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buildroot.html: html code clean-up and other issues - Part1

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The current DocType declaration was incorrect. It is neither xhtml strict nor
xhtml transitional. So, instead of dealing with that issue, converted it to
validated Html5.

Fixed white-space errors.
Removed validator html4.01 code.
Color corrected the code sections.
Removed redundant or useless html code.
Changed foo to libfoo, for consistency.
Changed page bookmarking to use header id's.
Re-flowed paragraphs to line break at 80 characters.
Re-formatted the code sections for consistency and correctness.
Kept all list items, headings, and href's on a single line (where possible).

Signed-off-by: Martin Banky <Martin.Banky@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
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Martin Banky 2010-10-12 15:17:53 -07:00 committed by Peter Korsgaard
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@ -1,12 +1,10 @@
<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!DOCTYPE html>
<html lang="en">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Buildroot - Usage and documentation</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<link rel="stylesheet" type="text/css" href="stylesheet.css" />
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<link rel="stylesheet" href="stylesheet.css">
</head>
<body>
@ -15,26 +13,21 @@
<h1>Buildroot</h1>
</div>
<p><a href="http://buildroot.net/">Buildroot</a>
usage and documentation by Thomas Petazzoni. Contributions from
Karsten Kruse, Ned Ludd, Martin Herren and others. </p>
<p><a href="http://buildroot.net/">Buildroot</a> usage and documentation
by Thomas Petazzoni. Contributions from Karsten Kruse, Ned Ludd, Martin
Herren and others.</p>
<ul>
<li><a href="#about">About Buildroot</a></li>
<li><a href="#download">Obtaining Buildroot</a></li>
<li><a href="#using">Using Buildroot</a></li>
<li><a href="#custom_targetfs">Customizing the generated target filesystem</a></li>
<li><a href="#custom_busybox">Customizing the Busybox
configuration</a></li>
<li><a href="#custom_uclibc">Customizing the uClibc
configuration</a></li>
<li><a href="#custom_linux26">Customizing the Linux kernel
configuration</a></li>
<li><a href="#custom_busybox">Customizing the Busybox configuration</a></li>
<li><a href="#custom_uclibc">Customizing the uClibc configuration</a></li>
<li><a href="#custom_linux26">Customizing the Linux kernel configuration</a></li>
<li><a href="#rebuilding_packages">Understanding how to rebuild packages</a></li>
<li><a href="#buildroot_innards">How Buildroot works</a></li>
<li><a href="#using_toolchain">Using the uClibc toolchain
outside Buildroot</a></li>
<li><a href="#using_toolchain">Using the uClibc toolchain outside Buildroot</a></li>
<li><a href="#external_toolchain">Use an external toolchain</a></li>
<li><a href="#downloaded_packages">Location of downloaded packages</a></li>
<li><a href="#add_packages">Adding new packages to Buildroot</a></li>
@ -42,12 +35,12 @@
<li><a href="#links">Resources</a></li>
</ul>
<h2><a name="about" id="about"></a>About Buildroot</h2>
<h2 id="about">About Buildroot</h2>
<p>Buildroot is a set of Makefiles and patches that allows you to
easily generate a cross-compilation toolchain, a root filesystem
and a Linux kernel image for your target. Buildroot can be used
for one, two or all of these options, independently.</p>
<p>Buildroot is a set of Makefiles and patches that allows you to easily
generate a cross-compilation toolchain, a root filesystem and a Linux
kernel image for your target. Buildroot can be used for one, two or all
of these options, independently.</p>
<p>Buildroot is useful mainly for people working with embedded systems.
Embedded systems often use processors that are not the regular x86
@ -55,45 +48,45 @@
processors, MIPS processors, ARM processors, etc.</p>
<p>A compilation toolchain is the set of tools that allows you to
compile code for your system. It consists of a compiler (in our
case, <code>gcc</code>), binary utils like assembler and linker
(in our case, <code>binutils</code>) and a C standard library (for
example <a href="http://www.gnu.org/software/libc/libc.html">GNU
Libc</a>, <a href="http://www.uclibc.org/">uClibc</a> or <a
href="http://www.fefe.de/dietlibc/">dietlibc</a>). The system
installed on your development station certainly already has a
compilation toolchain that you can use to compile an application that
runs on your system. If you're using a PC, your compilation
toolchain runs on an x86 processor and generates code for an x86
processor. Under most Linux systems, the compilation toolchain
uses the GNU libc (glibc) as the C standard library. This compilation
toolchain is called the &quot;host compilation toolchain&quot;.
