ps on my Linux box shows that
systemd runs with the command line options
--deserialize. Nothing in the man page or
/usr/share/doc/systemd mentions them, and Google hasn't been much help. So, what do they do? I'm guessing that
--switched-root has something to do with pivot_root, but that's just a guess.
These are intentionally undocumented internal parts of systemd. Very simply, therefore:
--deserializeis used to restore saved internal state that a previous invocation of
exec()ing this one, has written out to a file. Its option argument is an open file descriptor for that process.
--switched-rootis used to tell this invocation of
systemdthat it has been invoked from
systemdmanaging an initramfs, and so should behave accordingly — including turning off some of the behaviour otherwise caused by