source: chapter05/glibc.xml@ 32a531e

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<sect1 id="ch-tools-glibc">
<title>Glibc-&glibc-version;</title>
<?dbhtml filename="glibc.html"?>

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

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<sect2>
<title>Installation of Glibc</title>

<para>This package is known to behave badly when you change its default
optimization flags (including the <emphasis>-march</emphasis> and
<emphasis>-mcpu</emphasis> options). Therefore, if you have defined any
environment variables that override default optimizations, such as CFLAGS and
CXXFLAGS, we recommend un-setting them when building Glibc.</para>

<para>Basically, compiling Glibc in any other way than the book suggests
is putting the stability of your system at risk.</para>

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

<screen><userinput>mkdir ../glibc-build
cd ../glibc-build</userinput></screen>

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

<screen><userinput>../glibc-&glibc-version;/configure --prefix=/tools \
    --disable-profile --enable-add-ons=nptl --with-tls \
    --with-binutils=/tools/bin --without-gd --without-cvs \
    --with-headers=/tools/glibc-kernheaders</userinput></screen>

<para>The meaning of the configure options:</para>

<itemizedlist>
<listitem><para><userinput>--disable-profile</userinput>: This builds the
libraries without profiling information. Omit this option if you plan to do
profiling on the temporary tools.</para></listitem> 

<listitem><para><userinput>--enable-add-ons=nptl</userinput>: This
tells Glibc to use the NPTL add-on as its threading library.</para></listitem>

<listitem><para><userinput>--with-tls</userinput>: This tells Glibc to include
support for TLS (thread-local storage).  This is required for NPTL to work.
</para></listitem>

<listitem><para><userinput>--with-binutils=/tools/bin</userinput>: Strictly
speaking this switch is not required. But it does ensure nothing can go wrong
with regard to what Binutils programs get used during the Glibc build.</para></listitem>

<listitem><para><userinput>--without-gd</userinput>: This prevents the build
of the <command>memusagestat</command> program, which strangely enough insists
on linking against the host's libraries (libgd, libpng, libz, and so forth).
</para></listitem>

<listitem><para><userinput>--without-cvs</userinput>: This is meant to prevent
the Makefiles from attempting automatic CVS checkouts when using a CVS
snapshot. But it's not actually needed these days. We use it because it
suppresses an annoying but harmless warning about a missing
<command>autoconf</command> program.</para></listitem>

<listitem><para><userinput>--with-headers=/tools/glibc-kernheaders</userinput>:
This tells Glibc to compile against the <quote>raw</quote> kernel headers, so
that it knows exactly what features the kernel has, and can optimize itself
accordingly.  Not strictly necessary, but nice to have.</para></listitem>
</itemizedlist>

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

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

<para>The missing or incompatible <command>msgfmt</command> program is
generally harmless, but it's believed it can sometimes cause problems when
running the test suite.</para>

<para>Compile the package:</para>

<screen><userinput>make</userinput></screen>

<para>Compilation is now complete. As mentioned earlier, we don't recommend
running the test suites for the temporary system here in this chapter. If you
still want to run the Glibc test suite anyway, the following command will do
so:</para>

<screen><userinput>make check</userinput></screen>

<para>The Glibc test suite is highly dependent on certain functions of your host
system, in particular the kernel. Additionally, here in this chapter some tests
can be adversely affected by existing tools or environmental issues on the host
system. Of course, these won't be a problem when we run the Glibc test suite
inside the chroot environment of <xref linkend="chapter-building-system"/>. In
general, the Glibc test suite is always expected to pass. However, as mentioned
above, in certain circumstances some failures are unavoidable. Here is a list
of the most common issues we are aware of:</para>

<itemizedlist>
<listitem><para>The <emphasis>math</emphasis> tests sometimes fail when running
on systems where the CPU is not a relatively new genuine Intel or authentic AMD.
Certain optimization settings are also known to be a factor here.</para></listitem>

<listitem><para>The <emphasis>gettext</emphasis> test sometimes fails due to
host system issues. The exact reasons are not yet clear.</para></listitem>

<listitem><para>The <emphasis>atime</emphasis> test sometimes fails when the
LFS partition is mounted with the <emphasis>noatime</emphasis> option, or due
to other file system quirks.</para></listitem>

<listitem><para>The <emphasis>shm</emphasis> test might fail when the host
system is running the devfs file system but doesn't have the tmpfs file system
mounted at <filename>/dev/shm</filename> due to lack of support for tmpfs in
the kernel.</para></listitem>

<listitem><para>When running on older and slower hardware, some tests might
fail due to test timeouts being exceeded.</para></listitem>
</itemizedlist>

<para>In summary, don't worry too much if you see Glibc test suite failures
here in this chapter. The Glibc in <xref linkend="chapter-building-system"/> is
the one we'll ultimately end up using, so that is the one we would really like
to see pass the tests (but even there some failures could still occur -- the
<emphasis>math</emphasis> tests, for example). When experiencing a failure,
make a note of it, then continue by reissuing the <command>make
check</command>. The test suite should pick up where it left off and continue.
You can circumvent this stop-start sequence by issuing a <command>make -k
check</command>. But if you do that, be sure to log the output so that you can
later peruse the log file and examine the total number of failures.</para>

<para>Though it is a harmless message, the install stage of Glibc will at the
end complain about the absence of <filename>/tools/etc/ld.so.conf</filename>.
Prevent this confusing little warning with:</para>

<screen><userinput>mkdir /tools/etc
touch /tools/etc/ld.so.conf</userinput></screen>

<para>Now install the package:</para>

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

<para>Different countries and cultures have varying conventions for how to
communicate. These conventions range from very simple ones, such as the format
for representing dates and times, to very complex ones, such as the language
spoken. The <quote>internationalization</quote> of GNU programs works by means
of <emphasis>locales</emphasis>.</para>

<note><para>If you are not running the test suites here in this chapter as per
our recommendation, there is little point in installing the locales now. We'll
be installing the locales in the next chapter.</para></note>

<para>If you still want to install the Glibc locales anyway, the following
command will do so:</para>

<screen><userinput>make localedata/install-locales</userinput></screen>

<para>An alternative to running the previous command is to install only those
locales which you need or want. This can be achieved by using the
<command>localedef</command> command. Information on this can be found in
the <filename>INSTALL</filename> file in the Glibc source. However, there are
a number of locales that are essential for the tests of future packages to
pass, in particular, the <emphasis>libstdc++</emphasis> tests from GCC. The
following instructions, instead of the install-locales target above, will
install the minimum set of locales necessary for the tests to run
successfully:</para>

<screen><userinput>mkdir -p /tools/lib/locale
localedef -i de_DE -f ISO-8859-1 de_DE
localedef -i de_DE@euro -f ISO-8859-15 de_DE@euro
localedef -i en_HK -f ISO-8859-1 en_HK
localedef -i en_PH -f ISO-8859-1 en_PH
localedef -i en_US -f ISO-8859-1 en_US
localedef -i es_MX -f ISO-8859-1 es_MX
localedef -i fa_IR -f UTF-8 fa_IR
localedef -i fr_FR -f ISO-8859-1 fr_FR
localedef -i fr_FR@euro -f ISO-8859-15 fr_FR@euro
localedef -i it_IT -f ISO-8859-1 it_IT
localedef -i ja_JP -f EUC-JP ja_JP</userinput></screen>

</sect2>

<sect2><title/>
<para>The details on this package are found in <xref linkend="contents-glibc"/>.</para>
</sect2>

</sect1>