[3be4d97] | 1 | <sect1 id="ch-tools-gcc-pass2">
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[aafceef] | 2 | <title>Installing GCC-&gcc-version; - Pass 2</title>
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[bc82645e] | 3 | <?dbhtml filename="gcc-pass2.html" dir="chapter05"?>
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| 4 |
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[69276a94] | 5 | <screen>&buildtime; &gcc-time-tools-pass2;
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| 6 | &diskspace; &gcc-compsize-tools-pass2;</screen>
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[bc82645e] | 7 |
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[5888299] | 8 | &aa-gcc-down;
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| 9 | &aa-gcc-dep;
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[73aedd1d] | 10 |
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| 11 | <sect2><title> </title><para> </para></sect2>
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| 12 |
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| 13 | <sect2>
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| 14 | <title>Re-installation of GCC</title>
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| 15 |
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| 16 | <para>The tools required to test GCC and Binutils are installed now (Tcl, Expect
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| 17 | and DejaGnu). We can continue on rebuilding GCC and Binutils, link them against
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[443cace] | 18 | the new Glibc, and test them properly (if performing the test suites in this
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| 19 | chapter). One thing to note, however, is that these test suites are highly
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| 20 | dependent on properly functioning pseudo terminals (PTYs) which are provided by
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| 21 | your host distribution. These days, PTYs are most commonly implemented via the
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| 22 | <emphasis>devpts</emphasis> file system. You can quickly check if your host
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| 23 | system is set up correctly in this regard by performing a simple test:</para>
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[73aedd1d] | 24 |
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| 25 | <screen><userinput>expect -c "spawn ls"</userinput></screen>
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| 26 |
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| 27 | <para>If you receive the message:</para>
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| 28 |
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| 29 | <blockquote><screen>The system has no more ptys. Ask your system administrator to create more.</screen></blockquote>
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| 30 |
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| 31 | <para>Your host distribution is not set up for proper PTY operation. In this
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[daaa0941] | 32 | case there is no point in running the test suites for GCC and Binutils until
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| 33 | you are able to resolve the issue. You can consult the LFS Wiki at
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| 34 | <ulink url="&wiki-root;"/> for more information on how to get PTYs
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| 35 | working.</para>
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[73aedd1d] | 36 |
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[37dcf2a] | 37 | <para>This time we will build both the C and the C++ compilers, so you'll have
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| 38 | to unpack all three GCC tarballs (-core, -g++, and -testsuite) in one and the
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[73aedd1d] | 39 | same working directory. They will all unfold into a single
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[d962702] | 40 | <filename>&gcc-dir;/</filename> subdirectory.</para>
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[73aedd1d] | 41 |
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| 42 | <para>First correct one problem and make an essential adjustment:</para>
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| 43 |
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| 44 | <screen><userinput>patch -Np1 -i ../&gcc-nofixincludes-patch;
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| 45 | patch -Np1 -i ../&gcc-specs-patch;</userinput></screen>
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| 46 |
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[17476c5] | 47 | <para>The first patch disables the GCC "fixincludes" script. We mentioned this
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[73aedd1d] | 48 | briefly earlier, but a slightly more in-depth explanation of the fixincludes
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[17476c5] | 49 | process is warranted here. Under normal circumstances, the GCC fixincludes
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| 50 | script scans your system for header files that need to be fixed. It might find
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[73aedd1d] | 51 | that some Glibc header files on your host system need to be fixed, fix them and
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[17476c5] | 52 | put them in the GCC private include directory. Then, later on in
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[73aedd1d] | 53 | <xref linkend="chapter06"/>, after we've installed the newer Glibc, this
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| 54 | private include directory would be searched before the system include
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| 55 | directory, resulting in GCC finding the fixed headers from the host system,
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| 56 | which would most likely not match the Glibc version actually used for the LFS
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| 57 | system.</para>
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| 58 |
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| 59 | <para>The last patch changes GCC's default location of the dynamic linker
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| 60 | (typically <filename>ld-linux.so.2</filename>). It also removes
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| 61 | <filename class="directory">/usr/include</filename> from GCC's include search
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| 62 | path. Patching now rather than adjusting the specs file after installation
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| 63 | ensures that our new dynamic linker gets used during the actual build of GCC.
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| 64 | That is, all the final (and temporary) binaries created during the build will
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| 65 | link against the new Glibc.</para>
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| 66 |
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[f4993cf] | 67 | <important><para>The above patches are <emphasis>critical</emphasis> in ensuring
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| 68 | a successful overall build. Do not forget to apply them.</para></important>
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[73aedd1d] | 69 |
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| 70 | <para>Create a separate build directory again:</para>
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| 71 |
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| 72 | <screen><userinput>mkdir ../gcc-build
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| 73 | cd ../gcc-build</userinput></screen>
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| 74 |
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| 75 | <para>Before starting to build GCC, remember to unset any environment
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| 76 | variables that override the default optimization flags.</para>
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| 77 |
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[d27a27b] | 78 | <para>Now prepare GCC for compilation:</para>
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[73aedd1d] | 79 |
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[d962702] | 80 | <screen><userinput>../&gcc-dir;/configure --prefix=/tools \
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[73aedd1d] | 81 | --with-local-prefix=/tools \
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| 82 | --enable-clocale=gnu --enable-shared \
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| 83 | --enable-threads=posix --enable-__cxa_atexit \
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| 84 | --enable-languages=c,c++</userinput></screen>
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| 85 |
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| 86 | <para>The meaning of the new configure options:</para>
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| 87 |
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| 88 | <itemizedlist>
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| 89 | <listitem><para><userinput>--enable-threads=posix</userinput>: This enables
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| 90 | C++ exception handling for multi-threaded code.</para></listitem>
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| 91 |
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| 92 | <listitem><para><userinput>--enable-__cxa_atexit</userinput>: This option
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| 93 | allows use of __cxa_atexit, rather than atexit, to register C++ destructors for
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| 94 | local statics and global objects and is essential for fully standards-compliant
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| 95 | handling of destructors. It also affects the C++ ABI and therefore results in
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| 96 | C++ shared libraries and C++ programs that are interoperable with other Linux
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| 97 | distributions.</para></listitem>
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| 98 |
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| 99 | <listitem><para><userinput>--enable-clocale=gnu</userinput>: This option ensures
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| 100 | the correct locale model is selected for the C++ libraries under all
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| 101 | circumstances. If the configure script finds the <emphasis>de_DE</emphasis>
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| 102 | locale installed, it will select the correct model of <emphasis>gnu</emphasis>.
