[bc82645e] | 1 | <sect2><title> </title><para> </para></sect2>
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| 2 |
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| 3 | <sect2>
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[ab6f1859] | 4 | <title>Re-installation of GCC</title>
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| 5 |
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[990ba6b] | 6 | <para>The tools required to test GCC and Binutils are installed now (Tcl, Expect
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| 7 | and DejaGnu). We can continue on rebuilding GCC and Binutils, link them against
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| 8 | the new Glibc, and test them properly. One thing to note, however, is that these
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| 9 | test suites are highly dependent on properly functioning pseudo terminals (PTYs)
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| 10 | which are provided by your host distribution. These days, PTYs are most commonly
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| 11 | implemented via the <emphasis>devpts</emphasis> file system. You can quickly
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| 12 | check if your host system is set up correctly in this regard by performing a
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| 13 | simple test:</para>
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| 14 |
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| 15 | <para><screen><userinput>expect -c "spawn ls"</userinput></screen></para>
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| 16 |
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| 17 | <para>If you receive the message:</para>
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| 18 |
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| 19 | <para><screen>The system has no more ptys. Ask your system administrator to create more.</screen></para>
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| 20 |
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| 21 | <para>Your host distribution is not set up for proper PTY operation. In this
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| 22 | case there is no point in running the test suites for GCC and Binutils until you
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| 23 | are able to resolve the issue. You can consult the LFS Wiki at
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| 24 | <ulink url="http://wiki.linuxfromscratch.org"/> for more information on how to
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| 25 | get PTYs working.</para>
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[62d0130] | 26 |
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[297d8ee0] | 27 | <note><para>It's worth pointing out that the GCC test suite we run in this
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[ccaabde] | 28 | section is considered not as important as the one we run in Chapter 6.</para></note>
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[1f53626] | 29 |
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[aa49729] | 30 | <para>Unpack all three GCC tarballs (-core, -g++, and -testsuite) in one and the
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| 31 | same working directory. They will all unfold into a single
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| 32 | <filename>gcc-&gcc-version;/</filename> subdirectory.</para>
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[bc82645e] | 33 |
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[40b88c2] | 34 | <para>First correct one problem and make an essential adjustment:</para>
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[775a268] | 35 |
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[b19d5f96] | 36 | <para><screen><userinput>patch -Np1 -i ../gcc-&gcc-version;-no_fixincludes-2.patch
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[775a268] | 37 | patch -Np1 -i ../gcc-&gcc-specs-version;.patch</userinput></screen></para>
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| 38 |
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[be2dd91] | 39 | <para>The first patch disables the GCC "fixincludes" script. We mentioned this
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| 40 | briefly earlier, but a slightly more in-depth explanation of the fixincludes
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| 41 | process is warranted here. Under normal circumstances, the GCC fixincludes
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| 42 | script scans your system for header files that need to be fixed. It might find
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[1cb7ced] | 43 | that some Glibc header files on your host system need to be fixed, fix them and
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[be2dd91] | 44 | put them in the GCC private include directory. Then, later on in Chapter 6,
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| 45 | after we've installed the newer Glibc, this private include directory would be
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| 46 | searched before the system include directory, resulting in GCC finding the
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| 47 | fixed headers from the host system, which would most likely not match the Glibc
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| 48 | version actually used for the LFS system.</para>
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| 49 |
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[dc19fb6] | 50 | <para>The last patch changes GCC's default location of the dynamic linker
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[76d113f] | 51 | (typically <filename>ld-linux.so.2</filename>). It also removes
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| 52 | <filename class="directory">/usr/include</filename> from GCC's include search
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| 53 | path. Patching now rather than adjusting the specs file after installation
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| 54 | ensures that our new dynamic linker gets used during the actual build of GCC.
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| 55 | That is, all the final (and temporary) binaries created during the build will
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| 56 | link against the new Glibc.</para>
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| 57 |
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| 58 | <important><para>These patches are <emphasis>critical</emphasis> in ensuring a
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| 59 | successful overall build. Do not forget to apply them.</para></important>
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[775a268] | 60 |
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| 61 | <para>Create a separate build directory again:</para>
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[bc82645e] | 62 |
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| 63 | <para><screen><userinput>mkdir ../gcc-build
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| 64 | cd ../gcc-build</userinput></screen></para>
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| 65 |
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[ab6f1859] | 66 | <para>Before starting to build GCC, remember to unset any environment
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| 67 | variables that override the default optimization flags.</para>
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| 68 |
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[775a268] | 69 | <para>Now prepare GCC to be compiled:</para>
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| 70 |
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[148bb04] | 71 | <para><screen><userinput>../gcc-&gcc-version;/configure --prefix=/tools \
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| 72 | --with-local-prefix=/tools \
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[6b2f69c] | 73 | --enable-clocale=gnu --enable-shared \
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[0939e573] | 74 | --enable-threads=posix --enable-__cxa_atexit \
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[775a268] | 75 | --enable-languages=c,c++</userinput></screen></para>
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| 76 |
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[aa49729] | 77 | <para>The meaning of the new configure options:</para>
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| 78 |
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| 79 | <itemizedlist>
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| 80 | <listitem><para><userinput>--enable-threads=posix</userinput>: This enables
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| 81 | C++ exception handling for multi-threaded code.</para></listitem>
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| 82 |
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| 83 | <listitem><para><userinput>--enable-__cxa_atexit</userinput>: This option
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| 84 | allows use of __cxa_atexit, rather than atexit, to register C++ destructors for
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| 85 | local statics and global objects and is essential for fully standards-compliant
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| 86 | handling of destructors. It also affects the C++ ABI and therefore results in
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| 87 | C++ shared libraries and C++ programs that are interoperable with other Linux
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| 88 | distributions.</para></listitem>
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| 89 |
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| 90 | <listitem><para><userinput>--enable-clocale=gnu</userinput>: This option ensures
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| 91 | the correct locale model is selected for the C++ libraries under all
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| 92 | circumstances. If the configure script finds the <emphasis>de_DE</emphasis>
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| 93 | locale installed, it will select the correct model of <emphasis>gnu</emphasis>.
