Ignore:
Timestamp:
11/01/2003 10:31:50 PM (21 years ago)
Author:
Alex Gronenwoud <alex@…>
Branches:
10.0, 10.0-rc1, 10.1, 10.1-rc1, 11.0, 11.0-rc1, 11.0-rc2, 11.0-rc3, 11.1, 11.1-rc1, 11.2, 11.2-rc1, 11.3, 11.3-rc1, 12.0, 12.0-rc1, 12.1, 12.1-rc1, 6.0, 6.1, 6.1.1, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.5-systemd, 7.6, 7.6-systemd, 7.7, 7.7-systemd, 7.8, 7.8-systemd, 7.9, 7.9-systemd, 8.0, 8.1, 8.2, 8.3, 8.4, 9.0, 9.1, arm, bdubbs/gcc13, ml-11.0, multilib, renodr/libudev-from-systemd, s6-init, trunk, v5_0, v5_1, v5_1_1, xry111/arm64, xry111/arm64-12.0, xry111/clfs-ng, xry111/lfs-next, xry111/loongarch, xry111/loongarch-12.0, xry111/loongarch-12.1, xry111/mips64el, xry111/pip3, xry111/rust-wip-20221008, xry111/update-glibc
Children:
49f4dd5
Parents:
0b400add
Message:

Merging caption and installation sections for all packages in chapters 5 and 6.

git-svn-id: ​http://svn.linuxfromscratch.org/LFS/trunk/BOOK@3052 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

