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[linux_from_scratch.git] / BOOK / chapter06 / binutils.xml

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<sect1 id="ch-system-binutils" xreflabel="Binutils">
<title>Binutils-&binutils-version;</title>
<?dbhtml filename="binutils.html"?>

<indexterm zone="ch-system-binutils"><primary sortas="a-Binutils">Binutils</primary></indexterm>

<para>The Binutils package contains a linker, an assembler, and other tools for
handling object files.</para>

<screen>&buildtime; 1.4 SBU
&diskspace; 167 MB</screen>

<para>Binutils installation depends on: Bash, Coreutils, Diffutils, GCC, Gettext,
Glibc, Grep, Make, Perl, Sed, Texinfo.</para>



<sect2><title>Installation of Binutils</title>

<para>Now is an appropriate time to verify that your pseudo terminals (PTYs) are
working properly inside the chroot environment. We will again quickly check that
everything is set up correctly by performing a simple test:</para>

<screen><userinput>expect -c "spawn ls"</userinput></screen>

<para>If you receive the message:</para>

<blockquote><screen>The system has no more ptys.  Ask your system administrator to create more.</screen></blockquote>

<para>Your chroot environment is not set up for proper PTY operation. In this
case there is no point in running the test suites for Binutils and GCC until you
are able to resolve the issue. Please refer back to <xref linkend="ch-system-proc"/>
and the <xref linkend="ch-system-MAKEDEV"/> section and perform the recommended steps
to fix the problem.</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 un-setting
or modifying them when building Binutils.</para>

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

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

<para>Now prepare Binutils for compilation:</para>

<screen><userinput>../binutils-&binutils-version;/configure --prefix=/usr --enable-shared</userinput></screen>

<para>Compile the package:</para>

<screen><userinput>make tooldir=/usr</userinput></screen>

<para>Normally, the <emphasis>tooldir</emphasis> (the directory where the
executables end up) is set to $(exec_prefix)/$(target_alias), which expands
into, for example, <filename>/usr/i686-pc-linux-gnu</filename>. Since we only
build for our own system, we don't need this target specific directory in
<filename>/usr</filename>. That setup would be used if the system was used to
cross-compile (for example compiling a package on an Intel machine that
generates code that can be executed on PowerPC machines).</para>

<important><para>The test suite for Binutils in this section is considered
<emphasis>critical</emphasis>. Our advice is to not skip it under any
circumstances.</para></important>

<para>Test the results:</para>

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

<para>The test suite notes from <xref linkend="ch-tools-binutils-pass2"/> are still
very much appropriate here. Be sure to refer back there should you have any
doubts.</para>

<para>Install the package:</para>

<screen><userinput>make tooldir=/usr install</userinput></screen>

<para>Install the <emphasis>libiberty</emphasis> header file that is needed by
some packages:</para>

<screen><userinput>cp ../binutils-&binutils-version;/include/libiberty.h /usr/include</userinput></screen>

</sect2>


<sect2 id="contents-binutils"><title>Contents of Binutils</title>

<para><emphasis>Installed programs</emphasis>: addr2line, ar, as, c++filt,
gprof, ld, nm, objcopy, objdump, ranlib, readelf, size, strings and
strip</para>

<para><emphasis>Installed libraries</emphasis>: libiberty.a, libbfd.[a,so] and
libopcodes.[a,so]</para>

</sect2>


<sect2><title>Short descriptions</title>

<indexterm zone="ch-system-binutils addr2line"><primary sortas="b-addr2line">addr2line</primary></indexterm>
<para id="addr2line"><command>addr2line</command> translates program addresses to file
names and line numbers. Given an address and the name of an executable, it
uses the debugging information in the executable to figure out which source
file and line number are associated with the address.</para>

