Book Image

Mastering Embedded Linux Programming

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming

By: Chris Simmonds

Overview of this book

Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will begin by learning about toolchains, bootloaders, the Linux kernel, and how to configure a root filesystem to create a basic working device. You will then learn how to use the two most commonly used build systems, Buildroot and Yocto, to speed up and simplify the development process. Building on this solid base, the next section considers how to make best use of raw NAND/NOR flash memory and managed flash eMMC chips, including mechanisms for increasing the lifetime of the devices and to perform reliable in-field updates. Next, you need to consider what techniques are best suited to writing applications for your device. We will then see how functions are split between processes and the usage of POSIX threads, which have a big impact on the responsiveness and performance of the final device The closing sections look at the techniques available to developers for profiling and tracing applications and kernel code using perf and ftrace.
Table of Contents (16 chapters)
15
Index

Booting with UEFI firmware


Most embedded PC designs and some ARM designs have firmware based on the Universal Extensible Firmware Interface (UEFI) standard, see the official website at http://www.uefi.org for more information. The boot sequence is fundamentally the same as described in the preceding section:

Phase 1: The processor loads the UEFI boot manager firmware from flash memory. In some designs, it is loaded directly from NOR flash memory, in others there is ROM code on-chip which loads the boot manager from SPI flash memory. The boot manager is roughly equivalent to the SPL, but may allow user interaction through a text-based or graphical interface.

Phase 2: The boot manager loads the boot firmware from the EFI System Partition (ESP) or a hard disk or SSD, or from a network server via PXE boot. If loading from a local disk drive, the EXP is identified by a well-known GUID value of C12A7328-F81F-11D2-BA4B-00A0C93EC93B. The partition should be formatted using the FAT32 format. The third...