嵌入式Linux操作系统Chapter.docVIP

Chapter 1. Introduction Since its first public release in 1991, Linux has been put to ever wider uses. Initially confined to a loosely tied group of developers and enthusiasts on the Internet, it eventually matured into a solid Unix-like operating system for workstations, servers, and clusters. Its growth and popularity accelerated the work started by the Free Software Foundation (FSF) and fueled what would later be known as the open source movement. All the while, it attracted media and business interest, which contributed to establishing Linuxs presence as a legitimate and viable choice for an operating system. Yet, oddly enough, it is through an often ignored segment of computerized devices that Linux is poised to become the preferred operating system. That segment is embedded systems, and the bulk of the computer systems found in our modern day lives belong to it. Embedded systems are everywhere in our lives, from mobile phones to medical equipment, including air navigation systems, automated bank tellers, MP3 players, printers, cars, and a slew of other devices about which we are often unaware. Every time you look around and can identify a device as containing a microprocessor, youve most likely found another embedded system. If you are reading this book, you probably have a basic idea why one would want to run an embedded system using Linux. Whether because of its flexibility, its robustness, its price tag, the community developing it, or the large number of vendors supporting it, there are many reasons for choosing to build an embedded system with Linux and many ways to carry out the task. This chapter provides the background for the material presented in the rest of the book by discussing definitions, real-life issues, generic embedded Linux systems architecture, examples, and methodology. 1.1 Definitions The words Linux, embedded Linux, and real-time Linux are often used with little reference to what is being designated. Sometimes, the designations may mean