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132 lines
6.2 KiB
XML
132 lines
6.2 KiB
XML
<sect2><title> </title><para> </para></sect2>
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<sect2>
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<title>Re-installation of GCC</title>
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<para>The tools required to test GCC and Binutils are installed now (Tcl, Expect
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and DejaGnu). We can continue on rebuilding GCC and Binutils, link them against
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the new Glibc, and test them properly. One thing to note, however, is that these
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test suites are highly dependent on properly functioning pseudo terminals (PTYs)
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which are provided by your host distribution. These days, PTYs are most commonly
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implemented via the <emphasis>devpts</emphasis> file system. You can quickly
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check if your host system is set up correctly in this regard by performing a
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simple test:</para>
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<para><screen><userinput>expect -c "spawn ls"</userinput></screen></para>
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<para>If you receive the message:</para>
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<para><screen>The system has no more ptys. Ask your system administrator to create more.</screen></para>
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<para>Your host distribution is not set up for proper PTY operation. In this
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case there is no point in running the test suites for GCC and Binutils until you
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are able to resolve the issue. You can consult the LFS Wiki at
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<ulink url="http://wiki.linuxfromscratch.org"/> for more information on how to
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get PTYs working.</para>
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<note><para>It's worth pointing out that the GCC test suite we run in this
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section is considered not as important as the one we run in Chapter 6.</para></note>
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<para>Unpack all three GCC tarballs (-core, -g++, and -testsuite) in one and the same working directory.
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They will all unfold into a single <filename>gcc-&gcc-version;/</filename>
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subdir.</para>
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<para>First correct one problem and make an essential adjustment:</para>
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<para><screen><userinput>patch -Np1 -i ../gcc-&gcc-version;-no_fixincludes-2.patch
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patch -Np1 -i ../gcc-&gcc-specs-version;.patch</userinput></screen></para>
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<para>The first patch disables the GCC "fixincludes" script. We mentioned this
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briefly earlier, but a slightly more in-depth explanation of the fixincludes
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process is warranted here. Under normal circumstances, the GCC fixincludes
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script scans your system for header files that need to be fixed. It might find
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that the Glibc header files on your host system need to be fixed, fix them and
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put them in the GCC private include directory. Then, later on in Chapter 6,
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after we've installed the newer Glibc, this private include directory would be
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searched before the system include directory, resulting in GCC finding the
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fixed headers from the host system, which would most likely not match the Glibc
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version actually used for the LFS system.</para>
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<para>The last patch changes GCC's default location of the dynamic linker
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(typically <filename>ld-linux.so.2</filename>). It also removes
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<filename class="directory">/usr/include</filename> from GCC's include search
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path. Patching now rather than adjusting the specs file after installation
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ensures that our new dynamic linker gets used during the actual build of GCC.
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That is, all the final (and temporary) binaries created during the build will
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link against the new Glibc.</para>
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<important><para>These patches are <emphasis>critical</emphasis> in ensuring a
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successful overall build. Do not forget to apply them.</para></important>
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<para>Create a separate build directory again:</para>
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<para><screen><userinput>mkdir ../gcc-build
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cd ../gcc-build</userinput></screen></para>
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<para>Before starting to build GCC, remember to unset any environment
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variables that override the default optimization flags.</para>
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<para>Now prepare GCC to be compiled:</para>
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<para><screen><userinput>../gcc-&gcc-version;/configure --prefix=/tools \
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--with-local-prefix=/tools \
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--enable-clocale=gnu --enable-shared \
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--enable-threads=posix --enable-__cxa_atexit \
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--enable-languages=c,c++</userinput></screen></para>
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<para>Compile the package:</para>
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<para><screen><userinput>make</userinput></screen></para>
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<para>There is no need to use the <userinput>bootstrap</userinput> target now,
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as the compiler we're using to compile this GCC was built from the exact same
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version of the GCC sources we used earlier.</para>
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<note><para>At this point it is strongly recommended to repeat the sanity check
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we performed earlier in the chapter. Refer back to the "Locking in" Glibc section
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and repeat the check. If the results are wrong then most likely, you forgot to
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apply the abovementioned GCC Specs patch.</para></note>
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<para>Test the results:</para>
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<para><screen><userinput>make -k check</userinput></screen></para>
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<para>The <userinput>-k</userinput> flag is used to make the test suite run
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through to completion and not stop at the first failure. The GCC test suite is
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very comprehensive and is almost guaranteed to generate a few failures. To get
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a summary of the test suite results, run this:</para>
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<para><screen><userinput>../gcc-&gcc-version;/contrib/test_summary | less</userinput></screen></para>
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<para>You can compare your results to those posted to the gcc-testresults
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mailing list for similar configurations to your own. For an example of how
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current GCC-3.3.1 should look on i686-pc-linux-gnu, see
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<ulink url="http://gcc.gnu.org/ml/gcc-testresults/2003-08/msg01612.html"/>.</para>
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<para>Note that the results contain:</para>
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<screen>* 1 XPASS (unexpected pass) for g++
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* 1 FAIL for g++
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* 2 FAIL for gcc
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* 26 XPASS's for libstdc++</screen>
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<para>The unexpected pass for g++ is due to the use of
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<userinput>--enable-__cxa_atexit</userinput>. Apparently not all platforms
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supported by GCC have support for "__cxa_atexit" in their C libraries, so this
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test is not always expected to pass.</para>
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<para>The 26 unexpected passes for libstdc++ are due to the use of
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<userinput>--enable-clocale=gnu</userinput>, which is the correct choice on
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Glibc-based systems of versions 2.2.5 and above. The underlying locale support
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in the GNU C library is superior to that of the otherwise selected "generic"
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model (which may be applicable if for instance you were using Newlibc, Sun-libc
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or whatever libc). The libstdc++ test suite is apparently expecting the
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"generic" model, hence those tests are not always expected to pass.</para>
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<para>And finally install the package:</para>
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<para><screen><userinput>make install</userinput></screen></para>
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</sect2>
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