What Is Embedded Linux?

Embedded Linux typically refers to a complete system, or in the context of an embedded Linux vendor, to a distribution targeted at embedded devices. Although the term “embedded” is often also used in kernel discussions (especially between developers who have “embedded concerns”—words often used in the community), there is no special form of the Linux kernel targeted at embedded applications. Instead, the same Linux kernel source code is intended to be built for the widest range of devices, workstations, and servers imaginable, although obviously it is possible to configure a variety of optional features according to the intended use of the kernel. For example, it is unlikely that your embedded device will feature 128 processors and terrabytes of memory, and so it is possible to configure out support for certain features typically found only on larger Linux systems. In the context of embedded development, you will typically encounter embedded Linux systems—devices that use the Linux kernel and a variety of other software—and embedded

Linux distributions—a prepackaged set of applications tailored for embedded systems and development tools to build a complete system. It is the latter that you are paying for when you go to an embedded Linux vendor. They provide development tools such as cross-compilers, debuggers, project management software, boot image builders, and so on. A growing number of vendors have chosen to integrate much of this functionality into customized plug-ins for their own versions of the communitydeveloped Eclipse graphical IDE framework.

Whether you use a vendor is entirely up to you—few of the examples mentioned  will make any assumption as to your reliance or otherwise on a Linux vendor. In fact, much of this book is intended to equip you to build your own tools and tailored Linux distributions. This helps both those who want to use vendor supplied tools and those who do not. Understanding is key in either case, since greater understanding will help you to get more done faster. The bottom line is, of course, about time and resources. Even though this book will help you, should you wish to go it alone, you may choose to buy into an embedded Linux vendor as a way to reduce your product time to market (and to have someone to yell at if things don’t work out according to plan).

 In general, we will refer to the host system used for developing the embedded Linux system as the “host system,” or “host” for short. The target, which will be the embedded Linux system, will be referred to as the “target system,” or “target.” Distributions providing development frameworks will be referred to as “development distributions” or something similar.This kind of nomenclature should be familiar to anyone who has experience working with embedded systems. Distributions that provide tailored software packages will be referred to as “target distributions.”