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-pass2" role="wrap">
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9 | <?dbhtml filename="gcc-pass2.html"?>
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10 |
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11 | <title>GCC-&gcc-version; - Pass 2</title>
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12 |
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13 | <indexterm zone="ch-tools-gcc-pass2">
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14 | <primary sortas="a-GCC">GCC</primary>
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15 | <secondary>tools, pass 2</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-ch5p2-sbu;</seg>
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31 | <seg>&gcc-ch5p2-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>Re-installation of GCC</title>
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39 |
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40 | <para>The tools required to test GCC and Binutils—Tcl, Expect
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41 | and DejaGNU—are installed now. GCC and Binutils can now be
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42 | rebuilt, linking them against the new Glibc and testing them properly
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43 | (if running the test suites in this chapter). Please note that these
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44 | test suites are highly dependent on properly functioning PTYs which
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45 | are provided by the host. PTYs are most commonly implemented via the
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46 | <systemitem class="filesystem">devpts</systemitem> file system. Check
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47 | to see if the host system is set up correctly in this regard by
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48 | performing a quick test:</para>
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49 |
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50 | <screen><userinput>expect -c "spawn ls"</userinput></screen>
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51 |
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52 | <para>The response might be:</para>
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53 |
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54 | <screen><computeroutput>The system has no more ptys.
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55 | Ask your system administrator to create more.</computeroutput></screen>
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56 |
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57 | <para>If the above message is received, the host does not have its PTYs
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58 | set up properly. In this case, there is no point in running the test
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59 | suites for GCC and Binutils until this issue is resolved. Please consult
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60 | the LFS FAQ at <ulink url="&lfs-root;/lfs/faq.html#no-ptys"/> for more
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61 | information on how to get PTYs working.</para>
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62 |
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63 | <para>As previously explained in <xref linkend="ch-tools-adjusting"/>,
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64 | under normal circumstances the GCC <command>fixincludes</command> script
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65 | is run in order to fix potentially broken header files. As GCC-&gcc-version;
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66 | and Glibc-&glibc-version; have already been installed at this point, and
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67 | their respective header files are known to not require fixing, the
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68 | <command>fixincludes</command> script is not required. As mentioned
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69 | previously, the script may in fact pollute the build environment by
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70 | installing fixed headers from the host system into GCC's private include
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71 | directory. The running of the <command>fixincludes</command> script can
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72 | be suppressed by issuing the following commands:</para>
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73 |
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74 | <screen><userinput>cp -v gcc/Makefile.in{,.orig}
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75 | sed 's@\./fixinc\.sh@-c true@' gcc/Makefile.in.orig > gcc/Makefile.in</userinput></screen>
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76 |
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77 | <para>The bootstrap build performed in <xref linkend="ch-tools-gcc-pass1"/>
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78 | built GCC with the <option>-fomit-frame-pointer</option> compiler flag.
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79 | Non-bootstrap builds omit this flag by default, so apply the following
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80 | <command>sed</command> to use it in order to ensure consistent compiler
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81 | builds:</para>
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82 |
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83 | <screen><userinput>cp -v gcc/Makefile.in{,.tmp}
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84 | sed 's/^XCFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in.tmp \
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85 | > gcc/Makefile.in</userinput></screen>
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86 |
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87 | <para>The following command will change the location of GCC's default
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88 | dynamic linker to use the one we installed in
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89 | <filename class="directory">/tools</filename>. It also removes <filename
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90 | class="directory">/usr/include</filename> from GCC's include search path.
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91 | Doing this now rather than adjusting the specs file after installation
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92 | ensures that the new dynamic linker is used during the actual build of
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93 | GCC. That is, all of the binaries created during the build will link
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94 | against the new Glibc. Issue:</para>
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95 |
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96 | <screen><userinput>for file in $(find gcc/config -name linux64.h -o -name linux.h)
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97 | do
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98 | cp -uv $file{,.orig}
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99 | sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \
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100 | -e 's@/usr@/tools@g' $file.orig > $file
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101 | echo "
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102 | #undef STANDARD_INCLUDE_DIR
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103 | #define STANDARD_INCLUDE_DIR 0" >> $file
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104 | touch $file.orig
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105 | done</userinput></screen>
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106 |
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107 | <para>In case the above seems hard to follow, let's break it down a bit.
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108 | First we find all the files under the gcc/config directory that are named
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109 | either <filename>linux.h</filename> or <filename>linux64.h</filename>.
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110 | For each file found, we copy it to a file of the same name but with an added
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111 | suffix of <quote>.orig</quote>. Then the first sed expression prepends
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112 | <quote>/tools</quote> to every instance of <quote>/lib/ld</quote>,
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113 | <quote>/lib64/ld</quote> or <quote>/lib32/ld</quote>, while the second one
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114 | replaces hard-coded instances of <quote>/usr</quote>. Then we add our define
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115 | statments altering the include search path to the end of the file. Finally,
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116 | we use <command>touch</command> to update the timestamp on the copied files.
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117 | When used in conjunction with <command>cp -u</command>, this prevents unexpected
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118 | changes to the original files in case the command is inadvertently run twice.
