When planning a move to Linux, embedded designers can easily become confused by the heterogeneity of the solutions found in the market. Evidence can help you in planning the move to the right Linux solution, supporting your company at all the fundamental steps.

Why using Linux in embedded systems ?

The increasing adoption of Linux for embedded systems is one of the most exciting changes of the last years. The simple and elegant design of Linux guarantees robustness and very good performance, while its Open Source license allows to modify and change the source code according to the user needs.

Linux is a full-featured operating system, originally designed to be used in server or desktop environments. Since then, Linux has evolved and grown to be used in almost all computer areas, embedded systems included. Linux currently supports almost every hardware processor, including x86, ARM, Hitachi SuperH, Intel Xscale PXA2xx and IXP4xx, MIPS, Motorola 68000, PowerPC and Samsung S3C24xx.

Linux is an Open Source project, meaning that the source code of the operating system is freely available to everybody, and can be customized according to the user needs. The Open Source license helped the growth of a large community of researchers and developers who continuously add new features to the kernel and port Linux to new architectures. Nowadays, there is a huge amount of programs, libraries and tools available as Open Source code that can be used to build a customized version of the OS.Thus, when compared to proprietary solutions in terms of cost of development, Linux is a better choice.

Linux has the simple and elegant design of the UNIX OSs, which guarantees a very stable, robust and secure system. Moreover, it has excellent performance and a very good TCP/IP protocol stack implementation. The portability of code from different operating systems is ensured by the well known "Portable Operating System Interface'' (POSIX) API. This is an IEEE standard defining the basic environment and set of functions offered by the operating system to the application programs.

Benefits of using Linux for embedded applications:

• No runtime royalties (in most cases) reducing the overall design cost; 

• Availability of source code and development tools at no charge;

• POSIX standard support to enhance portability across different systems; 

• Wide range of operating system services including effective network support;

• Support from a well established user and development community.

Moving to Linux

A fundamental prerequisite that must be satisfied when planning the porting or implementing new embedded applications under Linux is understanding the requirements that the application will impose upon the kernel and the underlying platform. To save time and money, software engineers must be able to match the applications requirements to the appropriate Linux variant. In Linux distributions for embedded systems, features/changes are purposely added in order to improve the general response times and the predictability of the kernel services.

Market reports currently place at over 100 the number of existing Linux distributions, each oriented to a specific market and scenario. Standard distributions are often based on the same Linux kernel, enriched by a collection of software packages including different installation scripts, utilities, compilers, editors, and other applications. Distributions for embedded and real-time systems add further complexity by proposing purposely designed kernel changes or improvements. When planning a move to Linux, embedded designers can easily become confused by the heterogeneity of the solutions found in the market. Evidence provides help in planning the move to the right Linux solution, supporting all the fundamental steps.