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  • chapter05/gcc-pass2.xml

    r0b400add r73aedd1d  
    66Estimated required disk space:  &gcc-compsize-tools-pass2;</screen>
    77
    8 &c5-gcc-pass2-inst;
     8
     9<sect2><title>&nbsp;</title><para>&nbsp;</para></sect2>
     10
     11<sect2>
     12<title>Re-installation of GCC</title>
     13
     14<para>The tools required to test GCC and Binutils are installed now (Tcl, Expect
     15and DejaGnu). We can continue on rebuilding GCC and Binutils, link them against
     16the new Glibc, and test them properly. One thing to note, however, is that these
     17test suites are highly dependent on properly functioning pseudo terminals (PTYs)
     18which are provided by your host distribution. These days, PTYs are most commonly
     19implemented via the <emphasis>devpts</emphasis> file system. You can quickly
     20check if your host system is set up correctly in this regard by performing a
     21simple test:</para>
     22
     23<screen><userinput>expect -c "spawn ls"</userinput></screen>
     24
     25<para>If you receive the message:</para>
     26
     27<blockquote><screen>The system has no more ptys.  Ask your system administrator to create more.</screen></blockquote>
     28
     29<para>Your host distribution is not set up for proper PTY operation. In this
     30case there is no point in running the test suites for GCC and Binutils until you
     31are able to resolve the issue. You can consult the LFS Wiki at
     32<ulink url="http://wiki.linuxfromscratch.org/"/> for more information on how to
     33get PTYs working.</para>
     34
     35<para>Unpack all three GCC tarballs (-core, -g++, and -testsuite) in one and the
     36same working directory. They will all unfold into a single
     37<filename>gcc-&gcc-version;/</filename> subdirectory.</para>
     38
     39<para>First correct one problem and make an essential adjustment:</para>
     40
     41<screen><userinput>patch -Np1 -i ../&gcc-nofixincludes-patch;
     42patch -Np1 -i ../&gcc-specs-patch;</userinput></screen>
     43
     44<para>The first patch disables the GCC "fixincludes" script.  We mentioned this
     45briefly earlier, but a slightly more in-depth explanation of the fixincludes
     46process is warranted here.  Under normal circumstances, the GCC fixincludes
     47script scans your system for header files that need to be fixed.  It might find
     48that some Glibc header files on your host system need to be fixed, fix them and
     49put them in the GCC private include directory.  Then, later on in
     50<xref linkend="chapter06"/>, after we've installed the newer Glibc, this
     51private include directory would be searched before the system include
     52directory, resulting in GCC finding the fixed headers from the host system,
     53which would most likely not match the Glibc version actually used for the LFS
     54system.</para>
     55
     56<para>The last patch changes GCC's default location of the dynamic linker
     57(typically <filename>ld-linux.so.2</filename>). It also removes
     58<filename class="directory">/usr/include</filename> from GCC's include search
     59path. Patching now rather than adjusting the specs file after installation
     60ensures that our new dynamic linker gets used during the actual build of GCC.
     61That is, all the final (and temporary) binaries created during the build will
     62link against the new Glibc.</para>
     63
     64<important><para>These patches are <emphasis>critical</emphasis> in ensuring a
     65successful overall build. Do not forget to apply them.</para></important>
     66
     67<para>Create a separate build directory again:</para>
     68
     69<screen><userinput>mkdir ../gcc-build
     70cd ../gcc-build</userinput></screen>
     71
     72<para>Before starting to build GCC, remember to unset any environment
     73variables that override the default optimization flags.</para>
     74
     75<para>Now prepare GCC to be compiled:</para>
     76
     77<screen><userinput>../gcc-&gcc-version;/configure --prefix=/tools \
     78&nbsp;&nbsp;&nbsp;&nbsp;--with-local-prefix=/tools \
     79&nbsp;&nbsp;&nbsp;&nbsp;--enable-clocale=gnu --enable-shared \
     80&nbsp;&nbsp;&nbsp;&nbsp;--enable-threads=posix --enable-__cxa_atexit \
     81&nbsp;&nbsp;&nbsp;&nbsp;--enable-languages=c,c++</userinput></screen>
     82
     83<para>The meaning of the new configure options:</para>
     84
     85<itemizedlist>
     86<listitem><para><userinput>--enable-threads=posix</userinput>: This enables
     87C++ exception handling for multi-threaded code.</para></listitem>
     88
     89<listitem><para><userinput>--enable-__cxa_atexit</userinput>: This option
     90allows use of __cxa_atexit, rather than atexit, to register C++ destructors for
     91local statics and global objects and is essential for fully standards-compliant
     92handling of destructors. It also affects the C++ ABI and therefore results in
     93C++ shared libraries and C++ programs that are interoperable with other Linux
     94distributions.</para></listitem>
     95
     96<listitem><para><userinput>--enable-clocale=gnu</userinput>: This option ensures
     97the correct locale model is selected for the C++ libraries under all
     98circumstances. If the configure script finds the <emphasis>de_DE</emphasis>
     99locale installed, it will select the correct model of <emphasis>gnu</emphasis>.
     100However, people who don't install the <emphasis>de_DE</emphasis> locale, run the
     101risk of building ABI incompatible C++ libraries due to the wrong locale model of
     102<emphasis>generic</emphasis> being selected.</para></listitem>
     103
     104<listitem><para><userinput>--enable-languages=c,c++</userinput>: This option is
     105needed to ensure that both C and C++ compilers are built.</para></listitem>
     106</itemizedlist>
     107
     108<para>Compile the package:</para>
     109
     110<screen><userinput>make</userinput></screen>
     111
     112<para>There is no need to use the <userinput>bootstrap</userinput> target now,
     113as the compiler we're using to compile this GCC was built from the exact same
     114version of the GCC sources we used earlier.</para>
     115
     116<note><para>It's worth pointing out that running the GCC test suite here
     117is considered not as important as running it in
     118<xref linkend="chapter06"/>.</para></note>
     119
     120<para>Test the results:</para>
     121
     122<screen><userinput>make -k check</userinput></screen>
     123
     124<para>The <userinput>-k</userinput> flag is used to make the test suite run
     125through to completion and not stop at the first failure. The GCC test suite is
     126very comprehensive and is almost guaranteed to generate a few failures. To get
     127a summary of the test suite results, run this:</para>
     128 
     129<screen><userinput>../gcc-&gcc-version;/contrib/test_summary | more</userinput></screen>
     130
     131<para>You can compare your results to those posted to the gcc-testresults
     132mailing list for similar configurations to your own. For an example of how
     133current GCC-&gcc-version; should look on i686-pc-linux-gnu, see
     134<ulink url="http://gcc.gnu.org/ml/gcc-testresults/2003-08/msg01612.html"/>.</para>
     135
     136<para>Note that the results contain:</para>
     137
     138<screen>* 1 XPASS (unexpected pass) for g++
     139* 1 FAIL (unexpected failure) for g++
     140* 2 FAIL for gcc
     141* 26 XPASS's for libstdc++</screen>
     142 
     143<para>The unexpected pass for g++ is due to the use of
     144<userinput>--enable-__cxa_atexit</userinput>. Apparently not all platforms
     145supported by GCC have support for "__cxa_atexit" in their C libraries, so this
     146test is not always expected to pass.</para>
     147
     148<para>The 26 unexpected passes for libstdc++ are due to the use of
     149<userinput>--enable-clocale=gnu</userinput>, which is the correct choice on
     150Glibc-based systems of versions 2.2.5 and above. The underlying locale support
     151in the GNU C library is superior to that of the otherwise selected "generic"
     152model (which may be applicable if for instance you were using Newlibc, Sun-libc
     153or whatever libc). The libstdc++ test suite is apparently expecting the
     154"generic" model, hence those tests are not always expected to pass.</para>
     155
     156<para>Unexpected failures often cannot be avoided. The GCC developers are
     157usually aware of them but haven't yet gotten around to fixing them. In short,
     158unless your results are vastly different from those at the above URL, it is safe
     159to continue on.</para>
     160
     161<para>And finally install the package:</para>                                             
     162
     163<screen><userinput>make install</userinput></screen>
     164
     165<note><para>At this point it is strongly recommended to repeat the sanity check
     166we performed earlier in the chapter. Refer back to
     167<xref linkend="ch05-locking-glibc"/> and repeat the check. If the results are
     168wrong, then most likely you forgot to apply the above mentioned GCC Specs
     169patch.</para></note>
     170
     171</sect2>
    9172
    10173</sect1>
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