Copyright © 2010-2014 Linux Foundation
Permission is granted to copy, distribute and/or modify this document under the terms of the Creative Commons Attribution-Share Alike 2.0 UK: England & Wales as published by Creative Commons.
Revision History | |
---|---|
Revision 1.0 | 6 April 2011 |
Released with the Yocto Project 1.0 Release. | |
Revision 1.0.1 | 23 May 2011 |
Released with the Yocto Project 1.0.1 Release. | |
Revision 1.1 | 6 October 2011 |
Released with the Yocto Project 1.1 Release. | |
Revision 1.2 | April 2012 |
Released with the Yocto Project 1.2 Release. | |
Revision 1.3 | October 2012 |
Released with the Yocto Project 1.3 Release. | |
Revision 1.4 | April 2013 |
Released with the Yocto Project 1.4 Release. | |
Revision 1.5 | October 2013 |
Released with the Yocto Project 1.5 Release. | |
Revision 1.5.1 | January 2014 |
Released with the Yocto Project 1.5.1 Release. | |
Revision 1.6 | April 2014 |
Released with the Yocto Project 1.6 Release. | |
Revision 1.6.1 | July 2014 |
Released with the Yocto Project 1.6.1 Release. |
Table of Contents
Welcome to the Yocto Project Application Developer's Guide. This manual provides information that lets you begin developing applications using the Yocto Project.
The Yocto Project provides an application development environment based on an Application Development Toolkit (ADT) and the availability of stand-alone cross-development toolchains and other tools. This manual describes the ADT and how you can configure and install it, how to access and use the cross-development toolchains, how to customize the development packages installation, how to use command line development for both Autotools-based and Makefile-based projects, and an introduction to the Eclipse™ IDE Yocto Plug-in.
Table of Contents
Part of the Yocto Project development solution is an Application Development Toolkit (ADT). The ADT provides you with a custom-built, cross-development platform suited for developing a user-targeted product application.
Fundamentally, the ADT consists of the following:
An architecture-specific cross-toolchain and matching sysroot both built by the OpenEmbedded build system. The toolchain and sysroot are based on a Metadata configuration and extensions, which allows you to cross-develop on the host machine for the target hardware.
The Eclipse IDE Yocto Plug-in.
The Quick EMUlator (QEMU), which lets you simulate target hardware.
Various user-space tools that greatly enhance your application development experience.
The Cross-Development Toolchain consists of a cross-compiler, cross-linker, and cross-debugger that are used to develop user-space applications for targeted hardware. This toolchain is created either by running the ADT Installer script, a toolchain installer script, or through a Build Directory that is based on your Metadata configuration or extension for your targeted device. The cross-toolchain works with a matching target sysroot.
The matching target sysroot contains needed headers and libraries for generating binaries that run on the target architecture. The sysroot is based on the target root filesystem image that is built by the OpenEmbedded build system and uses the same Metadata configuration used to build the cross-toolchain.
The Eclipse IDE is a popular development environment and it fully supports development using the Yocto Project. When you install and configure the Eclipse Yocto Project Plug-in into the Eclipse IDE, you maximize your Yocto Project experience. Installing and configuring the Plug-in results in an environment that has extensions specifically designed to let you more easily develop software. These extensions allow for cross-compilation, deployment, and execution of your output into a QEMU emulation session. You can also perform cross-debugging and profiling. The environment also supports a suite of tools that allows you to perform remote profiling, tracing, collection of power data, collection of latency data, and collection of performance data.
For information about the application development workflow that uses the Eclipse IDE and for a detailed example of how to install and configure the Eclipse Yocto Project Plug-in, see the "Working Within Eclipse" section of the Yocto Project Development Manual.
The QEMU emulator allows you to simulate your hardware while running your application or image. QEMU is made available a number of ways:
If you use the ADT Installer script to install ADT, you can specify whether or not to install QEMU.
If you have cloned the poky
Git
repository to create a
Source Directory
and you have sourced the environment setup script, QEMU is
installed and automatically available.