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| 103 | However, people who don't install the <emphasis>de_DE</emphasis> locale, run the
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| 104 | risk of building ABI incompatible C++ libraries due to the wrong locale model of
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| 105 | <emphasis>generic</emphasis> being selected.</para></listitem>
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| 106 |
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| 107 | <listitem><para><userinput>--enable-languages=c,c++</userinput>: This option is
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| 108 | needed to ensure that both C and C++ compilers are built.</para></listitem>
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| 109 | </itemizedlist>
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| 110 |
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| 111 | <para>Compile the package:</para>
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| 112 |
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| 113 | <screen><userinput>make</userinput></screen>
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| 114 |
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[90e3cb3] | 115 | <para>There is no need to use the <emphasis>bootstrap</emphasis> target now,
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[73aedd1d] | 116 | as the compiler we're using to compile this GCC was built from the exact same
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| 117 | version of the GCC sources we used earlier.</para>
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| 118 |
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[443cace] | 119 | <para>Compilation is now complete. As discussed earlier, we don't recommend
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| 120 | running the test suites for the temporary tools here in this chapter. If you
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| 121 | still want to run the GCC test suite anyway, the following command will do
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| 122 | so:</para>
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[73aedd1d] | 123 |
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| 124 | <screen><userinput>make -k check</userinput></screen>
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| 125 |
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[90e3cb3] | 126 | <para>The <emphasis>-k</emphasis> flag is used to make the test suite run
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[73aedd1d] | 127 | through to completion and not stop at the first failure. The GCC test suite is
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| 128 | very comprehensive and is almost guaranteed to generate a few failures. To get
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| 129 | a summary of the test suite results, run this:</para>
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| 130 |
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[d962702] | 131 | <screen><userinput>../&gcc-dir;/contrib/test_summary | more</userinput></screen>
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[73aedd1d] | 132 |
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| 133 | <para>You can compare your results to those posted to the gcc-testresults
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| 134 | mailing list for similar configurations to your own. For an example of how
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| 135 | current GCC-&gcc-version; should look on i686-pc-linux-gnu, see
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[e5888f5] | 136 | <ulink url="http://gcc.gnu.org/ml/gcc-testresults/2004-01/msg00826.html"/>.</para>
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[73aedd1d] | 137 |
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| 138 | <para>Note that the results contain:</para>
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| 139 |
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| 140 | <screen>* 1 XPASS (unexpected pass) for g++
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[bc827b39] | 141 | * 1 FAIL (unexpected failure) for gcc
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[e5888f5] | 142 | * 24 XPASS's for libstdc++</screen>
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[73aedd1d] | 143 |
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| 144 | <para>The unexpected pass for g++ is due to the use of
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[90e3cb3] | 145 | <emphasis>--enable-__cxa_atexit</emphasis>. Apparently not all platforms
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[73aedd1d] | 146 | supported by GCC have support for "__cxa_atexit" in their C libraries, so this
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| 147 | test is not always expected to pass.</para>
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| 148 |
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[e5888f5] | 149 | <para>The 24 unexpected passes for libstdc++ are due to the use of
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[90e3cb3] | 150 | <emphasis>--enable-clocale=gnu</emphasis>, which is the correct choice on
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[73aedd1d] | 151 | Glibc-based systems of versions 2.2.5 and above. The underlying locale support
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| 152 | in the GNU C library is superior to that of the otherwise selected "generic"
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| 153 | model (which may be applicable if for instance you were using Newlibc, Sun-libc
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| 154 | or whatever libc). The libstdc++ test suite is apparently expecting the
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| 155 | "generic" model, hence those tests are not always expected to pass.</para>
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| 156 |
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| 157 | <para>Unexpected failures often cannot be avoided. The GCC developers are
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| 158 | usually aware of them but haven't yet gotten around to fixing them. In short,
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| 159 | unless your results are vastly different from those at the above URL, it is safe
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| 160 | to continue on.</para>
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| 161 |
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[17476c5] | 162 | <para>And finally install the package:</para>
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[73aedd1d] | 163 |
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| 164 | <screen><userinput>make install</userinput></screen>
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| 165 |
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| 166 | <note><para>At this point it is strongly recommended to repeat the sanity check
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| 167 | we performed earlier in the chapter. Refer back to
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[3be4d97] | 168 | <xref linkend="ch-tools-locking-glibc"/> and repeat the check. If the results are
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[73aedd1d] | 169 | wrong, then most likely you forgot to apply the above mentioned GCC Specs
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| 170 | patch.</para></note>
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| 171 |
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| 172 | </sect2>
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[bc82645e] | 173 |
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[5888299] | 174 | <sect2><title> </title><para> </para>
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| 175 | <para>The details on this package are found in <xref linkend="contents-gcc"/>.</para>
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| 176 | <para> </para></sect2>
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| 177 |
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[bc82645e] | 178 | </sect1>
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| 179 |
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