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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % general-entities SYSTEM "../general.ent">
%general-entities;
]>
<sect1 id="ch-intro-how">
<?dbhtml filename="how.html"?>
<title>How to Build an LFS System</title>
<para>The LFS system will be built by using an already installed
Linux distribution (such as Debian, OpenMandriva, Fedora, or openSUSE). This
existing Linux 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 <quote>development</quote> option
during the distribution installation to be able to access these
tools.</para>
<para>As an alternative to installing a separate distribution onto your
machine, you may wish to use <!-- the Linux From Scratch LiveCD or --> a LiveCD from a
commercial distribution. <!-- The LFS LiveCD works well as a host system,
providing all the tools you need to successfully follow the instructions in
this book. The LiveCD version is behind the current book, but is still useful
as a host for building the current book. The <quote>-nosrc</quote> or
<quote>-min</quote> editions of the LiveCD are the most appropriate for
building a current LFS system. For more information about the LFS LiveCD or
to download a copy, visit <ulink url="&livecd-root;"/>. --></para>
<!--
<note>
<para>The LFS LiveCD might not work on newer hardware configurations,
failing to boot or failing to detect some devices such as some SATA hard
drives.</para>
</note> -->
<para><xref linkend="chapter-partitioning"/> of this book describes how
to create a new Linux native partition and file system. This is the place
where the new LFS system will be compiled and installed. <xref
linkend="chapter-getting-materials"/> explains which packages and
patches need to be downloaded to build an LFS system and how to store
them on the new file system. <xref linkend="chapter-final-preps"/>
discusses the setup of an appropriate working environment. Please read
<xref linkend="chapter-final-preps"/> carefully as it explains several
important issues you need be aware of before beginning to
work your way through <xref linkend="chapter-temporary-tools"/> and beyond.</para>
<para><xref linkend="chapter-temporary-tools"/> explains the installation of
a number of packages that are needed to resolve circular
dependencies—for example, to compile a compiler, you need a compiler.
or to unpack the tar package, you need tar.</para>
<para><xref linkend="chapter-temporary-tools"/> also shows you how to
build a C cross-compiling toolchain as a first step, including binutils
and GCC. Cross-compiling is not absolutely needed since the machine we'll
run LFS on is the same as the one we build on, but it has the advantage
of clearly separating the already installed system and the future LFS one.
The next step is to build Glibc, the C library. Glibc will be compiled by
the toolchain programs built previously. Then, the missing bits for a
C++ cross-compiling toolchain will be built. It is then possible to build
packages that are needed to resolve circular dependencies in such a way
that the produced executables and libraries are completely independent
from the installed distribution.</para>
<para>The remainder of <xref linkend="chapter-temporary-tools"/> adds
the packages necessary to get a complete build environment. This is done
after running the <command>chroot</command> (change root) program 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 system
does not actually reboot, but instead uses <command>chroot</command>
because creating a bootable system requires additional work which is not
ecessary just yet. The major advantage is that <quote>chrooting</quote>
allows to isolate the build process from the installed distribution, while
using the installed kernel.</para>
<para>This effort to isolate the new system from the host distribution may
seem excessive. A full technical explanation as to why this is done is
provided in <xref linkend="ch-tools-toolchaintechnotes"/>.</para>
<para>In <xref linkend="chapter-building-system"/>, The
full LFS system is built. Another advantage provided by the chroot
environment is that it allows you to continue using the host system
while LFS is being built. While waiting for package compilations to
complete, you can continue using your computer as normal.</para>
<para>To finish the installation, the basic system configuration is set up in
<xref linkend="chapter-config"/>, and the kernel and boot loader are set
up in <xref linkend="chapter-bootable"/>. <xref linkend="chapter-finalizing"/>
contains information on continuing the LFS experience beyond this book.
After the steps in this book have been implemented, the computer will be
ready to reboot into the new LFS system.</para>
<para>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 you embark on the LFS adventure.</para>
</sect1>
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