If you have downloaded a Yocto Project release and unpacked it to create a Source Directory and you have sourced the environment setup script, QEMU is installed and automatically available.
If you have installed the cross-toolchain tarball and you have sourced the toolchain's setup environment script, QEMU is also installed and automatically available.
User-space tools are included as part of the distribution. You will find these tools helpful during development. The tools include LatencyTOP, PowerTOP, OProfile, Perf, SystemTap, and Lttng-ust. These tools are common development tools for the Linux platform.
LatencyTOP: LatencyTOP focuses on latency that causes skips in audio, stutters in your desktop experience, or situations that overload your server even when you have plenty of CPU power left.
PowerTOP: Helps you determine what software is using the most power. You can find out more about PowerTOP at https://01.org/powertop/.
OProfile: A system-wide profiler for Linux systems that is capable of profiling all running code at low overhead. You can find out more about OProfile at http://oprofile.sourceforge.net/about/. For examples on how to setup and use this tool, see the "OProfile" section in the Yocto Project Profiling and Tracing Manual.
Perf: Performance counters for Linux used to keep track of certain types of hardware and software events. For more information on these types of counters see https://perf.wiki.kernel.org/. For examples on how to setup and use this tool, see the "perf" section in the Yocto Project Profiling and Tracing Manual.
SystemTap: A free software infrastructure that simplifies information gathering about a running Linux system. This information helps you diagnose performance or functional problems. SystemTap is not available as a user-space tool through the Eclipse IDE Yocto Plug-in. See http://sourceware.org/systemtap for more information on SystemTap. For examples on how to setup and use this tool, see the "SystemTap" section in the Yocto Project Profiling and Tracing Manual.
Lttng-ust: A User-space Tracer designed to provide detailed information on user-space activity. See http://lttng.org/ust for more information on Lttng-ust.
Table of Contents
In order to develop applications, you need set up your host development system. Several ways exist that allow you to install cross-development tools, QEMU, the Eclipse Yocto Plug-in, and other tools. This chapter describes how to prepare for application development.
The following list describes installation methods that set up varying degrees of tool
availability on your system.
Regardless of the installation method you choose,
you must source
the cross-toolchain
environment setup script before you use a toolchain.
See the "Setting Up the
Cross-Development Environment" section for more information.
Avoid mixing installation methods when installing toolchains for different architectures. For example, avoid using the ADT Installer to install some toolchains and then hand-installing cross-development toolchains by running the toolchain installer for different architectures. Mixing installation methods can result in situations where the ADT Installer becomes unreliable and might not install the toolchain.
If you must mix installation methods, you might avoid problems by deleting
/var/lib/opkg
, thus purging the opkg
package
metadata
Use the ADT installer script: This method is the recommended way to install the ADT because it automates much of the process for you. For example, you can configure the installation to install the QEMU emulator and the user-space NFS, specify which root filesystem profiles to download, and define the target sysroot location.
Use an existing toolchain: Using this method, you select and download an architecture-specific toolchain installer and then run the script to hand-install the toolchain. If you use this method, you just get the cross-toolchain and QEMU - you do not get any of the other mentioned benefits had you run the ADT Installer script.
Use the toolchain from within the Build Directory: If you already have a Build Directory, you can build the cross-toolchain within the directory. However, like the previous method mentioned, you only get the cross-toolchain and QEMU - you do not get any of the other benefits without taking separate steps.
To run the ADT Installer, you need to get the ADT Installer tarball, be sure you have the necessary host development packages that support the ADT Installer, and then run the ADT Installer Script.
For a list of the host packages needed to support ADT installation and use, see the "ADT Installer Extras" lists in the "Required Packages for the Host Development System" section of the Yocto Project Reference Manual.
The ADT Installer is contained in the ADT Installer tarball. You can get the tarball using either of these methods:
Download the Tarball: You can download the tarball from http://downloads.yoctoproject.org/releases/yocto/yocto-1.6.1/adt-installer into any directory.
Build the Tarball: You can use BitBake to generate the tarball inside an existing Build Directory.
