lfs-book-zh_CN/chapter06/gcc-inst.xml

<sect2><title>&nbsp;</title><para>&nbsp;</para></sect2>

<sect2>
<title>Installation of GCC</title>

<para>This package is known to behave badly when you have changed its
default optimization flags (including the -march and -mcpu options). GCC is
best left alone. Therefore, if you have defined any environment variables
that override default optimizations, such as CFLAGS and CXXFLAGS, we
recommend unsetting or modifying them when building GCC. You have
been warned.</para>

<para>We will be building the C and C++ compilers at this time, so you'll
need to unpack both the gcc-core and gcc-g++ tarballs. Other compilers are
available in the full gcc package; instructions for building them may be
found at <ulink url="&blfs-root;view/cvs/general/gcc.html"/>.</para>

<para>It is recommended by the GCC installation documentation to build GCC
in a dedicated directory outside of the source tree. Create the build
directory:</para>

<para><screen><userinput>mkdir ../gcc-build &amp;&amp;
cd ../gcc-build</userinput></screen></para>

<para>Prepare GCC to be compiled:</para>

<para><screen><userinput>../gcc-&gcc-version;/configure --prefix=/usr --enable-shared \
&nbsp;&nbsp;&nbsp;&nbsp;--enable-threads=posix --with-slibdir=/lib \
&nbsp;&nbsp;&nbsp;&nbsp;--enable-__cxa_atexit --enable-clocale=gnu</userinput></screen></para>

<para>The meanings of the configure options are:</para>

<itemizedlist>
<listitem><para><userinput>--enable-threads=posix:</userinput> This enables
C++ exception handling for multi-threaded code.</para></listitem>

<listitem><para><userinput>--enable-__cxa_atexit:</userinput> This option
will result in C++ shared libraries and C++ programs that are interoperable
with other Linux distributions.</para></listitem>

<listitem><para><userinput>--enable-clocale=gnu:</userinput> There is a risk
that some people will build ABI incompatible C++ libraries if they didn't
install all of the glibc localedata. Using --enable-clocale=gnu ensures that
the "right thing" is done in all cases. If you don't wish to use this option,
then at least build the <emphasis>de_DE</emphasis> locale. When GCC finds
this specific locale, then the correct locale mode (<emphasis>gnu</emphasis>)
is implemented.</para></listitem>
</itemizedlist>

<para>Continue with compiling the package:</para>

<para><screen><userinput>make bootstrap</userinput></screen></para>

<para>The <emphasis>bootstrap</emphasis> target doesn't just compile GCC, but
it compiles GCC a multiple times. It uses the first compiled programs to
compile itself a second and third time to make sure the compiler was compiled
properly.</para>

<para>Finish installing the package:</para>

<para><screen><userinput>make install</userinput></screen></para>

<para>Some packages require that the C++ compiler be installed in the
<filename>/lib</filename> and <filename>/usr/lib</filename> directories.
To honor those packages, create two symlinks:</para>

<para><screen><userinput>ln -s ../usr/bin/cpp /lib &amp;&amp;
ln -s ../bin/cpp /usr/lib</userinput></screen></para>

<para>Many packages compile using <emphasis>cc</emphasis> as the name for
the C compiler. To satisfy those packages, create a <emphasis>cc</emphasis>
symlink:</para>

<para><screen><userinput>ln -s gcc /usr/bin/cc</userinput></screen></para>

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