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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2012-07-17 17:42:40 (GMT)
committer Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2012-07-17 17:42:40 (GMT)
commitd56422a51af9e4c87aac365830f598fca6ca8a29 (patch)
tree0c475a5a18a9cf1d62e4504e6962c1d047b7ba6b
parentc6580011f12e6ca8f7eb87af11d4e9d6def4316f (diff)
downloadbuildroot-d56422a51af9e4c87aac365830f598fca6ca8a29.tar.gz
buildroot-d56422a51af9e4c87aac365830f598fca6ca8a29.tar.bz2
doc: get rid of the old HTML-only documentation
Users keep falling on this documentation, which is no longer kept up-to-date with the developments. Get rid of it now. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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-<!DOCTYPE html>
-<html lang="en">
-
-<head>
- <title>Buildroot - Usage and documentation</title>
- <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
- <link rel="stylesheet" href="stylesheet.css">
-</head>
-
-<body>
- <div class="main">
- <div class="titre">
- <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>
-
- <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="#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="#external_toolchain">Use an external toolchain</a></li>
- <li><a href="#ccache-support">Using <code>ccache</code> in Buildroot</li>
- <li><a href="#downloaded_packages">Location of downloaded packages</a></li>
- <li><a href="#add_packages">Adding new packages to Buildroot</a></li>
- <li><a href="#board_support">Creating your own board support</a></li>
- <li><a href="#faq">Frequently asked questions</a></li>
- <li><a href="#links">Resources</a></li>
- </ul>
-
- <p><b>WARNING:</b> Since the 2011.11 release, this page is on its way to be
- deprecated. Information may be incomplete and out-dated.</p>
-
- <p>To get an up-to-date documentation for
- <a href="http://buildroot.net/">Buildroot</a>-2011.11 or a git view, just
- run:</p>
-<pre>
- $ make manual
-</pre>
- <p><i>This requires <code>asciidoc</code> installed on the host system.</i></p>
-
- <p>For releases since <a href="http://buildroot.net/">Buildroot</a>-2012.02,
- manuals (html, pdf and text) are available in the <code>docs/manual</code>
- directory.</p>
-
- <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 useful mainly for people working with embedded systems.
- Embedded systems often use processors that are not the regular x86
- processors everyone is used to having in his PC. They can be PowerPC
- 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>
-
- <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>
-
- <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>
-
- <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>
- </ul>
-
- <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>
-
- <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>
-
- <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>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>
-
-<pre>
- $ git clone git://git.buildroot.net/buildroot
-</pre>
-
- <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
- (<a href="http://www.busybox.net/">http://www.busybox.net/</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>
-
-<pre>
- $ make menuconfig
-</pre>
-
- <p>to run the curses-based configurator, or</p>
-
-<pre>
- $ make xconfig
-</pre>
-
- <p>or</p>
-
-<pre>
- $ make gconfig
-</pre>
-
- <p>to run the Qt 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>libqt4-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 use 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>Once everything is configured, the configuration tool generates a
- <code>.config</code> file that contains the description of your
- configuration. It will be used by the Makefiles to do what's needed.</p>
-
-
- <p>Let's go:</p>
-
-<pre>
- $ make
-</pre>
-
- <p>You <b>should never</b> use <code>make -jN</code> with
- Buildroot: it does not support <i>top-level parallel
- make</i>. Instead, use the <code>BR2_JLEVEL</code> option to tell
- Buildroot to run each package compilation with <code>make
- -jN</code>.</p>
-
- <p>This command will generally perform the following steps:</p>
- <ul>
- <li>Download source files (as required)</li>
- <li>Configure, build and install the cross-compiling toolchain
- if an internal toolchain is used, or import a toolchain if an
- external toolchain is used</li>
- <li>Build/install selected target packages</li>
- <li>Build a kernel image, if selected</li>
- <li>Build a bootloader image, if selected</li>
- <li>Create a root filesystem in selected formats</li>
- </ul>
-
- <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>
-
- <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 complete
- 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 doesn't 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, unless the
- <code>development files in target filesystem</code> option is selected.
- </li>
-
- <li><code>host/</code> contains the installation of tools compiled for
- the host that are needed for the proper execution of Buildroot,
- including the cross-compilation toolchain.</li>
-
- <li><code>toolchain/</code> contains the build directories for the
- various components of the cross-compilation toolchain.</li>
- </ul>
-
- <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 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>
-
-<pre>
- $ make O=/tmp/build
-</pre>
-
- <p>Or:</p>
-
-<pre>
- $ 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>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>
-
-<pre>
- $ make &lt;target&gt;
-</pre>
-
- <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, used 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>
- </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 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>Create your own <i>target skeleton</i>. You can start with
- the default skeleton available under <code>fs/skeleton</code>
- and then customize it to suit your
- needs. The <code>BR2_ROOTFS_SKELETON_CUSTOM</code>
- and <code>BR2_ROOTFS_SKELETON_CUSTOM_PATH</code> will allow you
- to specify the location of your custom skeleton. At build time,
- the contents of the skeleton are copied to output/target before
- any package installation.</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 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 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>
-
- <ol>
- <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
- customize everything.</li>
-
- <li>Run the compilation of Buildroot again.</li>
- </ol>
-
- <p>Otherwise, you can simply change the
- <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 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
- configuration options. They allow you to select various
- functionalities depending on your needs and limitations.</p>
-
- <p>The easiest way to modify the configuration of uClibc is to
- follow these steps:</p>
-
- <ol>
- <li>Do an initial compilation of Buildroot without trying to
- customize uClibc.</li>
-
- <li>Invoke <code>make uclibc-menuconfig</code>.
- The nice configuration assistant, similar to
- the one used in the Linux kernel or Buildroot, appears. Make
- your configuration changes as appropriate.</li>
-
- <li>Copy the <code>$(O)/toolchain/uclibc-VERSION/.config</code>
- file to a different place
- (like <code>toolchain/uClibc/uClibc-myconfig.config</code>,
- or <code>board/mymanufacturer/myboard/uClibc.config</code>) and
- adjust the uClibc configuration (configuration
- option <code>BR2_UCLIBC_CONFIG</code>) to use this configuration
- instead of the default one.</li>
-
- <li>Run the compilation of Buildroot again.</li>
- </ol>
-
- <p>Otherwise, you can simply change
- <code>toolchain/uClibc/uClibc.config</code>, without running the
- configuration assistant.</p>
-
- <p>If you want to use an existing config file for uclibc, then see
- section <a href="#environment_variables">environment variables</a>.</p>
-
- <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> using <code>make linux-menuconfig
- </code>. Make sure you have enabled the kernel build in <code>make
- menuconfig</code> first. Once done, run <code>make</code> to (re)build
- everything.</p>
-
- <p>If you want to use an existing config file for Linux, then see
- section <a href="#environment_variables">environment variables</a>.</p>
-
- <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
- remove a package without rebuilding everything from scratch.</p>
-
- <p>Removing a package is currently unsupported by Buildroot
- without rebuilding from scratch. This is because Buildroot doesn't
- keep track of which package installs what files in the
- <code>output/staging</code> and <code>output/target</code>
- directories. However, implementing clean package removal is on the
- TODO-list of Buildroot developers.</p>
-
- <p>The easiest way to rebuild a single package from scratch is to
- remove its build directory in <code>output/build</code>. Buildroot
- will then re-extract, re-configure, re-compile and re-install this
- package from scratch.</p>
-
- <p>However, if you don't want to rebuild the package completely
- from scratch, a better understanding of the Buildroot internals is
- needed. Internally, to keep track of which steps have been done
- and which steps remain to be done, Buildroot maintains stamp
- files (empty files that just tell whether this or that action
- has been done). The problem is that these stamp files are not
- uniformly named and handled by the different packages, so some
- understanding of the particular package is needed.</p>
-
- <p>For packages relying on Buildroot packages infrastructures (see
- <a href="#add_packages">this section</a> for details), the
- 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
- <code>./configure</code>).</li>
-
- <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>
-
-<pre>
-$(ZLIB_DIR)/.configured: $(ZLIB_DIR)/.patched
- (cd $(ZLIB_DIR); rm -rf config.cache; \
- [...]
