Comprehensive Real-World Guidance for Every Embedded Developer and Engineer
This book brings together indispensable knowledge for building efficient, high-value, Linux-based embedded products: information that has never been assembled in one place before. Drawing on years of experience as an embedded Linux consultant and field application engineer, Christopher Hallinan offers solutions for the specific technical issues you're most likely to face, demonstrates how to build an effective embedded Linux environment, and shows how to use it as productively as possible.
Hallinan begins by touring a typical Linux-based embedded system, introducing key concepts and components, and calling attention to differences between Linux and traditional embedded environments. Writing from the embedded developer's viewpoint, he thoroughly addresses issues ranging from kernel building and initialization to bootloaders, device drivers to file systems.
Hallinan thoroughly covers the increasingly popular BusyBox utilities; presents a step-by-step walkthrough of porting Linux to custom boards; and introduces real-time configuration via CONFIG_RT--one of today's most exciting developments in embedded Linux. You'll find especially detailed coverage of using development tools to analyze and debug embedded systems--including the art of kernel debugging.
• Compare leading embedded Linux processors
• Understand the details of the Linux kernel initialization process
• Learn about the special role of bootloaders in embedded Linux systems, with specific emphasis on U-Boot
• Use embedded Linux file systems, including JFFS2--with detailed guidelines for building Flash-resident file system images
• Understand the Memory Technology Devices subsystem for flash (and other) memory devices
• Master gdb, KGDB, and hardware JTAG debugging
• Learn many tips and techniques for debugging within the Linux kernel
• Maximize your productivity in cross-development environments
• Prepare your entire development environment, including TFTP, DHCP, and NFS target servers
• Configure, build, and initialize BusyBox to support your unique requirements
7.5.3. Still More Bootloaders
7.5.3. Still More Bootloaders
Numerous other bootloaders have found their way into specific niches. For example, Redboot is another open-source bootloader that Intel and the XScale community have adopted for use on various evaluation boards based on the Intel IXP and PXA processor families. Micromonitor is in use by board vendors such as Cogent and others. YAMON has found popularity in MIPs circles.[60] LinuxBIOS is used primarily in X86 environments. In general, when you consider a boot loader, you should consider some important factors up front:
• Does it support my chosen processor?
• Has it been ported to a board similar to my own?
• Does it support the features I need?
• Does it support the hardware devices I intend to use?
• Is there a large community of users where I might get support?
• Are there any commercial vendors from which I can purchase support?
These are some of the questions you must answer when considering what bootloader to use in your embedded project. Unless you are doing something on the "bleeding edge" of technology using a brand-new processor, you are likely to find that someone has already done the bulk of the hard work in porting a bootloader to your chosen platform. Use the resources at the end of this chapter to help make your final decisions.
