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git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@2416 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
106 lines
4.7 KiB
XML
106 lines
4.7 KiB
XML
<sect2><title> </title><para> </para></sect2>
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<sect2>
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<title>Installation of GCC</title>
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<para>We won't be needing a C++ compiler until Chapter 6. So, only
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the gcc-core tarball needs to be unpacked at this time.</para>
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<para>This package is known to behave badly when you have changed its
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default optimization flags (including the -march and -mcpu options).
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Therefore, if you have defined any environment variables that override
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default optimizations, such as CFLAGS and CXXFLAGS, we recommend unsetting
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or modifying them when building GCC.</para>
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<para>It is recommended by the GCC installation documentation to build
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GCC outside of the source directory in a dedicated directory:</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>Prepare GCC to be compiled:</para>
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<para><screen><userinput>../gcc-&gcc-version;/configure --prefix=/static \
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--disable-nls --disable-shared \
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--with-as=$LFS/static/bin/as \
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--with-ld=$LFS/static/bin/ld</userinput></screen></para>
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<para>The meaning of the configure options are:</para>
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<itemizedlist>
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<listitem><para><userinput>--prefix=/static</userinput>: This is NOT a
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typo. GCC hard codes some paths while compiling and so we need to pass
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<filename class="directory">/static</filename> as the prefix during the
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configure stage. We will pass the real installation prefix (<filename
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class="directory">$LFS/static</filename>) during the installation
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stage later on.</para></listitem>
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<listitem><para><userinput>--disable-shared</userinput>: This prevents the
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build of dynamic libraries. They are useless to us at the moment. We'll
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create them when we reinstall GCC in chapter 6.</para></listitem>
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<listitem><para><userinput>--with-as=$LFS/static/bin/as and
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--with-ld=$LFS/static/bin/ld</userinput>: GCC can be miscompiled if your
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host distribution's Binutils package is quite old. We need a good working
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static GCC until we reinstall GCC later in chapter 6. So by using
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<filename>as</filename> and <filename>ld</filename> from the Binutils
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package we compiled earlier in this chapter we ensure that GCC will work
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correctly.</para></listitem>
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</itemizedlist>
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<para>Continue with compiling the package:</para>
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<para><screen><userinput>make BOOT_LDFLAGS="-static" bootstrap</userinput></screen></para>
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<para>The meaning of the make options are:</para>
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<itemizedlist>
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<listitem><para><userinput>BOOT_LDFLAGS="-static"</userinput>: This is
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GCC's equivalent to make LDFLAGS="-static" as we use with other packages to
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compile them statically.</para></listitem>
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<listitem><para><userinput>bootstrap</userinput>: The
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<emphasis>bootstrap</emphasis> target doesn't just compile GCC, but it
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compiles GCC a second time. It uses the first compiled programs to compile
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itself a second and third time to make sure the compiler was compiled properly
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and can compile itself properly.</para></listitem>
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</itemizedlist>
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<para>And finish off installing the package:</para>
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<para><screen><userinput>make prefix=$LFS/static install-no-fixedincludes</userinput></screen></para>
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<para>The meaning of the make option is:</para>
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<itemizedlist>
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<listitem><para><userinput>install-no-fixedincludes</userinput>: This prevents
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the fixincludes script from running. Preventing this is necessary because
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under normal circumstances the GCC installation will run the fixincludes
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script which scans your system for header files that need to be fixed. It
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might find that the Glibc header files of your host system need to be fixed.
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If so, it will fix them and put them in
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<filename>$LFS/static/lib/gcc-lib/i686-pc-linux-gnu/3.2</filename>. Later on
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in chapter 6 you will install Glibc which will put its header files in
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<filename>/usr/include</filename>. Next you will install other programs that
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use the Glibc headers and GCC will look in
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<filename>/static/lib/gcc-lib</filename> before looking in
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<filename>/usr/include</filename>, with the result of finding and using the
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fixed Glibc header files from your host distribution, which are probably
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incompatible with the Glibc version actually used on the LFS
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system.</para></listitem>
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</itemizedlist>
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<para>As the finishing touch we'll create the <filename
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class="symlink">$LFS/static/bin/cc</filename> symlink. A lot of programs
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and scripts try to run <userinput>cc</userinput> instead of
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<userinput>gcc</userinput> This is to keep programs generic and usable on
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all kinds of Unix systems. Not everybody has GNU CC installed. Just running
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<userinput>cc</userinput> (C Compiler) leaves the user free to decide which
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C compiler to install. The symlink will point to the system's default
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compiler.</para>
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<para><screen><userinput>ln -s gcc $LFS/static/bin/cc</userinput></screen></para>
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</sect2>
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