- )
- touch $@
-
-$(ZLIB_DIR)/libz.a: $(ZLIB_DIR)/.configured
- $(MAKE) -C $(ZLIB_DIR) all libz.a
- touch -c $@
-</pre>
-
- <p>If you want to trigger the reconfiguration, you need to
- remove <code>output/build/zlib-version/.configured</code>. If
- you want to trigger only the recompilation, you need to remove
- <code>output/build/zlib-version/libz.a</code>.</p>
-
- <p>Note that most packages, if not all, will progressively be
- ported over to the generic or autotools infrastructure, making it
- much easier to rebuild individual packages.</p>
-
- <h2 id="buildroot_innards">How Buildroot works</h2>
-
- <p>As mentioned above, Buildroot is basically a set of Makefiles that
- download, configure, and compile 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>
-
- <ul>
- <li><b>toolchain</b> (in the <code>toolchain/</code> directory) contains
- the Makefiles and associated files for all software related to the
- cross-compilation toolchain: <code>binutils</code>, <code>gcc</code>,
- <code>gdb</code>, <code>kernel-headers</code> and <code>uClibc</code>.</li>
-
- <li><b>package</b> (in the <code>package/</code> directory) contains the
- Makefiles and associated files for all user-space tools that Buildroot
- can compile and add to the target root filesystem. There is one
- sub-directory per tool.</li>
-
- <li><b>target</b> (in the <code>target</code> directory) contains the
- Makefiles and associated files for software related to the generation of
- the target root filesystem image. Four types of filesystems are supported:
- ext2, jffs2, cramfs and squashfs. For each of them there is a
- sub-directory with the required files. There is also a
- <code>default/</code> directory that contains the target filesystem
- skeleton.</li>
- </ul>
-
- <p>Each directory contains at least 2 files:</p>
-
- <ul>
- <li><code>something.mk</code> is the Makefile that downloads, configures,
- compiles and installs the package <code>something</code>.</li>
-
- <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,
- another value can be specified using <code>O=</code>)</li>
-
- <li>Generate all the targets listed in the
- <code>BASE_TARGETS</code> variable. When an internal toolchain
- is used, this means generating the cross-compilation
- toolchain. When an external toolchain is used, this means checking
- the features of the external toolchain and importing it into the
- Buildroot environment.</li>
-
- <li>Generate all the targets listed in the <code>TARGETS</code>
- variable. This variable is filled by all the individual
- components' Makefiles. Generating these targets will
- 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 id="board_support"> Creating your own board support</h2>
-
- <p>Creating your own board support in Buildroot allows users of a
- particular hardware platform to easily build a system that is
- known to work.</p>
-
- <p>To do so, you need to create a normal Buildroot configuration
- that builds a basic system for the hardware: toolchain, kernel,
- bootloader, filesystem and a simple Busybox-only userspace. No
- specific package should be selected: the configuration should be
- as minimal as possible, and should only build a working basic
- Busybox system for the target platform. You can of course use more
- complicated configurations for your internal projects, but the
- Buildroot project will only integrate basic board
- configurations. This is because package selections are highly
- application-specific.</p>
-
- <p>Once you have a known working configuration, run <code>make
- savedefconfig</code>. This will generate a
- minimal <code>defconfig</code> file at the root of the Buildroot
- source tree. Move this file into the <code>configs/</code>
- directory, and rename it <code>MYBOARD_defconfig</code>.</p>
-
- <p>It is recommended to use as much as possible upstream versions
- of the Linux kernel and bootloaders, and to use as much as
- possible default kernel and bootloader configurations. If they are
- incorrect for your platform, we encourage you to send fixes to the
- corresponding upstream projects.</p>
-
- <p>However, in the mean time, you may want to store kernel or
- bootloader configuration or patches specific to your target
- platform. To do so, create a
- directory <code>board/MANUFACTURER</code> and a
- subdirectory <code>board/MANUFACTURER/BOARDNAME</code> (after
- replacing, of course, MANUFACTURER and BOARDNAME with the
- appropriate values, in lower case letters). You can then store
- your patches and configurations in these directories, and
- reference them from the main Buildroot configuration.</p>
-
- <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
- use the toolchain that was generated by Buildroot.</p>
-
- <p>The toolchain generated by Buildroot is located by default in
- <code>output/host/</code>. The simplest way to use it is to add
- <code>output/host/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>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/host</code> by using the <code>
- Build options -&gt; Host dir</code> option.
- This could be useful if the toolchain must be shared with other users.</p>
-
- <h2 id="ccache-support">Using <code>ccache</code> in Buildroot</h2>
-
- <p><a href="http://ccache.samba.org">ccache</a> is a compiler
- cache. It stores the object files resulting from each compilation
- process, and is able to skip future compilation of the same source
- file (with same compiler and same arguments) by using the
- pre-existing object files. When doing almost identical builds from
- scratch a number of times, it can nicely speed up the build
- process.</p>
-
- <p><code>ccache</code> support is integrated in Buildroot. You
- just have to enable <code>Enable compiler cache</code>
- in <code>Build options</code>. This will automatically build
- <code>ccache</code> and use it for every host and target
- compilation.</p>
-
- <p>The cache is located
- in <code>$HOME/.buildroot-ccache</code>. It is stored outside of
- Buildroot output directory so that it can be shared by separate
- Buildroot builds. If you want to get rid of the cache, simply
- remove this directory.</p>
-
- <p>You can get statistics on the cache (its size, number of hits,
- misses, etc.) by running <code>make ccache-stats</code>.</p>
-
- <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
- known 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>
-
-<pre>
- $ ln -s &lt;shared download location&gt; dl
-</pre>
-
- <p>Another way of accessing a shared download location is to
- 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>
-
-<pre>
- $ export BUILDROOT_DL_DIR &lt;shared download location&gt;
-</pre>
-
- <h2 id="external_toolchain">Using an external toolchain</h2>
-
- <p>Using an already existing toolchain is useful for different
- reasons:</p>
-
- <ul>
- <li>you already have a toolchain that is known to work for your
- specific CPU</li>
- <li>you want to speed up the Buildroot build process by skipping
- the long toolchain build part</li>
- <li>the toolchain generation feature of Buildroot is not
- sufficiently flexible for you (for example if you need to
- generate a system with <i>glibc</i> instead of
- <i>uClibc</i>)</li>
- </ul>
-
- <p>Buildroot supports using existing toolchains through a
- mechanism called <i>external toolchain</i>. The external toolchain
- mechanism is enabled in the <code>Toolchain</code> menu, by
- selecting <code>External toolchain</code> in <code>Toolchain
- type</code>.</p>
-
- <p>Then, you have three solutions to use an external
- toolchain:</p>
-
- <ul>
-
- <li>Use a predefined external toolchain profile, and let
- Buildroot download, extract and install the toolchain. Buildroot
- already knows about a few CodeSourcery toolchains for ARM,
- PowerPC, MIPS and SuperH. Just select the toolchain profile
- in <code>Toolchain</code> through the available ones. This is
- definitely the easiest solution.</li>
-
- <li>Use a predefined external toolchain profile, but instead of
- having Buildroot download and extract the toolchain, you can
- tell Buildroot where your toolchain is already installed on your
- system. Just select the toolchain profile
- in <code>Toolchain</code> through the available ones,
- unselect <code>Download toolchain automatically</code>, and fill
- the <code>Toolchain path</code> text entry with the path to your
- cross-compiling toolchain.</li>
-
- <li>Use a completely custom external toolchain. This is
- particularly useful for toolchains generated using
- Crosstool-NG. To do this, select the <code>Custom
- toolchain</code> solution in the <code>Toolchain</code>
- list. You need to fill the <code>Toolchain
- path</code>, <code>Toolchain prefix</code> and <code>External
- toolchain C library</code> options. Then, you have to tell
- Buildroot what your external toolchain supports. If your
- external toolchain uses the <i>glibc</i> library, you only have
- to tell whether your toolchain supports C++ or not. If your
- external toolchain uses the <i>uclibc</i> library, then you have
- to tell Buildroot if it supports largefile, IPv6, RPC,
- wide-char, locale, program invocation, threads and C++. At the
- beginning of the execution, Buildroot will tell you if the
- selected options do not match the toolchain configuration.</li>
-
- </ul>
-
- <p>Our external toolchain support has been tested with toolchains
- from CodeSourcery, toolchains generated
- by <a href="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool">Crosstool-NG</a>,
- and toolchains generated by Buildroot itself. In general, all
- toolchains that support the <i>sysroot</i> feature should
- work. If not, do not hesitate to contact the developers.</p>
-
- <p>We do not support toolchains from
- the <a href="http://www.denx.de/wiki/DULG/ELDK">ELDK of Denx</a>,
- for two reasons:</p>
-
- <ul>
-
- <li>The ELDK does not contain a pure toolchain (i.e just the
- compiler, binutils, the C and C++ libraries), but a toolchain
- that comes with a very large set of pre-compiled libraries and
- programs. Therefore, Buildroot cannot import the <i>sysroot</i>
- of the toolchain, as it would contain hundreds of megabytes of
- pre-compiled libraries that are normally built by
- Buildroot.</li>
-
- <li>The ELDK toolchains have a completely non-standard custom
- mechanism to handle multiple library variants. Instead of using
- the standard GCC <i>multilib</i> mechanism, the ARM ELDK uses
- different symbolic links to the compiler to differentiate
- between library variants (for ARM soft-float and ARM VFP), and
- the PowerPC ELDK compiler uses a <code>CROSS_COMPILE</code>
- environment variable. This non-standard behaviour makes it
- difficult to support ELDK in Buildroot.</li>
-
- </ul>
-
- <p>We also do not support using the distribution toolchain (i.e
- the gcc/binutils/C library installed by your distribution) as the
- toolchain to build software for the target. This is because your
- distribution toolchain is not a "pure" toolchain (i.e only with
- the C/C++ library), so we cannot import it properly into the
- Buildroot build environment. So even if you are building a system
- for a x86 or x86_64 target, you have to generate a
- cross-compilation toolchain with Buildroot or Crosstool-NG.</p>
-
- <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 shows how existing
- packages are integrated, which is needed for fixing issues or tuning 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="#cmake-tutorial">Makefile for CMake-based packages : tutorial</a></li>
- <li><a href="#cmake-reference">Makefile for CMake-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>
- </ul>
-
- <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>libfoo</code>.</p>
-
- <p>Some packages have been grouped by topic in a sub-directory:
- <code>multimedia</code>, <code>x11r7</code>, and
- <code>games</code>. If your package fits in one of these
- categories, then create your package directory in these.</p>
-
- <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
- <code>libfoo</code> software that will be used and displayed in the
- configuration tool. It should basically contain :</p>
-
-<pre>
-config BR2_PACKAGE_LIBFOO
- bool "libfoo"
- help
- This is a comment that explains what libfoo is.