If you use BitBake to generate the ADT Installer
tarball, you must source
the
environment setup script
(oe-init-build-env
or
oe-init-build-env-memres
)
located in the Source Directory before running the
bitbake
command that creates the
tarball.
The following example commands establish
the
Source Directory,
check out the current release branch, set up the
build environment while also creating the default
Build Directory, and run the
bitbake
command that results in the
tarball
poky/build/tmp/deploy/sdk/adt_installer.tar.bz2
:
local.conf
file is properly
configured.
$ cd ~ $ git clone git://git.yoctoproject.org/poky $ cd poky $ git checkout -b daisy origin/daisy $ source oe-init-build-env $ bitbake adt-installer
Before running the ADT Installer script, you need to unpack the tarball.
You can unpack the tarball in any directory you wish.
For example, this command copies the ADT Installer tarball from where
it was built into the home directory and then unpacks the tarball into
a top-level directory named adt-installer
:
$ cd ~ $ cp poky/build/tmp/deploy/sdk/adt_installer.tar.bz2 $HOME $ tar -xjf adt_installer.tar.bz2
Unpacking it creates the directory adt-installer
,
which contains the ADT Installer script (adt_installer
)
and its configuration file (adt_installer.conf
).
Before you run the script, however, you should examine the ADT Installer configuration file and be sure you are going to get what you want. Your configurations determine which kernel and filesystem image are downloaded.
The following list describes the configurations you can define for the ADT Installer.
For configuration values and restrictions, see the comments in
the adt-installer.conf
file:
YOCTOADT_REPO
: This area
includes the IPKG-based packages and the root filesystem upon which
the installation is based.
If you want to set up your own IPKG repository pointed to by
YOCTOADT_REPO
, you need to be sure that the
directory structure follows the same layout as the reference directory
set up at http://adtrepo.yoctoproject.org.
Also, your repository needs to be accessible through HTTP.
YOCTOADT_TARGETS
: The machine
target architectures for which you want to set up cross-development
environments.
YOCTOADT_QEMU
: Indicates whether
or not to install the emulator QEMU.
YOCTOADT_NFS_UTIL
: Indicates whether
or not to install user-mode NFS.
If you plan to use the Eclipse IDE Yocto plug-in against QEMU,
you should install NFS.
portmap
or rpcbind
.
If you are running rpcbind
, you will also need to add the
-i
option when rpcbind
starts up.
Please make sure you understand the security implications of doing this.
You might also have to modify your firewall settings to allow
NFS booting to work.YOCTOADT_ROOTFS_<arch>
: The root
filesystem images you want to download from the
YOCTOADT_IPKG_REPO
repository.
YOCTOADT_TARGET_SYSROOT_IMAGE_<arch>
: The
particular root filesystem used to extract and create the target sysroot.
The value of this variable must have been specified with
YOCTOADT_ROOTFS_<arch>
.
For example, if you downloaded both minimal
and
sato-sdk
images by setting
YOCTOADT_ROOTFS_<arch>
to "minimal sato-sdk", then YOCTOADT_ROOTFS_<arch>
must be set to either "minimal" or "sato-sdk".
YOCTOADT_TARGET_SYSROOT_LOC_<arch>
: The
location on the development host where the target sysroot is created.
After you have configured the adt_installer.conf
file,
run the installer using the following command:
$ cd adt-installer $ ./adt_installer
Once the installer begins to run, you are asked to enter the
location for cross-toolchain installation.
The default location is
/opt/poky/<release>
.
After either accepting the default location or selecting your
own location, you are prompted to run the installation script
interactively or in silent mode.
If you want to closely monitor the installation,
choose “I” for interactive mode rather than “S” for silent mode.
Follow the prompts from the script to complete the installation.
Once the installation completes, the ADT, which includes the
cross-toolchain, is installed in the selected installation
directory.
You will notice environment setup files for the cross-toolchain
in the installation directory, and image tarballs in the
adt-installer
directory according to your
installer configurations, and the target sysroot located
according to the
YOCTOADT_TARGET_SYSROOT_LOC_<arch>
variable also in your configuration file.
If you want to simply install a cross-toolchain by hand, you can
do so by running the toolchain installer.
