1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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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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4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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5 | %general-entities;
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6 | ]>
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7 |
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8 | <sect1 id="ch-tools-gcc-pass1" role="wrap">
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9 | <?dbhtml filename="gcc-pass1.html"?>
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10 |
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11 | <title>GCC-&gcc-version; - Pass 1</title>
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12 |
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13 | <indexterm zone="ch-tools-gcc-pass1">
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14 | <primary sortas="a-GCC">GCC</primary>
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15 | <secondary>tools, pass 1</secondary>
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16 | </indexterm>
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17 |
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18 | <sect2 role="package">
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19 | <title/>
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20 |
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21 | <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
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22 | href="../chapter06/gcc.xml"
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23 | xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
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24 |
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25 | <segmentedlist>
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26 | <segtitle>&buildtime;</segtitle>
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27 | <segtitle>&diskspace;</segtitle>
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28 |
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29 | <seglistitem>
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30 | <seg>&gcc-ch5p1-sbu;</seg>
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31 | <seg>&gcc-ch5p1-du;</seg>
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32 | </seglistitem>
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33 | </segmentedlist>
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34 |
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35 | </sect2>
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36 |
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37 | <sect2 role="installation">
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38 | <title>Installation of GCC</title>
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39 |
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40 | <para>The GCC documentation recommends building GCC outside of the
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41 | source directory in a dedicated build directory:</para>
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42 |
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43 | <screen><userinput>mkdir -v ../gcc-build
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44 | cd ../gcc-build</userinput></screen>
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45 |
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46 | <para>Test to see if the host is a multilib capable machine and set a variable
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47 | if it is. This ensures that only 64-bit binaries are built if using such a host.
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48 | Also, the --with-arch flag is only necessary for x86 machines.</para>
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49 |
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50 | <screen><userinput>case $(uname -m) in
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51 | i?86) WITHARCH="--with-arch=i486" ;;
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52 | x86_64) M64="-m64" ;;
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53 | esac</userinput></screen>
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54 |
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55 | <para>Prepare GCC for compilation:</para>
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56 |
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57 | <screen><userinput>CC="gcc -B/usr/bin/ $M64" ../gcc-&gcc-version;/configure --prefix=/tools \
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58 | --with-local-prefix=/tools --disable-nls --disable-shared \
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59 | --enable-languages=c --disable-multilib \
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60 | $WITHARCH
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61 | unset M64 WITHARCH</userinput></screen>
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62 |
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63 | <variablelist>
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64 | <title>The meaning of the configure options:</title>
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65 |
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66 | <varlistentry>
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67 | <term><envar>CC="gcc -B/usr/bin/"</envar></term>
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68 | <listitem>
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69 | <para>This forces <command>gcc</command> to prefer the linker from
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70 | the host in <filename class="directory">/usr/bin</filename>. This
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71 | is necessary on some hosts where the new <command>ld</command>
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72 | built in the previous section is not compatible with the host's
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73 | <command>gcc</command>.</para>
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74 | </listitem>
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75 | </varlistentry>
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76 |
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77 | <varlistentry>
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78 | <term><parameter>--with-local-prefix=/tools</parameter></term>
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79 | <listitem>
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80 | <para>The purpose of this switch is to remove <filename
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81 | class="directory">/usr/local/include</filename> from
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82 | <command>gcc</command>'s include search path. This is not
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83 | absolutely essential, however, it helps to minimize the
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84 | influence of the host system.</para>
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85 | </listitem>
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86 | </varlistentry>
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87 |
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88 | <varlistentry>
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89 | <term><parameter>--disable-shared</parameter></term>
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90 | <listitem>
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91 | <para>This forces gcc to link its internal libraries statically. We do this
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92 | to avoid possible issues with the host system.</para>
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93 | </listitem>
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94 | </varlistentry>
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95 |
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96 | <varlistentry>
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97 | <term><parameter>--enable-languages=c</parameter></term>
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98 | <listitem>
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99 | <para>This option ensures that only the C compiler is built.</para>
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100 | </listitem>
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101 | </varlistentry>
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102 |
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103 | <varlistentry>
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104 | <term><parameter>--disable-multilib</parameter></term>
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105 | <listitem>
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106 | <para>We currently only want to build support for 64-bit libraries.</para>
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107 | </listitem>
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108 | </varlistentry>
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109 |
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110 | <varlistentry>
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111 | <term><parameter>--with-arch=i486</parameter></term>
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112 | <listitem>
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113 | <para>On x86 machines Glibc-&glibc-version; needs to be built for a
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114 | minimum architecture of <quote>i486</quote>. In fact, Glibc developers suggest
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115 | setting the compiler flag <parameter>-march=i486</parameter> when compiling it.
