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- <?xml version="1.0" encoding="ISO-8859-1"?>
- <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
- <!ENTITY % general-entities SYSTEM "../general.ent">
- <!ENTITY % patches-entities SYSTEM "../patches.ent">
- %general-entities;
- %patches-entities;
- ]>
- <sect1 id="ch-tools-gcc-pass2" role="wrap">
- <title>GCC-&gcc-version; - Pass 2</title>
- <?dbhtml filename="gcc-pass2.html"?>
- <indexterm zone="ch-tools-gcc-pass2">
- <primary sortas="a-GCC">GCC</primary>
- <secondary>tools, pass 2</secondary></indexterm>
- <sect2 role="package"><title/>
- <segmentedlist>
- <segtitle>&buildtime;</segtitle>
- <segtitle>&diskspace;</segtitle>
- <seglistitem><seg>11.0 SBU</seg><seg>292 MB</seg></seglistitem>
- </segmentedlist>
- <xi:include xmlns:xi="http://www.w3.org/2003/XInclude" href="../chapter06/gcc.xml" xpointer="xpointer(/sect1/sect2[1]/segmentedlist[2])"/>
- </sect2>
- <sect2 role="installation">
- <title>Re-installation of GCC</title>
- <para>This package is known to have issues when its default
- optimization flags (including the <parameter>-march</parameter> and
- <parameter>-mcpu</parameter> options) are changed. If any environment
- variables that override default optimizations have been defined, such
- as <envar>CFLAGS</envar> and <envar>CXXFLAGS</envar>,
- unset them when building GCC.</para>
- <para>The tools required to test GCC and Binutils—Tcl, Expect
- and DejaGNU—are installed now. GCC and Binutils can now be
- rebuilt, linking them against the new Glibc and testing them properly
- (if running the test suites in this chapter). Please note that these
- test suites are highly dependent on properly functioning PTYs which
- are provided by the host. PTYs are most commonly implemented via the
- <systemitem class="filesystem">devpts</systemitem> file system. Check
- to see if the host system is set up correctly in this regard by
- performing a quick test:</para>
- <screen><userinput>expect -c "spawn ls"</userinput></screen>
- <para>The response might be:</para>
- <screen><computeroutput>The system has no more ptys.
- Ask your system administrator to create more.</computeroutput></screen>
- <para>If the above message is received, the host does not have its
- PTYs set up properly. In this case, there is no point in running the
- test suites for GCC and Binutils until this issue is resolved. Please
- consult the LFS Wiki at <ulink url="&wiki-root;"/> for more
- information on how to get PTYs working.</para>
- <para>First correct a known problem and make an essential adjustment:</para>
- <screen><userinput>patch -Np1 -i ../&gcc-no_fixincludes-patch;
- patch -Np1 -i ../&gcc-specs-patch;</userinput></screen>
- <para>The first patch disables the GCC <command>fixincludes</command>
- script. This was briefly mentioned earlier, but a more in-depth
- explanation of the fixincludes process is warranted here. Under normal
- circumstances, the GCC <command>fixincludes</command> script scans the
- system for header files that need to be fixed. It might find that some
- Glibc header files on the host system need to be fixed, and will fix
- them and put them in the GCC private include directory. In <xref
- linkend="chapter-building-system"/>, after the newer Glibc has been
- installed, this private include directory will be searched before the
- system include directory. This may result in GCC finding the fixed
- headers from the host system, which most likely will not match the
- Glibc version used for the LFS system.</para>
- <para>The second patch changes GCC's default location of the dynamic
- linker (typically <filename class="libraryfile">ld-linux.so.2</filename>). It also removes
- <filename class="directory">/usr/include</filename> from GCC's include
- search path. Patching now rather than adjusting the specs file after
- installation ensures that the new dynamic linker is used during the
- actual build of GCC. That is, all of the final (and temporary)
- binaries created during the build will link against the new
- Glibc.</para>
- <important><para>The above patches are critical in ensuring a
- successful overall build. Do not forget to apply
- them.</para></important>
- <para>Create a separate build directory again:</para>
- <screen><userinput>mkdir ../gcc-build
- cd ../gcc-build</userinput></screen>
- <para>Before starting to build GCC, remember to unset any environment
- variables that override the default optimization flags.</para>
