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<sect1 id="ch-system-introduction">
<?dbhtml filename="introduction.html"?>
<title>Introduction</title>
<para>In this chapter, we enter the building site and start constructing the
LFS system in earnest. That is, we chroot into the temporary mini Linux system,
make a few final preparations, and then begin installing the packages.</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 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 when using optimization, try to compile it without optimization and
see if that fixes the problem. Even if the package does compile when using
optimization, there is the risk it may have been compiled incorrectly because
of the complex interactions between the code and 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 in using compiler optimizations are often outweighed by the risks.
First-time builders of LFS are encouraged to build without custom
optimizations. The subsequent system will still run very fast and be stable
at the same time.</para>
<para>The order that packages are installed in this chapter needs to be
strictly followed to ensure that no program accidentally acquires a path
referring to <filename class="directory">/tools</filename> hard-wired into
it. For the same reason, do not compile separate packages in parallel.
Compiling in parallel may save time (especially on dual-CPU machines), but it
could result in a program containing a hard-wired path to <filename
class="directory">/tools</filename>, which will cause the program to stop
working when that directory is removed.</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 of these) that the package installs.</para>
<note><para>The SBU values and required disk space includes
test suite data for all applicable packages in Chapter 6.</para></note>
<sect2>
<title>About libraries</title>
<para>In general, the LFS editors discourage building and installing static
libraries. The original purpose for most static libraries has 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, all programs that use the static library will
need to be relinked to the new library. Since the use of static libraries
is not always obvious, deciding which programs (and the procedures needed to
do the linking) may not even be known.</para>
<para>In the prcedures in Chapter 6, we remove or disable installation of
most static libraries. In a few cases, especially glibc and gcc, the use
of static libraries remains essential to the general package building
process. Usually this is done by passing a
<option>--disable-static</option> option to <command>configure</command>.
In other cases, alternate means are needed.</para>
<para>For a more complete discussion of libraries, see the discussion
<ulink url="&blfs-root;/view/&short-version;/introduction/libraries.html">
Libraries: Static or shared?</ulink> in the BLFS book.</para>
</sect2>
</sect1>
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