Creating Kernel-level Device Drivers

Creating Kernel-level Device Drivers

If you decide to write a kernel-level device driver, you need to become familiar with the software environment, conventions, and data structures that apply to device drivers running under the IRIX operating system. To create a kernel-level driver from scratch, you must:

Create a device-special file.
Create a master file.
Write and compile the driver code (-coff)[4].
Create a kernel that includes the driver object code.
Reboot using the new kernel.
Debug the driver.

Steps 4 and 5 may be omitted if the driver is loadable. See Chapter 11, "Kernel-level Dynamically Loadable Modules (DLMs)," on how to make a device driver loadable.

Except for step 3, all the steps in this procedure are simple and mechanical.

[4] Compile the object file with the -coff compiler flag for all IRIX 5.x drivers but not for IRIX 6.0 drivers. While Indigo and Indigo2 platforms require this flag, IRIX 64-bit compilers do not support it. For the most appropriate flags for various system configurations, see the file /var/sysgen/Makefile.kernio.