The machine on which it is running, and on which you're
working, is called the &quot;host system&quot;. The compilation toolchain
is provided by your distribution, and Buildroot has nothing to do
with it (other than using it to build a cross-compilation toolchain
and other tools that are run on the development host). </p>
compile code for your system. It consists of a compiler (in our case,
<code>gcc</code>), binary utils like assembler and linker (in our case,
<code>binutils</code>) and a C standard library (for example
<a href="http://www.gnu.org/software/libc/libc.html">GNU Libc</a>,
<a href="http://www.uclibc.org/">uClibc</a> or
<a href="http://www.fefe.de/dietlibc/">dietlibc</a>). The system installed
on your development station certainly already has a compilation
toolchain that you can use to compile an application that runs on your
system. If you're using a PC, your compilation toolchain runs on an x86
processor and generates code for an x86 processor. Under most Linux
systems, the compilation toolchain uses the GNU libc (glibc) as the C
standard library. This compilation toolchain is called the &quot;host
compilation toolchain&quot;. The machine on which it is running, and on
which you're working, is called the &quot;host system&quot;. The
compilation toolchain is provided by your distribution, and Buildroot
has nothing to do with it (other than using it to build a
cross-compilation toolchain and other tools that are run on the
development host).</p>
<p>As said above, the compilation toolchain that comes with your system
runs on and generates code for the processor in your host system. As your
embedded system has a different processor, you need a cross-compilation
toolchain &mdash; a compilation toolchain that runs on your host system but
generates code for your target system (and target processor). For
example, if your host system uses x86 and your target system uses ARM, the
regular compilation toolchain on your host runs on x86 and generates code
for x86, while the cross-compilation toolchain runs on x86 and generates
code for ARM. </p>
runs on and generates code for the processor in your host system. As
your embedded system has a different processor, you need a
cross-compilation toolchain &mdash; a compilation toolchain that runs on
your host system but generates code for your target system (and target
processor). For example, if your host system uses x86 and your target
system uses ARM, the regular compilation toolchain on your host runs on
x86 and generates code for x86, while the cross-compilation toolchain
runs on x86 and generates code for ARM.</p>
<p>Even if your embedded system uses an x86 processor, you might be interested
in Buildroot for two reasons:</p>
<p>Even if your embedded system uses an x86 processor, you might be
interested in Buildroot for two reasons:</p>
<ul>
<li>The compilation toolchain on your host certainly uses the GNU Libc
which is a complete but huge C standard library. Instead of using GNU
Libc on your target system, you can use uClibc which is a tiny C standard
library. If you want to use this C library, then you need a compilation
toolchain to generate binaries linked with it. Buildroot can do that for
you. </li>
Libc on your target system, you can use uClibc which is a tiny C
standard library. If you want to use this C library, then you need a
compilation toolchain to generate binaries linked with it. Buildroot
can do that for you.</li>
<li>Buildroot automates the building of a root filesystem with all needed
tools like busybox. That makes it much easier than doing it by hand.</li>
@ -101,55 +94,53 @@
<p>You might wonder why such a tool is needed when you can compile
<code>gcc</code>, <code>binutils</code>, <code>uClibc</code> and all
the other tools by hand.
Of course doing so is possible. But, dealing with all of the configure options
and problems of every <code>gcc</code> or <code>binutils</code>
version is very time-consuming and uninteresting. Buildroot automates this
process through the use of Makefiles and has a collection of patches for
each <code>gcc</code> and <code>binutils</code> version to make them work
on most architectures. </p>
the other tools by hand. Of course doing so is possible. But, dealing with
all of the configure options and problems of every <code>gcc</code> or
<code>binutils</code> version is very time-consuming and uninteresting.
Buildroot automates this process through the use of Makefiles and has a
collection of patches for each <code>gcc</code> and <code>binutils</code>
version to make them work on most architectures.</p>
<p>Moreover, Buildroot provides an infrastructure for reproducing
the build process of your kernel, cross-toolchain, and embedded root filesystem. Being able to
reproduce the build process will be useful when a component needs
to be patched or updated or when another person is supposed to
take over the project.</p>
the build process of your kernel, cross-toolchain, and embedded root
filesystem. Being able to reproduce the build process will be useful when a
component needs to be patched or updated or when another person is supposed
to take over the project.</p>
<h2><a name="download" id="download"></a>Obtaining Buildroot</h2>
<h2 id="download">Obtaining Buildroot</h2>
<p>Buildroot releases are made approximately every 3
months. Direct Git access and daily snapshots are also
available if you want more bleeding edge.</p>
<p>Releases are available at <a
href="http://buildroot.net/downloads/">http://buildroot.net/downloads/</a>.</p>
<p>Releases are available at
<a href="http://buildroot.net/downloads/">http://buildroot.net/downloads/</a>.</p>
<p>The latest snapshot is always available at <a
href="http://buildroot.net/downloads/snapshots/buildroot-snapshot.tar.bz2">http://buildroot.net/downloads/snapshots/buildroot-snapshot.tar.bz2</a>,
and previous snapshots are also available at <a
href="http://buildroot.net/downloads/snapshots/">http://buildroot.net/downloads/snapshots/</a>. </p>
<p>The latest snapshot is always available at
<a href="http://buildroot.net/downloads/snapshots/buildroot-snapshot.tar.bz2">http://buildroot.net/downloads/snapshots/buildroot-snapshot.tar.bz2</a>,
and previous snapshots are also available at
<a href="http://buildroot.net/downloads/snapshots/">http://buildroot.net/downloads/snapshots/</a>.</p>
<p>To download Buildroot using Git you can simply follow
the rules described on the &quot;Accessing Git&quot; page (<a href=
"http://buildroot.net/git.html">http://buildroot.net/git.html</a>)
of the Buildroot website (<a href=
"http://buildroot.net">http://buildroot.net</a>).