-
- http://foosoftware.org/libfoo/
-</pre>
-
- <p>Of course, you can add other options to configure particular
- 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>
-
- <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
- you decided to put your package in one of the existing
- categories). The files included there are <em>sorted
- alphabetically</em> per category and are <em>NOT</em> supposed to
- contain anything but the <em>bare</em> name of the package.</p>
-
-<pre>
-source "package/libfoo/Config.in"
-</pre>
-
- <h3 id="mk-file">The <code>.mk</code> file</h3>
-
- <p>Finally, here's the hardest part. Create a file named
- <code>libfoo.mk</code>. It describes how the package should be
- downloaded, configured, built, installed, etc.</p>
-
- <p>Depending on the package type, the <code>.mk</code> file must be
- written in a different way, using different infrastructures:</p>
-
- <ul>
- <li><b>Makefiles for generic packages</b> (not using autotools): These
- are based on an infrastructure similar to the one used for
- autotools-based packages, but requires a little more work from the
- developer. They specify what should be done for the configuration,
- compilation, installation and cleanup of the package. This
- infrastructure must be used for all packages that do not use the
- autotools as their build system. In the future, other specialized
- infrastructures might be written for other build systems.<br/>We cover
- them through a <a href="#generic-tutorial">tutorial</a> and a
- <a href="#generic-reference">reference</a>.</li>
-
- <li><b>Makefiles for autotools-based software</b> (autoconf, automake,
- etc.): We provide a dedicated infrastructure for such packages, since
- autotools is a very common build system. This infrastructure <i>must
- </i> be used for new packages that rely on the autotools as their
- build system.<br/>We cover them through a
- <a href="#autotools-tutorial">tutorial</a> and a
- <a href="#autotools-reference">reference</a>.</li>
-
- <li><b>Manual Makefiles:</b> These are currently obsolete, and no new
- manual Makefiles should be added. However, since there are still many
- of them in the tree, we keep them documented in a
- <a href="#manual-tutorial">tutorial</a>.</li>
- </ul>
-
- <h4 id="generic-tutorial">Makefile for generic packages : tutorial</h4>
-
-<pre>
-<span style="color: #000000">01:</span><span style="font-style: italic; color: #9A1900"> #############################################################</span>
-<span style="color: #000000">02:</span><span style="font-style: italic; color: #9A1900"> #</span>
-<span style="color: #000000">03:</span><span style="font-style: italic; color: #9A1900"> # libfoo</span>
-<span style="color: #000000">04:</span><span style="font-style: italic; color: #9A1900"> #</span>
-<span style="color: #000000">05:</span><span style="font-style: italic; color: #9A1900"> #############################################################</span>
-<span style="color: #000000">06:</span><span style="color: #009900"> LIBFOO_VERSION</span> = 1.0
-<span style="color: #000000">07:</span><span style="color: #009900"> LIBFOO_SOURCE</span> = libfoo-<span style="color: #009900">$(LIBFOO_VERSION)</span>.tar.gz
-<span style="color: #000000">08:</span><span style="color: #009900"> LIBFOO_SITE</span> = http://www.foosoftware.org/download
-<span style="color: #000000">09:</span><span style="color: #009900"> LIBFOO_INSTALL_STAGING</span> = YES
-<span style="color: #000000">10:</span><span style="color: #009900"> LIBFOO_DEPENDENCIES</span> = host-libaaa libbbb
-<span style="color: #000000">11:</span>
-<span style="color: #000000">12:</span> define LIBFOO_BUILD_CMDS
-<span style="color: #000000">13:</span> <span style="color: #009900">$(MAKE)</span> CC=<span style="color: #009900">"$(TARGET_CC)"</span> LD=<span style="color: #009900">"$(TARGET_LD)"</span> -C <span style="color: #009900">$(@D)</span> all
-<span style="color: #000000">14:</span> endef
-<span style="color: #000000">15:</span>
-<span style="color: #000000">16:</span> define LIBFOO_INSTALL_STAGING_CMDS
-<span style="color: #000000">17:</span> <span style="color: #009900">$(INSTALL)</span> -D -m 0755 <span style="color: #009900">$(@D)</span>/libfoo.a <span style="color: #009900">$(STAGING_DIR)</span>/usr/lib/libfoo.a
-<span style="color: #000000">18:</span> <span style="color: #009900">$(INSTALL)</span> -D -m 0644 <span style="color: #009900">$(@D)</span>/foo.h <span style="color: #009900">$(STAGING_DIR)</span>/usr/include/foo.h
-<span style="color: #000000">19:</span> <span style="color: #009900">$(INSTALL)</span> -D -m 0755 <span style="color: #009900">$(@D)</span>/libfoo.so* <span style="color: #009900">$(STAGING_DIR)</span>/usr/lib
-<span style="color: #000000">20:</span> endef
-<span style="color: #000000">21:</span>
-<span style="color: #000000">22:</span> define LIBFOO_INSTALL_TARGET_CMDS
-<span style="color: #000000">23:</span> <span style="color: #009900">$(INSTALL)</span> -D -m 0755 <span style="color: #009900">$(@D)</span>/libfoo.so* <span style="color: #009900">$(TARGET_DIR)</span>/usr/lib
-<span style="color: #000000">24:</span> <span style="color: #009900">$(INSTALL)</span> -d -m 0755 <span style="color: #009900">$(TARGET_DIR)</span>/etc/foo.d
-<span style="color: #000000">25:</span> endef
-<span style="color: #000000">26:</span>
-<span style="color: #000000">27:</span><span style="color: #009900"> $(eval $(call GENTARGETS,package,libfoo))</span>
-</pre>
-
- <p>The Makefile begins on line 6 to 8 with metadata information: the
- version of the package (<code>LIBFOO_VERSION</code>), the name of the
- tarball containing the package (<code>LIBFOO_SOURCE</code>) and the
- Internet location at which the tarball can be downloaded
- (<code>LIBFOO_SITE</code>). All variables must start with the same prefix,
- <code>LIBFOO_</code> in this case. This prefix is always the uppercased
- version of the package name (see below to understand where the package
- name is defined).</p>
-
- <p>On line 9, we specify that this package wants to install something to
- the staging space. This is often needed for libraries, since they must
- install header files and other development files in the staging space.
- This will ensure that the commands listed in the
- <code>LIBFOO_INSTALL_STAGING_CMDS</code> variable will be executed.</p>
-
- <p>On line 10, we specify the list of dependencies this package relies
- on. These dependencies are listed in terms of lower-case package names,
- which can be packages for the target (without the <code>host-</code>
- prefix) or packages for the host (with the <code>host-</code>) prefix).
- Buildroot will ensure that all these packages are built and installed
- <i>before</i> the current package starts its configuration.</p>
-
- <p>The rest of the Makefile defines what should be done at the different
- steps of the package configuration, compilation and installation.
