1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/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-pass2" role="wrap">
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7 | <title>GCC-&gcc-version; - Pass 2</title>
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8 | <?dbhtml filename="gcc-pass2.html"?>
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9 |
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10 | <indexterm zone="ch-tools-gcc-pass2">
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11 | <primary sortas="a-GCC">GCC</primary>
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12 | <secondary>tools, pass 2</secondary></indexterm>
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13 |
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14 | <sect2 role="package"><title/>
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15 |
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16 | <segmentedlist>
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17 | <segtitle>&buildtime;</segtitle>
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18 | <segtitle>&diskspace;</segtitle>
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19 | <seglistitem><seg>11.0 SBU</seg><seg>292 MB</seg></seglistitem>
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20 | </segmentedlist>
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21 |
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22 | <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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23 |
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24 | </sect2>
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25 |
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26 | <sect2 role="installation">
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27 | <title>Re-installation of GCC</title>
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28 |
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29 | <para>This package is known to have issues when its default
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30 | optimization flags (including the <parameter>-march</parameter> and
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31 | <parameter>-mcpu</parameter> options) are changed. If any environment
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32 | variables that override default optimizations have been defined, such
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33 | as <envar>CFLAGS</envar> and <envar>CXXFLAGS</envar>,
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34 | unset them when building GCC.</para>
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35 |
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36 | <para>The tools required to test GCC and Binutils—Tcl, Expect
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37 | and DejaGNU—are installed now. GCC and Binutils can now be
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38 | rebuilt, linking them against the new Glibc and testing them properly
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39 | (if running the test suites in this chapter). Please note that these
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40 | test suites are highly dependent on properly functioning PTYs which
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41 | are provided by the host. PTYs are most commonly implemented via the
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42 | <systemitem class="filesystem">devpts</systemitem> file system. Check
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43 | to see if the host system is set up correctly in this regard by
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44 | performing a quick test:</para>
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45 |
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46 | <screen><userinput>expect -c "spawn ls"</userinput></screen>
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47 |
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48 | <para>The response might be:</para>
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49 |
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50 | <screen><computeroutput>The system has no more ptys.
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51 | Ask your system administrator to create more.</computeroutput></screen>
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52 |
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53 | <para>If the above message is received, the host does not have its PTYs set up
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54 | properly. In this case, there is no point in running the test suites for GCC and
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55 | Binutils until this issue is resolved. Please consult the LFS FAQ at <ulink
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56 | url="&lfs-root;/lfs/faq.html#no-ptys"/> for more information on how to get PTYs
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57 | working.</para>
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58 |
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59 | <para>First correct a known problem and make an essential adjustment:</para>
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60 |
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61 | <screen><userinput>patch -Np1 -i ../gcc-&gcc-version;-no_fixincludes-1.patch
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62 | patch -Np1 -i ../gcc-&gcc-version;-specs-2.patch</userinput></screen>
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63 |
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64 | <para>The first patch disables the GCC <command>fixincludes</command>
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65 | script. This was briefly mentioned earlier, but a more in-depth
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66 | explanation of the fixincludes process is warranted here. Under normal
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67 | circumstances, the GCC <command>fixincludes</command> script scans the
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68 | system for header files that need to be fixed. It might find that some
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69 | Glibc header files on the host system need to be fixed, and will fix
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70 | them and put them in the GCC private include directory. In <xref
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71 | linkend="chapter-building-system"/>, after the newer Glibc has been
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72 | installed, this private include directory will be searched before the
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73 | system include directory. This may result in GCC finding the fixed
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74 | headers from the host system, which most likely will not match the
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75 | Glibc version used for the LFS system.</para>
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76 |
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77 | <para>The second patch changes GCC's default location of the dynamic
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78 | linker (typically <filename class="libraryfile">ld-linux.so.2</filename>). It also removes
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79 | <filename class="directory">/usr/include</filename> from GCC's include
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80 | search path. Patching now rather than adjusting the specs file after
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81 | installation ensures that the new dynamic linker is used during the
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82 | actual build of GCC. That is, all of the final (and temporary)
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83 | binaries created during the build will link against the new
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84 | Glibc.</para>
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85 |
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86 | <beginpage/>
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87 |
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88 | <important><para>The above patches are critical in ensuring a
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89 | successful overall build. Do not forget to apply
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90 | them.</para></important>
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91 |
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92 | <para>Create a separate build directory again:</para>
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93 |
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94 | <screen><userinput>mkdir ../gcc-build
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95 | cd ../gcc-build</userinput></screen>
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96 |
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97 | <para>Before starting to build GCC, remember to unset any environment
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98 | variables that override the default optimization flags.</para>
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99 |
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100 | <para>Now prepare GCC for compilation:</para>
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101 |
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102 | <screen><userinput>../gcc-&gcc-version;/configure --prefix=/tools \
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103 | --libexecdir=/tools/lib --with-local-prefix=/tools \
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104 | --enable-clocale=gnu --enable-shared \
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105 | --enable-threads=posix --enable-__cxa_atexit \