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116 | However, by using the above parameter for the GCC build, we can set a default
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117 | value for <parameter>-march</parameter> at the compiler level, ensuring that
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118 | the entire system is built consistently, i.e., for the same cpu-type.
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119 | Of course, values greater or more specific than <quote>i486</quote> could be
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120 | used. See <command>man gcc</command> for other acceptable cpu-types.
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121 | Keep in mind that using an incompatible cpu-type for the machine will result
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122 | in breakage. The advantage of <quote>i486</quote> is that it is a generic
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123 | option and will work for all modern x86 machines.</para>
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124 | </listitem>
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125 | </varlistentry>
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126 |
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127 | </variablelist>
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128 |
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129 | <para>The following command will compile GCC not once, but several times. It
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130 | uses the programs compiled in a first round to compile itself a second time,
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131 | and then again a third time. It then compares these second and third compiles
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132 | to make sure it can reproduce itself flawlessly. This is called
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133 | <quote>bootstrapping</quote>. Building GCC in this way ensures that it was
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134 | compiled correctly and is now the default configuration for the released
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135 | package. Continue with compiling by running:</para>
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136 |
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137 | <screen><userinput>make</userinput></screen>
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138 |
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139 | <para>Compilation is now complete. At this point, the test suite would
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140 | normally be run, but, as mentioned before, the test suite framework is
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141 | not in place yet. The benefits of running the tests at this point
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142 | are minimal since the programs from this first pass will soon be
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143 | replaced.</para>
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144 |
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145 | <para>Install the package:</para>
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146 |
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147 | <screen><userinput>make install</userinput></screen>
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148 |
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149 | <para>Using <command>--disable-shared</command> means that the file
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150 | <filename class="libraryfile">libgcc_eh.a</filename>
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151 | isn't created and installed. The next package, Glibc, depends on this
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152 | library as it uses <command>-lgcc_eh</command> within its build system.
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153 | We can satisfy that dependency by creating a symlink to
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154 | <filename class="libraryfile">libgcc.a</filename>, since that file will
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155 | end up containing the objects normally contained in
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156 | <filename class="libraryfile">libgcc_eh.a</filename>.</para>
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157 |
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158 | <screen><userinput>ln -vs libgcc.a `gcc -print-libgcc-file-name | \
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159 | sed 's/libgcc/&_eh/'`</userinput></screen>
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160 |
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161 | <para>As a finishing touch, create a symlink. Many programs and scripts
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162 | run <command>cc</command> instead of <command>gcc</command>, which is
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163 | used to keep programs generic and therefore usable on all kinds of UNIX
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164 | systems where the GNU C compiler is not always installed. Running
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165 | <command>cc</command> leaves the system administrator free to decide
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166 | which C compiler to install:</para>
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167 |
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168 | <screen><userinput>ln -vs gcc /tools/bin/cc</userinput></screen>
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169 |
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170 | </sect2>
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171 |
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172 | <sect2 role="content">
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173 | <title/>
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174 |
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175 | <para>Details on this package are located in
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176 | <xref linkend="contents-gcc" role="."/></para>
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177 |
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178 | </sect2>
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179 |
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180 | </sect1>
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