Bug#773386: release-notes: Systemd related updates to "before reboot" and Recovery proceedures

[Niels Thykier]

Package: release-notes
Severity: normal
Tags: jessie

(X-CC to systemd maintainers for input)

The release notes have a "Prepare for recovery"[1] and "Things
to do before rebooting" section[2].  They currently does not cover any
systemd related preparation.

I believe we should consider covering some/all of:

 * My system does not boot after upgrading to systemd.  How do I figure out
   what the problem is and how do I get a shell/some method to fix it?

 * Is there someone I can do to check for issues after upgrading but before
   rebooting?  Like do we have a tool to report:
   - There are cycles in your init configuration between the following
     services / init.d scripts.
   - You have an old init.d script laying around that is likely to break
     stuff because of reason X
   - etc.


So far, I got following for recovery:

  * (When boot fails) Reboot and alter kernel command line to include
    "systemd.unit=rescue.target".
  * (Before reboot or from rescue shell) Run systemctl enable
    debug-shell.service to get a (passwordless) root shell on TTY9
    "just in case"
  * (Before upgrade) Back up /sbin/init and use it on the kernel cmd line
     as last resort [Presumably Jessie-only]


On the "before reboot", I got nothing so far.  I am hoping you do.

If you got known issues to be documented in the Release Notes (or
other suggestions for improvements), please file additional bugs.
We got some items covered in [3], but I would not be surprised if I
had missed one or some of the existing ones could be improved.

Thanks,
~Niels

[1] https://www.debian.org/releases/jessie/amd64/release-notes/ch-upgrading.en.html#recovery

[2] https://www.debian.org/releases/jessie/amd64/release-notes/ch-upgrading.en.html#nownownow

[3] https://www.debian.org/releases/jessie/amd64/release-notes/ch-information.en.html#systemd-upgrade-default-init-system

(udev/CONFIG_DEVTMPFS): https://www.debian.org/releases/jessie/amd64/release-notes/ch-information.en.html#udev-needs-kernel-with-devtmpfs