Book Image

Mastering Embedded Linux Programming - Third Edition

By : Frank Vasquez, Chris Simmonds
5 (3)
Book Image

Mastering Embedded Linux Programming - Third Edition

5 (3)
By: Frank Vasquez, Chris Simmonds

Overview of this book

If you’re looking for a book that will demystify embedded Linux, then you’ve come to the right place. Mastering Embedded Linux Programming is a fully comprehensive guide that can serve both as means to learn new things or as a handy reference. The first few chapters of this book will break down the fundamental elements that underpin all embedded Linux projects: the toolchain, the bootloader, the kernel, and the root filesystem. After that, you will learn how to create each of these elements from scratch and automate the process using Buildroot and the Yocto Project. As you progress, the book will show you how to implement an effective storage strategy for flash memory chips and install updates to a device remotely once it’s deployed. You’ll also learn about the key aspects of writing code for embedded Linux, such as how to access hardware from apps, the implications of writing multi-threaded code, and techniques to manage memory in an efficient way. The final chapters demonstrate how to debug your code, whether it resides in apps or in the Linux kernel itself. You’ll also cover the different tracers and profilers that are available for Linux so that you can quickly pinpoint any performance bottlenecks in your system. By the end of this Linux book, you’ll be able to create efficient and secure embedded devices using Linux.
Table of Contents (27 chapters)
1
Section 1: Elements of Embedded Linux
10
Section 2: System Architecture and Design Decisions
18
Section 3: Writing Embedded Applications
22
Section 4: Debugging and Optimizing Performance

Finding out about drivers at runtime

Once you have a running Linux system, it is useful to know which device drivers have been loaded and what state they are in. You can find out a lot by reading the files in
/proc and /sys.

First of all, you can list the character and block device drivers that are currently loaded and active by reading /proc/devices:

# cat /proc/devices
Character devices:
  1 mem 
  2 pty 
  3 ttyp 
  4 /dev/vc/0 
  4 tty 
  4 ttyS 
  5 /dev/tty 
  5 /dev/console 
  5 /dev/ptmx 
  7 vcs 
 10 misc 
 13 input 
 29 fb 
 81 video4linux 
 89 i2c 
 90 mtd
116 alsa
128 ptm
136 pts
153 spi
180 usb
189 usb_device
204 ttySC
204 ttyAMA
207 ttymxc
226 drm
239 ttyLP
240 ttyTHS
241 ttySiRF
242 ttyPS
243 ttyWMT
244 ttyAS
245 ttyO
246 ttyMSM
247 ttyAML
248 bsg
249 iio
250 watchdog
251 ptp
252 pps
253 media
254 rtc
Block devices:
259 blkext
  7 loop
  8 sd...