Autoconfiguration and Newbus Drivers

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. For each identified device, an appropriate Newbus driver is assigned to configure and initialize it. Note that it’s possible for a device to be unidentifiable or unsupported. As a result, no Newbus driver will be assigned.

A Newbus driver is any driver in FreeBSD that controls a device that is bound to an I/O bus (that is, roughly every driver that is not a pseudo-device driver).

In general, three components are common to all Newbus drivers: