[7152faa] | 1 | <?xml version="1.0" encoding="UTF-8"?>
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[b06ca36] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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[673b0d8] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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[b78c747] | 7 |
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[fcc02767] | 8 | <sect1 id="ch-system-introduction">
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[b78c747] | 9 | <?dbhtml filename="introduction.html"?>
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[6370fa6] | 10 |
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[b78c747] | 11 | <title>Introduction</title>
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[6370fa6] | 12 |
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[6a156bab] | 13 | <para>In this chapter, we start constructing the LFS system in earnest.
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| 14 | </para>
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[fcc02767] | 15 |
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| 16 | <para>The installation of this software is straightforward. Although in many
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| 17 | cases the installation instructions could be made shorter and more generic,
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| 18 | we have opted to provide the full instructions for every package to minimize
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| 19 | the possibilities for mistakes. The key to learning what makes a Linux system
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| 20 | work is to know what each package is used for and why you (or the system)
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| 21 | may need it.</para>
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| 22 |
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[b1c8283] | 23 | <para>We do not recommend using customized optimizations. They can make
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[fcc02767] | 24 | a program run slightly faster, but they may also cause compilation
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[091d624d] | 25 | difficulties, and problems when running the program. If a package refuses to
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[b1c8283] | 26 | compile with a customized optimization, try to compile it without
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| 27 | optimization and see if that fixes the problem. Even if the package does compile when using a customized
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[fcc02767] | 28 | optimization, there is the risk it may have been compiled incorrectly because
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[091d624d] | 29 | of the complex interactions between the code and the build tools. Also note that
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[fcc02767] | 30 | the <option>-march</option> and <option>-mtune</option> options using values
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| 31 | not specified in the book have not been tested. This may cause problems with
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| 32 | the toolchain packages (Binutils, GCC and Glibc). The small potential gains
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[b1c8283] | 33 | achieved by customizing compiler optimizations are often outweighed by the risks.
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[fcc02767] | 34 | First-time builders of LFS are encouraged to build without custom
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[b1c8283] | 35 | optimizations.</para>
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| 36 |
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[7115c88] | 37 | <para>On the other hand, we keep the optimizations enabled by the default
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| 38 | configuration of the packages. In addition, we sometimes explicitly enable an
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| 39 | optimized configuration provided by a package but not enabled by
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[b1c8283] | 40 | default. The package maintainers have already tested these configurations
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| 41 | and consider them safe, so it's not likely they would break the build.
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| 42 | Generally the default configuration already enables <option>-O2</option>
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| 43 | or <option>-O3</option>, so the resulting system will still run very fast
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| 44 | without any customized optimization, and be stable at the same time.</para>
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[fcc02767] | 45 |
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| 46 | <para>Before the installation instructions, each installation page provides
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| 47 | information about the package, including a concise description of what it
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| 48 | contains, approximately how long it will take to build, and how much disk
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| 49 | space is required during this building process. Following the installation
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| 50 | instructions, there is a list of programs and libraries (along with brief
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[6a156bab] | 51 | descriptions) that the package installs.</para>
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[fcc02767] | 52 |
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[091d624d] | 53 | <note><para>The SBU values and required disk space include test suite data
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[6a156bab] | 54 | for all applicable packages in <xref linkend="chapter-building-system"/>. SBU
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[7c92d6d] | 55 | values have been calculated using four CPU cores (-j4) for all
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| 56 | operations unless specified otherwise.</para></note>
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[fcc02767] | 57 |
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| 58 | <sect2>
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[091d624d] | 59 | <title>About Libraries</title>
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[fcc02767] | 60 |
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| 61 | <para>In general, the LFS editors discourage building and installing static
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[091d624d] | 62 | libraries. Most static libraries have been made
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[6a156bab] | 63 | obsolete in a modern Linux system. In addition, linking a static library
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[fcc02767] | 64 | into a program can be detrimental. If an update to the library is needed
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[091d624d] | 65 | to remove a security problem, every program that uses the static library will
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| 66 | need to be relinked with the new library. Since the use of static libraries
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[fcc02767] | 67 | is not always obvious, the relevant programs (and the procedures needed to
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| 68 | do the linking) may not even be known.</para>
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| 69 |
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[091d624d] | 70 | <para>The procedures in this chapter remove or disable installation of
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[fcc02767] | 71 | most static libraries. Usually this is done by passing a
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| 72 | <option>--disable-static</option> option to <command>configure</command>.
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| 73 | In other cases, alternate means are needed. In a few cases, especially
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[091d624d] | 74 | Glibc and GCC, the use of static libraries remains an essential feature of the
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[fcc02767] | 75 | package building process. </para>
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| 76 |
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[091d624d] | 77 | <para>For a more complete discussion of libraries, see
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[35d2578] | 78 | <ulink url="&blfs-book;introduction/libraries.html">
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[fcc02767] | 79 | Libraries: Static or shared?</ulink> in the BLFS book.</para>
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| 80 |
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| 81 | </sect2>
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[81fd230] | 82 |
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[b78c747] | 83 | </sect1>
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