For the impatient, here's a quick
recipe:</p>
the rules described on the &quot;Accessing Git&quot; page
(<a href= "http://buildroot.net/git.html">http://buildroot.net/git.html</a>)
of the Buildroot website
(<a href="http://buildroot.net">http://buildroot.net</a>).
For the impatient, here's a quick recipe:</p>
<pre>
$ git clone git://git.buildroot.net/buildroot
</pre>
<h2><a name="using" id="using"></a>Using Buildroot</h2>
<h2 id="using">Using Buildroot</h2>
<p>Buildroot has a nice configuration tool similar to the one you can find
in the Linux kernel (<a href=
"http://www.kernel.org/">http://www.kernel.org/</a>) or in Busybox
in the Linux kernel
(<a href="http://www.kernel.org/">http://www.kernel.org/</a>) or in Busybox
(<a href="http://www.busybox.org/">http://www.busybox.org/</a>). Note that
you can (and should) build everything as a normal user. There is no need to be root to
configure and use Buildroot. The first step is to run the configuration
assistant:</p>
you can (and should) build everything as a normal user. There is no need to
be root to configure and use Buildroot. The first step is to run the
configuration assistant:</p>
<pre>
$ make menuconfig
@ -161,7 +152,7 @@
$ make xconfig
</pre>
or
<p>or</p>
<pre>
$ make gconfig
@ -170,17 +161,15 @@ or
<p>to run the Qt3 or GTK-based configurators.</p>
<p>All of these "make" commands will need to build a configuration
utility, so you may need to install "development" packages for
relevant libraries used by the configuration utilities.
On Debian-like systems, the
<code>libncurses5-dev</code> package is required to use the
<i>menuconfig</i> interface, <code>libqt3-mt-dev</code> is
required to use the <i>xconfig</i> interface, and
<code>libglib2.0-dev, libgtk2.0-dev and libglade2-dev</code> are
needed to used the <i>gconfig</i> interface.</p>
utility, so you may need to install "development" packages for relevant
libraries used by the configuration utilities. On Debian-like systems,
the <code>libncurses5-dev</code> package is required to use the <i>
menuconfig</i> interface, <code>libqt3-mt-dev</code> is required to use
the <i>xconfig</i> interface, and <code>libglib2.0-dev, libgtk2.0-dev
and libglade2-dev</code> are needed to used the <i>gconfig</i> interface.</p>
<p>For each menu entry in the configuration tool, you can find associated help
that describes the purpose of the entry. </p>
<p>For each menu entry in the configuration tool, you can find associated
help that describes the purpose of the entry.</p>
<p>Once everything is configured, the configuration tool generates a
<code>.config</code> file that contains the description of your
@ -192,6 +181,7 @@ or
<pre>
$ make
</pre>
<p>This command will generally perform the following steps:</p>
<ul>
<li>Download source files (as required)</li>
@ -205,74 +195,69 @@ or
selected in the Buildroot configuration.
</p>
<p>Buildroot output is stored in a single directory,
<code>output/</code>. This directory contains several
subdirectories:</p>
<p>Buildroot output is stored in a single directory, <code>output/</code>.
This directory contains several subdirectories:</p>
<ul>
<li><code>images/</code> where all the images (kernel image,
bootloader and root filesystem images) are stored.</li>
<li><code>build/</code> where all the components except for the
cross-compilation toolchain are built
(this includes tools needed to run Buildroot on the host and packages compiled
for the target). The <code>build/</code> directory contains one
subdirectory for each of these components.</li>
cross-compilation toolchain are built (this includes tools needed to
run Buildroot on the host and packages compiled for the target). The
<code>build/</code> directory contains one subdirectory for each of
these components.</li>
<li><code>staging/</code> which contains a hierarchy similar to
a root filesystem hierarchy. This directory contains the
installation of the cross-compilation toolchain and all the
userspace packages selected for the target. However, this
directory is <i>not</i> intended to be the root filesystem for
the target: it contains a lot of development files, unstripped
binaries and libraries that make it far too big for an embedded
system. These development files are used to compile libraries
and applications for the target that depend on other
<li><code>staging/</code> which contains a hierarchy similar to a root
filesystem hierarchy. This directory contains the installation of the
cross-compilation toolchain and all the userspace packages selected
for the target. However, this directory is <i>not</i> intended to be
the root filesystem for the target: it contains a lot of development
files, unstripped binaries and libraries that make it far too big for
an embedded system. These development files are used to compile
libraries and applications for the target that depend on other
libraries.</li>
<li><code>target/</code> which contains <i>almost</i> the root
filesystem for the target: everything needed is present except
the device files in <code>/dev/</code> (Buildroot can't create
them because Buildroot doesn't run as root and does not want to
run as root). Therefore, this directory <b>should not be used on
your target</b>. Instead, you should use one of the images
built in the <code>images/</code> directory. If you need an
extracted image of the root filesystem for booting over NFS,
then use the tarball image generated in <code>images/</code> and
extract it as root.<br/>Compared to <code>staging/</code>,
<code>target/</code> contains only the files and libraries needed
to run the selected target applications: the development files
(headers, etc.) are not present.</li>
filesystem for the target: everything needed is present except the
device files in <code>/dev/</code> (Buildroot can't create them
because Buildroot doesn't run as root and does not want to run as
root). Therefore, this directory <b>should not be used on your target</b>.
