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documentation: update after major changes

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* Remove the huge section describing the design of the removed
   "project" feature

 * Update all references to the output directory hierarchy to match
   the new one

 * Add new sections on how to rebuild single packages and how to
   create board support

 * Other updates, clarifications, reorganizations

 Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
This commit is contained in:
Thomas Petazzoni 2009-09-11 20:40:42 +02:00
parent 3b2a803d28
commit 84a8eafd4c
1 changed files with 265 additions and 404 deletions
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docs/buildroot.html
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@ -24,32 +24,30 @@
<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 target filesystem</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="#rebuilding_packages">Understanding how to rebuild packages</a></li>
<li><a href="#buildroot_innards">How Buildroot works</a></li>
<li><a href="#multi_project">Building several projects in the
same buildroot source tree</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="#adapting_rootfs">Adapting the rootfs for own binaries</a></li>
<li><a href="#add_software">Extending Buildroot with more
Software</a></li>
<li><a href="#board_support">Creating your own board support</a></li>
<li><a href="#links">Resources</a></li>
</ul>
<h2><a name="about" id="about"></a>About Buildroot</h2>
<p>Buildroot is a set of Makefiles and patches that allow to easily
generate both a cross-compilation toolchain and a root filesystem for your
target. The cross-compilation toolchain uses uClibc (<a href=
"http://www.uclibc.org/">http://www.uclibc.org/</a>), a tiny C standard
library. </p>
<p>Buildroot is a set of Makefiles and patches that allow to
easily generate a cross-compilation toolchain, a root filesystem
and a Linux kernel image for your target. Buildroot can be used
for either 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
@ -169,10 +167,6 @@
<p>For each entry of the configuration tool, you can find associated help
that describes the purpose of the entry. </p>
<p>One of the key configuration items is the <code>PROJECT</code> which
determines where some board specific packages are built and where the
results are stored. </p>
<p>Once everything is configured, the configuration tool has generated 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>
@ -184,48 +178,51 @@
$ make
</pre>
<p>This command will download, configure and compile all the selected
tools, and finally generate a target filesystem. The target filesystem will
be named <code>root_fs_ARCH.EXT</code> where <code>ARCH</code> is your
architecture and <code>EXT</code> depends on the type of target filesystem
selected in the <code>Target options</code> section of the configuration
tool.
The file is stored in the "binaries/<code>$(PROJECT)</code>/" directory</p>
<p>This command will download, configure and compile all the
selected tools, and finally generate a toolchain, a root
filesystem image and a kernel image (or only one of these
elements, depending on the configuration).</p>
<h3><a name="local_board_support" id="local_board_support"></a>
Creating your own board support</h3>
<p>Buildroot output is stored in a single directory,
<code>output/</code>. This directory contains several
subdirectories:</p>
<p>Once a package has been unpacked, it is possible to manually update
configuration files. Buildroot can automatically save the configuration
of buildroot, linux, busybox, uclibc and u-boot in "local/$(PROJECT) by
using the command:
</p>
<ul>
<pre>
$ make saveconfig
</pre>
<li><code>images/</code> where all the images (kernel image,
bootloader and root filesystem images) are stored.</li>
<p>Once a buildroot configuration has been created by saveconfig,
the default "$(TOPDIR)/.config" file can be overridden by</p>
<li><code>build/</code> where all the components are built
(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. The toolchain
components are however built in a separate directory.</li>
<pre>
$ make BOARD=&lt;project&gt;
</pre>
<li><code>staging/</code> which contains a hierarchy similar to
a root filesystem hierarchy. This directory contains the
installation of 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.</li>
<p>Buildroot will then use "local/&lt;project&gt;/&lt;project&gt;.config"
instead of ".config". </p>
<li><code>target/<code> which contains the root filesystem for
the target. Only the necessary files to run the libraries and
applications are installed in this directory. However,
<code>target/dev/</code> doesn't contain the device files, as
creating device files requires the root access. The device files
only exist in the root filesystem image produced by
Buildroot.</li>
<p>If you want to modify your board, you can copy the project configuration
file to ".config" by using the command:</p>
<li><code>host/</code> contains the installation of tools
compiled for the host that are needed for the proper execution
of Buildroot.</li>
<pre>
$ make BOARD=&lt;project&gt; getconfig
</pre>
<p>You can share your custom board support directory between several buildroot trees
by setting the environment variable <code>BUILDROOT_LOCAL</code> to this directory,
</p>
<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>
@ -259,13 +256,18 @@
<p>Buildroot optionally honors some environment variables that are passed
to <code>make</code> :</p>
<ul>
<li>HOSTCXX</li>
<li>HOSTCC</li>
<li>UCLIBC_CONFIG_FILE=&lt;path/to/.config&gt;</li>
<li>BUSYBOX_CONFIG_FILE=&lt;path/to/.config&gt;</li>
<li>BUILDROOT_COPYTO</li>
<li>BUILDROOT_DL_DIR</li>
<li>BUILDROOT_LOCAL</li>
<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
internal toolchain is selected</li>
<li><code>BUSYBOX_CONFIG_FILE=&lt;path/to/.config&gt;</code>, path
to the Busybox configuration file</li>
<li><code>BUILDROOT_COPYTO</code>, an additional location at which
the binary images of the root filesystem, kernel, etc. built by
Buildroot are copied</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
@ -289,43 +291,14 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
$ export BUILDROOT_COPYTO=/tftpboot
</pre>
<h3><a name="helper_completion" id="helper_completion"></a>
Using auto-completion</h3>
<p>If you are lazy enough that you don't want to type the entire <i>make
menuconfig</i> command line, you can enable auto-completion in your shell.
Here is how you can do that using <i>bash</i>:</p>
<pre>
$ complete -W menuconfig make
</pre>
<p>Then just enter the beginning of the line, and ask <i>bash</i> to
complete it for you by pressing the <i>TAB</i> key:</p>
<pre>
$ make me&lt;TAB&gt;
</pre>
<p>will result in <i>bash</i> to append <i>nuconfig</i> for you!</p>
<p>Alternatively, some distributions (of which Debian and Mandriva are but
an example) have more powerful make completion. Depending on you
distribution, you may have to install a package to enable completion. Under
Mandriva, this is <i>bash-completion</i>, while Debian ships it as part of
the <i>bash</i> package.</p>
<p>Other shells, such as <i>zsh</i>, also have completion facilities. See
the documentation for your shell.</p>
<h2><a name="custom_targetfs" id="custom_targetfs"></a>Customizing the
target filesystem</h2>
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>project_build_ARCH/root/</code>
where <code>ARCH</code> is the chosen target architecture.
target filesystem is available under <code>output/target/</code>.
You can simply make your changes here, and run make afterwards, which will
rebuild the target filesystem image. This method allows to do everything
on the target filesystem, but if you decide to completely rebuild your
@ -347,14 +320,31 @@ $ make me&lt;TAB&gt;
inside the skeleton because it contains symlinks that would be broken
otherwise. <br />
These customizations are deployed into
<code>project_build_ARCH/root/</code> just before the actual image
<code>output/target/</code> just before the actual image
is made. So simply rebuilding the image by running
make should propagate any new changes to the image. </li>
<li>When configuring the build system, using <code>make
menuconfig</code> or <code>make xconfig</code>, you can specify
the contents of the /etc/hostname and /etc/issue (the welcome
banner) in the <code>PROJECT</code> section</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 Buildroot configuration, you can specify the path to a
post-build script that gets called <i>after</i> Buildroot built
all the selected software, but <i>before</i> the the rootfs
packages are assembled. The destination root filesystem folder
is given as 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
that feature with care. Whenever you find that a certain package
generates wrong or unneeded files, you should rather fix than
package than working around it with a 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 from the configuration system.</li>
</ul>
<h2><a name="custom_busybox" id="custom_busybox"></a>Customizing the
@ -423,6 +413,73 @@ $ make me&lt;TAB&gt;
<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="#rebuilding_packages"
id="rebuilding_packages">Understanding how to rebuild
packages</a></h2>
<p>One of the most common question and issue about Buildroot
encountered by 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, implement clean package removal is on the
TODO-list of Buildroot developers.</p>
<p>To rebuild a single package from scratch, the easiest way 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 remains to be done, Buildroot maintains stamps
files (i.e, empty files that just tell whether this or this action
has been done). The problem is that these stamps files are not
uniformely named and handled by the different packages, so some
understanding of the particular package is needed.</p>
<p>For packages relying on the <i>autotools</i> Buildroot
infrastructure (see <a href="#add_software">this section</a> for
details), the following stamps files are interesting:</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
looks like:</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>So, if you want to trigger the reconfiguration, you need to
remove <code>output/build/zlib-version/.configured</code> and if
you want to trigger only the recompilation, you need to remove
<code>output/build/zlib-version/libz.a</code>.</p>
<h2><a name="buildroot_innards" id="buildroot_innards"></a>How Buildroot
works</h2>
@ -477,334 +534,154 @@ $ make me&lt;TAB&gt;
configuration is done) :</p>
<ol>
<li>Create the download directory (<code>dl/</code> by default). This is
where the tarballs will be downloaded. It is interesting to know that the
tarballs are in this directory because it may be useful to save them
somewhere to avoid further downloads. </li>
<li>Create the shared build directory (<code>build_ARCH/</code> by
default, where <code>ARCH</code> is your architecture). This is where all
non configurable user-space tools will be compiled.When building two or
more targets using the same architecture, the first build will go through
the full download, configure, make process, but the second and later
builds will only copy the result from the first build to its project
specific target directory significantly speeding up the build process</li>
<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>Create the project specific build directory
(<code>project_build_ARCH/$(PROJECT)</code> by default, where
<code>ARCH</code> is your architecture). This is where all configurable
user-space tools will be compiled. The project specific build directory
is neccessary, if two different targets needs to use a specific package,
but the packages have different configuration for both targets. Some
examples of packages built in this directory are busybox and linux.