- <code>LIBFOO_BUILD_CMDS</code> tells what steps should be performed to
- build the package. <code>LIBFOO_INSTALL_STAGING_CMDS</code> tells what
- steps should be performed to install the package in the staging space.
- <code>LIBFOO_INSTALL_TARGET_CMDS</code> tells what steps should be
- performed to install the package in the target space.</p>
-
- <p>All these steps rely on the <code>$(@D)</code> variable, which
- contains the directory where the source code of the package has been
- extracted.</p>
-
- <p>Finally, on line 27, we call the <code>GENTARGETS</code> which
- generates, according to the variables defined previously, all the
- Makefile code necessary to make your package working.</p>
-
- <h4 id="generic-reference">Makefile for generic packages : reference</h4>
-
- <p>The <code>GENTARGETS</code> macro takes three arguments:</p>
-
- <ul>
- <li>The first argument is the package directory prefix. If your
- package is in <code>package/libfoo</code>, then the directory prefix
- is <code>package</code>. If your package is in
- <code>package/editors/foo</code>, then the directory prefix must be
- <code>package/editors</code>.</li>
-
- <li>The second argument is the lower-cased package name. It must match
- the prefix of the variables in the <code>.mk</code> file and must
- match the configuration option name in the <code>Config.in</code>
- file. For example, if the package name is <code>libfoo</code>, then the
- variables in the <code>.mk</code> file must start with
- <code>LIBFOO_</code> and the configuration option in the
- <code>Config.in</code> file must be <code>BR2_PACKAGE_LIBFOO</code>.</li>
-
- <li>The third argument is optional. It can be used to tell if the
- package is a target package (cross-compiled for the target) or a host
- package (natively compiled for the host). If unspecified, it is
- assumed that it is a target package. See below for details.</li>
- </ul>
-
- <p>For a given package, in a single <code>.mk</code> file, it is
- possible to call GENTARGETS twice, once to create the rules to generate
- a target package and once to create the rules to generate a host package:
- </p>
-
-<pre>
-$(eval $(call GENTARGETS,package,libfoo))
-$(eval $(call GENTARGETS,package,libfoo,host))
-</pre>
-
- <p>This might be useful if the compilation of the target package
- requires some tools to be installed on the host. If the package name is
- <code>libfoo</code>, then the name of the package for the target is also
- <code>libfoo</code>, while the name of the package for the host is
- <code>host-libfoo</code>. These names should be used in the DEPENDENCIES
- variables of other packages, if they depend on <code>libfoo</code> or
- <code>host-libfoo</code>.</p>
-
- <p>The call to the <code>GENTARGETS</code> macro <b>must</b> be at the
- end of the <code>.mk</code> file, after all variable definitions.</p>
-
- <p>For the target package, the <code>GENTARGETS</code> uses the
- variables defined by the .mk file and prefixed by the uppercased package
- name: <code>LIBFOO_*</code>. For the host package, it uses the
- <code>HOST_LIBFOO_*</code>. For <i>some</i> variables, if the
- <code>HOST_LIBFOO_</code> prefixed variable doesn't exist, the package
- infrastructure uses the corresponding variable prefixed by
- <code>LIBFOO_</code>. This is done for variables that are likely to have
- the same value for both the target and host packages. See below for
- details.</p>
-
- <p>The list of variables that can be set in a <code>.mk</code> file to
- give metadata information is (assuming the package name is
- <code>libfoo</code>) :</p>
-
- <ul>
- <li><code>LIBFOO_VERSION</code>, mandatory, must contain the
- version of the package. Note that
- if <code>HOST_LIBFOO_VERSION</code> doesn't exist, it is assumed
- to be the same as <code>LIBFOO_VERSION</code>. It can also be a
- Subversion or Git branch or tag, for packages that are fetched
- directly from their revision control system.<br/>
- Example: <code>LIBFOO_VERSION = 0.1.2</code></li>
-
- <li><code>LIBFOO_SOURCE</code> may contain the name of the tarball of
- the package. If <code>HOST_LIBFOO_SOURCE</code> is not specified, it
- defaults to <code>LIBFOO_SOURCE</code>. If none are specified, then
- the value is assumed to be
- <code>packagename-$(LIBFOO_VERSION).tar.gz</code>.<br/>Example:
- <code>LIBFOO_SOURCE = foobar-$(LIBFOO_VERSION).tar.bz2</code></li>
-
- <li><code>LIBFOO_PATCH</code> may contain the name of a patch, that
- will be downloaded from the same location as the tarball indicated in
- <code>LIBFOO_SOURCE</code>. If <code>HOST_LIBFOO_PATCH</code> is not
- specified, it defaults to <code>LIBFOO_PATCH</code>. Also note that
- another mechanism is available to patch a package: all files of the
- form <code>packagename-packageversion-description.patch</code> present
- in the package directory inside Buildroot will be applied to the
- package after extraction.</li>
-
- <li><code>LIBFOO_SITE</code> may contain the Internet location
- of the package. It can either be the HTTP or FTP location of a
- tarball, or the URL of a Git or Subversion repository
- (see <code>LIBFOO_SITE_METHOD</code>
- below). If <code>HOST_LIBFOO_SITE</code> is not specified, it
- defaults to <code>LIBFOO_SITE</code>. If none are specified,
- then the location is assumed to be
- <code>http://$$(BR2_SOURCEFORGE_MIRROR).dl.sourceforge.net/sourceforge/packagename</code>.
- <br/>Examples:<br/>
- <code>LIBFOO_SITE=http://www.libfoosoftware.org/libfoo</code><br/>
- <code>LIBFOO_SITE=http://svn.xiph.org/trunk/Tremor/</code></li>
-
- <li><code>LIBFOO_SITE_METHOD</code> may contain the method to
- fetch the package source code. It can either
- be <code>wget</code> (for normal FTP/HTTP downloads of
- tarballs), <code>svn</code>, <code>git</code> or <code>bzr</code>.
- When not specified, it is guessed from the URL given
- in <code>LIBFOO_SITE</code>: <code>svn://</code>, <code>git://</code>
- and <code>bzr://</code> URLs will use the <code>svn</code>,
- <code>git</code> and <code>bzr</code> methods respectively. All other
- URL-types will use the <code>wget</code> method. So for example, in the
- case of a package whose source code is available through
- Subversion repository on HTTP, one <i>must</i>
- specifiy <code>LIBFOO_SITE_METHOD=svn</code>. For <code>svn</code>
- and <code>git</code> methods, what Buildroot does is a
- checkout/clone of the repository which is then tarballed and
- stored into the download cache. Next builds will not
- checkout/clone again, but will use the tarball
- directly. When <code>HOST_LIBFOO_SITE_METHOD</code> is not
- specified, it defaults to the value
- of <code>LIBFOO_SITE_METHOD</code>. See <code>package/multimedia/tremor/</code>
- for an example.</li>
-
- <li><code>LIBFOO_DEPENDENCIES</code> lists the dependencies (in terms
- of package name) that are required for the current target package to
- compile. These dependencies are guaranteed to be compiled and
- installed before the configuration of the current package starts. In a
- similar way, <code>HOST_LIBFOO_DEPENDENCIES</code> lists the
- dependency for the current host package.</li>
-
- <li><code>LIBFOO_INSTALL_STAGING</code> can be set to <code>YES</code>
- or <code>NO</code> (default). If set to <code>YES</code>, then the
- commands in the <code>LIBFOO_INSTALL_STAGING_CMDS</code> variables are
- executed to install the package into the staging directory.</li>
-
- <li><code>LIBFOO_INSTALL_TARGET</code> can be set to <code>YES</code>
- (default) or <code>NO</code>. If set to <code>YES</code>, then the
- commands in the <code>LIBFOO_INSTALL_TARGET_CMDS</code> variables are
- executed to install the package into the target directory.</li> </ul>
-
- <p>The recommended way to define these variables is to use the following
- syntax:</p>
-
-<pre>
-LIBFOO_VERSION = 2.32
-</pre>
-
- <p>Now, the variables that define what should be performed at the
- different steps of the build process.</p>
-
- <ul>
- <li><code>LIBFOO_CONFIGURE_CMDS</code>, used to list the actions to be
- performed to configure the package before its compilation</li>
-
- <li><code>LIBFOO_BUILD_CMDS</code>, used to list the actions to be
- performed to compile the package</li>
-
- <li><code>HOST_LIBFOO_INSTALL_CMDS</code>, used to list the actions to
- be performed to install the package, when the package is a host
- package. The package must install its files to the directory given by
- <code>$(HOST_DIR)</code>. All files, including development files such
- as headers should be installed, since other packages might be compiled
- on top of this package.</li>
-
- <li><code>LIBFOO_INSTALL_TARGET_CMDS</code>, used to list the actions
- to be performed to install the package to the target directory, when
- the package is a target package. The package must install its files to
- the directory given by <code>$(TARGET_DIR)</code>. Only the files
- required for <i>documentation</i> and <i>execution</i> of the package
- should be installed. Header files should not be installed, they will
- be copied to the target, if the
- <code>development files in target filesystem</code> option is selected.
