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

Mounting the root filesystem using NFS


If your device has a network interface, it is best to mount the root filesystem over the network during development. It gives you access to almost unlimited storage so you can add in debug tools and executables with large symbol tables. As an added bonus, updates made to the root filesystem hosted on the development machine are made available on the target immediately. You also have a copy of log files.

For this to work, your kernel has to be configured with CONFIG_ROOT_NFS. Then, you can configure Linux to do the mount at boot time by adding the following to the kernel command line:

root=/dev/nfs

Give the details of the NFS export as follows:

nfsroot=<host-ip>:<root-dir>

Configure the network interface that connects to the NFS server so that it is available at boot time, before the init program runs by using this command:

ip=<target-ip>

There is more information about NFS root mounts in the kernel source in Documentation/filesystems...