Chapter 7. Bootloaders

In this chapter

• Role of a Bootloader page 158

• Bootloader Challenges page 159

• A Universal Bootloader: Das U-Boot page 164

• Porting U-Boot page 172

• Other Bootloaders page 183

• Chapter Summary page 186

Previous chapters have made reference to and even provided examples of bootloader operations. A critical component of an embedded system, the bootloader provides the foundation from which the other system software is spawned. This chapter starts by examining the bootloader's role in a system. We follow this with an introduction to some common features of bootloaders. Armed with this background, we take a detailed look at a popular bootloader used for embedded systems. We conclude this chapter by introducing a few of the more popular bootloaders.

Numerous bootloaders are in use today. It would be impractical in the given space to cover much detail on even the most popular ones. Therefore, we have chosen to explain concepts and use examples based on one of the more popular bootloaders in the open source community for PowerPC, MIPS, ARM, and other architectures: the U-Boot bootloader.