented through the RCng way. After some test I will post the patch for review.

A skel jail is a jail that share essential binaries/libraries with the base system (optionally, other base template if you want) through mount_nullfs.

The RCng system was developed by NetBSD and FreeBSD have adopted it. _rc_subr_loaded is a flag that both system adopts to speed up the startup.

The FreeBSD approach is to determine whether to run for the whole rc.subr script, while NetBSD approach is to define it as a “:” so rc_subr won’t be loaded.

Which is better?

Dag-Erling Smørgrav has posted a discussion on FreeBSD-arch (I have to use a outside link instead of FreeBSD’s own mailing list archive, because it didn’t updated from 2004-01-26 for unknown reason), accroding to this post, we see a need of running init(8) in jails, which allows us to terminate a jail cleanly.