Instead, you should use one of the images built in the
<code>images/</code> directory. If you need an extracted image of the
root filesystem for booting over NFS, then use the tarball image
generated in <code>images/</code> and extract it as root.<br/>Compared
to <code>staging/</code>, <code>target/</code> contains only the
files and libraries needed to run the selected target applications:
the development files (headers, etc.) are not present.</li>
<li><code>host/</code> contains the installation of tools
compiled for the host that are needed for the proper execution
of Buildroot except for the cross-compilation toolchain which is
installed under <code>staging/</code>.</li>
<li><code>toolchain/</code> contains the build directories for
the various components of the cross-compilation toolchain.</li>
<li><code>host/</code> contains the installation of tools compiled for
the host that are needed for the proper execution of Buildroot except
for the cross-compilation toolchain which is installed under
<code>staging/</code>.</li>
<li><code>toolchain/</code> contains the build directories for the
various components of the cross-compilation toolchain.</li>
</ul>
<h3><a name="offline_builds" id="offline_builds"></a>
Offline builds</h3>
<h3 id="offline_builds">Offline builds</h3>
<p>If you intend to do an offline build and just want to download
all sources that you previously selected in the configurator
(<i>menuconfig</i>, <i>xconfig</i> or <i>gconfig</i>), then issue:</p>
<pre>
$ make source
</pre>
<p>You can now disconnect or copy the content of your <code>dl</code>
directory to the build-host.</p>
<h3><a name="building_out_of_tree" id="building_out_of_tree"></a>
Building out-of-tree</h3>
<h3 id="building_out_of_tree">Building out-of-tree</h3>
<p>Buildroot supports building out of tree with a syntax similar
to the Linux kernel. To use it, add O=&lt;directory&gt; to the
make command line:</p>
<p>Buildroot supports building out of tree with a syntax similar to the
Linux kernel. To use it, add O=&lt;directory&gt; to the make command
line:</p>
<pre>
$ make O=/tmp/build
@ -284,115 +269,110 @@ or
$ cd /tmp/build; make O=$PWD -C path/to/buildroot
</pre>
<p>All the output files will be located under
<code>/tmp/build</code>.</p>
<p>All the output files will be located under <code>/tmp/build</code>.</p>
<p>When using out-of-tree builds, the Buildroot
<code>.config</code> and temporary files are also stored in the
output directory. This means that you can safely run multiple
builds in parallel using the same source tree as long as they use
unique output directories.</p>
<p>When using out-of-tree builds, the Buildroot <code>.config</code> and
temporary files are also stored in the output directory. This means that
you can safely run multiple builds in parallel using the same source
tree as long as they use unique output directories.</p>
<p>For ease of use, Buildroot generates a Makefile wrapper in the
output directory - So after the first run, you no longer need to
pass <code>O=..</code> and <code>-C ..</code>, simply run (in the
output directory):</p>
<p>For ease of use, Buildroot generates a Makefile wrapper in the output
directory - So after the first run, you no longer need to pass
<code>O=..</code> and <code>-C ..</code>, simply run (in the output
directory):</p>
<pre>
$ make &lt;target&gt;
</pre>
<h3><a name="environment_variables" id="environment_variables"></a>
Environment variables</h3>
<h3 id="environment_variables">Environment variables</h3>
<p>Buildroot also honors some environment variables when they are passed
to <code>make</code> or set in the environment:</p>
<ul>
<li><code>HOSTCXX</code>, the host C++ compiler to use</li>
<li><code>HOSTCC</code>, the host C compiler to use</li>
<li><code>UCLIBC_CONFIG_FILE=&lt;path/to/.config&gt;</code>, path
to the uClibc configuration file to use to compile uClibc if an
<li><code>UCLIBC_CONFIG_FILE=&lt;path/to/.config&gt;</code>, path to
the uClibc configuration file to use to compile uClibc if an
internal toolchain is being built</li>
<li><code>BUSYBOX_CONFIG_FILE=&lt;path/to/.config&gt;</code>, path
to the Busybox configuration file</li>
<li><code>BUILDROOT_DL_DIR</code> to override the directory in
which Buildroot stores/retrieves downloaded files</li>
<li><code>BUSYBOX_CONFIG_FILE=&lt;path/to/.config&gt;</code>, path to
the Busybox configuration file</li>
<li><code>BUILDROOT_DL_DIR</code> to override the directory in which
Buildroot stores/retrieves downloaded files</li>
</ul>
<p>An example that uses config files located in the toplevel directory and
in your $HOME:</p>
<pre>
$ make UCLIBC_CONFIG_FILE=uClibc.config BUSYBOX_CONFIG_FILE=$HOME/bb.config
</pre>
<p>If you want to use a compiler other than the default <code>gcc</code>
or <code>g++</code> for building helper-binaries on your host, then do</p>
<pre>
$ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
</pre>
<h2><a name="custom_targetfs" id="custom_targetfs"></a>Customizing the
generated target filesystem</h2>
<h2 id="custom_targetfs">Customizing the generated target filesystem</h2>
<p>There are a few ways to customize the resulting target filesystem:</p>
<ul>
<li>Customize the target filesystem directly and rebuild the image. The
target filesystem is available under <code>output/target/</code>.
You can simply make your changes here and run make afterwards &mdash; this will
rebuild the target filesystem image. This method allows you to do anything
to the target filesystem, but if you decide to completely rebuild your
toolchain and tools, these changes will be lost. </li>
<li>Customize the target filesystem directly and rebuild the image.
The target filesystem is available under <code>output/target/</code>.
You can simply make your changes here and run make afterwards &mdash;
this will rebuild the target filesystem image. This method allows you
to do anything to the target filesystem, but if you decide to
completely rebuild your toolchain and tools, these changes will be
lost.</li>
<li>Customize the target filesystem skeleton available under
<code>fs/skeleton/</code>. You can customize
configuration files or other stuff here. However, the full file hierarchy
is not yet present because it's created during the compilation process.
Therefore, you can't do everything on this target filesystem skeleton, but
changes to it do remain even if you completely rebuild the cross-compilation
toolchain and the tools. <br />
You can also customize the <code>target/generic/device_table.txt</code>
file which is used by the tools that generate the target filesystem image
to properly set permissions and create device nodes.<br />
These customizations are deployed into
<code>output/target/</code> just before the actual image
is made. Simply rebuilding the image by running
make should propagate any new changes to the image. </li>
<li>Customize the target filesystem skeleton available under <code>
fs/skeleton/</code>. You can customize configuration files or other
stuff here. However, the full file hierarchy is not yet present
because it's created during the compilation process. Therefore, you
can't do everything on this target filesystem skeleton, but changes to
it do remain even if you completely rebuild the cross-compilation
toolchain and the tools. <br /> You can also customize the <code>
target/generic/device_table.txt</code> file which is used by the
tools that generate the target filesystem image to properly set
permissions and create device nodes.<br /> These customizations are
deployed into <code>output/target/</code> just before the actual image
is made. Simply rebuilding the image by running make should propagate
any new changes to the image.</li>
<li>Add support for your own target in Buildroot so that you
have your own target skeleton (see <a href="#board_support">this
section</a> for details).</li>
<li>In the Buildroot configuration, you can specify the path to a
post-build script that gets called <i>after</i> Buildroot builds
all the selected software but <i>before</i> the the rootfs
packages are assembled. The destination root filesystem folder
is given as the first argument to this script, and this script can
then be used to copy programs, static data or any other needed
file to your target filesystem.<br/>You should, however, use
this feature with care. Whenever you find that a certain package
generates wrong or unneeded files, you should fix that
package rather than work around it with a post-build cleanup script.</li>
post-build script that gets called <i>after</i> Buildroot builds all
the selected software but <i>before</i> the the rootfs packages are
assembled. The destination root filesystem folder is given as the
first argument to this script, and this script can then be used to
copy programs, static data or any other needed file to your target
filesystem.<br/>You should, however, use this feature with care.
Whenever you find that a certain package generates wrong or unneeded
files, you should fix that package rather than work around it with a
post-build cleanup script.</li>
<li>A special package, <i>customize</i>, stored in
<code>package/customize</code> can be used. You can put all the
files that you want to see in the final target root filesystem
in <code>package/customize/source</code> and then enable this
special package in the configuration system.</li>
</ul>
<h2><a name="custom_busybox" id="custom_busybox"></a>Customizing the
Busybox configuration</h2>
<h2 id="custom_busybox">Customizing the Busybox configuration</h2>
<p><a href="http://www.busybox.net/">Busybox</a> is very configurable, and
you may want to customize it. You can
follow these simple steps to do so. This method isn't optimal, but it's
simple and it works:</p>
<p><a href="http://www.busybox.net/">Busybox</a> is very configurable,
and you may want to customize it. You can follow these simple steps to
do so. This method isn't optimal, but it's simple and it works:</p>
<ol>
<li>Do an initial compilation of Buildroot with busybox without trying to
customize it. </li>
<li>Do an initial compilation of Buildroot with busybox without
trying to customize it.</li>
<li>Invoke <code>make busybox-menuconfig</code>.
The nice configuration tool appears, and you can
@ -405,11 +385,11 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
<code>package/busybox/busybox-&lt;version&gt;.config</code> file if you
know the options you want to change without using the configuration tool.
</p>
<p>If you want to use an existing config file for busybox, then see
section <a href="#environment_variables">environment variables</a>.</p>
<h2><a name="custom_uclibc" id="custom_uclibc"></a>Customizing the uClibc
configuration</h2>
<h2 id="custom_uclibc">Customizing the uClibc configuration</h2>
<p>Just like <a href="#custom_busybox">BusyBox</a>, <a
href="http://www.uclibc.org/">uClibc</a> offers a lot of
@ -420,7 +400,6 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
follow these steps:</p>
<ol>
<li>Do an initial compilation of Buildroot without trying to
customize uClibc.</li>
@ -437,7 +416,6 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
locale support.</li>
<li>Run the compilation of Buildroot again.</li>
</ol>
<p>Otherwise, you can simply change
@ -448,8 +426,7 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
<p>If you want to use an existing config file for uclibc, then see
section <a href="#environment_variables">environment variables</a>.</p>
<h2><a name="custom_linux26" id="custom_linux26"></a>Customizing
the Linux kernel configuration</h2>
<h2 id="custom_linux26">Customizing the Linux kernel configuration</h2>
<p>The Linux kernel configuration can be customized just like <a
href="#custom_busybox">BusyBox</a> and <a href="#custom_uclibc">uClibc</a>
@ -460,9 +437,7 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
<p>If you want to use an existing config file for Linux, then see
section <a href="#environment_variables">environment variables</a>.</p>
<h2><a name="#rebuilding_packages"
id="rebuilding_packages">Understanding how to rebuild
packages</a></h2>
<h2 id="rebuilding_packages">Understanding how to rebuild packages</h2>
<p>One of the most common questions asked by Buildroot
users is how to rebuild a given package or how to
@ -494,7 +469,6 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
following stamp files are relevant:</p>
<ul>
<li><code>output/build/packagename-version/.stamp_configured</code>. If
removed, Buildroot will trigger the recompilation of the package
from the configuration step (execution of
@ -503,13 +477,11 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
<li><code>output/build/packagename-version/.stamp_built</code>. If
removed, Buildroot will trigger the recompilation of the package
from the compilation step (execution of <code>make</code>).</li>
</ul>
<p>For other packages, an analysis of the specific
<i>package.mk</i> file is needed. For example, the zlib Makefile
used to look like this (before it was converted to the generic
package infrastructure):</p>
<p>For other packages, an analysis of the specific <i>package.mk</i>
file is needed. For example, the zlib Makefile used to look like this
(before it was converted to the generic package infrastructure):</p>
<pre>
$(ZLIB_DIR)/.configured: $(ZLIB_DIR)/.patched
@ -532,18 +504,17 @@ $(ZLIB_DIR)/libz.a: $(ZLIB_DIR)/.configured
ported over the generic or the autotools infrastructure, making it
much easier to rebuild individual packages.</p>
<h2><a name="buildroot_innards" id="buildroot_innards"></a>How Buildroot
works</h2>
<h2 id="buildroot_innards">How Buildroot works</h2>
<p>As mentioned above, Buildroot is basically a set of Makefiles that downloads,
configures and compiles software with the correct options. It also includes
patches for various software packages &mdash; mainly the ones involved in the
cross-compilation tool chain (<code>gcc</code>, <code>binutils</code> and
<code>uClibc</code>). </p>
<p>As mentioned above, Buildroot is basically a set of Makefiles that
downloads, configures and compiles software with the correct options. It
also includes patches for various software packages &mdash; mainly the
ones involved in the cross-compilation tool chain (<code>gcc</code>,
<code>binutils</code> and <code>uClibc</code>).</p>
<p>There is basically one Makefile per software package, and they are named with
the <code>.mk</code> extension. Makefiles are split into three main
sections:</p>
<p>There is basically one Makefile per software package, and they are
named with the <code>.mk</code> extension. Makefiles are split into
three main sections:</p>
<ul>
<li><b>toolchain</b> (in the <code>toolchain/</code> directory) contains
@ -575,14 +546,12 @@ $(ZLIB_DIR)/libz.a: $(ZLIB_DIR)/.configured
<li><code>Config.in</code> is a part of the configuration tool
description file. It describes the options related to the
package.</li>
</ul>
<p>The main Makefile performs the following steps (once the
configuration is done):</p>
<ol>
<li>Create all the output directories: <code>staging</code>,
<code>target</code>, <code>build</code>, <code>stamps</code>,
etc. in the output directory (<code>output/</code> by default,
@ -601,11 +570,9 @@ $(ZLIB_DIR)/libz.a: $(ZLIB_DIR)/.configured
trigger the compilation of the userspace packages (libraries,
programs), the kernel, the bootloader and the generation of the
root filesystem images, depending on the configuration.</li>
</ol>
<h2><a name="board_support" id="board_support"></a>
