On Wednesday, December 19, 2001 7:09 PM BOUWSMA Beery wrote: > > Is it safe (relatively speaking) to use the null and the union > filesystems? The LINT kernel config file still includes dire > warnings, as do the man pages, but so far I've successfully > mounted a handful of filesystems without panicking my system, > though I've been careful to do it read-only when possible > ... > I do this by keeping the actual source read-write for cvsup > in /usr/local/system, which I then mount_null read-only on > /usr/src. (Likewise ports and stuff) > > Over top of this nullfs /usr/src I mount read-write my own > directory which gets my changes in /usr/local/source-hacks.
It looks like there are still some serious problems with this. I just tried a similar thing on FreeBSD 4.4 and 4.5. I created a directory of binaries to use for multiple jails, then null-mounted (read-only) the binaries for each of the jails to use. To allow the /etc and other parts of the jails to be written, I union-mounted a per-jail writeable filesystem over each of the null mounts. It seemed to work well until my jail setup program actually started a binary from inside the jail (i.e., from the null mount) when the kernel panic'ed with trap 12. Guy Helmer Palisade Systems, Inc. To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
