Writing Device Drivers

Installing and Removing Drivers

Before a driver can be used, the system must be informed that it exists. The add_drv(1M) utility must be used to correctly install the device driver. Once the driver is installed, it can be loaded and unloaded from memory without using add_drv(1M) again.

Copying the Driver to a Module Directory

Device drivers reside in different directories depending on the platform they run on and whether they are needed at boot time. Platform-dependent device drivers reside in the following locations:

To install a driver, the driver and its configuration file must be copied to a drv directory in the module path. For example, to copy a driver to /usr/kernel/drv, type:

$ su# cp xx /usr/kernel/drv# cp xx.conf /usr/kernel/drv

Optionally Editing /etc/devlink.tab

If the driver creates minor nodes that do not represent disks, tapes, or ports (terminal devices), /etc/devlink.tab can be modified to cause devlinks(1M) to create logical device names in /dev. See devlink.tab(4) for a description of the syntax of this file.

Alternatively, logical names can be created by a program run at driver installation time.

Running add_drvadd_drv(1M)

Run add_drv(1M) to install the driver in the system. If the driver installs successfully, add_drv(1M) will run disks(1M), tapes(1M), ports(1M), and devlinks(1M) to create the logical names in /dev.

# add_drv xx

This is a simple case in which the device identifies itself as xx and the device special files will have default ownership and permissions (0600 root sys). add_drv(1M) also allows additional names for the device (aliases) to be specified. See add_drv(1M) to determine how to add aliases and set file permissions explicitly.

Note -

add_drv(1M) should not be run when installing a STREAMS module. See the STREAMS Programming Guide for details.