Date: Wed, 22 Aug 2012 14:27:28 -0700 From: Jeremy Chadwick <jdc@koitsu.org> To: freebsd-stable@freebsd.org Subject: FreeBSD 9.x default filesystem layout and installworld Message-ID: <20120822212728.GA3561@icarus.home.lan>
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(Please keep me CC'd, as I am not subscribed to the list) With the release of FreeBSD 9.0-RELEASE that the default filesystem layout (specifically the "Guided" -> "Entire Disk" choice) is to have a single filesystem (/). Shown here: http://www.freebsd.org/doc/handbook/bsdinstall-partitioning.html I'm not against this idea (I'm well-aware of the pros and cons), but there seems to be a conundrum here. The Handbook: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html ...says in Section 25.7.1 and 25.7.5 to use "mount -u /" (effectively the same thing as "mount -u -w /"). But neither /usr/src/UPDATING nor /usr/src/Makefile (the latter being more important if you ask me) mention this fact. Section 25.7.10 -- which is explicitly for installworld -- says nothing about needing this. Yet, if you don't, installworld will fail complaining that the root filesystem is read-only: Trying to mount root from ufs:/dev/da0p2 [rw]... Enter full pathname of shell or RETURN for /bin/sh: # cd /usr/src # make installworld mktemp: mkdtemp failed on /tmp/install.k0ti89Mb: Read-only file system "/usr/src/Makefile.inc1", line 186: warning: "/usr/bin/mktemp -d -u -t install" returned non-zero status mkdir -p usage: mkdir [-pv] [-m mode] directory_name *** Error code 64 Stop in /usr/src. *** Error code 1 Stop in /usr/src. # mount /dev/da0p2 on / (ufs, local, read-only) devfs on /dev (devfs, local, multilabel) Thus: # mount -u / # make installworld {...works fine...} That got me wondering: in all my years of having separate filesystems, I've never had to "mount -u /" after booting into SU and doing an installworld -- which updates contents in /lib (key point there). So what's doing it? The answer is "mount -a" or "mount -a -t ufs", which most of us do to mount things like /usr, /var, and /tmp when in SUM. /etc/fstab obviously says / should be mounted rw and "mount -a" does in fact honour that. Per the man page (last part is what's important): -a All the file systems described in fstab(5) are mounted. Excep- tions are those marked as ``noauto'', those marked as ``late'' (unless the -l option was specified), those excluded by the -t flag (see below), or if they are already mounted (except the root file system which is always remounted to preserve traditional single user mode behavior). Verification: # reboot {...} Trying to mount root from ufs:/dev/da0p2 [rw]... Enter full pathname of shell or RETURN for /bin/sh: # mount /dev/da0p2 on / (ufs, local, read-only) devfs on /dev (devfs, local, multilabel) # mount -a -t ufs # mount /dev/da0p2 on / (ufs, local, journaled soft-updates) devfs on /dev (devfs, local, multilabel) Either way, the documentation should be updated (both in the Handbook and in /usr/src/Makefile) to reflect this need (either "mount -u /" or "mount -a -t ufs", even on systems with only one filesystem). And while I'm here: this line in /usr/src/Makefile has been wrong for quite some time (over a decade): # 5. `reboot' (in single user mode: boot -s from the loader prompt). That should be "shutdown -r now". Yes there is a quite a difference. However, just to make it clear, the "reboot" in step 10 is correct. I can file a PR for all of this, but the /usr/src/Makefile modifications are not maintained by the doc team so I imagine someone with src commit bits would need to fix that. HTH, or at least food for thought. -- | Jeremy Chadwick jdc@koitsu.org | | UNIX Systems Administrator http://jdc.koitsu.org/ | | Mountain View, CA, US | | Making life hard for others since 1977. PGP 4BD6C0CB |
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