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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-system-introduction">
<?dbhtml filename="introduction.html"?>
<title>Introduction</title>
<para>In this chapter, we start constructing the LFS system in earnest.
</para>
<para>The installation of this software is straightforward. Although in many
cases the installation instructions could be made shorter and more generic,
we have opted to provide the full instructions for every package to minimize
the possibilities for mistakes. The key to learning what makes a Linux system
work is to know what each package is used for and why you (or the system)
may need it.</para>
<para>We do not recommend using customized optimizations. They can make
a program run slightly faster, but they may also cause compilation
difficulties, and problems when running the program. If a package refuses to
compile with a customized optimization, try to compile it without
optimization and see if that fixes the problem. Even if the package does compile when using a customized
optimization, there is the risk it may have been compiled incorrectly because
of the complex interactions between the code and the build tools. Also note that
the <option>-march</option> and <option>-mtune</option> options using values
not specified in the book have not been tested. This may cause problems with
the toolchain packages (Binutils, GCC and Glibc). The small potential gains
achieved by customizing compiler optimizations are often outweighed by the risks.
First-time builders of LFS are encouraged to build without custom
optimizations.</para>
<para>On the other hand, we keep the optimizations enabled by the default
configuration of the packages. In addition, we sometimes explicitly enable an
optimized configuration provided by a package but not enabled by
default. The package maintainers have already tested these configurations
and consider them safe, so it's not likely they would break the build.
Generally the default configuration already enables <option>-O2</option>
or <option>-O3</option>, so the resulting system will still run very fast
without any customized optimization, and be stable at the same time.</para>
<para>Before the installation instructions, each installation page provides
information about the package, including a concise description of what it
contains, approximately how long it will take to build, and how much disk
space is required during this building process. Following the installation
instructions, there is a list of programs and libraries (along with brief
descriptions) that the package installs.</para>
<note><para>The SBU values and required disk space include test suite data
for all applicable packages in <xref linkend="chapter-building-system"/>. SBU
values have been calculated using four CPU cores (-j4) for all
operations unless specified otherwise.</para></note>
<sect2>
<title>About Libraries</title>
<para>In general, the LFS editors discourage building and installing static
libraries. Most static libraries have been made
obsolete in a modern Linux system. In addition, linking a static library
into a program can be detrimental. If an update to the library is needed
to remove a security problem, every program that uses the static library will
need to be relinked with the new library. Since the use of static libraries
is not always obvious, the relevant programs (and the procedures needed to
do the linking) may not even be known.</para>
<para>The procedures in this chapter remove or disable installation of
most static libraries. Usually this is done by passing a
<option>--disable-static</option> option to <command>configure</command>.
In other cases, alternate means are needed. In a few cases, especially
Glibc and GCC, the use of static libraries remains an essential feature of the
package building process. </para>
<para>For a more complete discussion of libraries, see
<ulink url="&blfs-book;introduction/libraries.html">
Libraries: Static or shared?</ulink> in the BLFS book.</para>
</sect2>
</sect1>
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