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

Libraries for the root filesystem


Programs are linked with libraries. You could link them all statically, in which case, there would be no libraries on the target device. But, that takes up an unnecessarily large amount of storage if you have more than two or three programs. So, you need to copy shared libraries from the toolchain to the staging directory. How do you know which libraries?

One option is to copy all of them since they must be of some use, otherwise they wouldn't exist! That is certainly logical and, if you are creating a platform to be used by others for a range of applications, that would be the correct approach. Be aware, though, that a full glibc is quite large. In the case of a CrossTool-NG build of glibc 2.19, the space taken by /lib and /usr/lib is 33 MiB. Of course, you could cut down on that considerably by using uClibc or Musel libc libraries.

Another option is to cherry pick only those libraries that you require, for which you need a means of discovering library dependencies...