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
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Booting your kernel


Booting is highly device-dependent, but here is an example using U-Boot on a BeagleBone Black and QEMU:.

BeagleBone Black

The following U-Boot commands show how to boot Linux on a BeagleBone Black:

U-Boot# fatload mmc 0:1 0x80200000 zImage
reading zImage
4606360 bytes read in 254 ms (17.3 MiB/s)
U-Boot# fatload mmc 0:1 0x80f00000 am335x-boneblack.dtb
reading am335x-boneblack.dtb
29478 bytes read in 9 ms (3.1 MiB/s)
U-Boot# setenv bootargs console=ttyO0,115200
U-Boot# bootz 0x80200000 - 0x80f00000
Kernel image @ 0x80200000 [ 0x000000 - 0x464998 ]
## Flattened Device Tree blob at 80f00000
   Booting using the fdt blob at 0x80f00000
   Loading Device Tree to 8fff5000, end 8ffff325 ... OK
Starting kernel ...
[   0.000000] Booting Linux on physical CPU 0x0
...

Note that we set the kernel command line to console=ttyO0,115200. That tells Linux which device to use for console output which, in this case, is the first UART on the board, device ttyO0, at a speed of 115,200 bits per...