Chapter 2: Understanding Linux Kernel Module Basic Concepts

A kernel module is a piece of software whose aim is to extend the Linux kernel with a new feature. A kernel module can be a device driver, in which case it would control and manage a particular hardware device, hence the name device driver. A module can also add a framework support (for example IIO, the Industrial Input Output framework), extend an existing framework, or even a new filesystem or an extension of it. The thing to keep in mind is that kernel modules are not always device drivers, whereas device drivers are always kernel modules.

In opposition to kernel modules, there might be simple modules or user space modules, running in user space, with low privileges. This book, however, exclusively deals with kernel space modules, particularly Linux kernel modules.

That being said, this chapter will discuss the following topics:

• An introduction to the concept of modules
• Building a Linux kernel module
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