When a system is booted for the first time, a device hierarchy is created to represent all the devices connected to the system. The kernel uses the device hierarchy information to associate drivers with their appropriate devices. The kernel also provides a set of pointers to the drivers that perform specific operations.
The device hierarchy consists of the following:
The /devices directory – the name space of all devices on the system. This directory represents the physical devices that consists of actual bus and device addresses. The devfs file system manages this directory.
The /dev directory – the name space of logical device names. The dev file system manages this directory.
The devfsadm command manages system devices by performing the following operations:
It attempts to load every driver in the system and attach to all possible device instances.
It creates the device files in the /devices directory and the logical links in the /dev directory.
The devfsadmd daemon automatically updates the /dev and /devices directories in response to dynamic reconfiguration events or file system accesses. This daemon is started by the service management facility when a system is booted.
For more information, see the following references: