lfs-book/chapter06/introduction.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "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 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, the relevant programs (and the procedures needed to
    do the linking) may not even be known.</para>

    <para>In the procedures 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>