- </li>
-
- <li><code>LIBFOO_INSTALL_STAGING_CMDS</code>, used to list the actions
- to be performed to install the package to the staging directory, when
- the package is a target package. The package must install its files to
- the directory given by <code>$(STAGING_DIR)</code>. All development
- files should be installed, since they might be needed to compile other
- packages.</li>
-
- <li><code>LIBFOO_CLEAN_CMDS</code>, used to list the actions to
- perform to clean up the build directory of the package.</li>
-
- <li><code>LIBFOO_UNINSTALL_TARGET_CMDS</code>, used to list the actions
- to uninstall the package from the target directory
- <code>$(TARGET_DIR)</code></li>
-
- <li><code>LIBFOO_UNINSTALL_STAGING_CMDS</code>, used to list the
- actions to uninstall the package from the staging directory
- <code>$(STAGING_DIR)</code>.</li>
- </ul>
-
- <p>The preferred way to define these variables is:</p>
-
-<pre>
-define LIBFOO_CONFIGURE_CMDS
- action 1
- action 2
- action 3
-endef
-</pre>
-
- <p>In the action definitions, you can use the following variables:</p>
-
- <ul>
- <li><code>$(@D)</code>, which contains the directory in which the
- package source code has been uncompressed.</li>
-
- <li><code>$(TARGET_CC)</code>, <code>$(TARGET_LD)</code>, etc. to get
- the target cross-compilation utilities</li>
-
- <li><code>$(TARGET_CROSS)</code> to get the cross-compilation
- toolchain prefix</li>
-
- <li>Of course the <code>$(HOST_DIR)</code>, <code>$(STAGING_DIR)</code>
- and <code>$(TARGET_DIR)</code> variables to install the packages
- properly.</li>
- </ul>
-
- <p>The last feature of the generic infrastructure is the ability to add
- hooks. These define further actions to perform after existing steps.
- Most hooks aren't really useful for generic packages, since the
- <code>.mk</code> file already has full control over the actions
- performed in each step of the package construction. The hooks are more
- useful for packages using the autotools infrastructure described below.
- However, since they are provided by the generic infrastructure, they are
- documented here. The exception is <code>LIBFOO_POST_PATCH_HOOKS</code>.
- Patching the package is not user definable, so
- <code>LIBFOO_POST_PATCH_HOOKS</code> will be userful for generic packages.
- </p>
-
- <p>The following hook points are available:</p>
-
- <ul>
- <li><code>LIBFOO_POST_PATCH_HOOKS</code></li>
- <li><code>LIBFOO_PRE_CONFIGURE_HOOKS</code></li>
- <li><code>LIBFOO_POST_CONFIGURE_HOOKS</code></li>
- <li><code>LIBFOO_POST_BUILD_HOOKS</code></li>
- <li><code>LIBFOO_POST_INSTALL_HOOKS</code> (for host packages only)</li>
- <li><code>LIBFOO_POST_INSTALL_STAGING_HOOKS</code> (for target packages only)</li>
- <li><code>LIBFOO_POST_INSTALL_TARGET_HOOKS</code> (for target packages only)</li>
- </ul>
-
- <p>These variables are <i>lists</i> of variable names containing actions
- to be performed at this hook point. This allows several hooks to be
- registered at a given hook point. Here is an example:</p>
-
-<pre>
-define LIBFOO_POST_PATCH_FIXUP
- action1
- action2
-endef
-
-LIBFOO_POST_PATCH_HOOKS += LIBFOO_POST_PATCH_FIXUP
-</pre>
-
- <h4 id="autotools-tutorial">Makefile for autotools-based packages : tutorial</h4>
-
- <p>First, let's see how to write a <code>.mk</code> file for an
- autotools-based package, with an example :</p>
-
-<pre>
-<span style="color: #000000">01:</span><span style="font-style: italic; color: #9A1900"> #############################################################</span>
-<span style="color: #000000">02:</span><span style="font-style: italic; color: #9A1900"> #</span>
-<span style="color: #000000">03:</span><span style="font-style: italic; color: #9A1900"> # libfoo</span>
-<span style="color: #000000">04:</span><span style="font-style: italic; color: #9A1900"> #</span>
-<span style="color: #000000">05:</span><span style="font-style: italic; color: #9A1900"> #############################################################</span>
-<span style="color: #000000">06:</span><span style="color: #009900"> LIBFOO_VERSION</span> = 1.0
-<span style="color: #000000">07:</span><span style="color: #009900"> LIBFOO_SOURCE</span> = libfoo-<span style="color: #009900">$(LIBFOO_VERSION)</span>.tar.gz
-<span style="color: #000000">08:</span><span style="color: #009900"> LIBFOO_SITE</span> = http://www.foosoftware.org/download
-<span style="color: #000000">09:</span><span style="color: #009900"> LIBFOO_INSTALL_STAGING</span> = YES
-<span style="color: #000000">10:</span><span style="color: #009900"> LIBFOO_INSTALL_TARGET</span> = YES
-<span style="color: #000000">11:</span><span style="color: #009900"> LIBFOO_CONF_OPT</span> = --enable-shared
-<span style="color: #000000">12:</span><span style="color: #009900"> LIBFOO_DEPENDENCIES</span> = libglib2 host-pkg-config
-<span style="color: #000000">13:</span>
-<span style="color: #000000">14:</span><span style="color: #009900"> $(eval $(call AUTOTARGETS,package,libfoo))</span>
-</pre>
-
- <p>On line 6, we declare the version of the package.</p>
-
- <p>On line 7 and 8, we declare the name of the tarball and the location
- of the tarball on the Web. Buildroot will automatically download the
- tarball from this location.</p>
-
- <p>On line 9, we tell Buildroot to install the package to the staging
- directory. The staging directory, located in <code>output/staging/</code>
- is the directory where all the packages are installed, including their
- development files, etc. By default, packages are not installed to the
- staging directory, since usually, only libraries need to be installed in
- the staging directory: their development files are needed to compile
- other libraries or applications depending on them. Also by default, when
- staging installation is enabled, packages are installed in this location
- using the <code>make install</code> command.</p>
-
- <p>On line 10, we tell Buildroot to also install the package to the
- target directory. This directory contains what will become the root
- filesystem running on the target. Usually, we try not to install header
- files and to install stripped versions of the binary. By default, target
- installation is enabled, so in fact, this line is not strictly
- necessary. Also by default, packages are installed in this location
- using the <code>make install</code> command.</p>
-
- <p>On line 11, we tell Buildroot to pass a custom configure option, that
- will be passed to the <code>./configure</code> script before configuring
- and building the package.</p>
-
- <p>On line 12, we declare our dependencies, so that they are built
- before the build process of our package starts.</p>
-
- <p>Finally, on line line 14, we invoke the <code>AUTOTARGETS</code>
- macro that generates all the Makefile rules that actually allows the
- package to be built.</p>
-
- <h4 id="autotools-reference">Makefile for autotools packages : reference</h4>
-
- <p>The main macro of the autotools package infrastructure is
- <code>AUTOTARGETS</code>. It has the same number of arguments and the
- same semantic as the <code>GENTARGETS</code> macro, which is the main
- macro of the generic package infrastructure. For autotools packages, the
- ability to have target and host packages is also available (and is
- actually widely used).</p>
-
- <p>Just like the generic infrastructure, the autotools infrastructure
- works by defining a number of variables before calling the
- <code>AUTOTARGETS</code> macro.</p>
-
- <p>First, all the package metadata information variables that exist in the
- generic infrastructure also exist in the autotools infrastructure:
- <code>LIBFOO_VERSION</code>, <code>LIBFOO_SOURCE</code>,
- <code>LIBFOO_PATCH</code>, <code>LIBFOO_SITE</code>,
- <code>LIBFOO_SUBDIR</code>, <code>LIBFOO_DEPENDENCIES</code>,
- <code>LIBFOO_INSTALL_STAGING</code>, <code>LIBFOO_INSTALL_TARGET</code>.</p>
-
- <p>A few additional variables, specific to the autotools infrastructure,
