Chapter 1. Introduction
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## Chapter 1. Introduction

## How things are going to be done

You are going to build your LFS system by using a previously installed Linux distribution (such as Debian, Mandrake, Red Hat, or SuSE). This existing Linux system (the host) will be used as a starting point, because you will need programs like a compiler, linker and shell to build the new system. Normally all the required tools are available if you selected “development” as one of the options when you installed your distribution.

In Chapter 2 you will first create a new Linux native partition and file system, the place where your new LFS system will be compiled and installed. Then in Chapter 3 you download all the packages and patches needed to build an LFS system, and store them on the new file system. In Chapter 4 you set up a good environment to work in.

Chapter 5 then discusses the installation of a number of packages that will form the basic development suite (or toolchain) which is used to build the actual system in Chapter 6. Some of these packages are needed to resolve circular dependencies -- for example, to compile a compiler you need a compiler.

The first thing to be done in Chapter 5 is build a first pass of the toolchain, made up of Binutils and GCC. The programs from these packages will be linked statically in order for them to be usable independently of the host system. The second thing to do is build Glibc, the C library. Glibc will be compiled by the toolchain programs just built in the first pass. The third thing to do is build a second pass of the toolchain. This time the toolchain will be dynamically linked against the newly built Glibc. The remaining Chapter 5 packages are all built using this second pass toolchain and dynamically linked against the new host-independent Glibc. When this is done, the LFS installation process will no longer depend on the host distribution, with the exception of the running kernel.

You may be thinking that “this seems like a lot of work, just to get away from my host distribution”. Well, a full technical explanation is provided at the start of Chapter 5, including some notes on the differences between statically and dynamically linked programs.

In Chapter 6 your real LFS system will be built. The chroot (change root) program is used to enter a virtual environment and start a new shell whose root directory will be set to the LFS partition. This is very similar to rebooting and instructing the kernel to mount the LFS partition as the root partition. The reason that you don't actually reboot, but instead chroot, is that creating a bootable system requires additional work which isn't necessary just yet. But the major advantage is that “chrooting” allows you to continue using the host while LFS is being built. While waiting for package compilation to complete, you can simply switch to a different VC (Virtual Console) or X desktop and continue using the computer as you normally would.

To finish the installation, the bootscripts are set up in Chapter 7, the kernel and bootloader are set up in Chapter 8, and Chapter 9 contains some pointers to help you after you finish the book. Then, finally, you're ready to reboot your computer into your new LFS system.

This is the process in a nutshell. Detailed information on the steps you will take are discussed in the chapters and package descriptions as you progress through them. If something isn't completely clear now, don't worry, everything will fall into place soon.

Please read Chapter 4 carefully as it explains a few important things you should be aware of before you begin to work through Chapter 5 and beyond.

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