[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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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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[1f7ca93] | 7 |
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[9652249] | 8 | <sect1 id="ch-tools-gcc-pass2" role="wrap">
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[1f7ca93] | 9 | <?dbhtml filename="gcc-pass2.html"?>
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| 10 |
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[e747759] | 11 | <sect1info condition="script">
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| 12 | <productname>gcc</productname>
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| 13 | <productnumber>&gcc-version;</productnumber>
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| 14 | <address>&gcc-url;</address>
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| 15 | </sect1info>
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| 16 |
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[1f7ca93] | 17 | <title>GCC-&gcc-version; - Pass 2</title>
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| 18 |
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| 19 | <indexterm zone="ch-tools-gcc-pass2">
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| 20 | <primary sortas="a-GCC">GCC</primary>
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| 21 | <secondary>tools, pass 2</secondary>
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| 22 | </indexterm>
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| 23 |
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| 24 | <sect2 role="package">
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| 25 | <title/>
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[bc82645e] | 26 |
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[d9441360] | 27 | <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
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[1f7ca93] | 28 | href="../chapter06/gcc.xml"
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| 29 | xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
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[81fd230] | 30 |
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[1f7ca93] | 31 | <segmentedlist>
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| 32 | <segtitle>&buildtime;</segtitle>
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| 33 | <segtitle>&diskspace;</segtitle>
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[73aedd1d] | 34 |
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[1f7ca93] | 35 | <seglistitem>
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[e4a5635] | 36 | <seg>&gcc-ch5p2-sbu;</seg>
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| 37 | <seg>&gcc-ch5p2-du;</seg>
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[1f7ca93] | 38 | </seglistitem>
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| 39 | </segmentedlist>
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[73aedd1d] | 40 |
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[1f7ca93] | 41 | </sect2>
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[9652249] | 42 |
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[1f7ca93] | 43 | <sect2 role="installation">
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[4e82d47] | 44 | <title>Installation of GCC</title>
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[73aedd1d] | 45 |
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[4e82d47] | 46 | <para>Versions of GCC later than 4.3 will treat this build as if
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| 47 | it were a relocated compiler and disallow searching for startfiles in
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| 48 | the location specified by <parameter>--prefix</parameter>. Since this
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| 49 | will not be a relocated compiler, and the startfiles in
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| 50 | <filename class="directory">/tools</filename> are crucial to building
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| 51 | a working compiler linked to the libs in <filename class="directory">/tools</filename>,
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| 52 | apply the following patch which partially reverts GCC to its old behavior:</para>
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[73aedd1d] | 53 |
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[4e82d47] | 54 | <screen><userinput remap="pre">patch -Np1 -i ../&gcc-startfiles-patch;</userinput></screen>
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[73aedd1d] | 55 |
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[4e82d47] | 56 | <para>Under normal circumstances the GCC <command>fixincludes</command> script
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[1f7ca93] | 57 | is run in order to fix potentially broken header files. As GCC-&gcc-version;
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| 58 | and Glibc-&glibc-version; have already been installed at this point, and
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| 59 | their respective header files are known to not require fixing, the
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[550f9f4] | 60 | <command>fixincludes</command> script is not required. In fact, running
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| 61 | this script may actually pollute the build environment by
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[1f7ca93] | 62 | installing fixed headers from the host system into GCC's private include
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| 63 | directory. The running of the <command>fixincludes</command> script can
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| 64 | be suppressed by issuing the following commands:</para>
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[2e02c35] | 65 |
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[0445a3d] | 66 | <screen><userinput remap="pre">cp -v gcc/Makefile.in{,.orig}
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[27ced84] | 67 | sed 's@\./fixinc\.sh@-c true@' gcc/Makefile.in.orig > gcc/Makefile.in</userinput></screen>
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[2e02c35] | 68 |
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[07312f6] | 69 | <para>For x86 machines, a bootstrap build of GCC uses the
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| 70 | <option>-fomit-frame-pointer</option> compiler flag. Non-bootstrap builds
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| 71 | omit this flag by default, and the goal should be to produce a compiler
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| 72 | that is exactly the same as if it were bootstrapped. Apply the following
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| 73 | <command>sed</command> command to force the build to use the flag:</para>
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[2e02c35] | 74 |
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[0445a3d] | 75 | <screen><userinput remap="pre">cp -v gcc/Makefile.in{,.tmp}
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[d35b7f3] | 76 | sed 's/^T_CFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in.tmp \
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[1f7ca93] | 77 | > gcc/Makefile.in</userinput></screen>
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[2e02c35] | 78 |
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[b0a4c9a] | 79 | <para>The following command will change the location of GCC's default
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[4e82d47] | 80 | dynamic linker to use the one installed in
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[b0a4c9a] | 81 | <filename class="directory">/tools</filename>. It also removes <filename
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[1f7ca93] | 82 | class="directory">/usr/include</filename> from GCC's include search path.
