1.2. How to Build a CLFS System

The CLFS system will be built by using a previously installed Unix system or Linux distribution (such as Debian, Fedora, openSUSE, or Ubuntu). This existing system (the host) will be used as a starting point to provide necessary programs, including a compiler, linker, and shell, to build the new system. Select the “development” option during the distribution installation to be able to access these tools.

As an alternative to installing an entire separate distribution onto your machine, you may wish to use a livecd. Most distributions provide a livecd, which provides an environment to which you can add the required tools onto, allowing you to successfully follow the instructions in this book. Remember that if you reboot the livecd you will need to reconfigure the host environment before continuing with your build.

Preparing a New Partition of this book describes how to create a new Linux native partition and file system, the place where the new CLFS system will be compiled and installed. Packages and Patches explains which packages and patches need to be downloaded to build a CLFS system and how to store them on the new file system. Final Preparations discusses the setup for an appropriate working environment. Please read Final Preparations carefully as it explains several important issues the developer should be aware of before beginning to work through Constructing Cross-Compile Tools and beyond.

Constructing Cross-Compile Tools explains the installation of cross-compile tools which will be built on the host but be able to compile programs that run on the target machine. These cross-compile tools will be used to create a temporary, minimal system that will be the basis for building the final CLFS system. Some of these packages are needed to resolve circular dependencies—for example, to compile a compiler, you need a compiler.

The process of building cross-compile tools first involves building and installing all the necessary tools to create a build system for the target machine. With these cross-compiled tools, we eliminate any dependencies on the toolchain from our host distro.

After we build our “Cross-Tools”, we start building a very minimal working system in /tools, using the cross-toolchain in /cross-tools. Once the temporary system is finished, we perform a few additional tasks to prepare to enter this temporary build environment, either by booting or chrooting into it. For more details about the difference between these methods, see Section 6.31, “To Boot or to Chroot?”.

In Installing Basic System Software, after having booted or chrooted into the temporary build environment, the full CLFS system is built.

To finish the installation, several configuration files are created in System Configuration, and the kernel and boot loader are set up in Making the CLFS System Bootable. The End contains information on furthering the CLFS experience beyond this book. After the steps in this book have been implemented, the computer will be ready to reboot into the new CLFS system.

This is the process in a nutshell. Detailed information on each step is discussed in the following chapters and package descriptions. Items that may seem complicated will be clarified, and everything will fall into place as the reader embarks on the CLFS adventure.