Cross-Compiled Linux From Scratch - Embedded - Version GIT-20190419-x86

Chapter 4. Constructing Cross-Compile Tools

4.6. Binutils-2.27

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

4.6.1. Installation of Cross Binutils

It is important that Binutils be the first package compiled because both the C library and GCC perform various tests on the available linker and assembler to determine which of their own features to enable.

The Binutils documentation recommends building Binutils outside of the source directory in a dedicated build directory: 

mkdir -v ../binutils-build
cd ../binutils-build

Prepare Binutils for compilation: 

../binutils-2.27/configure \
   --prefix=${CLFS}/cross-tools \
   --target=${CLFS_TARGET} \
   --with-sysroot=${CLFS}/cross-tools/${CLFS_TARGET} \
   --disable-nls \
   --disable-multilib

The meaning of the configure options:

--prefix=${CLFS}/cross-tools

This tells the configure script to prepare to install the package in the ${CLFS}/cross-tools directory.

--target=${CLFS_TARGET}

This creates a cross-architecture executable that creates files for ${CLFS_TARGET} but runs on the host system.

--with-sysroot=${CLFS}/cross-tools/${CLFS_TARGET}

This tells configure that ${CLFS} is going to be the root of our system. It will now use the specified sysroot, ${CLFS}, as a prefix of the default search paths.

--disable-nls

This disables internationalization as i18n is not needed for the cross-compile tools.

--disable-multilib

This option disables the building of a multilib capable binutils.

Compile the package: 

make configure-host
make

The meaning of the make options:

configure-host

This checks the host environment and makes sure all the necessary tools are available to compile Binutils.

Install the package: 

make install

4.6.2. Contents of Binutils

Installed programs: addr2line, ar, as, c++filt, elfedit, gprof, ld, nm, objcopy, objdump, ranlib, readelf, size, strings, and strip
Installed libraries: libiberty.a, libbfd.[a,so], and libopcodes.[a,so]

Short Descriptions

addr2line

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 determine which source file and line number are associated with the address

ar

Creates, modifies, and extracts from archives

as

An assembler that assembles the output of gcc into object files

c++filt

Used by the linker to de-mangle C++ and Java symbols and to keep overloaded functions from clashing

elfedit

Examine and modify ELF metadata within an ELF object

gprof

Displays call graph profile data

ld

A linker that combines a number of object and archive files into a single file, relocating their data and tying up symbol references

nm

Lists the symbols occurring in a given object file

objcopy

Copy the contents of one object file to another

objdump

Displays information about the given object file, with options controlling the particular information to display; the information shown is useful to programmers who are working on the compilation tools

ranlib

Generates an index of the contents of an archive and stores it in the archive; the index lists all of the symbols defined by archive members that are relocatable object files

readelf

Displays information about ELF type binaries

size

Lists the section sizes and the total size for the given object files

strings

Outputs, for each given file, the sequences of printable characters that are of at least the specified length (defaulting to four); for object files, it prints, by default, only the strings from the initializing and loading sections while for other types of files, it scans the entire file

strip

Discards symbols from object files

libiberty

Contains routines used by various GNU programs, including getopt, obstack, strerror, strtol, and strtoul

libbfd

The Binary File Descriptor library

libopcodes

A library for dealing with opcodes—the “readable text” versions of instructions for the processor; it is used for building utilities like objdump.