On Sat, Sep 26, 2020 at 10:02:10AM -0700, Rodney W. Grimes wrote: > > > On Fri, 2020-09-25 at 10:55 -0700, Rodney W. Grimes wrote: > > > > I was under the impression from previous reading and kib's response > > > > that this is a complete non-issue, there's no way you can go > > > > multi-user without a mounted /dev and we go to somewhat great > > > > lengths to make sure we're good. > > > > > > Though kib can assert that, it does not change the fact that I > > > frequently find /dev/null FILES on unmounted root file systems. > > > > > > But lets not mix the 2 separate things of boot time /dev dependency > > > and build time /dev dependency. > > > > If you look in sys/kern/vfs_mountroot.c you can see that the code to > > mount /dev is invoked unconditionally as the first step of mounting > > root, and that all the calls it makes to get devfs mounted have their > > results checked with KASSERTs. > > > > That's pretty strong evidence that devfs is mounted before rc scripts > > run. That creates a situation where you are making an extraordinary > > claim, so you need to provide extraordinary evidence to support it. A > > sequence of actions that allows others to recreate the situation would > > do the trick. > > I have provided ways one can look for this file in > other messages of the threads. A dump of a UFS root > can show it up, and iirc you can find it in a > zfs send of a boot dataset. > > > > > (A question that occurs to me: could it be that the files you've seen > > got created at shutdown after devfs was unmounted, rather than at > > startup? I don't know enough about the shutdown sequence to know > > whether that's possible.) > > Its not "the files" it is "a file, /dev/null". And yes, it could > be very possible that it is during shutdown. Sadly the files is > usually of 0 length so leave little clue as to what is creating them.
Out of curiosity I checked it on 3 of my machines, oldest of them was installed in 2014 and had numerous issues with boot and shutdown meantime. Roots are on UFS, and everywhere I see solo% sudo dump -0 -f - / | (cd /tmp && restore -i -f -) ~ DUMP: WARNING: should use -L when dumping live read-write filesystems! DUMP: Date of this level 0 dump: Sat Sep 26 22:07:39 2020 DUMP: Date of last level 0 dump: the epoch DUMP: Dumping /dev/nda0p2 (/) to standard output DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 785484 tape blocks. DUMP: dumping (Pass III) [directories] DUMP: dumping (Pass IV) [regular files] restore > cd /dev restore > ls ./dev: restore > quit DUMP: Broken pipe DUMP: The ENTIRE dump is aborted. So for me the question how do you get your /dev/null on root is open. _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
