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 (16 chapters)
15
Index

Anatomy of a toolchain

To get an idea of what is in a typical toolchain, I want to examine the crosstool-NG toolchain you have just created.

The toolchain is in the directory ~/x-tools/arm-cortex_a8-linux-gnueabihf/bin. In there you will find the cross compiler, arm-cortex_a8-linux-gnueabihf-gcc. To make use of it, you need to add the directory to your path using the following command:

$ PATH=~/x-tools/arm-cortex_a8-linux-gnueabihf/bin:$PATH

Now you can take a simple hello world program that looks like this:

#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
  printf ("Hello, world!\n");
  return 0;
}

And compile it like this:

$ arm-cortex_a8-linux-gnueabihf-gcc helloworld.c -o helloworld

You can confirm that it has been cross compiled by using the file command to print the type of the file:

$ file helloworld
helloworld: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 3.15.4, not stripped

Finding...