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[b0a4c9a] | 83 | Doing this now rather than adjusting the specs file after installation
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[1f7ca93] | 84 | ensures that the new dynamic linker is used during the actual build of
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| 85 | GCC. That is, all of the binaries created during the build will link
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[b0a4c9a] | 86 | against the new Glibc. Issue:</para>
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| 87 |
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[6e88633] | 88 | <screen><userinput remap="pre">for file in \
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| 89 | $(find gcc/config -name linux64.h -o -name linux.h -o -name sysv4.h)
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[b0a4c9a] | 90 | do
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| 91 | cp -uv $file{,.orig}
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| 92 | sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \
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| 93 | -e 's@/usr@/tools@g' $file.orig > $file
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[4e82d47] | 94 | echo '
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[b0a4c9a] | 95 | #undef STANDARD_INCLUDE_DIR
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[4e82d47] | 96 | #define STANDARD_INCLUDE_DIR 0
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| 97 | #define STANDARD_STARTFILE_PREFIX_1 ""
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| 98 | #define STANDARD_STARTFILE_PREFIX_2 ""' >> $file
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[b0a4c9a] | 99 | touch $file.orig
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| 100 | done</userinput></screen>
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| 101 |
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| 102 | <para>In case the above seems hard to follow, let's break it down a bit.
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[5f7456b] | 103 | First we find all the files under the
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| 104 | <filename class="directory">gcc/config</filename> directory that are named
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[6e88633] | 105 | either <filename>linux.h</filename>, <filename>linux64.h</filename> or
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| 106 | <filename>sysv4.h</filename>.
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[b0a4c9a] | 107 | For each file found, we copy it to a file of the same name but with an added
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| 108 | suffix of <quote>.orig</quote>. Then the first sed expression prepends
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| 109 | <quote>/tools</quote> to every instance of <quote>/lib/ld</quote>,
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| 110 | <quote>/lib64/ld</quote> or <quote>/lib32/ld</quote>, while the second one
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| 111 | replaces hard-coded instances of <quote>/usr</quote>. Then we add our define
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[4e82d47] | 112 | statements which alter the include search path and the default startfile prefix
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| 113 | to the end of the file.
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| 114 | Finally, we use <command>touch</command> to update the timestamp on the copied files.
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[b0a4c9a] | 115 | When used in conjunction with <command>cp -u</command>, this prevents unexpected
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[5f7456b] | 116 | changes to the original files in case the commands are inadvertently run twice.
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[b0a4c9a] | 117 | </para>
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[81fd230] | 118 |
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[55fa5a3] | 119 | <para>On x86_64, unsetting the multilib spec for GCC ensures that it
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[6e88633] | 120 | won't attempt to link against libraries on the host:</para>
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| 121 |
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[4e82d47] | 122 | <screen><userinput remap="pre">case $(uname -m) in
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| 123 | x86_64)
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| 124 | 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
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| 128 | ;;
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| 129 | esac</userinput></screen>
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[6e88633] | 130 |
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[4916842] | 131 | <para>As in the first build of GCC it requires the GMP, MPFR and MPC
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| 132 | packages. Unpack the tarballs and move them into the required directory
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| 133 | names:</para>
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[c49647b1] | 134 |
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| 135 | <screen><userinput remap="pre">tar -jxf ../mpfr-&mpfr-version;.tar.bz2
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[e311865] | 136 | mv -v mpfr-&mpfr-version; mpfr
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[c49647b1] | 137 | tar -jxf ../gmp-&gmp-version;.tar.bz2
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[4916842] | 138 | mv -v gmp-&gmp-version; gmp
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| 139 | tar -zxf ../mpc-&mpc-version;.tar.gz
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| 140 | mv -v mpc-&mpc-version; mpc</userinput></screen>
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[c49647b1] | 141 |
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[1f7ca93] | 142 | <para>Create a separate build directory again:</para>
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[73aedd1d] | 143 |
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[0445a3d] | 144 | <screen><userinput remap="pre">mkdir -v ../gcc-build
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[73aedd1d] | 145 | cd ../gcc-build</userinput></screen>
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| 146 |
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[1f7ca93] | 147 | <para>Before starting to build GCC, remember to unset any environment
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| 148 | variables that override the default optimization flags.</para>
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[81fd230] | 149 |
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[1f7ca93] | 150 | <para>Now prepare GCC for compilation:</para>