Creating your own board support</h2>
<h2 id="board_support"> Creating your own board support</h2>
<p>Creating your own board support in Buildroot allows you to have
a convenient place to store your project's target filesystem skeleton
@ -614,7 +581,6 @@ $(ZLIB_DIR)/libz.a: $(ZLIB_DIR)/.configured
<p>Follow these steps to integrate your board in Buildroot:</p>
<ol>
<li>Create a new directory in <code>target/device/</code> named
after your company or organization</li>
@ -657,6 +623,7 @@ ifeq ($(BR2_TARGET_COMPANY_PROJECT_FOOBAR),y)
include target/device/yourcompany/project-foobar/Makefile.in
endif
</pre>
</li>
<li>Create the
@ -666,18 +633,14 @@ endif
<code>target/device/yourcompany/project-foobar</code> as it
will simplify further definitions. Then, the file might define
one or several of the following variables:
<ul>
<li><code>TARGET_SKELETON</code> to a directory that contains
the target skeleton for your project. If this variable is
defined, this target skeleton will be used instead of the
default one. If defined, the convention is to define it to
<code>$(BOARD_PATH)/target_skeleton</code> so that the target
skeleton is stored in the board specific directory.</li>
</ul>
</li>
<li>In the
@ -691,51 +654,45 @@ endif
<code>configs/</code> directory. Your users will then be able
to run <code>make something_defconfig</code> and get the right
configuration for your project</li>
</ol>
<h2><a name="using_toolchain" id="using_toolchain"></a>Using the
generated toolchain outside Buildroot</h2>
<h2 id="using_toolchain">Using the generated toolchain outside Buildroot</h2>
<p>You may want to compile for your target your own programs or other software
that are not packaged in Buildroot. In order to do this you can
<p>You may want to compile for your target your own programs or other
software that are not packaged in Buildroot. In order to do this you can
use the toolchain that was generated by Buildroot.</p>
<p>The toolchain generated by Buildroot is located by default in
<code>output/staging/</code>. The simplest way to use it
is to add <code>output/staging/usr/bin/</code> to your PATH
environment variable and then to use
<code>ARCH-linux-gcc</code>, <code>ARCH-linux-objdump</code>,
<code>output/staging/</code>. The simplest way to use it is to add
<code>output/staging/usr/bin/</code> to your PATH environment variable and
then to use <code>ARCH-linux-gcc</code>, <code>ARCH-linux-objdump</code>,
<code>ARCH-linux-ld</code>, etc.</p>
<p><b>Important</b>: do not try to move a gcc-3.x toolchain to another
directory &mdash; it won't work because there are some hardcoded paths in the
gcc-3.x configuration. If you are using a current gcc-4.x, it
is possible to relocate the toolchain &mdash; but then
<code>--sysroot</code> must be passed every time the compiler is
called to tell where the libraries and header files are.</p>
directory &mdash; it won't work because there are some hardcoded paths
in the gcc-3.x configuration. If you are using a current gcc-4.x, it is
possible to relocate the toolchain &mdash; but then <code>--sysroot</code>
must be passed every time the compiler is called to tell where the
libraries and header files are.</p>
<p>It is also possible to generate the Buildroot toolchain in
a directory other than <code>output/staging</code> by using the
<code>Build options -&gt; Toolchain and header file
location</code> options. This could be useful if the toolchain
must be shared with other users.</p>
<p>It is also possible to generate the Buildroot toolchain in a
directory other than <code>output/staging</code> by using the <code>
Build options -&gt; Toolchain and header file location</code> options.
This could be useful if the toolchain must be shared with other users.</p>
<h2><a name="downloaded_packages"
id="downloaded_packages"></a>Location of downloaded packages</h2>
<h2 id="downloaded_packages">Location of downloaded packages</h2>
<p>It might be useful to know that the various tarballs that are
downloaded by the Makefiles are all stored in the
<code>DL_DIR</code> which by default is the <code>dl</code>
directory. It's useful, for example, if you want to keep a complete
version of Buildroot which is know to be working with the
associated tarballs. This will allow you to regenerate the
toolchain and the target filesystem with exactly the same
downloaded by the Makefiles are all stored in the <code>DL_DIR</code>
which by default is the <code>dl</code> directory. It's useful, for
example, if you want to keep a complete version of Buildroot which is
know to be working with the associated tarballs. This will allow you to
regenerate the toolchain and the target filesystem with exactly the same
versions.</p>
<p>If you maintain several Buildroot trees, it might be better to have
a shared download location. This can be accessed by creating a symbolic link
from the <code>dl</code> directory to the shared download location: </p>
<p>If you maintain several Buildroot trees, it might be better to have a
shared download location. This can be accessed by creating a symbolic
link from the <code>dl</code> directory to the shared download location:</p>
<pre>
ln -s &lt;shared download location&gt; dl
@ -745,14 +702,13 @@ ln -s &lt;shared download location&gt; dl
create the <code>BUILDROOT_DL_DIR</code> environment variable.
