lfs-book/chapter06/glibc-inst.xml

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

<sect2>
<title>Glibc installation</title>

<para>Before starting to install glibc, you must cd into the
glibc-&glibc-version; directory and unpack glibc-linuxthreads inside
the glibc-&glibc-version; directory, not in /usr/src as you normally
would do.</para>

<para>This package is known to behave badly when you have changed its
default optimization flags (including the -march and -mcpu options).
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 Glibc.</para>

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

<para>We'll start by applying a patch to Glibc that fixes the following:</para>

<itemizedlist>
<listitem><para>It converts all occurrences of <emphasis>$(PERL)</emphasis>
to <emphasis>/usr/bin/perl</emphasis> in the
<filename>malloc/Makefile</filename> file. This is done because Glibc
can't autodetect the location of perl because the Perl package hasn't been
installed yet. And if Glibc thinks Perl isn't installed, the
<userinput>mtrace</userinput> perl program won't be installed
either.</para></listitem>

<listitem><para>It replaces all occurrences of <emphasis>root</emphasis>
with <emphasis>0</emphasis> in the <filename>login/Makefile</filename>
file. This is done because Glibc itself isn't installed yet and therefore
username to userid resolving isn't working yet, so a
<userinput>chown root file</userinput> will fail, however it'll work fine
if you use the numeric IDs (such as <userinput>chown 0
file</userinput>).</para></listitem>

</itemizedlist>

<para><screen><userinput>patch -Np1 -i ../glibc-&glibc-rootperl-patch-version;-root-perl.patch</userinput></screen></para>

<para>There is a potential problem that causes statically linked binaries
to crash that were linked against Glibc-2.2 or older libraries. Even though
static binaries have all the necessary parts of Glibc built-in, they still
rely on one external library set: Glibc's NSS libraries. These libraries,
among other things, tell programs where the system's password database is
(/etc/password, or NIS, or whatever other scheme has been
configured).</para>

<para>Glibc has undergone some changes since version 2.2.x and the new NSS
code is incompatible with the old one. So when Glibc is installed, it will
install its new NSS libraries and static programs will load these new NSS
libraries and start to abort with <emphasis>segmentation fault</emphasis>
error. This patch undoes a few of the changes to overcome the problem.</para>

<para>If you started chapter 5 with a host system that uses Glibc-2.2.x
or older, you must apply the following patch. We will install Glibc again at
the end of this chapter to remove this patch so you'll have a pristine Glibc
as the developers intended it.</para>

<para><screen><userinput>patch -Np1 -i ../glibc-&glibc-libnss-patch-version;-libnss.patch</userinput></screen></para>

<para>Glibc will check for the <filename>/etc/ld.so.conf</filename> file
and abort with an error if the file is missing, so we must create it:</para>

<para><screen><userinput>touch /etc/ld.so.conf</userinput></screen></para>

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

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

<para>Next, prepare Glibc to be compiled:</para>

<para><screen><userinput>../glibc-&glibc-version;/configure --prefix=/usr \
&nbsp;&nbsp;&nbsp;&nbsp;--disable-profile --enable-add-ons \
&nbsp;&nbsp;&nbsp;&nbsp;--libexecdir=/usr/bin</userinput></screen></para>

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

<itemizedlist>
<listitem><para><userinput>--disable-profile</userinput>: This disables the
building of libraries with profiling information. This command may be
omitted if you plan to do profiling.</para></listitem>

<listitem><para><userinput>--enable-add-ons</userinput>: This enables the
add-on that we install with Glibc, linuxthreads</para></listitem>

<listitem><para><userinput>--libexecdir=/usr/bin</userinput>: This will
cause the pt_chown program to be installed in the /usr/bin
directory.</para></listitem>
</itemizedlist>

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

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

<para>The missing msgfmt (from the gettext package which we will install
later in this chapter) won't cause any problems. msgfmt is used to generate
the binary translation files that are used to make your system talk in a
different language. Because these translation files have already been
generated for you, there is no need for msgfmt. You'd only need msgfmt if
you change the translation source files (the <filename>*.po</filename>
files in the <filename class="directory">po</filename> subdirectory) which
would require you to re-generate the binary files.</para>

<para>Because Glibc hasn't been installed yet, one of the tests that was
run by the configure script failed. This test is supposed to test gcc to
determine whether or not a cross-compiler is installed. However, Glibc
needs to be installed already to run this test. Since the test failed, the
configure script automatically assumed we do have a cross-compiler. We have
to override that assumption by explicitly telling Glibc we're not
cross-compiling. Not doing this has a couple of unintended side effects,
such as the timezone files not being installed.</para>

<para><screen><userinput>echo "cross-compiling = no" &gt; configparms</userinput></screen></para>

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

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

<para>We'll continue with installing the package. The Linuxthreads man
pages are not going to be installed at this point because it requires a
working Perl installation. We'll install Perl later on in this chapter,
and the man pages will be installed when Glibc is installed for the second
time at the end of this chapter.</para>

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

<para>Locales aren't installed when you ran
<userinput>make install</userinput>, so we have to do that ourselves now.
Locales are used by Glibc to make your Linux system talk in a different
language:</para>

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

<para>An alternative to running <userinput>make
localedata/install-locales</userinput> is to only install those locales
which you need or want. This can be achieved using the localedef
command. Information on this can be found in the INSTALL
file in the glibc-&glibc-version; tree.</para>

<para>To finish off the installation we'll reload Bash so it uses the
libnss files. This will also get rid of the
<emphasis>I have no name!</emphasis> message in the command prompt:</para>

<para><screen><userinput>exec /static/bin/bash --login</userinput></screen></para>

</sect2>