7.6 Chapter Summary
- The bootloader’s role in an embedded system cannot be overstated. It is the first piece of software that takes control upon applying power.
- This chapter examined the role of the bootloader and discovered the limited execution context in which a bootloader must exist.
- Das U-Boot has become a popular universal bootloader for many processor architectures. It supports a large number of processors, reference hardware platforms, and custom boards.
- U-Boot is configured using a series of configuration variables in a board-specific header file. Appendix B, contains a list of all the standard U-Boot command sets supported in a recent U-Boot release.
- Porting U-Boot to a new board based on a supported processor is relatively straightforward. In this chapter, we walked through the steps of a typical port to a board with similar support in U-Boot.
- There is no substitute for detailed knowledge of your processor and hardware platform when bootloader modification or porting must be accomplished.
- We briefly introduced additional bootloaders in use today so you can make an informed choice for your particular requirements.
7.6.1 Suggestions for Additional Reading
Application Note: Introduction to Synchronous DRAM
Maxwell Technologies
www.maxwell.com/pdf/me/app_notes/Intro_to_SDRAM.pdf
Using LD, the GNU linker
Free Software Foundation
www.gnu.org/software/binutils/manual/ld-2.9.1/ld.html
The DENX U-Boot and Linux Guide (DLUG) for TQM8xxL
Wolfgang Denx et al., Denx Software Engineering
www.denx.de/twiki/bin/view/DULG/Manual
RFC 793, “Trivial File Transfer Protocol”
The Internet Engineering Task Force
www.ietf.org/rfc/rfc793.txt
RFC 951, “Bootstrap Protocol”
The Internet Engineering Task Force
www.ietf.org/rfc/rfc951.txt
RFC 1531, “Dynamic Host Control Protocol”
The Internet Engineering Task Force
www.ietf.org/rfc/rfc1531.txt
PowerPC 405GP Embedded Processor user’s manual
International Business Machines, Inc.
Programming Environments Manual for 32-bit Implementations
of the PowerPC Architecture
Freescale Semiconductor, Inc.
Lilo Bootloader
www.tldp.org/HOWTO/LILO.html
GRUB Bootloader www.gnu.org/software/grub/