Device and Drivers

When the kernel is booted or is loaded into memory it detects the hardware attached to the system

via "devfs", also devfs is continuously probing for new hardware if it is attached to the system and if

drivers are there then the device is ready to use.

Kernel comes to knows via "devfs" whether hardware has changed or not i.e

for example "hot swapping of hard drives", "hot swapping of PCI devices"

Now, Hardware are referenced by three ways

1) /devices

2) /dev

3) /path_to_inst

1) /devices

Devices which are physically connected to the system are referenced in the /devices directory

"devfs" is responsible for mounting the /devices and it is in memory.

devfs solely manages the /devices directory, however administrator could use devfsadm to manage

however that is normally not required.

2) /dev

Even though the devices are physically referenced in the /devices directory, we use the devices via

their logical representation which are stored in the /dev directory.

i.e /dev holds the logical representation of the physical device. If you go the /dev directory you will find

symbolic links to physical representation i.e to /devices directory.

Also utilities such as format, prtconf, sysdef etc use the logical representation i.e /dev to interact with the

devices attached to the system

3) /etc/path_to_inst

Contains current hardware instances, entries in this file represent the hardware connected to the system.

Names listed here are used by the kernel to interact with the hardware device.