Automatically Configuring Devices

The Solaris kernel is configured automatically. A kernel module is a software component that performs a specific task on the system. An example of a loadable kernel module is a device driver that is loaded when the device is accessed.

At boot time, the OpenBoot PROM determines what devices are attached to the system and creates an internal device tree, which it hands off to the kernel. The kernel then configures itself dynamically, loading needed modules into memory. Device drivers are loaded when devices such as disk and tape devices are accessed for the first time. This process is called autoconfiguration because all kernel modules are loaded automatically as they are needed.

With autoconfiguration, main memory is used more efficiently because modules are loaded as they are needed. Also, you do not need to reconfigure the kernel when new devices are added to the system.

You can customize the way kernel modules are loaded by modifying the /etc/system file. See system(4) for more information.

Improved Device Configuration (defvsadm)

In previous Solaris releases, the drvconfig command handled device configuration to manage the physical device entries in the /devices directory. Five link generators—devlinks, disks, tapes, ports, and audlinks—managed the logical links in the /dev directory. These commands were not aware of hot-pluggable devices nor were they flexible enough for devices with multiple instances. For compatibility, in the Solaris 8 release, these commands are symbolic links to the new devfsadm command.

In the Solaris 8 release, the devfsadm command manages the special device files in the /dev and /devices directories. By default, devfsadm tries to load every driver in the system and attach to all possible device instances. It then creates the device files in the /devices directory and the logical links in the /dev directory. In addition, devfsadm also maintains the path_to_inst(4) database.

devfsadmd, the devfsadm daemon, handles both processing the reconfiguration boot and updating the /dev and /devices directories in response to dynamic reconfiguration events. This daemon is started from the /etc/rcS.d/S50devfsadm script when a system is booted.

Because devfsadmd automatically detects device configuration changes generated by any reconfiguration event, you do not need to run devfsadm interactively.

Display of Device Configuration Information

Use the commands in Table 55 to display system and device configuration information.

Table 55. Device Configuration Commands

prtconf(1M)	Display system configuration information, including total amount of memory and the device configuration as described by the device hierarchy of the system.
sysdef(1M)	Display device configuration information, including system hardware, pseudodevices, loadable modules, and selected kernel parameters.
dmesg(1M)	Display system diagnostic messages as well as a list of devices attached to the system since the last reboot.

See Chapter 9, "Administering Systems," for examples of these commands.