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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
<chapter id='using-the-command-line'>
<title>Using the Command Line</title>
<para>
Recall that earlier the manual discussed how to use an existing toolchain
tarball that had been installed into <filename>/opt/poky</filename>,
which is outside of the
<ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
(see the section "<link linkend='using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball)</link>".
And, that sourcing your architecture-specific environment setup script
initializes a suitable cross-toolchain development environment.
During the setup, locations for the compiler, QEMU scripts, QEMU binary,
a special version of <filename>pkgconfig</filename> and other useful
utilities are added to the <filename>PATH</filename> variable.
Variables to assist <filename>pkgconfig</filename> and <filename>autotools</filename>
are also defined so that,
for example, <filename>configure.sh</filename> can find pre-generated
test results for tests that need target hardware on which to run.
These conditions allow you to easily use the toolchain outside of the
OpenEmbedded build environment on both autotools-based projects and
Makefile-based projects.
</para>
<section id='autotools-based-projects'>
<title>Autotools-Based Projects</title>
<para>
Once you have a suitable cross-toolchain installed, it is very easy to
develop a project outside of the OpenEmbedded build system.
This section presents a simple "Helloworld" example that shows how
to set up, compile, and run the project.
</para>
<section id='creating-and-running-a-project-based-on-gnu-autotools'>
<title>Creating and Running a Project Based on GNU Autotools</title>
<para>
Follow these steps to create a simple autotools-based project:
<orderedlist>
<listitem><para><emphasis>Create your directory:</emphasis>
Create a clean directory for your project and then make
that directory your working location:
<literallayout class='monospaced'>
$ mkdir $HOME/helloworld
$ cd $HOME/helloworld
</literallayout></para></listitem>
<listitem><para><emphasis>Populate the directory:</emphasis>
Create <filename>hello.c</filename>, <filename>Makefile.am</filename>,
and <filename>configure.in</filename> files as follows:
<itemizedlist>
<listitem><para>For <filename>hello.c</filename>, include
these lines:
<literallayout class='monospaced'>
#include <stdio.h>
main()
{
printf("Hello World!\n");
}
</literallayout></para></listitem>
<listitem><para>For <filename>Makefile.am</filename>,
include these lines:
<literallayout class='monospaced'>
bin_PROGRAMS = hello
hello_SOURCES = hello.c
</literallayout></para></listitem>
<listitem><para>For <filename>configure.in</filename>,
include these lines:
<literallayout class='monospaced'>
AC_INIT(hello.c)
AM_INIT_AUTOMAKE(hello,0.1)
AC_PROG_CC
AC_CONFIG_HEADERS(config.h)
AC_PROG_INSTALL
AC_OUTPUT(Makefile)
</literallayout></para></listitem>
</itemizedlist></para></listitem>
<listitem><para><emphasis>Source the cross-toolchain
environment setup file:</emphasis>
Installation of the cross-toolchain creates a cross-toolchain
environment setup script in <filename>/opt/poky/<release></filename>.
Before you can use the tools to develop your project, you must
source this setup script.
The script begins with the string "environment-setup" and contains
the machine architecture, which is followed by the string
"poky-linux".
Here is an example for an environment setup using the
32-bit Intel x86 Architecture and using the
&DISTRO_NAME; Yocto Project release:
<literallayout class='monospaced'>
$ source /opt/poky/&DISTRO;/environment-setup-i586-poky-linux
</literallayout></para></listitem>
<listitem><para><emphasis>Generate the local <filename>aclocal.m4</filename>
files and create the configure script:</emphasis>
The following GNU Autotools generate the local
<filename>aclocal.m4</filename> files and create the
configure script:
<literallayout class='monospaced'>
$ aclocal
$ autoconf
</literallayout></para></listitem>
<listitem><para><emphasis>Generate files needed by GNU
coding standards:</emphasis>
GNU coding standards require certain files in order for the
project to be compliant.
This command creates those files:
<literallayout class='monospaced'>
$ touch NEWS README AUTHORS ChangLog
</literallayout></para></listitem>
<listitem><para><emphasis>Generate the <filename>configure</filename>
file:</emphasis>
This command generates the <filename>configure</filename>:
<literallayout class='monospaced'>
$ automake -a
</literallayout></para></listitem>
<listitem><para><emphasis>Cross-compile the project:</emphasis>
This command compiles the project using the cross-compiler:
<literallayout class='monospaced'>
$ ./configure ${CONFIGURE_FLAGS}
</literallayout></para></listitem>
<listitem><para><emphasis>Make and install the project:</emphasis>
These two commands generate and install the project into the
destination directory:
<literallayout class='monospaced'>
$ make
$ make install DESTDIR=./tmp
</literallayout></para></listitem>
<listitem><para><emphasis>Verify the installation:</emphasis>
This command is a simple way to verify the installation
of your project.
Running the command prints the architecture on which
the binary file can run.
This architecture should be the same architecture that
the installed cross-toolchain supports.
<literallayout class='monospaced'>
$ file ./tmp/usr/local/bin/hello
</literallayout></para></listitem>
<listitem><para><emphasis>Execute your project:</emphasis>
To execute the project in the shell, simply enter the name.
You could also copy the binary to the actual target hardware
and run the project there as well:
<literallayout class='monospaced'>
$ ./hello
</literallayout>
As expected, the project displays the "Hello World!" message.
</para></listitem>
</orderedlist>
</para>
</section>
<section id='passing-host-options'>
<title>Passing Host Options</title>
<para>
For an Autotools-based project, you can use the cross-toolchain by just
passing the appropriate host option to <filename>configure.sh</filename>.
The host option you use is derived from the name of the environment setup
script in <filename>/opt/poky</filename> resulting from installation of the
cross-toolchain tarball.
For example, the host option for an ARM-based target that uses the GNU EABI
is <filename>armv5te-poky-linux-gnueabi</filename>.
You will notice that the name of the script is
<filename>environment-setup-armv5te-poky-linux-gnueabi</filename>.
Thus, the following command works:
<literallayout class='monospaced'>
$ ./configure --host=armv5te-poky-linux-gnueabi \
--with-libtool-sysroot=<sysroot-dir>
</literallayout>
</para>
<para>
This single command updates your project and rebuilds it using the appropriate
cross-toolchain tools.
<note>
If <filename>configure</filename> script results in problems recognizing the
<filename>--with-libtool-sysroot=<sysroot-dir></filename> option,
regenerate the script to enable the support by doing the following and then
re-running the script:
<literallayout class='monospaced'>
$ libtoolize --automake
$ aclocal -I ${OECORE_NATIVE_SYSROOT}/usr/share/aclocal \
[-I <dir_containing_your_project-specific_m4_macros>]
$ autoconf
$ autoheader
$ automake -a
</literallayout>
</note>
</para>
</section>
</section>
<section id='makefile-based-projects'>
<title>Makefile-Based Projects</title>
<para>
For a Makefile-based project, you use the cross-toolchain by making sure
the tools are used.
You can do this as follows:
<literallayout class='monospaced'>
CC=arm-poky-linux-gnueabi-gcc
LD=arm-poky-linux-gnueabi-ld
CFLAGS=”${CFLAGS} --sysroot=<sysroot-dir>”
CXXFLAGS=”${CXXFLAGS} --sysroot=<sysroot-dir>”
</literallayout>
</para>
</section>
</chapter>
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