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


The kernel build system, kbuild, is a set of make scripts that take the configuration information from the .config file, work out the dependencies and compile everything that is necessary to produce a kernel image containing all the statically linked components, possibly a device tree binary and possibly one or more kernel modules. The dependencies are expressed in the makefiles that are in each directory with buildable components. For instance, these two lines are taken from drivers/char/Makefile:

obj-y                    += mem.o random.o
obj-$(CONFIG_TTY_PRINTK) += ttyprintk.o

The obj-y rule unconditionally compiles a file to produce the target, so mem.c and random.c are always part of the kernel. In the second line, ttyprintk.c is dependent on a configuration parameter. If CONFIG_TTY_PRINTK is y it is compiled as a built in, if it is m it is built as a module and, if the parameter is undefined, it is not compiled at all.

For most targets, just typing make (with the appropriate...