If this is set, then the value of DL_DIR in the project is
overridden. The following line should be added to
<code>&quot;~/.bashrc&quot;</code>. <p>
<code>&quot;~/.bashrc&quot;</code>.</p>
<pre>
export BUILDROOT_DL_DIR &lt;shared download location&gt;
</pre>
<h2><a name="external_toolchain" id="external_toolchain"></a>Using
an external toolchain</h2>
<h2 id="external_toolchain">Using an external toolchain</h2>
<p>It might be useful not to use the toolchain generated by
Buildroot, for example if you already have a toolchain that is known
@ -763,7 +719,7 @@ need to generate a system with <i>glibc</i> instead of
toolchain</i>.</p>
<p>To enable the use of an external toolchain, go in the
<code>Toolchain</code> menu, and&nbsp;:</p>
<code>Toolchain</code> menu, and :</p>
<ul>
<li>Select the <code>External binary toolchain</code> toolchain
@ -783,52 +739,46 @@ should already have correct values. However, if your external
toolchain is based on <i>glibc</i>, you'll have to change these values
according to your cross-compiling toolchain.</p>
<p>To generate external toolchains, we recommend using <a
href="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool">Crosstool-NG</a>.
<p>To generate external toolchains, we recommend using
<a href="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool">Crosstool-NG</a>.
It allows generating toolchains based on <i>uClibc</i>, <i>glibc</i>
and <i>eglibc</i> for a wide range of architectures and has good
community support.</p>
<h2><a name="add_packages" id="add_packages"></a>Adding new
packages to Buildroot</h2>
<h2 id="add_packages">Adding new packages to Buildroot</h2>
<p>This section covers how new packages (userspace libraries or
applications) can be integrated into Buildroot. It also allows to
understand how existing packages are integrated, which is needed
to fix issues or tune their configuration.</p>
understand how existing packages are integrated, which is needed to fix
issues or tune their configuration.</p>
<ul>
<li><a href="#package-directory">Package directory</a></li>
<li><a href="#config-in-file"><code>Config.in</code> file</a></li>
<li><a href="#mk-file">The <code>.mk</code> file</a>
<ul>
<li><a href="#generic-tutorial">Makefile for generic
packages : tutorial</a></li>
<li><a href="#generic-reference">Makefile for
generic packages : reference</a></li>
<li><a href="#autotools-tutorial">Makefile for autotools-based
packages : tutorial</a></li>
<li><a href="#autotools-reference">Makefile for autotools-based
packages : reference</a></li>
<li><a href="#generic-tutorial">Makefile for generic packages : tutorial</a></li>
<li><a href="#generic-reference">Makefile for generic packages : reference</a></li>
<li><a href="#autotools-tutorial">Makefile for autotools-based packages : tutorial</a></li>
<li><a href="#autotools-reference">Makefile for autotools-based packages : reference</a></li>
<li><a href="#manual-tutorial">Manual Makefile : tutorial</a></li>
</ul>
</li>
<li><a href="#gettext-integration">Gettext integration and
interaction with packages</a></li>
<li><a href="#gettext-integration">Gettext integration and interaction with packages</a></li>
</ul>
<h3><a name="package-directory"></a>Package directory</h3>
<h3 id="package-directory">Package directory</h3>
<p>First of all, create a directory under the <code>package</code>
directory for your software, for example <code>foo</code>.</p>
<p>Some packages have been grouped by topic in a sub-directory:
<code>multimedia</code>, <code>java</code>,
<code>databases</code>, <code>editors</code>, <code>x11r7</code>,
<code>games</code>. If your package fits in one of these
categories, then create your package directory in these.</p>
<code>multimedia</code>, <code>java</code>, <code>databases</code>,
<code>editors</code>, <code>x11r7</code>, <code>games</code>. If your
package fits in one of these categories, then create your package
directory in these.</p>
<h3><a name="config-in-file"></a><code>Config.in</code> file</h3>
<h3 id="config-in-file"><code>Config.in</code> file</h3>
<p>Then, create a file named <code>Config.in</code>. This file
will contain the option descriptions related to our
@ -848,8 +798,9 @@ config BR2_PACKAGE_LIBFOO
things in your software. You can look at examples in other
packages. The syntax of the Config.in file is the same as the one
for the kernel Kconfig file. The documentation for this syntax is
available at <a
href="http://lxr.free-electrons.com/source/Documentation/kbuild/kconfig-language.txt">http://lxr.free-electrons.com/source/Documentation/kbuild/kconfig-language.txt</a></p>
available at
<a href="http://lxr.free-electrons.com/source/Documentation/kbuild/kconfig-language.txt">http://lxr.free-electrons.com/source/Documentation/kbuild/kconfig-language.txt</a>
</p>
<p>Finally you have to add your new <code>libfoo/Config.in</code> to
<code>package/Config.in</code> (or in a category subdirectory if