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[73aedd1d] | 151 |
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[4e82d47] | 152 | <screen><userinput remap="configure">CC="$LFS_TGT-gcc -B/tools/lib/" \
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| 153 | AR=$LFS_TGT-ar RANLIB=$LFS_TGT-ranlib \
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| 154 | ../gcc-&gcc-version;/configure --prefix=/tools \
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[f684ec6c] | 155 | --with-local-prefix=/tools --enable-clocale=gnu \
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| 156 | --enable-shared --enable-threads=posix \
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| 157 | --enable-__cxa_atexit --enable-languages=c,c++ \
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[6e88633] | 158 | --disable-libstdcxx-pch --disable-multilib \
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[bd7123b] | 159 | --disable-bootstrap --disable-libgomp \
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[6123afe] | 160 | --with-gmp-include=$(pwd)/gmp --with-gmp-lib=$(pwd)/gmp/.libs \
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| 161 | --without-ppl --without-cloog</userinput></screen>
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[73aedd1d] | 162 |
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[1f7ca93] | 163 | <variablelist>
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| 164 | <title>The meaning of the new configure options:</title>
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| 165 |
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| 166 | <varlistentry>
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| 167 | <term><parameter>--enable-clocale=gnu</parameter></term>
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| 168 | <listitem>
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| 169 | <para>This option ensures the correct locale model is selected
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| 170 | for the C++ libraries under all circumstances. If the configure
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| 171 | script finds the <emphasis>de_DE</emphasis> locale installed,
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| 172 | it will select the correct gnu locale model. However, if the
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| 173 | <emphasis>de_DE</emphasis> locale is not installed, there is the
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| 174 | risk of building Application Binary Interface (ABI)-incompatible
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| 175 | C++ libraries because the incorrect generic locale model may be
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| 176 | selected.</para>
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| 177 | </listitem>
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| 178 | </varlistentry>
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| 179 |
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| 180 | <varlistentry>
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| 181 | <term><parameter>--enable-threads=posix</parameter></term>
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| 182 | <listitem>
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| 183 | <para>This enables C++ exception handling for multi-threaded code.</para>
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| 184 | </listitem>
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| 185 | </varlistentry>
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| 186 |
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| 187 | <varlistentry>
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| 188 | <term><parameter>--enable-__cxa_atexit</parameter></term>
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| 189 | <listitem>
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| 190 | <para>This option allows use of <function>__cxa_atexit</function>,
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| 191 | rather than <function>atexit</function>, to register C++ destructors
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| 192 | for local statics and global objects. This option is essential for
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| 193 | fully standards-compliant handling of destructors. It also affects
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| 194 | the C++ ABI, and therefore results in C++ shared libraries and C++
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| 195 | programs that are interoperable with other Linux distributions.</para>
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| 196 | </listitem>
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| 197 | </varlistentry>
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| 198 |
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| 199 | <varlistentry>
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| 200 | <term><parameter>--enable-languages=c,c++</parameter></term>
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| 201 | <listitem>
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| 202 | <para>This option ensures that both the C and C++ compilers are
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| 203 | built.</para>
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| 204 | </listitem>
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| 205 | </varlistentry>
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| 206 |
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| 207 | <varlistentry>
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| 208 | <term><parameter>--disable-libstdcxx-pch</parameter></term>
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| 209 | <listitem>
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| 210 | <para>Do not build the pre-compiled header (PCH) for
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| 211 | <filename class="libraryfile">libstdc++</filename>. It takes up a
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| 212 | lot of space, and we have no use for it.</para>
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| 213 | </listitem>
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| 214 | </varlistentry>
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| 215 |
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[b0a4c9a] | 216 | <varlistentry>
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| 217 | <term><parameter>--disable-bootstrap</parameter></term>
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| 218 | <listitem>
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[fe6ca49] | 219 | <para>For native builds of GCC, the default is to do a "bootstrap"
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| 220 | build. This does not just compile GCC, but compiles it several times.