The installer includes the pre-built cross-toolchain, the
runqemu
script, and support files.
If you use this method to install the cross-toolchain, you
might still need to install the target sysroot by installing and
extracting it separately.
For information on how to install the sysroot, see the
"Extracting the Root Filesystem" section.
Follow these steps:
Get your toolchain installer using one of the following methods:
Go to
http://downloads.yoctoproject.org/releases/yocto/yocto-1.6.1/toolchain/
and find the folder that matches your host
development system (i.e. i686
for 32-bit machines or x86_64
for 64-bit machines).
Go into that folder and download the toolchain
installer whose name includes the appropriate target
architecture.
The toolchains provided by the Yocto Project
are based off of the
core-image-sato
image and
contain libraries appropriate for developing
against that image.
For example, if your host development system is a
64-bit x86 system and you are going to use
your cross-toolchain for a 32-bit x86
target, go into the x86_64
folder and download the following installer:
poky-eglibc-x86_64-core-image-sato-i586-toolchain-1.6.1.sh
Build your own toolchain installer. For cases where you cannot use an installer from the download area, you can build your own as described in the "Optionally Building a Toolchain Installer" section.
Once you have the installer, run it to install the toolchain:
The following command shows how to run the installer
given a toolchain tarball for a 64-bit x86 development host
system and a 32-bit x86 target architecture.
The example assumes the toolchain installer is located
in ~/Downloads/
.
$ ~/Downloads/poky-eglibc-x86_64-core-image-sato-i586-toolchain-1.6.1.sh
The first thing the installer prompts you for is the
directory into which you want to install the toolchain.
The default directory used is
/opt/poky/1.6.1
.
If you do not have write permissions for the directory
into which you are installing the toolchain, the
toolchain installer notifies you and exits.
Be sure you have write permissions in the directory and
run the installer again.
When the script finishes, the cross-toolchain is installed. You will notice environment setup files for the cross-toolchain in the installation directory.
A final way of making the cross-toolchain available is to use BitBake
to generate the toolchain within an existing
Build Directory.
This method does not install the toolchain into the default
/opt
directory.
As with the previous method, if you need to install the target sysroot, you must
do that separately as well.
Follow these steps to generate the toolchain into the Build Directory:
Set up the Build Environment:
Source the OpenEmbedded build environment setup
script (i.e.
oe-init-build-env
or
oe-init-build-env-memres
)
located in the
Source Directory.
Check your Local Configuration File:
At this point, you should be sure that the
MACHINE
variable
in the local.conf
file found in the
conf
directory of the Build Directory
is set for the target architecture.
Comments within the local.conf
file
list the values you can use for the
MACHINE
variable.
MACHINE
variable in the local.conf
file and
re-run the bitbake
command.
Generate the Cross-Toolchain:
Run bitbake meta-ide-support
to
complete the cross-toolchain generation.
Once the bitbake
command finishes,
the cross-toolchain is
generated and populated within the Build Directory.
You will notice environment setup files for the
cross-toolchain that contain the string
"environment-setup
" in the
Build Directory's tmp
folder.
Be aware that when you use this method to install the toolchain, you still need to separately extract and install the sysroot filesystem. For information on how to do this, see the "Extracting the Root Filesystem" section.
Before you can develop using the cross-toolchain, you need to set up the
cross-development environment by sourcing the toolchain's environment setup script.
If you used the ADT Installer or hand-installed cross-toolchain,
then you can find this script in the directory you chose for installation.
For this release, the default installation directory is
/opt/poky/1.6.1
.
If you installed the toolchain in the
Build Directory,
you can find the environment setup
script for the toolchain in the Build Directory's tmp
directory.
Be sure to run the environment setup script that matches the
architecture for which you are developing.
Environment setup scripts begin with the string
"environment-setup
" and include as part of their
name the architecture.
For example, the toolchain environment setup script for a 64-bit
IA-based architecture installed in the default installation directory
would be the following:
/opt/poky/1.6.1/environment-setup-x86_64-poky-linux
You will need to have a kernel and filesystem image to boot using your hardware or the QEMU emulator. Furthermore, if you plan on booting your image using NFS or you want to use the root filesystem as the target sysroot, you need to extract the root filesystem.