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106 | --enable-languages=c,c++ --disable-libstdcxx-pch</userinput></screen>
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107 |
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108 | <para>The meaning of the new configure options:</para>
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109 |
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110 | <variablelist>
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111 | <varlistentry>
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112 | <term><parameter>--enable-clocale=gnu</parameter></term>
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113 | <listitem><para>This option ensures the correct locale model is
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114 | selected for the C++ libraries under all circumstances. If the
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115 | configure script finds the <emphasis>de_DE</emphasis> locale installed, it will select the
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116 | correct gnu locale model. However, if the <emphasis>de_DE</emphasis> locale is not
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117 | installed, there is the risk of building Application Binary Interface
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118 | (ABI)-incompatible C++ libraries because the incorrect generic locale
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119 | model may be selected.</para></listitem>
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120 | </varlistentry>
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121 |
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122 | <varlistentry>
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123 | <term><parameter>--enable-threads=posix</parameter></term>
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124 | <listitem><para>This enables C++ exception handling for multi-threaded
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125 | code.</para></listitem>
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126 | </varlistentry>
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127 |
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128 | <varlistentry>
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129 | <term><parameter>--enable-__cxa_atexit</parameter></term>
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130 | <listitem><para>This option allows use of
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131 | <emphasis>__cxa_atexit</emphasis>, rather than
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132 | <emphasis>atexit</emphasis>, to register C++ destructors for local
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133 | statics and global objects. This option is essential for fully
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134 | standards-compliant handling of destructors. It also affects the C++
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135 | ABI, and therefore results in C++ shared libraries and C++ programs
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136 | that are interoperable with other Linux
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137 | distributions.</para></listitem>
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138 | </varlistentry>
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139 |
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140 | <varlistentry>
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141 | <term><parameter>--enable-languages=c,c++</parameter></term>
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142 | <listitem><para>This option
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143 | ensures that both the C and C++ compilers are built.</para></listitem>
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144 | </varlistentry>
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145 |
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146 | <varlistentry>
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147 | <term><parameter>--disable-libstdcxx-pch</parameter></term>
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148 | <listitem><para>Do not build the pre-compiled header (PCH) for
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149 | <filename class="libraryfile">libstdc++</filename>. It takes up a lot of space,
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150 | and we have no use for it.</para></listitem>
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151 | </varlistentry>
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152 | </variablelist>
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153 |
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154 | <para>Compile the package:</para>
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155 |
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156 | <screen><userinput>make</userinput></screen>
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157 |
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158 | <para>There is no need to use the <parameter>bootstrap</parameter>
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159 | target now because the compiler being used to compile this GCC was
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160 | built from the exact same version of the GCC sources used
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161 | earlier.</para>
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162 |
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163 | <beginpage/>
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164 |
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165 | <para>Compilation is now complete. As previously mentioned, running
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166 | the test suites for the temporary tools compiled in this chapter is
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167 | not mandatory. To run the GCC test suite anyway, use the following
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168 | command:</para>
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169 |
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170 | <screen><userinput>make -k check</userinput></screen>
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171 |
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172 | <para>The <parameter>-k</parameter> flag is used to make the test suite run
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173 | through to completion and not stop at the first failure. The GCC test
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174 | suite is very comprehensive and is almost guaranteed to generate a few
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175 | failures. To receive a summary of the test suite results, run:</para>
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176 |
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177 | <screen><userinput>../gcc-&gcc-version;/contrib/test_summary</userinput></screen>
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178 |
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179 | <para>For only the summaries, pipe the output through
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180 | <userinput>grep -A7 Summ</userinput>.</para>
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181 |
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182 | <para>Results can be compared with those located at <ulink
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183 | url="&test-results;"/>.</para>
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184 |
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185 | <para>A few unexpected failures cannot always be avoided. The
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186 | GCC developers are usually aware of these issues, but have not
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187 | resolved them yet. Unless the test results are vastly different from
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188 | those at the above URL, it is safe to continue.</para>
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189 |
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190 | <para>Install the package:</para>
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191 |
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192 | <screen><userinput>make install</userinput></screen>
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193 |
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194 | <note><para>At this point it is strongly recommended to repeat the
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195 | sanity check we performed earlier in this chapter. Refer back to <xref
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196 | linkend="ch-tools-adjusting" role=","/> and repeat the test compilation. If
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197 | the result is wrong, the most likely reason is that the GCC Specs
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198 | patch was not properly applied.</para></note>
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199 |
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200 | </sect2>
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201 |
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202 | <sect2 role="content"><title/>
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203 | <para>Details on this package are located in <xref
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204 | linkend="contents-gcc" role="."/></para>
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205 | </sect2>
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206 |
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207 | </sect1>
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208 |
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