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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % general-entities SYSTEM "../general.ent">
%general-entities;
]>
<sect1 id="ch-tools-gcc-pass2" role="wrap">
<?dbhtml filename="gcc-pass2.html"?>
<title>GCC-&gcc-version; - Pass 2</title>
<indexterm zone="ch-tools-gcc-pass2">
<primary sortas="a-GCC">GCC</primary>
<secondary>tools, pass 2</secondary>
</indexterm>
<sect2 role="package">
<title/>
<xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
href="../chapter06/gcc.xml"
xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
<segmentedlist>
<segtitle>&buildtime;</segtitle>
<segtitle>&diskspace;</segtitle>
<seglistitem>
<seg>&gcc-ch5p2-sbu;</seg>
<seg>&gcc-ch5p2-du;</seg>
</seglistitem>
</segmentedlist>
</sect2>
<sect2 role="installation">
<title>Re-installation of GCC</title>
<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 FAQ at <ulink url="&lfs-root;/lfs/faq.html#no-ptys"/> for more
information on how to get PTYs working.</para>
<para>As previously explained in <xref linkend="ch-tools-adjusting"/>,
under normal circumstances the GCC <command>fixincludes</command> script
is run in order to fix potentially broken header files. As GCC-&gcc-version;
and Glibc-&glibc-version; have already been installed at this point, and
their respective header files are known to not require fixing, the
<command>fixincludes</command> script is not required. As mentioned
previously, the script may in fact pollute the build environment by
installing fixed headers from the host system into GCC's private include
directory. The running of the <command>fixincludes</command> script can
be suppressed by issuing the following commands:</para>
<screen><userinput>cp -v gcc/Makefile.in{,.orig} &&
sed 's@\./fixinc\.sh@-c true@' gcc/Makefile.in.orig > gcc/Makefile.in</userinput></screen>
<para>The bootstrap build performed in <xref linkend="ch-tools-gcc-pass1"/>
built GCC with the <option>-fomit-frame-pointer</option> compiler flag.
Non-bootstrap builds omit this flag by default, so apply the following
<command>sed</command> to use it in order to ensure consistent compiler
builds.</para>
<screen><userinput>cp -v gcc/Makefile.in{,.tmp} &&
sed 's/^XCFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in.tmp \
> gcc/Makefile.in</userinput></screen>
<para>Apply the following patch to change the location of GCC's default
dynamic linker (typically <filename
class="libraryfile">ld-linux.so.2</filename>):</para>
<screen><userinput>patch -Np1 -i ../&gcc-specs-patch;</userinput></screen>
<para>The above patch 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 binaries created during the build will link
against the new Glibc.</para>
<important>
<para>The above patch is critical in ensuring a successful overall
build. Do not forget to apply it.</para>
</important>
<para>Create a separate build directory again:</para>
<screen><userinput>mkdir -v ../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 \
--with-local-prefix=/tools --enable-clocale=gnu \
--enable-shared --enable-threads=posix \
--enable-__cxa_atexit --enable-languages=c,c++ \
--disable-libstdcxx-pch</userinput></screen>
<variablelist>
<title>The meaning of the new configure options:</title>
<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 <function>__cxa_atexit</function>,
rather than <function>atexit</function>, to register C++ destructors
for local statics and global objects. This option is essential for
fully standards-compliant handling of destructors. It also affects
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.</para>
<para>For a discussion of test failures that are of particular
importance, please see <xref linkend="ch-system-gcc" role="."/></para>
<para>Install the package:</para>
<screen><userinput>make install</userinput></screen>
<xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
href="adjusting.xml"
xpointer="xpointer(/sect1/caution[1])"/>
</sect2>
<sect2 role="content">
<title/>
<para>Details on this package are located in
<xref linkend="contents-gcc" role="."/></para>
</sect2>
</sect1>
|