To get the kernel and filesystem images, you either have to build them or download pre-built versions. You can find examples for both these situations in the "A Quick Test Run" section of the Yocto Project Quick Start.
The Yocto Project ships basic kernel and filesystem images for several
architectures (x86
, x86-64
,
mips
, powerpc
, and arm
)
that you can use unaltered in the QEMU emulator.
These kernel images reside in the release
area - http://downloads.yoctoproject.org/releases/yocto/yocto-1.6.1/machines
and are ideal for experimentation using Yocto Project.
For information on the image types you can build using the OpenEmbedded build system,
see the
"Images" chapter in
the Yocto Project Reference Manual.
If you are planning on developing against your image and you are not
building or using one of the Yocto Project development images
(e.g. core-image-*-dev
), you must be sure to
include the development packages as part of your image recipe.
Furthermore, if you plan on remotely deploying and debugging your
application from within the
Eclipse IDE, you must have an image that contains the Yocto Target Communication
Framework (TCF) agent (tcf-agent
).
By default, the Yocto Project provides only one type of pre-built
image that contains the tcf-agent
.
And, those images are SDK (e.g.core-image-sato-sdk
).
If you want to use a different image type that contains the tcf-agent
,
you can do so one of two ways:
Modify the conf/local.conf
configuration in
the Build Directory
and then rebuild the image.
With this method, you need to modify the
EXTRA_IMAGE_FEATURES
variable to have the value of "tools-debug" before rebuilding the image.
Once the image is rebuilt, the tcf-agent
will be included
in the image and is launched automatically after the boot.
Manually build the tcf-agent
.
To build the agent, follow these steps:
Be sure the ADT is installed as described in the "Installing the ADT and Toolchains" section.
Set up the cross-development environment as described in the "Setting Up the Cross-Development Environment" section.
Get the tcf-agent
source code using
the following commands:
$ git clone http://git.eclipse.org/gitroot/tcf/org.eclipse.tcf.agent.git $ cd org.eclipse.tcf.agent/agent
Locate the
Makefile.inc
file inside the
agent
folder and modify it
for the cross-compilation environment by setting the
OPSYS
and
MACHINE
variables according to your target.
Use the cross-development tools to build the
tcf-agent
.
Before you "Make" the file, be sure your cross-tools are set up first.
See the "Makefile-Based Projects"
section for information on how to make sure the cross-tools are set up
correctly.
If the build is successful, the tcf-agent
output will
be obj/$(OPSYS)/$(MACHINE)/Debug/agent
.
Deploy the agent into the image's root filesystem.
If you install your toolchain by hand or build it using BitBake and you need a root filesystem, you need to extract it separately. If you use the ADT Installer to install the ADT, the root filesystem is automatically extracted and installed.
Here are some cases where you need to extract the root filesystem:
You want to boot the image using NFS.
You want to use the root filesystem as the target sysroot. For example, the Eclipse IDE environment with the Eclipse Yocto Plug-in installed allows you to use QEMU to boot under NFS.
You want to develop your target application using the root filesystem as the target sysroot.
To extract the root filesystem, first source
the cross-development environment setup script.
If you built the toolchain in the Build Directory, you will find
the toolchain environment script in the
tmp
directory.
If you installed the toolchain by hand, the environment setup
script is located in /opt/poky/1.6.1
.
After sourcing the environment script, use the
runqemu-extract-sdk
command and provide the
filesystem image.
Following is an example.
The second command sets up the environment.
In this case, the setup script is located in the
/opt/poky/1.6.1
directory.
The third command extracts the root filesystem from a previously
built filesystem that is located in the
~/Downloads
directory.
Furthermore, this command extracts the root filesystem into the
qemux86-sato
directory:
$ cd ~ $ source /opt/poky/1.6.1/environment-setup-i586-poky-linux $ runqemu-extract-sdk \ ~/Downloads/core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2 \ $HOME/qemux86-sato
You could now point to the target sysroot at
qemux86-sato
.