</li>
<li>Generate all the targets listed in the
<code>BASE_TARGETS</code> variable. When an internal toolchain
is used, it means generating the cross-compilation
toolchain. When an external toolchain is used, it means checking
the features of the external toolchain and importing it into the
Buildroot environment.</li>
<li>Create the project specific result directory
(<code>binaries/$(PROJECT)</code> by default, where <code>ARCH</code>
is your architecture). This is where the root filesystem images are
stored, It is also used to store the linux kernel image and any
utilities, boot-loaders etc. needed for a target.
</li>
<li>Generate all the targets listed in the <code>TARGETS</code>
variable. This variable is filled by all the individual
components Makefiles. So, generating all 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>
<li>Create the toolchain build directory
(<code>toolchain_build_ARCH/</code> by default, where <code>ARCH</code>
is your architecture). This is where the cross compilation toolchain will
be compiled. </li>
<li>Setup the staging directory (<code>build_ARCH/staging_dir/</code> by
default). This is where the cross-compilation toolchain will be
installed. If you want to use the same cross-compilation toolchain for
other purposes, such as compiling third-party applications, you can add
<code>build_ARCH/staging_dir/usr/bin</code> to your PATH, and then use
<code>arch-linux-gcc</code> to compile your application. In order to
setup this staging directory, it first removes it, and then it creates
various subdirectories and symlinks inside it. </li>
<li>Create the target directory (<code>project_build_ARCH/root/</code> by
default) and the target filesystem skeleton. This directory will contain
the final root filesystem. To setup it up, it first deletes it, then it
uncompress the <code>target/generic/skel.tar.gz</code> file to create the
main subdirectories and symlinks, copies the skeleton available in
<code>target/generic/target_skeleton</code> and then removes useless
<code>.svn/CVS</code> directories. </li>
<li>Add the <code>TARGETS</code> dependency. This should generally check
if the configuration option for this package is enabled, and if so then
&quot;subscribe&quot; this package to be compiled by adding it to the
TARGETS global variable. </li>
</ol>
<h2><a name="multi_project" id="multi_project"></a>Building several
projects in the same buildroot source tree</h2>
<h2><a name="board_support" id="board_support"></a>
Creating your own board support</h2>
<p><i>Note: the contents of this section are obsolete since this
feature has been implemented.</i></p>
<p>Creating your own board support in Buildroot allows you to have
a convenient place to store the Busybox, uClibc, kernel
configurations, your target filesystem skeleton, and a Buildroot
configuration that match your project.</p>
<h3>Background</h3>
<p>Follow these steps to integrate your board in Buildroot:</p>
<p>Buildroot has always supported building several projects in the same
tree if each project was for a different architecture. </p>
<p>The root file system has been created in the
<code>&quot;build_&lt;ARCH&gt;/root&quot;</code>
directory which is unique for each architecture.
Toolchains have been built in
<code>&quot;toolchain_build_&lt;ARCH&gt;&quot;</code>. </p>
<p> It the user wanted to build several root file systems for the same
architecture, a prefix or suffix could be added in the configuration file
so the root file system would be built in
<code>&quot;&lt;PREFIX&gt;_build_&lt;ARCH&gt;_&lt;SUFFIX&gt;/root&quot;</code>
By supplying <u>unique</u> combinations of
<code>&quot;&lt;PREFIX&gt;&quot;</code> and
<code>&quot;&lt;SUFFIX&gt;&quot;</code>
each project would get a <u>unique</u> root file system tree. </p>
<p>The disadvantage of this approach is that a new toolchain was
built for each project, adding considerable time to the build
process, even if it was two projects for the same chip. </p>
<p>This drawback has been somewhat lessened with
<code>gcc-4.x.y</code> which allows buildroot to use an external
toolchain. Certain packages requires special
features in the toolchain, and if an external toolchain is selected,
this may lack the neccessary features to complete the build of the root
file system.</p>
<p>A bigger problem was that the
<code>&quot;build_&lt;ARCH&gt;&quot;</code> tree
was also duplicated, so each </code>package</code> would also
be rebuilt once per project, resulting in even longer build times.</p>
<h3>Project to share toolchain and package builds</h3>
<p>Work has started on a project which will allow the user to build
multiple root file systems for the same architecture in the same tree.