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| 94 | However, people who don't install the <emphasis>de_DE</emphasis> locale, run the
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| 95 | risk of building ABI incompatible C++ libraries due to the wrong locale model of
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| 96 | <emphasis>generic</emphasis> being selected.</para></listitem>
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| 97 |
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| 98 | <listitem><para><userinput>--enable-languages=c,c++</userinput>: This option is
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| 99 | needed to ensure that both C and C++ compilers are built.</para></listitem>
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| 100 | </itemizedlist>
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| 101 |
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[775a268] | 102 | <para>Compile the package:</para>
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| 103 |
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| 104 | <para><screen><userinput>make</userinput></screen></para>
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[ccaabde] | 105 |
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[775a268] | 106 | <para>There is no need to use the <userinput>bootstrap</userinput> target now,
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[ccaabde] | 107 | as the compiler we're using to compile this GCC was built from the exact same
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| 108 | version of the GCC sources we used earlier.</para>
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| 109 |
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| 110 | <note><para>At this point it is strongly recommended to repeat the sanity check
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| 111 | we performed earlier in the chapter. Refer back to the "Locking in" Glibc section
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| 112 | and repeat the check. If the results are wrong then most likely, you forgot to
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| 113 | apply the abovementioned GCC Specs patch.</para></note>
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[775a268] | 114 |
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[ab6f1859] | 115 | <para>Test the results:</para>
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[775a268] | 116 |
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| 117 | <para><screen><userinput>make -k check</userinput></screen></para>
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| 118 |
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| 119 | <para>The <userinput>-k</userinput> flag is used to make the test suite run
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| 120 | through to completion and not stop at the first failure. The GCC test suite is
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| 121 | very comprehensive and is almost guaranteed to generate a few failures. To get
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| 122 | a summary of the test suite results, run this:</para>
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| 123 |
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[0b5fd844] | 124 | <para><screen><userinput>../gcc-&gcc-version;/contrib/test_summary | less</userinput></screen></para>
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[775a268] | 125 |
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| 126 | <para>You can compare your results to those posted to the gcc-testresults
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| 127 | mailing list for similar configurations to your own. For an example of how
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[bef49bf] | 128 | current GCC-3.3.1 should look on i686-pc-linux-gnu, see
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| 129 | <ulink url="http://gcc.gnu.org/ml/gcc-testresults/2003-08/msg01612.html"/>.</para>
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[775a268] | 130 |
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| 131 | <para>Note that the results contain:</para>
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| 132 |
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| 133 | <screen>* 1 XPASS (unexpected pass) for g++
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[9e24a7d] | 134 | * 1 FAIL for g++
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| 135 | * 2 FAIL for gcc
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| 136 | * 26 XPASS's for libstdc++</screen>
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[775a268] | 137 |
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| 138 | <para>The unexpected pass for g++ is due to the use of
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| 139 | <userinput>--enable-__cxa_atexit</userinput>. Apparently not all platforms
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| 140 | supported by GCC have support for "__cxa_atexit" in their C libraries, so this
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| 141 | test is not always expected to pass.</para>
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| 142 |
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| 143 | <para>The 26 unexpected passes for libstdc++ are due to the use of
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| 144 | <userinput>--enable-clocale=gnu</userinput>, which is the correct choice on
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| 145 | Glibc-based systems of versions 2.2.5 and above. The underlying locale support
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| 146 | in the GNU C library is superior to that of the otherwise selected "generic"
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| 147 | model (which may be applicable if for instance you were using Newlibc, Sun-libc
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| 148 | or whatever libc). The libstdc++ test suite is apparently expecting the
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| 149 | "generic" model, hence those tests are not always expected to pass.</para>
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| 150 |
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| 151 | <para>And finally install the package:</para>
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| 152 |
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| 153 | <para><screen><userinput>make install</userinput></screen></para>
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[bc82645e] | 154 |
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| 155 | </sect2>
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| 156 |
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