Am 19.05.2017 um 19:58 schrieb Maximilian Stein: > Package: systemd > Version: 232-23 > Severity: normal > > Dear Maintainer, > > After having upgraded to Stretch, I noticed that > systemd-tmpfiles-setup.service attempts to create /etc/mtab as > configured in /usr/lib/tmpfiles.d/debian.conf. Unfortunately, this > does not work on some of my machines where / is mounted read-only and > consequently, systemd-tmpfiles-setup.service fails. > > Moreover, this step does not seem to be necessary, as /etc/mtab is > symlinked to /proc/mounts after a fresh debootstrap. /proc/mounts in > turn symlinks to /proc/self/mounts, the same file as configured in > /usr/lib/tmpfiles.d/debian.conf. > > What exactly are the reasons for re-creating /etc/mtab on every boot? Is > this step really necessary?
Well, it's not really re-created on every boot, just if /etc/mtab is *not* a relative symlink to ../proc/self/mounts. debootstrap from sid creates /etc/mtab as relative symlink to ../proc/mounts afaics (the version from jessie seems to create it as an absolute symlink to /proc/mounts) So I guess the problem here is that there is a mismatch between what debootstrap creates and what systemd-tmpfiles (i.e. debian.conf) expects. In jessie we handled this slightly differently [1]. We had a dedicated service unit which checked if /etc/mtab was a symlink. So we didn't run into the issue there, that the symlink can be absolute or relative and point to either /proc/mounts or /proc/self/mounts. We chose ../proc/self/mounts in debian.conf since that's also what's used by systemd upstream [2], i.e. we are consistent with other distros in that aspect. Maybe we can change debootstrap to use ../proc/self/mounts or is there a good reason why it should point to ../proc/mounts? CCed the debootstrap maintainers for their input. Regards, Michael [1] https://anonscm.debian.org/cgit/pkg-systemd/systemd.git/commit/?id=b3ba0e60 [2] https://github.com/systemd/systemd/blob/master/tmpfiles.d/etc.conf.m4#L12 -- Why is it that all of the instruments seeking intelligent life in the universe are pointed away from Earth?
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