lfs-book/chapter05/glibc.xml

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<sect1 id="ch-tools-glibc" role="wrap">
  <?dbhtml filename="glibc.html"?>

  <sect1info condition="script">
    <productname>glibc</productname>
    <productnumber>&glibc-version;</productnumber>
    <address>&glibc-url;</address>
  </sect1info>

  <title>Glibc-&glibc-version;</title>

  <indexterm zone="ch-tools-glibc">
    <primary sortas="a-Glibc">Glibc</primary>
    <secondary>tools</secondary>
  </indexterm>

  <sect2 role="package">
    <title/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="../chapter06/glibc.xml"
    xpointer="xpointer(/sect1/sect2[1]/para[1])"/>

    <segmentedlist>
      <segtitle>&buildtime;</segtitle>
      <segtitle>&diskspace;</segtitle>

      <seglistitem>
        <seg>&glibc-ch5-sbu;</seg>
        <seg>&glibc-ch5-du;</seg>
      </seglistitem>
    </segmentedlist>

  </sect2>

  <sect2 role="installation">
    <title>Installation of Glibc</title>

    <!-- This sed can be removed for any glibc newer than 2.10.1 (along with the
         matching sed in chapter 6).  See glibc bug 10262. -->
    <para>Fix an error in the constants that get passed to the futex system
    call in some cases, causing certain pthread_mutex operations to fail:</para>

<screen><userinput remap="pre">cp -v nptl/sysdeps/unix/sysv/linux/i386/i486/lowlevellock.S{,.orig}
sed -e 's/FUTEX_WAIT\( | FUTEX_CLOCK_REALTIME, reg\)/FUTEX_WAIT_BITSET\1/' \
        &lt;nptl/sysdeps/unix/sysv/linux/i386/i486/lowlevellock.S.orig \
        &gt;nptl/sysdeps/unix/sysv/linux/i386/i486/lowlevellock.S</userinput></screen>

    <para>The Glibc documentation recommends building Glibc outside of the source
    directory in a dedicated build directory:</para>

<screen><userinput remap="pre">mkdir -v ../glibc-build
cd ../glibc-build</userinput></screen>

    <para>Because Glibc no longer supports i386, its developers say to use the
    compiler flag <parameter>-march=i486</parameter> when building it for x86
    machines. There are several ways to accomplish that, but testing shows that
    the flag is best placed inside the build variable <quote>CFLAGS</quote>.
    Instead of overriding completely what Glibc's internal build system uses
    for CFLAGS, append the new flag to the existing contents of CFLAGS by
    making use of the special file <filename>configparms</filename>. The
    -mtune=native flag is also necessary to reset a reasonable value for -mtune
    that is changed when setting -march.</para>

<screen><userinput remap="configure">case `uname -m` in
  i?86) echo "CFLAGS += -march=i486 -mtune=native" &gt; configparms ;;
esac</userinput></screen>

    <para>Next, prepare Glibc for compilation:</para>

<screen><userinput remap="configure">../glibc-&glibc-version;/configure --prefix=/tools \
    --host=$LFS_TGT --build=$(../glibc-&glibc-version;/scripts/config.guess) \
    --disable-profile --enable-add-ons \
    --enable-kernel=2.6.18 --with-headers=/tools/include \
    libc_cv_forced_unwind=yes libc_cv_c_cleanup=yes</userinput></screen>

    <variablelist>
      <title>The meaning of the configure options:</title>

      <varlistentry>
        <term><parameter>--host=$LFS_TGT, --build=$(../glibc-&glibc-version;/scripts/config.guess)</parameter></term>
        <listitem>
          <para>The combined effect of these switches is that Glibc's build system
          configures itself to cross-compile, using the cross-linker and
          cross-compiler in <filename class="directory">/tools</filename>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>--disable-profile</parameter></term>
        <listitem>
          <para>This builds the libraries without profiling information. Omit
          this option if profiling on the temporary tools is necessary.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>--enable-add-ons</parameter></term>
        <listitem>
          <para>This tells Glibc to use the NPTL add-on as its threading
          library.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>--enable-kernel=2.6.18</parameter></term>
        <listitem>
          <para>This tells Glibc to compile the library with support
          for 2.6.18 and later Linux kernels.  Workarounds for older
          kernels are not enabled.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>--with-headers=/tools/include</parameter></term>
        <listitem>
          <para>This tells Glibc to compile itself against the headers recently
          installed to the tools directory, so that it knows exactly what
          features the kernel has and can optimize itself accordingly.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>libc_cv_forced_unwind=yes</parameter></term>
        <listitem>
          <para>The build requires support for forced unwind, but because it is
          being cross compiled, it cannot auto detect it. Setting this variable
          on the command line explicitly tells the
          <command>configure</command> script that support is available.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><parameter>libc_cv_c_cleanup=yes</parameter></term>
        <listitem>
          <para>The build also requires support for C cleanup handling, which it
          cannot auto detect when being cross compiled. Enable it explicitly.</para>
        </listitem>
      </varlistentry>

    </variablelist>

    <para>During this stage the following warning might appear:</para>

    <blockquote>
<screen><computeroutput>configure: WARNING:
*** These auxiliary programs are missing or
*** incompatible versions: msgfmt
*** some features will be disabled.
*** Check the INSTALL file for required versions.</computeroutput></screen>
    </blockquote>

    <para>The missing or incompatible <command>msgfmt</command> program is
    generally harmless, but it can sometimes cause issues when running the
    test suite. This <command>msgfmt</command> program is part of the
    Gettext package which the host distribution should provide. If
    <command>msgfmt</command> is present but deemed incompatible, upgrade
    the host system's Gettext package or continue without it and see if
    the test suite runs without problems regardless.</para>

    <para>Compile the package:</para>

<screen><userinput remap="make">make</userinput></screen>

    <para>This package does come with a test suite, however, it cannot be
    run at this time because we do not have a C++ compiler yet.</para>

    <note>
      <para>The test suite also requires locale data to be installed in order to run
      successfully. Locale data provides information to the system regarding
      such things as the date, time, and currency formats accepted and output by
      system utilities. If the test suites are not being run in this chapter
      (as per the recommendation), there is no need to install the locales now.
      The appropriate locales will be installed in the next chapter. To install
      the Glibc locales anyway, use instructions from <xref
      linkend="ch-system-glibc" role="."/></para>
    </note>

    <para>Install the package:</para>

<screen><userinput remap="install">make install</userinput></screen>

  </sect2>

  <sect2 role="content">
    <title/>

    <para>Details on this package are located in
    <xref linkend="contents-glibc" role="."/></para>

  </sect2>

</sect1>