Autoconfiguration procedure in FreeBSD

[Nomad Esst]

I'm studying FreeBSD kernel internals on my own, I'm reading "FreeBSD Device Drivers: A Guide for the Intrepid" by Joesph Kong. In chapter 7 "newbus and resource allocation", he says "Autoconfiguration is the procedure carried out by FreeBSD to enable the hardware devices on a machine (McKusick and Neville-Neil, 2005). It works by systematically probing a machine’s I/O buses in order to identify their child devices". I'm wondering where this "Autoconfiguraion procedure" is deployed in FreeBSD?
Thanks in advance.