- <para>Now prepare GCC for compilation:</para>
- <screen><userinput>../gcc-&gcc-version;/configure --prefix=/tools \
- --libexecdir=/tools/lib --with-local-prefix=/tools \
- --enable-clocale=gnu --enable-shared \
- --enable-threads=posix --enable-__cxa_atexit \
- --enable-languages=c,c++ --disable-libstdcxx-pch</userinput></screen>
- <para>The meaning of the new configure options:</para>
- <variablelist>
- <varlistentry>
- <term><parameter>--enable-clocale=gnu</parameter></term>
- <listitem><para>This option ensures the correct locale model is
- selected for the C++ libraries under all circumstances. If the
- configure script finds the <emphasis>de_DE</emphasis> locale installed, it will select the
- correct gnu locale model. However, if the <emphasis>de_DE</emphasis> locale is not
- installed, there is the risk of building Application Binary Interface
- (ABI)-incompatible C++ libraries because the incorrect generic locale
- model may be selected.</para></listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>--enable-threads=posix</parameter></term>
- <listitem><para>This enables C++ exception handling for multi-threaded
- code.</para></listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>--enable-__cxa_atexit</parameter></term>
- <listitem><para>This option allows use of
- <emphasis>__cxa_atexit</emphasis>, rather than
- <emphasis>atexit</emphasis>, to register C++ destructors for local
- statics and global objects. This option is essential for fully
- standards-compliant handling of destructors. It also effects the C++
- ABI, and therefore results in C++ shared libraries and C++ programs
- that are interoperable with other Linux
- distributions.</para></listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>--enable-languages=c,c++</parameter></term>
- <listitem><para>This option
- ensures that both the C and C++ compilers are built.</para></listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>--disable-libstdcxx-pch</parameter></term>
- <listitem><para>Do not build the pre-compiled header (PCH) for
- <filename class="libraryfile">libstdc++</filename>. It takes up a lot of space,
- and we have no use for it.</para></listitem>
- </varlistentry>
- </variablelist>
- <para>Compile the package:</para>
- <screen><userinput>make</userinput></screen>
- <para>There is no need to use the <parameter>bootstrap</parameter>
- target now because the compiler being used to compile this GCC was
- built from the exact same version of the GCC sources used
- earlier.</para>
- <para>Compilation is now complete. As previously mentioned, running
- the test suites for the temporary tools compiled in this chapter is
- not mandatory. To run the GCC test suite anyway, use the following
- command:</para>
- <screen><userinput>make -k check</userinput></screen>
- <para>The <parameter>-k</parameter> flag is used to make the test suite run
- through to completion and not stop at the first failure. The GCC test
- suite is very comprehensive and is almost guaranteed to generate a few
- failures. To receive a summary of the test suite results, run:</para>
-
- <screen><userinput>../gcc-&gcc-version;/contrib/test_summary</userinput></screen>
- <para>For only the summaries, pipe the output through
- <userinput>grep -A7 Summ</userinput>.</para>
- <para>Results can be compared to those posted to the gcc-testresults
- mailing list to see similar configurations to the one being built. For
- an example of how current GCC-&gcc-version; should look on
- i686-pc-linux-gnu, see <ulink
- url="http://gcc.gnu.org/ml/gcc-testresults/2004-07/msg00179.html"/>.</para>
- <para>A few unexpected failures cannot always be avoided. The
- GCC developers are usually aware of these issues, but have not
- resolved them yet. Unless the test results are vastly different from
- those at the above URL, it is safe to continue.</para>
- <para>Install the package:</para>
- <screen><userinput>make install</userinput></screen>
- <note><para>At this point it is strongly recommended to repeat the
- sanity check we performed earlier in this chapter. Refer back to <xref
- linkend="ch-tools-adjusting" role=","/> and repeat the test compilation. If
- the result is wrong, the most likely reason is that the GCC Specs
- patch was not properly applied.</para></note>
- </sect2>
- <sect2 role="content"><title/>
- <para>Details on this package are located in <xref
- linkend="contents-gcc" role="."/></para>
- </sect2>
- </sect1>
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