As an alternative to locating and downloading a toolchain installer, you can build the toolchain installer one of two ways if you have a Build Directory:
Use bitbake meta-toolchain
.
This method requires you to still install the target
sysroot by installing and extracting it separately.
For information on how to install the sysroot, see the
"Extracting the Root Filesystem"
section.
Use bitbake <image> -c populate_sdk
.
This method has significant advantages over the previous method
because it results in a toolchain installer that contains the
sysroot that matches your target root filesystem.
Another powerful feature is that the toolchain is
completely self-contained.
The binaries are linked against their own copy of
libc
, which results in no dependencies
on the target system.
To achieve this, the pointer to the dynamic loader is
configured at install time since that path cannot be dynamically
altered.
This is the reason for a wrapper around the
populate_sdk
archive.
Another feature is that only one set of cross-canadian
toolchain binaries are produced per architecture.
This feature takes advantage of the fact that the target
hardware can be passed to gcc
as a set of
compiler options.
Those options are set up by the environment script and
contained in variables like CC and LD.
This reduces the space needed for the tools.
Understand, however, that a sysroot is still needed for every
target since those binaries are target-specific.
Remember, before using any BitBake command, you
must source the build environment setup script
(i.e.
oe-init-build-env
or
oe-init-build-env-memres
)
located in the Source Directory and you must make sure your
conf/local.conf
variables are correct.
In particular, you need to be sure the
MACHINE
variable matches the architecture for which you are building and that
the
SDKMACHINE
variable is correctly set if you are building a toolchain designed to
run on an architecture that differs from your current development host
machine (i.e. the build machine).
When the bitbake
command completes, the toolchain
installer will be in
tmp/deploy/sdk
in the Build Directory.
IMAGE_INSTALL
variable inside your local.conf
file to
install the appropriate library packages.
Following is an example using eglibc
static
development libraries:
IMAGE_INSTALL_append = " eglibc-staticdev"
Table of Contents
Because the Yocto Project is suited for embedded Linux development, it is likely that you will need to customize your development packages installation. For example, if you are developing a minimal image, then you might not need certain packages (e.g. graphics support packages). Thus, you would like to be able to remove those packages from your target sysroot.
The OpenEmbedded build system supports the generation of sysroot files using three different Package Management Systems (PMS):
OPKG: A less well known PMS whose use
originated in the OpenEmbedded and OpenWrt embedded Linux projects.
This PMS works with files packaged in an .ipk
format.
See http://en.wikipedia.org/wiki/Opkg for more
information about OPKG.
RPM: A more widely known PMS intended for GNU/Linux
distributions.
This PMS works with files packaged in an .rms
format.
The build system currently installs through this PMS by default.
See http://en.wikipedia.org/wiki/RPM_Package_Manager
for more information about RPM.
Debian: The PMS for Debian-based systems
is built on many PMS tools.
The lower-level PMS tool dpkg
forms the base of the Debian PMS.
For information on dpkg see
http://en.wikipedia.org/wiki/Dpkg.
Whichever PMS you are using, you need to be sure that the
PACKAGE_CLASSES
variable in the conf/local.conf
file is set to reflect that system.
The first value you choose for the variable specifies the package file format for the root
filesystem at sysroot.
Additional values specify additional formats for convenience or testing.
See the configuration file for details.
package.bbclass
"
section in the Yocto Project Reference Manual.
As an example, consider a scenario where you are using OPKG and you want to add
the libglade
package to the target sysroot.
First, you should generate the IPK file for the
libglade
package and add it
into a working opkg
repository.
Use these commands:
$ bitbake libglade $ bitbake package-index
Next, source the environment setup script found in the
Source Directory.
Follow that by setting up the installation destination to point to your
sysroot as <sysroot_dir>
.
Finally, have an OPKG configuration file <conf_file>
that corresponds to the opkg
repository you have just created.
