Recent versions of FreeBSD include a new device driver framework, Newbus, that allows for device drivers to be implemented in a more platform independent manner, as well as allowing for the dynamic loading and unloading of drivers using the FreeBSD kernel module mechanism. The Newbus architecture makes extensive use of many FreeBSD kernel features that are currently not well documented. This tutorial aims to remove some of the mystery surrounding these features. Each aspect of the kernel used by the Newbus architecture will be covered in depth, including a walk through of the structures and algorithms used in their implementation.

As well as providing background information on the implementation of Newbus, the tutorial will also provide an example of how to convert a legacy driver to the Newbus architecture and discuss the steps involved in implementing device drivers using the Newbus API.

Who should attend?
Kernel developers interested in writing loadable device drivers or other kernel modules and anyone interested in learning about the more FreeBSD specific features of the kernel. A reasonable amount of C experience is assumed as well as a basic understanding of data structures and algorithms. Some knowledge of the kernel and device drivers would be advantageous.

Course outline

• Newbus features
• Kernel modules
• Linker sets
• Kernel linker
• Kernel objects
• Drivers, devices and classes
• The kernel resource manager
• Writing a device driver
• Porting legacy drivers