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

Finding out about drivers at runtime

Once you have a running Linux system, it is useful to know which device drivers are 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 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
 11 sr
 31 mtdblock
 65 sd
 66 sd
 67 sd
 68 sd
 69 sd
 70 sd
 71 sd
128 sd
129 sd
130 sd
131 sd
132 sd
133 sd
134 sd
135 sd
179 mmc

For each driver, you can see...