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git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@8389 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
248 lines
10 KiB
XML
248 lines
10 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY % general-entities SYSTEM "../general.ent">
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%general-entities;
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]>
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<sect1 id="ch-tools-gcc-pass2" role="wrap">
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<?dbhtml filename="gcc-pass2.html"?>
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<sect1info condition="script">
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<productname>gcc</productname>
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<productnumber>&gcc-version;</productnumber>
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<address>&gcc-url;</address>
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</sect1info>
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<title>GCC-&gcc-version; - Pass 2</title>
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<indexterm zone="ch-tools-gcc-pass2">
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<primary sortas="a-GCC">GCC</primary>
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<secondary>tools, pass 2</secondary>
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</indexterm>
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<sect2 role="package">
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<title/>
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<xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
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href="../chapter06/gcc.xml"
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xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
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<segmentedlist>
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<segtitle>&buildtime;</segtitle>
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<segtitle>&diskspace;</segtitle>
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<seglistitem>
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<seg>&gcc-ch5p2-sbu;</seg>
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<seg>&gcc-ch5p2-du;</seg>
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</seglistitem>
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</segmentedlist>
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</sect2>
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<sect2 role="installation">
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<title>Re-installation of GCC</title>
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<para>The tools required to test GCC and Binutils—Tcl, Expect
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and DejaGNU—are installed now. GCC and Binutils can now be
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rebuilt, linking them against the new Glibc and testing them properly
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(if running the test suites in this chapter). Please note that these
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test suites are highly dependent on properly functioning PTYs which
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are provided by the host. PTYs are most commonly implemented via the
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<systemitem class="filesystem">devpts</systemitem> file system. Check
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to see if the host system is set up correctly in this regard by
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performing a quick test:</para>
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<screen><userinput remap="test">expect -c "spawn ls"</userinput></screen>
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<para>The response might be:</para>
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<screen><computeroutput>The system has no more ptys.
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Ask your system administrator to create more.</computeroutput></screen>
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<para>If the above message is received, the host does not have its PTYs
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set up properly. In this case, there is no point in running the test
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suites for GCC and Binutils until this issue is resolved. Please consult
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the LFS FAQ at <ulink url="&lfs-root;/lfs/faq.html#no-ptys"/> for more
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information on how to get PTYs working.</para>
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<para>As previously explained in <xref linkend="ch-tools-adjusting"/>,
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under normal circumstances the GCC <command>fixincludes</command> script
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is run in order to fix potentially broken header files. As GCC-&gcc-version;
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and Glibc-&glibc-version; have already been installed at this point, and
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their respective header files are known to not require fixing, the
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<command>fixincludes</command> script is not required. As mentioned
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previously, the script may in fact pollute the build environment by
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installing fixed headers from the host system into GCC's private include
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directory. The running of the <command>fixincludes</command> script can
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be suppressed by issuing the following commands:</para>
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<screen><userinput remap="pre">cp -v gcc/Makefile.in{,.orig}
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sed 's@\./fixinc\.sh@-c true@' gcc/Makefile.in.orig > gcc/Makefile.in</userinput></screen>
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<para>The bootstrap build performed in <xref linkend="ch-tools-gcc-pass1"/>
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built GCC with the <option>-fomit-frame-pointer</option> compiler flag.
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Non-bootstrap builds omit this flag by default, so apply the following
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<command>sed</command> to use it in order to ensure consistent compiler
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builds:</para>
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<screen><userinput remap="pre">cp -v gcc/Makefile.in{,.tmp}
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sed 's/^XCFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in.tmp \
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> gcc/Makefile.in</userinput></screen>
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<para>The following command will change the location of GCC's default
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dynamic linker to use the one we installed in
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<filename class="directory">/tools</filename>. It also removes <filename
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class="directory">/usr/include</filename> from GCC's include search path.
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Doing this now rather than adjusting the specs file after installation
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ensures that the new dynamic linker is used during the actual build of
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GCC. That is, all of the binaries created during the build will link
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against the new Glibc. Issue:</para>
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<screen><userinput remap="pre">for file in $(find gcc/config -name linux64.h -o -name linux.h)
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do
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cp -uv $file{,.orig}
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sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \
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-e 's@/usr@/tools@g' $file.orig > $file
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echo "
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#undef STANDARD_INCLUDE_DIR
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#define STANDARD_INCLUDE_DIR 0" >> $file
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touch $file.orig
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done</userinput></screen>
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<para>In case the above seems hard to follow, let's break it down a bit.
