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

Filesystem choices


So far we have looked at the technology behind solid state memory and at the many types of filesystems. Now it is time to summarize the options.

In most cases, you will be able to divide your storage requirements into these three categories:

  • Permanent, readable, and writable data: Runtime configuration, network parameters, passwords, data logs, and user data

  • Permanent, read-only data: Programs, libraries, and configurations files that are constant, for example, the root filesystem

  • Volatile data: Temporary storage for example /tmp

The choices for read-write storage are as follows:

  • NOR: UBIFS or JFFS2

  • NAND: UBIFS, JFFS2, or YAFFS2

  • eMMC: ext4 or F2FS

    Note

    For read-only storage, you can use all of the above mounted with the ro attribute. Additionally, if you want to save space, you could use squashfs, in the case of NAND flash using UBI mtdblock device emulation to handle the bad blocks for you.

Finally, for volatile storage, there is only one choice, tmpfs.