<indexterm zone="ch-system-binutils ar"><primary sortas="b-ar">ar</primary></indexterm>
<para id="ar"><command>ar</command> creates, modifies, and extracts from archives. An archive
is a single file holding a collection of other files in a structure that makes
it possible to retrieve the original individual files (called members of
the archive).</para>

<indexterm zone="ch-system-binutils as"><primary sortas="b-as">as</primary></indexterm>
<para id="as"><command>as</command> is an assembler. It assembles the output of
gcc into object files.</para>

<indexterm zone="ch-system-binutils c-filt"><primary sortas="b-c++filt">c++filt</primary></indexterm>
<para id="c-filt"><command>c++filt</command> is used by the linker to de-mangle C++ and
Java symbols, to keep overloaded functions from clashing.</para>

<indexterm zone="ch-system-binutils gprof"><primary sortas="b-gprof">gprof</primary></indexterm>
<para id="gprof"><command>gprof</command> displays call graph profile data.</para>

<indexterm zone="ch-system-binutils ld"><primary sortas="b-ld">ld</primary></indexterm>
<para id="ld"><command>ld</command> is a linker. It combines a number of object
and archive files into a single file, relocating their data and tying up symbol
references.</para>

<indexterm zone="ch-system-binutils nm"><primary sortas="b-nm">nm</primary></indexterm>
<para id="nm"><command>nm</command> lists the symbols occurring in a given object file.</para>

<indexterm zone="ch-system-binutils objcopy"><primary sortas="b-objcopy">objcopy</primary></indexterm>
<para id="objcopy"><command>objcopy</command> is used to translate one type of object
file into another.</para>

<indexterm zone="ch-system-binutils objdump"><primary sortas="b-objdump">objdump</primary></indexterm>
<para id="objdump"><command>objdump</command> displays information about the given
object file, with options controlling what particular information to display.
The information shown is mostly only useful to programmers who are working on
the compilation tools.</para>

<indexterm zone="ch-system-binutils ranlib"><primary sortas="b-ranlib">ranlib</primary></indexterm>
<para id="ranlib"><command>ranlib</command> generates an index of the contents of an
archive, and stores it in the archive. The index lists all the symbols defined
by archive members that are relocatable object files.</para>

<indexterm zone="ch-system-binutils readelf"><primary sortas="b-readelf">readelf</primary></indexterm>
<para id="readelf"><command>readelf</command> displays information about elf type binaries.</para>

<indexterm zone="ch-system-binutils size"><primary sortas="b-size">size</primary></indexterm>
<para id="size"><command>size</command> lists the section sizes -- and the grand
total -- for the given object files.</para>

<indexterm zone="ch-system-binutils strings"><primary sortas="b-strings">strings</primary></indexterm>
<para id="strings"><command>strings</command> outputs, for each given file, the sequences
of printable characters that are of at least the specified length (defaulting to 4).
For object files it prints, by default, only the strings from the initializing
and loading sections. For other types of files it scans the whole file.</para>

<indexterm zone="ch-system-binutils strip"><primary sortas="b-strip">strip</primary></indexterm>
<para id="strip"><command>strip</command> discards symbols from object files.</para>

<indexterm zone="ch-system-binutils libiberty"><primary sortas="c-libiberty">libiberty</primary></indexterm>
<para id="libiberty"><command>libiberty</command> contains routines used by various GNU
programs, including getopt, obstack, strerror, strtol and strtoul.</para>

<indexterm zone="ch-system-binutils libbfd"><primary sortas="c-libbfd">libbfd</primary></indexterm>
<para id="libbfd"><command>libbfd</command> is the Binary File Descriptor library.</para>

<indexterm zone="ch-system-binutils libopcodes"><primary sortas="c-libopcodes">libopcodes</primary></indexterm>
<para id="libopcodes"><command>libopcodes</command> is a library for dealing with opcodes.
It is used for building utilities like objdump. Opcodes are the <quote>readable
text</quote> versions of instructions for the processor.</para>

</sect2>



</sect1>