1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
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3 | <!ENTITY % general-entities SYSTEM "../general.ent">
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4 | %general-entities;
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5 | ]>
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6 | <sect1 id="ch-tools-gcc-pass1" role="wrap">
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7 | <title>GCC-&gcc-version; - Pass 1</title>
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8 | <?dbhtml filename="gcc-pass1.html"?>
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9 |
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10 | <indexterm zone="ch-tools-gcc-pass1">
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11 | <primary sortas="a-GCC">GCC</primary>
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12 | <secondary>tools, pass 1</secondary></indexterm>
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13 |
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14 | <sect2 role="package"><title/>
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15 | <xi:include xmlns:xi="http://www.w3.org/2003/XInclude" href="../chapter06/gcc.xml" xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
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16 |
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17 | <segmentedlist>
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18 | <segtitle>&buildtime;</segtitle>
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19 | <segtitle>&diskspace;</segtitle>
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20 | <seglistitem><seg>4.4 SBU</seg><seg>300 MB</seg></seglistitem>
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21 | </segmentedlist>
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22 |
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23 | <xi:include xmlns:xi="http://www.w3.org/2003/XInclude" href="../chapter06/gcc.xml" xpointer="xpointer(/sect1/sect2[1]/segmentedlist[2])"/>
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24 |
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25 | </sect2>
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26 |
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27 | <sect2 role="installation">
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28 | <title>Installation of GCC</title>
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29 |
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30 | <para>Unpack only the GCC-core tarball, as we won't be needing the C++ compiler
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31 | nor the test suite here.</para>
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32 |
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33 | <para>This package is known to behave badly when you change its default
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34 | optimization flags (including the <parameter>-march</parameter> and
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35 | <parameter>-mcpu</parameter> options). Therefore, if you have defined any
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36 | environment variables that override default optimizations, such as CFLAGS and
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37 | CXXFLAGS, we recommend un-setting them when building GCC.</para>
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38 |
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39 | <para>The GCC documentation recommends building GCC outside of the source
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40 | directory in a dedicated build directory:</para>
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41 |
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42 | <screen><userinput>mkdir ../gcc-build
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43 | cd ../gcc-build</userinput></screen>
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44 |
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45 | <para>Prepare GCC for compilation:</para>
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46 |
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47 | <screen><userinput>CC="gcc -B/usr/bin" ../gcc-&gcc-version;/configure \
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48 | --prefix=/tools --libexecdir=/tools/lib \
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49 | --with-local-prefix=/tools --disable-nls \
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50 | --enable-shared --enable-languages=c</userinput></screen>
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51 |
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52 | <para>The meaning of the configure options:</para>
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53 |
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54 | <variablelist>
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55 | <varlistentry>
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56 | <term><parameter>CC="gcc -B/usr/bin"</parameter></term>
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57 | <listitem><para>This parameter fixes a possible problem with building GCC
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58 | at this stage, first noticed in LFS 5.1.1. If our host uses a new version
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59 | of Binutils than we compiled, the host compiler may try use features not
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60 | supported by our new linker, causing compilation errors. By passing the -B
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61 | flag to gcc, we cause the compiler to temporarily use the host's linker,
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62 | which solves the problem.</para></listitem>
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63 | </varlistentry>
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64 |
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65 | <varlistentry>
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66 | <term><parameter>--with-local-prefix=/tools</parameter></term>
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67 | <listitem><para>The purpose of this switch is to remove <filename class="directory">/usr/local/include</filename>
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68 | from <command>gcc</command>'s include search path. This is not absolutely
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69 | essential; however, we want to try to minimize the influence of the host
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70 | system, so this a sensible thing to do.</para></listitem>
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71 | </varlistentry>
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72 |
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73 | <varlistentry>
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74 | <term><parameter>--enable-shared</parameter></term>
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75 | <listitem><para>This switch may
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76 | seem counter-intuitive at first. But using it allows the building of
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77 | <filename>libgcc_s.so.1</filename> and <filename>libgcc_eh.a</filename>, and
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78 | having <filename>libgcc_eh.a</filename> available ensures that the configure
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79 | script for Glibc (the next package we compile) produces the proper results.
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80 | Note that the GCC binaries will still be linked
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81 | statically, as this is controlled by the <parameter>-static</parameter>
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82 | value of BOOT_LDFLAGS in the next step.</para></listitem>
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83 | </varlistentry>
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84 |
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85 | <varlistentry>
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86 | <term><parameter>--enable-languages=c</parameter></term>
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87 | <listitem><para>This option
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88 | ensures that only the C compiler is built. The option is only needed when you
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89 | have downloaded and unpacked the full GCC tarball.</para></listitem>
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90 | </varlistentry>
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91 | </variablelist>
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92 |
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93 | <para>Continue with compiling the package:</para>
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94 |
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95 | <screen><userinput>make BOOT_LDFLAGS="-static" bootstrap</userinput></screen>
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96 |
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97 | <para>The meaning of the make parameters:</para>
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98 |
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99 | <variablelist>
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100 | <varlistentry>
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101 | <term><parameter>BOOT_LDFLAGS="-static"</parameter></term>
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102 | <listitem><para>This tells GCC to link its programs statically.</para></listitem>
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103 | </varlistentry>
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104 |
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105 | <varlistentry>
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106 | <term><parameter>bootstrap</parameter></term>
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107 | <listitem><para>This target doesn't just
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108 | compile GCC, but compiles it several times. It uses the programs compiled in
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109 | a first round to compile itself a second time, and then again a third time.
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110 | It then compares these second and third compiles to make sure it can
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111 | reproduce itself flawlessly, which most probably means that it was
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112 | compiled correctly.</para></listitem>
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113 | </varlistentry>
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114 | </variablelist>
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115 |
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116 | <para>Compilation is now complete, and at this point we would normally run the
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117 | test suite. But, as mentioned before, the test suite framework is not in place
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118 | yet. And there would be little point in running the tests anyhow, since the
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119 | programs from this first pass will soon be replaced.</para>
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120 |
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121 | <para>Now install the package:</para>
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122 |
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123 | <screen><userinput>make install</userinput></screen>
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124 |
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125 | <para>As a finishing touch we'll create a symlink. Many programs and scripts
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126 | run <command>cc</command> instead of <command>gcc</command>,
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127 | a thing meant to keep programs generic and therefore usable on all kinds of
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128 | Unix systems. Not everybody has the GNU C compiler installed. Simply running
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129 | <command>cc</command> leaves the system administrator free to decide what
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130 | C compiler to install, as long as there's a symlink pointing to it:</para>
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131 |
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132 | <screen><userinput>ln -s gcc /tools/bin/cc</userinput></screen>
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133 |
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134 | </sect2>
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135 |
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136 | <sect2 role="content"><title/>
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137 | <para>The details on this package are found in <xref linkend="contents-gcc"/>.</para>
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138 | </sect2>
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139 |
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140 | </sect1>
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