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 (22 chapters)
Mastering Embedded Linux Programming
About the Author
About the Reviewers

Accessing flash memory from Linux

Raw NOR and NAND flash memory is handled by the memory technology device sub-system, or MTD, which provides basic interfaces to read, erase, and write blocks of flash memory. In the case of NAND flash, there are functions to handle the OOB area and to identify bad blocks.

For managed flash, you need drivers to handle the particular hardware interface. MMC/SD cards and eMMC use the mmcblk driver; CompactFlash and hard drives use the SCSI Disk driver, sd. USB flash drives use the usb_storage driver together with the sd driver.

Memory technology devices

The memory technology devices (MTD), sub-system was started by David Woodhouse in 1999 and has been extensively developed over the intervening years. In this section, I will concentrate on the way it handles the two main technologies, NOR and NAND flash.

MTD consists of three layers: a core set of functions, a set of drivers for various types of chips, and user-level drivers that present the flash memory as a...