- can also be defined. Many of them are only useful in very specific
- cases, typical packages will therefore only use a few of them.</p>
-
- <ul>
- <li><code>LIBFOO_SUBDIR</code> may contain the name of a subdirectory
- inside the package that contains the configure script. This is useful,
- if for example, the main configure script is not at the root of the
- tree extracted by the tarball. If <code>HOST_LIBFOO_SUBDIR</code> is
- not specified, it defaults to <code>LIBFOO_SUBDIR</code>.</li>
-
- <li><code>LIBFOO_CONF_ENV</code>, to specify additional environment
- variables to pass to the configure script. By default, empty.</li>
-
- <li><code>LIBFOO_CONF_OPT</code>, to specify additional configure
- options to pass to the configure script. By default, empty.</li>
-
- <li><code>LIBFOO_MAKE</code>, to specify an alternate <code>make</code>
- command. This is typically useful when parallel make is enabled in
- the configuration (using <code>BR2_JLEVEL</code>) but that this
- feature should be disabled for the given package, for one reason or
- another. By default, set to <code>$(MAKE)</code>. If parallel building
- is not supported by the package, then it should be set to
- <code>LIBFOO_MAKE=$(MAKE1)</code>.</li>
-
- <li><code>LIBFOO_MAKE_ENV</code>, to specify additional environment
- variables to pass to make in the build step. These are passed before
- the <code>make</code> command. By default, empty.</li>
-
- <li><code>LIBFOO_MAKE_OPT</code>, to specify additional variables to
- pass to make in the build step. These are passed after the
- <code>make</code> command. By default, empty.</li>
-
- <li><code>LIBFOO_AUTORECONF</code>, tells whether the package should
- be autoreconfigured or not (i.e, if the configure script and
- Makefile.in files should be re-generated by re-running autoconf,
- automake, libtool, etc.). Valid values are <code>YES</code> and
- <code>NO</code>. By default, the value is <code>NO</code></li>
-
- <li><code>LIBFOO_AUTORECONF_OPT</code> to specify additional options
- passed to the <i>autoreconf</i> program if
- <code>LIBFOO_AUTORECONF=YES</code>. By default, empty.</li>
-
- <li><code>LIBFOO_LIBTOOL_PATCH</code> tells whether the Buildroot
- patch to fix libtool cross-compilation issues should be applied or
- not. Valid values are <code>YES</code> and <code>NO</code>. By
- default, the value is <code>YES</code></li>
-
- <li><code>LIBFOO_INSTALL_STAGING_OPT</code> contains the make options
- used to install the package to the staging directory. By default, the
- value is <code>DESTDIR=$$(STAGING_DIR) install</code>, which is
- correct for most autotools packages. It is still possible to override
- it.</li>
-
- <li><code>LIBFOO_INSTALL_TARGET_OPT</code> contains the make options
- used to install the package to the target directory. By default, the
- value is <code>DESTDIR=$$(TARGET_DIR) install</code>. The default
- value is correct for most autotools packages, but it is still possible
- to override it if needed.</li>
-
- <li><code>LIBFOO_CLEAN_OPT</code> contains the make options used to
- clean the package. By default, the value is <code>clean</code>.</li>
-
- <li><code>LIBFOO_UNINSTALL_STAGING_OPT</code>, contains the make
- options used to uninstall the package from the staging directory. By
- default, the value is <code>DESTDIR=$$(STAGING_DIR) uninstall</code>.</li>
-
- <li><code>LIBFOO_UNINSTALL_TARGET_OPT</code>, contains the make
- options used to uninstall the package from the target directory. By
- default, the value is <code>DESTDIR=$$(TARGET_DIR) uninstall</code>.</li>
- </ul>
-
- <p>With the autotools infrastructure, all the steps required to build
- and install the packages are already defined, and they generally work
- well for most autotools-based packages. However, when required, it is
- still possible to customize what is done in any particular step:</p>
-
- <ul>
- <li>By adding a post-operation hook (after extract, patch, configure,
- build or install). See the reference documentation of the generic
- infrastructure for details.</li>
-
- <li>By overriding one of the steps. For example, even if the autotools
- infrastructure is used, if the package <code>.mk</code> file defines its
- own <code>LIBFOO_CONFIGURE_CMDS</code> variable, it will be used
- instead of the default autotools one. However, using this method
- should be restricted to very specific cases. Do not use it in the
- general case.</li>
- </ul>
-
- <h4 id="cmake-tutorial">Makefile for CMake-based packages : tutorial</h4>
-
- <p>First, let's see how to write a <code>.mk</code> file for a CMake-based
- package, with an example :</p>
-
-<pre>
-<span style="color: #000000">01:</span><span style="font-style: italic; color: #9A1900"> #############################################################</span>
-<span style="color: #000000">02:</span><span style="font-style: italic; color: #9A1900"> #</span>
-<span style="color: #000000">03:</span><span style="font-style: italic; color: #9A1900"> # libfoo</span>
-<span style="color: #000000">04:</span><span style="font-style: italic; color: #9A1900"> #</span>
-<span style="color: #000000">05:</span><span style="font-style: italic; color: #9A1900"> #############################################################</span>
-<span style="color: #000000">06:</span><span style="color: #009900"> LIBFOO_VERSION</span> = 1.0
-<span style="color: #000000">07:</span><span style="color: #009900"> LIBFOO_SOURCE</span> = libfoo-<span style="color: #009900">$(LIBFOO_VERSION)</span>.tar.gz
-<span style="color: #000000">08:</span><span style="color: #009900"> LIBFOO_SITE</span> = http://www.foosoftware.org/download
-<span style="color: #000000">09:</span><span style="color: #009900"> LIBFOO_INSTALL_STAGING</span> = YES
-<span style="color: #000000">10:</span><span style="color: #009900"> LIBFOO_INSTALL_TARGET</span> = YES
-<span style="color: #000000">11:</span><span style="color: #009900"> LIBFOO_CONF_OPT</span> = -DBUILD_DEMOS=ON
-<span style="color: #000000">12:</span><span style="color: #009900"> LIBFOO_DEPENDENCIES</span> = libglib2 host-pkg-config
-<span style="color: #000000">13:</span>
-<span style="color: #000000">14:</span><span style="color: #009900"> $(eval $(call CMAKETARGETS,package,libfoo))</span>
-</pre>
-
- <p>On line 6, we declare the version of the package.</p>
-
- <p>On line 7 and 8, we declare the name of the tarball and the location
- of the tarball on the Web. Buildroot will automatically download the
- tarball from this location.</p>
-
- <p>On line 9, we tell Buildroot to install the package to the staging
- directory. The staging directory, located in <code>output/staging/</code>
- is the directory where all the packages are installed, including their
- development files, etc. By default, packages are not installed to the
- staging directory, since usually, only libraries need to be installed in
- the staging directory: their development files are needed to compile
- other libraries or applications depending on them. Also by default, when
- staging installation is enabled, packages are installed in this location
- using the <code>make install</code> command.</p>
-
- <p>On line 10, we tell Buildroot to also install the package to the
- target directory. This directory contains what will become the root
- filesystem running on the target. Usually, we try not to install header
- files and to install stripped versions of the binary. By default, target
- installation is enabled, so in fact, this line is not strictly
- necessary. Also by default, packages are installed in this location
- using the <code>make install</code> command.</p>
-
- <p>On line 11, we tell Buildroot to pass custom options to CMake when it is
- configuring the package.</p>
-
- <p>On line 12, we declare our dependencies, so that they are built
- before the build process of our package starts.</p>
-
- <p>Finally, on line line 14, we invoke the <code>CMAKETARGETS</code>
- macro that generates all the Makefile rules that actually allows the
