networkd bus activation and exit on idle

[Lubomir Rintel <lkundrak v3 sk>]

> From systemd 219 release notes: [1]

>         * networkd now exits when idle. It will be automatically 
>           restarted as soon as interfaces show up, are removed or
>           change state. networkd will stay around as long as there is
>           at least one DHCP state machine or similar around, that keep
>           it non-idle.

[1] http://lists.freedesktop.org/archives/systemd-devel/2015-February/028447.html

Anyone knows details? How do they find out about an interface showing
up? Could we do the same thing too? At least for servers where only
devices are platform devices; no Bluetooth or Modems?

Lubo