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119 | </para>
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120 |
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121 | <para>Unsetting the multlib spec for GCC ensures that it
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122 | won't attempt to link against libraries on the host:</para>
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123 |
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124 | <screen><userinput>for file in $(find gcc/config -name t-linux64) ; do \
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125 | cp -v $file{,.orig}
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126 | sed '/MULTILIB_OSDIRNAMES/d' $file.orig > $file
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127 | done</userinput></screen>
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128 |
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129 | <para>Create a separate build directory again:</para>
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130 |
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131 | <screen><userinput>mkdir -v ../gcc-build
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132 | cd ../gcc-build</userinput></screen>
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133 |
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134 | <para>Before starting to build GCC, remember to unset any environment
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135 | variables that override the default optimization flags.</para>
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136 |
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137 | <para>Now prepare GCC for compilation:</para>
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138 |
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139 | <screen><userinput>../gcc-&gcc-version;/configure --prefix=/tools \
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140 | --with-local-prefix=/tools --enable-clocale=gnu \
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141 | --enable-shared --enable-threads=posix \
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142 | --enable-__cxa_atexit --enable-languages=c,c++ \
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143 | --disable-libstdcxx-pch --disable-multilib</userinput></screen>
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144 |
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145 | <variablelist>
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146 | <title>The meaning of the new configure options:</title>
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147 |
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148 | <varlistentry>
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149 | <term><parameter>--enable-clocale=gnu</parameter></term>
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150 | <listitem>
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151 | <para>This option ensures the correct locale model is selected
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152 | for the C++ libraries under all circumstances. If the configure
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153 | script finds the <emphasis>de_DE</emphasis> locale installed,
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154 | it will select the correct gnu locale model. However, if the
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155 | <emphasis>de_DE</emphasis> locale is not installed, there is the
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156 | risk of building Application Binary Interface (ABI)-incompatible
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157 | C++ libraries because the incorrect generic locale model may be
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158 | selected.</para>
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159 | </listitem>
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160 | </varlistentry>
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161 |
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162 | <varlistentry>
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163 | <term><parameter>--enable-threads=posix</parameter></term>
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164 | <listitem>
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165 | <para>This enables C++ exception handling for multi-threaded code.</para>
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166 | </listitem>
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167 | </varlistentry>
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168 |
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169 | <varlistentry>
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170 | <term><parameter>--enable-__cxa_atexit</parameter></term>
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171 | <listitem>
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172 | <para>This option allows use of <function>__cxa_atexit</function>,
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173 | rather than <function>atexit</function>, to register C++ destructors
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174 | for local statics and global objects. This option is essential for
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175 | fully standards-compliant handling of destructors. It also affects
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176 | the C++ ABI, and therefore results in C++ shared libraries and C++
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177 | programs that are interoperable with other Linux distributions.</para>
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178 | </listitem>
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179 | </varlistentry>
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180 |
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181 | <varlistentry>
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182 | <term><parameter>--enable-languages=c,c++</parameter></term>
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183 | <listitem>
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184 | <para>This option ensures that both the C and C++ compilers are
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185 | built.</para>
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186 | </listitem>
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187 | </varlistentry>
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188 |
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189 | <varlistentry>
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190 | <term><parameter>--disable-libstdcxx-pch</parameter></term>
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191 | <listitem>
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192 | <para>Do not build the pre-compiled header (PCH) for
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193 | <filename class="libraryfile">libstdc++</filename>. It takes up a
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194 | lot of space, and we have no use for it.</para>
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195 | </listitem>
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196 | </varlistentry>
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197 |
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198 | </variablelist>
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199 |
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200 | <para>Compile the package:</para>
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201 |
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202 | <screen><userinput>make</userinput></screen>
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203 |
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204 | <para>There is no need to use the <parameter>bootstrap</parameter> target
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205 | now because the compiler being used to compile this GCC was built from
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206 | the exact same version of the GCC sources used earlier.</para>
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207 |
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208 | <para>Compilation is now complete. As previously mentioned, running the test
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209 | suites for the temporary tools compiled in this chapter is not mandatory.
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210 | To run the GCC test suite anyway, use the following command:</para>
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211 |
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212 | <screen><userinput>make -k check</userinput></screen>
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213 |
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214 | <para>The <parameter>-k</parameter> flag is used to make the test suite run
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215 | through to completion and not stop at the first failure. The GCC test
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216 | suite is very comprehensive and is almost guaranteed to generate a few
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217 | failures.</para>
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218 |
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219 | <para>For a discussion of test failures that are of particular
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220 | importance, please see <xref linkend="ch-system-gcc" role="."/></para>
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221 |
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222 | <para>Install the package:</para>
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223 |
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224 | <screen><userinput>make install</userinput></screen>
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225 |
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226 | <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
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227 | href="adjusting.xml"
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228 | xpointer="xpointer(/sect1/caution[1])"/>
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229 |
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230 | </sect2>
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231 |
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232 | <sect2 role="content">
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233 | <title/>
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234 |
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235 | <para>Details on this package are located in
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236 | <xref linkend="contents-gcc" role="."/></para>
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237 |
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238 | </sect2>
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239 |
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240 | </sect1>
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