[systemd-devel] RFC: removing initctl support

[Martin Pitt]

Hello all,

sorry for the late reply, I've been swamped with other stuff recently.

Lennart Poettering [2015-09-22  2:31 +0200]:
> a) there's support in systemctl to reboot the system by sending the
>    right bytes to /dev/initctl as fallback, so that you can reboot a
>    sysvinit system with "systemctl reboot".

We indeed need this for upgrades: If you e. g. install Ubuntu 14.04
LTS (with upstart), or Debian Jessie (with SysV init) and install the
systemd packages during the upgrade, you need to be able to reboot
into the upgraded system (while upstart/sysvinit is still running). So
indeed it's only needed exactly once, but we need to keep this around
until at least April 2016 when Ubuntu 16.04 LTS will release (and then
we can reasonably assume that systemd will be running for any further
upgrades).

On Debian it's much harder to give a precise time line as the official
project decision is still to support multiple init systems. But if
there's a documented workaround, that'd also suffice.

> b) There's a mini-daemon "systemd-initctl.service" that is
>    fifo-activated on /dev/initctl, and forwards reboot requests from
>    old sysvinit clients to systemd.

This direction seems much less important to me -- you can always call
"systemctl reboot" while systemd is pid 1, no?

> We never even really used this stuff on Fedora properly (since we
> actually transitioned from Upstart, not sysvinit, and we never had the
> same level of compat for that...).

You should run into the same problem if you upgrade an upstart system
to systemd, no? You can't possibly exec systemd over upstart in a
running system.

Thanks,

Martin
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)