[systemd-devel] How does systemd (pid1) connect to system DBus?

[Dimitri John Ledkov]

I see that systemd pid1 manager is available on the system DBus.

But when/how does it connect to it?

I'm failing to trace it in both systemd & dbus code. I assume that
systemd starts, eventually starts dbus.socket/service, dbus starts,
and then something causes systemd to connect to the system bus.

I see that there is USR1 signal handler, but I'm failing to find
anything that sends it to PID1.

Please send links to source code line numbers / functions. Somehow I'm
failing to trace this stuff.

-- 
Regards,

Dimitri.