Lennart Poettering
7c764d4599
We previously would use MS_MOVE to move the old procfs, sysfs, /dev/ and
/run to the new place in some places, and MS_BIND in others.
The logic when to use MS_MOVE and when to use MS_BIND was pretty
arbitrary so far: we'd use MS_MOVE during the initrd → host transition
and MS_BIND when transitioning from host into the exitrd during
shutdown.
Traditionally, using MS_MOVE was preferable, because we didn't bother
with unmounting the old mount hierarchy before the switch root, and thus
using MS_MOVE did some clean-up as side-effect (because the old mounts
went away this way). But since we nowadays properly umount all remaining
mount points (since 268d1244e8) when
transitioning it's pointless.
Let's just use MS_BIND always. Let's tweak it though: let's use
MS_BIND|MS_REC for the kernel API VFS, and MS_BIND without MS_REC for
/run/. The latter reflects the fact that the submounts /run/ has usually
are not so much about just accessing kernel APIs but about auxiliary
user resources. Hence let's only move the main mount over for that.
While we are at it, also set up the base filesystem *before* we move the
mounts from the old to the new root, since the base filesystem setup
logic creates various needed inodes for us, which we really should make
use of instead of creating on our own.
System and Service Manager
Details
Most documentation is available on systemd's web site.
Assorted, older, general information about systemd can be found in the systemd Wiki.
Information about build requirements is provided in the README file.
Consult our NEWS file for information about what's new in the most recent systemd versions.
Please see the Code Map for information about this repository's layout and content.
Please see the Hacking guide for information on how to hack on systemd and test your modifications.
Please see our Contribution Guidelines for more information about filing GitHub Issues and posting GitHub Pull Requests.
When preparing patches for systemd, please follow our Coding Style Guidelines.
If you are looking for support, please contact our mailing list or join our IRC channel.
Stable branches with backported patches are available in the stable repo.