[systemd-devel] Minimal systemd configuration

[Zbigniew Jędrzejewski-Szmek]

On Sun, Apr 05, 2015 at 09:56:14AM +0200, sdrb wrote:
> Hello,
> 
> I've got a few very basic questions regarding configuration of systemd.
> 
> I'm trying to setup some minimal configuration for qemu running linux.
> 
> The qemu runs linux kernel which mounts nfs-root as root directory.
> I've made minimal nfs-root and now I'd like to start the system with
> systemd in it.
> I copied all the files from /usr/lib/systemd and /etc/systemd from
> my linux to nfs-root but when linux runs systemd - I got a lot of
> error messages like "[FAILED] Failed to start xxx service".
> 
> My questions are:
> 
> 1. Is there any documentation for creating minimal systemd
> configuration? I mean for example - for qemu or embedded systems -
> with only sshd daemon running and console to just log into the
> system?
Have a look at bootup(7) and systemd.special(7). Services are either
pulled in by those those targets, or are started based on udev rules.
So the list of units you need will depend on what hardware and configuration
you want to support.

> 2. Does the systemd require external applications like mount, login
> or other to work properly?
It requires mount. login is not strictly necessary.

> 3. Is it possible to reconfigure systemd to run some script at the
> end of initialisation?
No. There's no point where initialiation is complete. You should create a unit
and have it run After= whatever other units.

Zbyszek