This chapter and the following two chapters, Chapter 23, Debugging, Testing, and Tuning Device Drivers and Chapter 24, Recommended Coding Practices, provide detailed information on developing a device driver.
Take the following steps to build a device driver:
Write, compile, and link the new code.
Create the necessary hardware configuration files.
Create a hardware configuration file unique to the device called xx.conf where xx is the prefix for the device. This file is used to update the driver.conf(4) file. See Writing a Hardware Configuration File. For a pseudo device driver, create a pseudo(4) file.
Copy the driver to the appropriate module directory.
Install the device driver using add_drv(1M).
Installing the driver with add_drv is usually done as part of a postinstall script. See Installing Drivers with add_drv. Use the update_drv(1M) command to make any changes to the driver. See Updating Driver Information.
Load the driver.
The driver can be loaded automatically by accessing the device. See Loading and Unloading Drivers. Drivers can also be loaded by using the modload(1M) command. The modload command does not call any routines in the module and therefore is useful for testing. See Loading and Unloading Test Modules.
Test the driver.
Drivers should be rigorously tested in the following areas:
For additional driver-specific testing, see Testing Specific Types of Drivers.
Remove the driver if necessary.