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Mastering Embedded Linux Programming - Third Edition

You're reading from  Mastering Embedded Linux Programming - Third Edition

Product type Book
Published in May 2021
Publisher Packt
ISBN-13 9781789530384
Pages 758 pages
Edition 3rd Edition
Languages
Authors (2):
Frank Vasquez Frank Vasquez
Profile icon Frank Vasquez
Chris Simmonds Chris Simmonds
Profile icon Chris Simmonds
View More author details

Table of Contents (27) Chapters

Preface Section 1: Elements of Embedded Linux
Chapter 1: Starting Out Chapter 2: Learning about Toolchains Chapter 3: All about Bootloaders Chapter 4: Configuring and Building the Kernel Chapter 5: Building a Root Filesystem Chapter 6: Selecting a Build System Chapter 7: Developing with Yocto Chapter 8: Yocto Under the Hood Section 2: System Architecture and Design Decisions
Chapter 9: Creating a Storage Strategy Chapter 10: Updating Software in the Field Chapter 11: Interfacing with Device Drivers Chapter 12: Prototyping with Breakout Boards Chapter 13: Starting Up – The init Program Chapter 14: Starting with BusyBox runit Chapter 15: Managing Power Section 3: Writing Embedded Applications
Chapter 16: Packaging Python Chapter 17: Learning about Processes and Threads Chapter 18: Managing Memory Section 4: Debugging and Optimizing Performance
Chapter 19: Debugging with GDB Chapter 20: Profiling and Tracing Chapter 21: Real-Time Programming Other Books You May Enjoy

Read-only compressed filesystems

Compressing data is useful if you don't have quite enough storage to fit everything in. Both JFFS2 and UBIFS do on-the-fly data compression by default. However, if the files are never going to be written, as is usually the case with the root filesystem, you can achieve better compression ratios by using a read-only compressed filesystem. Linux supports several of these: romfs, cramfs, and squashfs. The first two are obsolete now, so I will only describe SquashFS.

SquashFS

The SquashFS filesystem was written by Phillip Lougher in 2002 as a replacement for cramfs. It existed as a kernel patch for a long time, eventually being merged into mainline Linux in version 2.6.29 in 2009. It is very easy to use: you create a filesystem image using mksquashfs and install it to the flash memory:

$ mksquashfs rootfs rootfs.squashfs

The resulting filesystem is read-only, so there is no mechanism for modifying any of the files at runtime. The only way...

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