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First we find all the files under the gcc/config directory that are named
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either <filename>linux.h</filename> or <filename>linux64.h</filename>.
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For each file found, we copy it to a file of the same name but with an added
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suffix of <quote>.orig</quote>. Then the first sed expression prepends
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<quote>/tools</quote> to every instance of <quote>/lib/ld</quote>,
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<quote>/lib64/ld</quote> or <quote>/lib32/ld</quote>, while the second one
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replaces hard-coded instances of <quote>/usr</quote>. Then we add our define
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statements which alter the include search path to the end of the file. Finally,
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we use <command>touch</command> to update the timestamp on the copied files.
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When used in conjunction with <command>cp -u</command>, this prevents unexpected
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changes to the original files in case the command is inadvertently run twice.
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</para>
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<para>Create a separate build directory again:</para>
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<screen><userinput remap="pre">mkdir -v ../gcc-build
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cd ../gcc-build</userinput></screen>
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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 for compilation:</para>
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<screen><userinput remap="configure">../gcc-&gcc-version;/configure --prefix=/tools \
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--with-local-prefix=/tools --enable-clocale=gnu \
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--enable-shared --enable-threads=posix \
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--enable-__cxa_atexit --enable-languages=c,c++ \
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--disable-libstdcxx-pch --disable-bootstrap</userinput></screen>
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<variablelist>
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<title>The meaning of the new configure options:</title>
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<varlistentry>
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<term><parameter>--enable-clocale=gnu</parameter></term>
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<listitem>
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<para>This option ensures the correct locale model is selected
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for the C++ libraries under all circumstances. If the configure
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script finds the <emphasis>de_DE</emphasis> locale installed,
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it will select the correct gnu locale model. However, if the
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<emphasis>de_DE</emphasis> locale is not installed, there is the
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risk of building Application Binary Interface (ABI)-incompatible
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C++ libraries because the incorrect generic locale model may be
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selected.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>--enable-threads=posix</parameter></term>
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<listitem>
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<para>This enables C++ exception handling for multi-threaded code.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>--enable-__cxa_atexit</parameter></term>
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<listitem>
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<para>This option allows use of <function>__cxa_atexit</function>,
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rather than <function>atexit</function>, to register C++ destructors
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for local statics and global objects. This option is essential for
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fully standards-compliant handling of destructors. It also affects
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the C++ ABI, and therefore results in C++ shared libraries and C++
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programs that are interoperable with other Linux distributions.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>--enable-languages=c,c++</parameter></term>
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<listitem>
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<para>This option ensures that both the C and C++ compilers are
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built.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>--disable-libstdcxx-pch</parameter></term>
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<listitem>
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<para>Do not build the pre-compiled header (PCH) for
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<filename class="libraryfile">libstdc++</filename>. It takes up a
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lot of space, and we have no use for it.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>--disable-bootstrap</parameter></term>
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<listitem>
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<para>Bootstrapping the compiler is now the default for GCC. However,
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our build method should provide us with a solid compiler without the
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need to bootstrap each time.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Compile the package:</para>
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<screen><userinput remap="make">make</userinput></screen>
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<para>There is no need to use the <parameter>bootstrap</parameter> target
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now because the compiler being used to compile this GCC was built from
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the exact same version of the GCC sources used earlier.</para>
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<para>Compilation is now complete. As previously mentioned, running the test
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suites for the temporary tools compiled in this chapter is not mandatory.
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To run the GCC test suite anyway, use the following command:</para>
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<screen><userinput remap="test">make -k check</userinput></screen>
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<para>The <parameter>-k</parameter> 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
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suite is very comprehensive and is almost guaranteed to generate a few
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failures.</para>
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<para>For a discussion of test failures that are of particular
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importance, please see <xref linkend="ch-system-gcc" role="."/></para>
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<para>Install the package:</para>
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<screen><userinput remap="install">make install</userinput></screen>
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<xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
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href="adjusting.xml"
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xpointer="xpointer(/sect1/caution[1])"/>
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</sect2>
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<sect2 role="content">
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<title/>
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<para>Details on this package are located in
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<xref linkend="contents-gcc" role="."/></para>
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</sect2>
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</sect1>
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