- package to be built.</p>
-
- <h4 id="cmake-reference">Makefile for CMake packages : reference</h4>
-
- <p>The main macro of the CMake package infrastructure is
- <code>CMAKETARGETS</code>. It has the same number of arguments and the
- same semantic as the <code>GENTARGETS</code> macro, which is the main
- macro of the generic package infrastructure. For CMake packages, the
- ability to have target and host packages is also available.</p>
-
- <p>Just like the generic infrastructure, the CMake infrastructure
- works by defining a number of variables before calling the
- <code>CMAKETARGETS</code> macro.</p>
-
- <p>First, all the package metadata information variables that exist in the
- generic infrastructure also exist in the CMake infrastructure:
- <code>LIBFOO_VERSION</code>, <code>LIBFOO_SOURCE</code>,
- <code>LIBFOO_PATCH</code>, <code>LIBFOO_SITE</code>,
- <code>LIBFOO_SUBDIR</code>, <code>LIBFOO_DEPENDENCIES</code>,
- <code>LIBFOO_INSTALL_STAGING</code>, <code>LIBFOO_INSTALL_TARGET</code>.</p>
-
- <p>A few additional variables, specific to the CMake infrastructure,
- can also be defined. Many of them are only useful in very specific
- cases, typical packages will therefore only use a few of them.</p>
-
- <ul>
- <li><code>LIBFOO_SUBDIR</code> may contain the name of a subdirectory
- inside the package that contains the main CMakeLists.txt file. This is
- useful, if for example, the main CMakeLists.txt file is not at the root
- of the tree extracted by the tarball. If <code>HOST_LIBFOO_SUBDIR</code>
- is not specified, it defaults to <code>LIBFOO_SUBDIR</code>.</li>
-
- <li><code>LIBFOO_CONF_ENV</code>, to specify additional environment
- variables to pass to CMake. By default, empty.</li>
-
- <li><code>LIBFOO_CONF_OPT</code>, to specify additional configure
- options to pass to CMake. By default, empty.</li>
-
- <li><code>LIBFOO_MAKE</code>, to specify an alternate <code>make</code>
- command. This is typically useful when parallel make is enabled in
- the configuration (using <code>BR2_JLEVEL</code>) but that this
- feature should be disabled for the given package, for one reason or
- another. By default, set to <code>$(MAKE)</code>. If parallel building
- is not supported by the package, then it should be set to
- <code>LIBFOO_MAKE=$(MAKE1)</code>.</li>
-
- <li><code>LIBFOO_MAKE_ENV</code>, to specify additional environment
- variables to pass to make in the build step. These are passed before
- the <code>make</code> command. By default, empty.</li>
-
- <li><code>LIBFOO_MAKE_OPT</code>, to specify additional variables to
- pass to make in the build step. These are passed after the
- <code>make</code> command. By default, empty.</li>
-
- <li><code>LIBFOO_INSTALL_STAGING_OPT</code> contains the make options
- used to install the package to the staging directory. By default, the
- value is <code>DESTDIR=$$(STAGING_DIR) install</code>, which is
- correct for most CMake packages. It is still possible to override
- it.</li>
-
- <li><code>LIBFOO_INSTALL_TARGET_OPT</code> contains the make options
- used to install the package to the target directory. By default, the
- value is <code>DESTDIR=$$(TARGET_DIR) install</code>. The default
- value is correct for most CMake packages, but it is still possible
- to override it if needed.</li>
-
- <li><code>LIBFOO_CLEAN_OPT</code> contains the make options used to
- clean the package. By default, the value is <code>clean</code>.</li>
- </ul>
-
- <p>With the CMake infrastructure, all the steps required to build
- and install the packages are already defined, and they generally work
- well for most CMake-based packages. However, when required, it is
- still possible to customize what is done in any particular step:</p>
-
- <ul>
- <li>By adding a post-operation hook (after extract, patch, configure,
- build or install). See the reference documentation of the generic
- infrastructure for details.</li>
-
- <li>By overriding one of the steps. For example, even if the CMake
- infrastructure is used, if the package <code>.mk</code> file defines its
- own <code>LIBFOO_CONFIGURE_CMDS</code> variable, it will be used
- instead of the default CMake one. However, using this method
- should be restricted to very specific cases. Do not use it in the
- general case.</li>
- </ul>
-
- <h4 id ="manual-tutorial">Manual Makefile : tutorial</h4>
-
- <p><b>NOTE: new manual makefiles should not be created, and existing
- manual makefiles should be converted either to the generic, autotools
- or cmake infrastructure. This section is only kept to document the existing
- manual makefiles and to help understand how they work.</b></p>
-
-<pre>
-01: #############################################################
-02: #
-03: # libfoo
-04: #
-05: #############################################################
-<span id="ex2line6">06: LIBFOO_VERSION:=1.0</span>
-07: LIBFOO_SOURCE:=libfoo-$(LIBFOO_VERSION).tar.gz
-08: LIBFOO_SITE:=http://www.foosoftware.org/downloads
-09: LIBFOO_DIR:=$(BUILD_DIR)/foo-$(FOO_VERSION)
-10: LIBFOO_BINARY:=foo
-11: LIBFOO_TARGET_BINARY:=usr/bin/foo
-12:
-<span id="ex2line13">13: $(DL_DIR)/$(LIBFOO_SOURCE):</span>
-14: $(call DOWNLOAD,$(LIBFOO_SITE),$(LIBFOO_SOURCE))
-15:
-<span id="ex2line16">16: $(LIBFOO_DIR)/.source: $(DL_DIR)/$(LIBFOO_SOURCE)</span>
-17: $(ZCAT) $(DL_DIR)/$(LIBFOO_SOURCE) | tar -C $(BUILD_DIR) $(TAR_OPTIONS) -
-18: touch $@
-19:
-<span id="ex2line20">20: $(LIBFOO_DIR)/.configured: $(LIBFOO_DIR)/.source</span>
-21: (cd $(LIBFOO_DIR); rm -rf config.cache; \
-22: $(TARGET_CONFIGURE_OPTS) \
-23: $(TARGET_CONFIGURE_ARGS) \
-24: ./configure \
-25: --target=$(GNU_TARGET_NAME) \
-26: --host=$(GNU_TARGET_NAME) \
-27: --build=$(GNU_HOST_NAME) \
-28: --prefix=/usr \
-29: --sysconfdir=/etc \
-30: )
-31: touch $@
-32:
-<span id="ex2line33">33: $(LIBFOO_DIR)/$(LIBFOO_BINARY): $(LIBFOO_DIR)/.configured</span>
-34: $(MAKE) CC=$(TARGET_CC) -C $(LIBFOO_DIR)
-35:
-<span id="ex2line36">36: $(TARGET_DIR)/$(LIBFOO_TARGET_BINARY): $(LIBFOO_DIR)/$(LIBFOO_BINARY)</span>
-37: $(MAKE) DESTDIR=$(TARGET_DIR) -C $(LIBFOO_DIR) install-strip
-38: rm -Rf $(TARGET_DIR)/usr/man
-39:
-<span id="ex2line40">40: libfoo: uclibc ncurses $(TARGET_DIR)/$(LIBFOO_TARGET_BINARY)</span>
-41:
-<span id="ex2line42">42: libfoo-source: $(DL_DIR)/$(LIBFOO_SOURCE)</span>
-43:
-<span id="ex2line44">44: libfoo-clean:</span>
-45: $(MAKE) prefix=$(TARGET_DIR)/usr -C $(LIBFOO_DIR) uninstall
-46: -$(MAKE) -C $(LIBFOO_DIR) clean
-47:
-<span id="ex2line48">48: libfoo-dirclean:</span>
-49: rm -rf $(LIBFOO_DIR)
-50:
-<span id="ex2line51">51: #############################################################</span>
-52: #
-53: # Toplevel Makefile options
-54: #
-55: #############################################################
-56: ifeq ($(BR2_PACKAGE_LIBFOO),y)
-57: TARGETS+=libfoo
-58: endif
-</pre>
-
- <p>First of all, this Makefile example works for a package which
- comprises a single binary executable. For other software, such as
- libraries or more complex stuff with multiple binaries, it must be
- adapted. For examples look at the other <code>*.mk</code> files in the
- <code>package</code> directory.</p>
-
- <p>At lines <a href="#ex2line6">6-11</a>, a couple of useful variables are
- defined:</p>
-
- <ul>
- <li><code>LIBFOO_VERSION</code>: The version of <i>libfoo</i> that
- should be downloaded.</li>
-
- <li><code>LIBFOO_SOURCE</code>: The name of the tarball of <i>libfoo</i>
- on the download website or FTP site. As you can see
- <code>LIBFOO_VERSION</code> is used.</li>
-
- <li><code>LIBFOO_SITE</code>: The HTTP or FTP site from which
- <i>libfoo</i> archive is downloaded. It must include the complete path to
- the directory where <code>LIBFOO_SOURCE</code> can be found.</li>
-
- <li><code>LIBFOO_DIR</code>: The directory into which the software will
- be configured and compiled. Basically, it's a subdirectory of
- <code>BUILD_DIR</code> which is created upon decompression of the tarball.
