Book Image

Embedded Linux Development Using Yocto Project Cookbook - Second Edition

By : Alex Gonzalez
Book Image

Embedded Linux Development Using Yocto Project Cookbook - Second Edition

By: Alex Gonzalez

Overview of this book

The Yocto Project has become the de facto distribution build framework for reliable and robust embedded systems with a reduced time to market.You'll get started by working on a build system where you set up Yocto, create a build directory, and learn how to debug it. Then, you'll explore everything about the BSP layer, from creating a custom layer to debugging device tree issues. In addition to this, you’ll learn how to add a new software layer, packages, data, scripts, and configuration files to your system. You will then cover topics based on application development, such as using the Software Development Kit and how to use the Yocto project in various development environments. Toward the end, you will learn how to debug, trace, and profile a running system. This second edition has been updated to include new content based on the latest Yocto release.
Table of Contents (13 chapters)
Title Page
Packt Upsell

Memory-based root filesystems

Early user space or initial memory images, known as initramfs images, are typically used as early user spaces with the task of mounting complex filesystems, such as for example when an encrypted partition needs to be set up. For that use case, initramfs will prepare the final root filesystem and then perform a switch_root, effectively replacing the old filesystem with the new and running a new init from the new filesystem. initramfs needs to contain all tools needed to mount the final root filesystem.

Other uses for initramfs include rescue and manufacturing systems.

This recipe will show how to configure the Yocto build system to build initramfs images.

Getting ready

When the Linux kernel mounts a file system from physical storage, it keeps a cache for quick access. A memory filesystem is just this kernel cache without a backing store.

An initramfs is a compressed cpio format file that the kernel extracts into a memory filesystem and uses as the root filesystem...