The following command forms should now work:
$ opkg-cl –f <conf_file> -o <sysroot_dir> update $ opkg-cl –f <cconf_file> -o <sysroot_dir> \ --force-overwrite install libglade $ opkg-cl –f <cconf_file> -o <sysroot_dir> \ --force-overwrite install libglade-dbg $ opkg-cl –f <conf_file> -o <sysroot_dir> \ --force-overwrite install libglade-dev
Table of Contents
Recall that earlier the manual discussed how to use an existing toolchain
tarball that had been installed into the default installation
directory, /opt/poky/1.6.1
, which is outside of the
Build Directory
(see the section "Using a Cross-Toolchain Tarball)".
And, that sourcing your architecture-specific environment setup script
initializes a suitable cross-toolchain development environment.
During this setup, locations for the compiler, QEMU scripts, QEMU binary,
a special version of pkgconfig
and other useful
utilities are added to the PATH
variable.
Also, variables to assist
pkgconfig
and autotools
are also defined so that, for example, configure.sh
can find pre-generated test results for tests that need target hardware
on which to run.
Collectively, these conditions allow you to easily use the toolchain outside of the OpenEmbedded build environment on both Autotools-based projects and Makefile-based projects. This chapter provides information for both these types of projects.
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.
Follow these steps to create a simple Autotools-based project:
Create your directory: Create a clean directory for your project and then make that directory your working location:
$ mkdir $HOME/helloworld $ cd $HOME/helloworld
Populate the directory:
Create hello.c
, Makefile.am
,
and configure.in
files as follows:
For hello.c
, include
these lines:
#include <stdio.h> main() { printf("Hello World!\n"); }
For Makefile.am
,
include these lines:
bin_PROGRAMS = hello hello_SOURCES = hello.c
For configure.in
,
include these lines:
AC_INIT(hello.c) AM_INIT_AUTOMAKE(hello,0.1) AC_PROG_CC AC_PROG_INSTALL AC_OUTPUT(Makefile)
Source the cross-toolchain environment setup file: Installation of the cross-toolchain creates a cross-toolchain environment setup script in the directory that the ADT was installed. 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 that sources a script from the default ADT installation directory that uses the 32-bit Intel x86 Architecture and using the daisy Yocto Project release:
$ source /opt/poky/1.6.1/environment-setup-i586-poky-linux
Generate the local aclocal.m4
files and create the configure script:
The following GNU Autotools generate the local
aclocal.m4
files and create the
configure script:
$ aclocal $ autoconf
Generate files needed by GNU coding standards: GNU coding standards require certain files in order for the project to be compliant. This command creates those files:
$ touch NEWS README AUTHORS ChangeLog
Generate the configure
file:
This command generates the configure
:
$ automake -a
Cross-compile the project: This command compiles the project using the cross-compiler:
$ ./configure ${CONFIGURE_FLAGS}
Make and install the project: These two commands generate and install the project into the destination directory:
$ make $ make install DESTDIR=./tmp
Verify the installation: 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.
$ file ./tmp/usr/local/bin/hello
Execute your project: 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:
$ ./hello
As expected, the project displays the "Hello World!" message.
For an Autotools-based project, you can use the cross-toolchain by just
passing the appropriate host option to configure.sh
.
The host option you use is derived from the name of the environment setup
script found in the directory in which you installed the cross-toolchain.
For example, the host option for an ARM-based target that uses the GNU EABI
is armv5te-poky-linux-gnueabi
.
You will notice that the name of the script is
environment-setup-armv5te-poky-linux-gnueabi
.
Thus, the following command works:
$ ./configure --host=armv5te-poky-linux-gnueabi \ --with-libtool-sysroot=<sysroot-dir>
This single command updates your project and rebuilds it using the appropriate cross-toolchain tools.
configure
script results in problems recognizing the
--with-libtool-sysroot=<sysroot-dir>
option,
regenerate the script to enable the support by doing the following and then
run the script again:
$ libtoolize --automake $ aclocal -I ${OECORE_NATIVE_SYSROOT}/usr/share/aclocal \ [-I <dir_containing_your_project-specific_m4_macros>] $ autoconf $ autoheader $ automake -a