- </li>
-
- <li><code>LIBFOO_BINARY</code>: Software binary name. As said previously,
- this is an example for a package with a single binary.</li>
-
- <li><code>LIBFOO_TARGET_BINARY</code>: The full path of the binary inside
- the target filesystem.</li> </ul>
-
- <p>Lines <a href="#ex2line13">13-14</a> define a target that downloads
- the tarball from the remote site to the download directory
- (<code>DL_DIR</code>).</p>
-
- <p>Lines <a href="#ex2line16">16-18</a> define a target and associated
- rules that uncompress the downloaded tarball. As you can see, this
- target depends on the tarball file so that the previous target (lines
- <a href="#ex2line13">13-14</a>) is called before executing the rules of
- the current target. Uncompressing is followed by <i>touching</i> a
- hidden file to mark the software as having been uncompressed. This trick
- is used everywhere in a Buildroot Makefile to split steps (download,
- uncompress, configure, compile, install) while still having correct
- dependencies.</p>
-
- <p>Lines <a href="#ex2line20">20-31</a> define a target and associated
- rules that configure the software. It depends on the previous target
- (the hidden <code>.source</code> file) so that we are sure the software
- has been uncompressed. In order to configure the package, it basically
- runs the well-known <code>./configure</code> script. As we may be doing
- cross-compilation, <code>target</code>, <code>host</code> and
- <code>build</code> arguments are given. The prefix is also set to
- <code>/usr</code>, not because the software will be installed in
- <code>/usr</code> on your host system, but because the software will be
- installed in <code> /usr</code> on the target filesystem. Finally it
- creates a <code>.configured</code> file to mark the software as
- configured.</p>
-
- <p>Lines <a href="#ex2line33">33-34</a> define a target and a rule that
- compile the software. This target will create the binary file in the
- compilation directory and depends on the software being already
- configured (hence the reference to the <code>.configured</code> file).
- It basically runs <code>make</code> inside the source directory.</p>
-
- <p>Lines <a href="#ex2line36">36-38</a> define a target and associated
- rules that install the software inside the target filesystem. They
- depend on the binary file in the source directory to make sure the
- software has been compiled. They use the <code>install-strip</code>
- target of the software <code>Makefile</code> by passing a
- <code>DESTDIR</code> argument so that the <code>Makefile</code> doesn't
- try to install the software in the host <code>/usr</code> but rather in
- the target <code>/usr</code>. After the installation, the
- <code>/usr/man </code> directory inside the target filesystem is removed
- to save space. </p>
-
- <p>Line <a href="#ex2line40">40</a> defines the main target of the
- software &mdash; the one that will eventually be used by the top level
- <code>Makefile</code> to download, compile, and then install this
- package. This target should first of all depend on all needed
- dependencies of the software (in our example, <i>uclibc</i> and
- <i>ncurses</i>) and also depend on the final binary. This last dependency
- will call all previous dependencies in the correct order.</p>
-
- <p>Line <a href="#ex2line42">42</a> defines a simple target that only
- downloads the code source. This is not used during normal operation of
- Buildroot, but is needed if you intend to download all required sources
- at once for later offline build. Note that if you add a new package,
- providing a <code>libfoo-source</code> target is <i>mandatory</i> to
- support users that wish to do offline-builds. Furthermore, it eases
- checking if all package-sources are downloadable.</p>
-
- <p>Lines <a href="#ex2line44">44-46</a> define a simple target to clean
- the software build by calling the Makefile with the appropriate options.
- The <code>-clean</code> target should run <code>make clean</code> on
- $(BUILD_DIR)/package-version and MUST uninstall all files of the package
- from $(STAGING_DIR) and from $(TARGET_DIR).</p>
-
- <p>Lines <a href="#ex2line48">48-49</a> define a simple target to
- completely remove the directory in which the software was uncompressed,
- configured and compiled. The <code>-dirclean</code> target MUST
- completely rm $(BUILD_DIR)/ package-version.</p>
-
- <p>Lines <a href="#ex2line51">51-58</a> add the target <code>libfoo</code>
- to the list of targets to be compiled by Buildroot, by first checking if
- the configuration option for this package has been enabled using the
- configuration tool. If so, it then &quot;subscribes&quot; this package
- to be compiled by adding the package to the TARGETS global variable.
- The name added to the TARGETS global variable is the name of this
- package's target, as defined on line <a href="#ex2line40">40</a>, which
- is used by Buildroot to download, compile, and then install this package.
- </p>
-
- <h3 id="gettext-integration">Gettext integration and interaction with packages</h3>
-
- <p>Many packages that support internationalization use the gettext
- library. Dependencies for this library are fairly complicated and therefore,
- deserves some explanation.</p>
-
- <p>The <i>uClibc</i> C library doesn't implement gettext functionality,
- therefore with this C library, a separate gettext must be compiled. On
- the other hand, the <i>glibc</i> C library does integrate its own
- gettext, and in this case, the separate gettext library should not be
- compiled, because it creates various kinds of build failures.</p>
-
- <p>Additionally, some packages (such as libglib2) do require gettext
- unconditionally, while other packages (those who support
- <code>--disable-nls</code> in general) only require gettext when locale
- support is enabled.</p>
-
- <p>Therefore, Buildroot defines two configuration options:</p>
-
- <ul>
- <li><code>BR2_NEEDS_GETTEXT</code>, which is true as soon as the
- toolchain doesn't provide its own gettext implementation</li>
-
- <li><code>BR2_NEEDS_GETTEXT_IF_LOCALE</code>, which is true if the
- toolchain doesn't provide its own gettext implementation and if locale
- support is enabled</li> </ul>
-
- <p>Therefore, packages that unconditionally need gettext should:</p>
-
- <ol>
- <li>Use <code>select BR2_PACKAGE_GETTEXT if BR2_NEEDS_GETTEXT</code>
- and possibly <code>select BR2_PACKAGE_LIBINTL if BR2_NEEDS_GETTEXT</code>,
- if libintl is also needed</li>
-
- <li>Use <code>$(if $(BR2_NEEDS_GETTEXT),gettext)</code> in the package
- <code>DEPENDENCIES</code> variable</li>
- </ol>
-
- <p>Packages that need gettext only when locale support is enabled should:
- </p>
-
- <ol>
- <li>Use
- <code>select BR2_PACKAGE_GETTEXT if BR2_NEEDS_GETTEXT_IF_LOCALE</code>
- and possibly
- <code>select BR2_PACKAGE_LIBINTL if BR2_NEEDS_GETTEXT_IF_LOCALE</code>,
- if libintl is also needed</li>
-
- <li>Use <code>$(if $(BR2_NEEDS_GETTEXT_IF_LOCALE),gettext)</code> in
- the package <code>DEPENDENCIES</code> variable</li>
- </ol>
-
- <h3>Conclusion</h3>
-
- <p>As you can see, adding a software package to Buildroot is simply a
- matter of writing a Makefile using an existing example and modifying it
- according to the compilation process required by the package.</p>
-
- <p>If you package software that might be useful for other people, don't
- forget to send a patch to Buildroot developers!</p>
-
- <h2 id="faq">Frequently asked questions</h2>
-
- <ul>
- <li><a href="#faq-boot-hangs">The boot hangs
- after <code>Starting network...</code></a></li>
- <li><a href="#module-init-tools-doesnt-build">module-init-tools
- fails to build with <code>cannot find -lc</code></a></li>
- </ul>
-
- <h3 id="faq-boot-hangs">The boot hangs after <code>Starting
- network...</code></h3>
-
- <p>If the boot process seems to hang after the following messages
- (messages not necessarly exactly similar, depending on the list of
- packages selected):</p>
-
- <pre>Freeing init memory: 3972K
-Initializing random number generator... done.
-Starting network...
-Starting dropbear sshd: generating rsa key... generating dsa key... OK</pre>
-
- <p>then it means that your system is running, but didn't start a
- shell on the serial console. In order to have the system start a
- shell on your serial console, you have to go in the Buildroot
- configuration, <code>System configuration</code>, and modify
- <code>Port to run a getty (login prompt) on</code> and
- <code>Baudrate to use</code> as appropriate. This will automatically tune
- the <code>/etc/inittab</code> file of the generated system so that
- a shell starts on the correct serial port.</p>
-
- <h3 id="module-init-tools-doesnt-build">module-init-tools
- fails to build with <code>cannot find -lc</code></h3>
-
- <p>If the build of <i>module-init-tools</i> for the host fails
- with:</p>
-
- <pre>/usr/bin/ld: cannot find -lc </pre>
-
- <p>then probably you are running a Fedora (or similar)
- distribution, and you should install the <code>glibc-static</code>
- package. This is because the <i>module-init-tools</i> build
- process wants to link statically against the C library.</p>
-
- <h2 id="links">Resources</h2>
-
- <p>To learn more about Buildroot you can visit these websites:</p>
-
- <ul>
- <li><a href="http://www.uclibc.org/">http://www.uclibc.org/</a></li>
- <li><a href="http://www.busybox.net/">http://www.busybox.net/</a></li>
- </ul>
- </div>
-</body>
-</html>