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| 221 | It uses the programs compiled in a first round to compile itself a
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[07312f6] | 222 | second time, and then again a third time. The second and third
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| 223 | iterations are compared to make sure it can reproduce itself
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| 224 | flawlessly. This also implies that it was compiled correctly.
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| 225 | However, the LFS build method should provide a solid compiler
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| 226 | without the need to bootstrap each time.</para>
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[b0a4c9a] | 227 | </listitem>
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| 228 | </varlistentry>
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| 229 |
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[1f7ca93] | 230 | </variablelist>
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| 231 |
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| 232 | <para>Compile the package:</para>
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[73aedd1d] | 233 |
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[bd7123b] | 234 | <screen><userinput remap="make">make</userinput></screen>
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[73aedd1d] | 235 |
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[1f7ca93] | 236 | <para>Install the package:</para>
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[73aedd1d] | 237 |
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[0445a3d] | 238 | <screen><userinput remap="install">make install</userinput></screen>
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[73aedd1d] | 239 |
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[4e82d47] | 240 | <para>As a finishing touch, create a symlink. Many programs and scripts
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| 241 | run <command>cc</command> instead of <command>gcc</command>, which is
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| 242 | used to keep programs generic and therefore usable on all kinds of UNIX
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| 243 | systems where the GNU C compiler is not always installed. Running
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| 244 | <command>cc</command> leaves the system administrator free to decide
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| 245 | which C compiler to install:</para>
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| 246 |
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| 247 | <screen><userinput remap="install">ln -vs gcc /tools/bin/cc</userinput></screen>
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| 248 |
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| 249 | <caution>
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| 250 | <para>At this point, it is imperative to stop and ensure that the basic
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| 251 | functions (compiling and linking) of the new toolchain are working as
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| 252 | expected. To perform a sanity check, run the following commands:</para>
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| 253 |
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| 254 | <screen><userinput>echo 'main(){}' > dummy.c
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| 255 | cc dummy.c
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| 256 | readelf -l a.out | grep ': /tools'</userinput></screen>
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| 257 |
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| 258 | <para>If everything is working correctly, there should be no errors,
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| 259 | and the output of the last command will be of the form:</para>
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| 260 |
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[dc96e56] | 261 | <screen><computeroutput>[Requesting program interpreter: /tools/lib/ld-linux.so.2]</computeroutput></screen>
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[4e82d47] | 262 |
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| 263 | <para>Note that <filename class="directory">/tools/lib</filename>, or
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| 264 | <filename class="directory">/tools/lib64</filename> for 64-bit machines
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| 265 | appears as the prefix of the dynamic linker.</para>
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| 266 |
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| 267 | <para>If the output is not shown as above or there was no output at all,
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| 268 | then something is wrong. Investigate and retrace the steps to find out
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| 269 | where the problem is and correct it. This issue must be resolved before
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| 270 | continuing on. First, perform the sanity check again, using
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| 271 | <command>gcc</command> instead of <command>cc</command>. If this works,
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| 272 | then the <filename class="symlink">/tools/bin/cc</filename> symlink is
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| 273 | missing. Install the symlink as per above.
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| 274 | Next, ensure that the <envar>PATH</envar> is correct. This
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| 275 | can be checked by running <command>echo $PATH</command> and verifying that
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| 276 | <filename class="directory">/tools/bin</filename> is at the head of the
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| 277 | list. If the <envar>PATH</envar> is wrong it could mean that you are not
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| 278 | logged in as user <systemitem class="username">lfs</systemitem> or that
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| 279 | something went wrong back in <xref linkend="ch-tools-settingenviron"
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| 280 | role="."/></para>
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| 281 |
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| 282 | <para>Once all is well, clean up the test files:</para>
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| 283 |
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| 284 | <screen><userinput>rm -v dummy.c a.out</userinput></screen>
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| 285 |
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| 286 | </caution>
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[73aedd1d] | 287 |
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[1f7ca93] | 288 | </sect2>
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[bc82645e] | 289 |
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[1f7ca93] | 290 | <sect2 role="content">
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| 291 | <title/>
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[81fd230] | 292 |
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[1f7ca93] | 293 | <para>Details on this package are located in
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| 294 | <xref linkend="contents-gcc" role="."/></para>
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[81fd230] | 295 |
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[1f7ca93] | 296 | </sect2>
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| 297 |
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| 298 | </sect1>
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