The toolchain and the package build directory will be shared, but each
project will have a dedicated directory tree for project specific
builds. </p>
<p>With this approach, most, if not all packages will be compiled
when the first project is built.
The process is almost identical to the original process.
Packages are downloaded and extracted to the shared
<code>&quot;build_&lt;ARCH&gt;/&lt;package&gt;&quot;</code>
directory. They are configured and compiled. </p>
<p>Package libraries and headers are installed in the shared $(STAGING_DIR),
and then the project specific root file system &quot;$(TARGET_DIR)&quot;
is populated. </p>
<p>At the end of the build, the root file system will be used
to generate the resulting root file system binaries. </p>
<p>Once the first project has been built, building other projects will
typically involve populating the new project's root file system directory
from the existing binaries generated in the shared
<code>&quot;build_&lt;ARCH&gt;/&lt;&gt;&quot;</code> directory. </p>
<p>Only packages, not used by the first project, will have to go
through the normal extract-configure-compile flow. </p>
<h3>Implementation</h3>
<p>The core of the solution is the introduction
of two new directories: </p>
<ul>
<li><code>project_build_&lt;ARCH&gt;</code></li>
<li><code>binaries;</code></li>
</ul>
<p>Each of the directories contain one subdirectory per project.
The name of the subdirectory is configured by the user in the
normal buildroot configuration, using the value of: </p>
<p><code>Project Options ---> Project name</code></p>
<p>The configuration defines the $(PROJECT) variable.</p>
<p>The default project name is <code>&quot;uclibc&quot;</code>.</p>
<p><code>&quot;package/Makefile.in&quot;</code> defines:
<pre>
<code>PROJECT_BUILD_DIR:=project_build_$(ARCH)/$(PROJECT)</code>
<code>BINARIES_DIR:=binaries/$(PROJECT)</code>
</pre>
</p>
<p>It also defines the location for the target root file system:
<pre>
<code>TARGET_DIR:=$(PROJECT_BUILD_DIR)/$(PROJECT)/root</code>
</pre>
</p>
<p>I.E: If the user has choosen
<code>&quot;myproject&quot;</code>
as the $(PROJECT) name:
<ul>
<li><code>&quot;project_build_&lt;ARCH&gt;/myproject&quot;</code></li>
<li><code>&quot;binaries/myproject&quot;</code></li>
</ul>
<p>will be created. </p>
<p>Currently, the <u>root file system</u>, <u>busybox</u> and an Atmel
customized version of
<u><code>U-Boot</code></u>, as well as some Atmel specific
bootloaders like <u>at91-bootstrap</u> and <u>dataflashboot.bin</u>
are built in
<code>&quot;$(PROJECT_BUILD_DIR)&quot;</code>
<p>The resulting binaries for all architectures are stored in the
<code>&quot;$(BINARIES_DIR)&quot;</code> directory. <p>
<h3>Summary</h3>
<p>The project will share directories which can be share without
conflicts, but will use unique build directories, where the user
can configure the build. </p>
<h2><a name="Linux" id="Linux"></a>Linux</h2>
<p>The user can select from three different Linux strategies:
<ul>
<li>Legacy: Only use version supported by the kernel headers</li>
<li>Advanced: Allow any 2.6.X.Y combination.
(Minimum 2.6.19)</li>
<li>Power-User Strategy: Allow
<code>&quot;-git&quot;</code>, or
<code>&quot;-mm&quot;</code>, or user downloadable kernels</li>
</ul>
<p>The current kernel patches can be applied to the
linux source tree even if the version differs from the
kernel header version. </p>
<p>Since the user can select any kernel-patch
he/she will be able to select a non-working combination.
If the patch fails, the user will have to generate a new
proprietary kernel-patch or decide to not apply the kernel
patches</p>
<p>There is also support for <u>board specific</u> and
<u>architecture specific</u> patches. </p>
<p>There will also be a way for the user to supply absolute
or relative paths to patches, possibly outside the main tree.
This can be used to apply custom kernel-header-patches, if
the versions available in buildroot cannot be applied to the
specific linux version used</p>
<p>Maybe, there will also be a possibility to supply an
<code>&quot;URL&quot;</code> to a patch available on Internet. </p>
<p>
If there is no linux config file available,
buildroot starts the linux configuration system, which
defaults to "make menuconfig".
</p>
<h3>Todo</h3>
<ol>
<li>Configurable packages</li>
<p>Many packages can, on top of the simple
&quot;enable/disable build&quot;,
be further configured using Kconfig.
Currently these packages will be compiled using the
configuration specified in the
<code>&quot;.config&quot;</code> file of the <u>first</u>
project demanding the build of the package.</p>
<li>Create a new directory in <code>target/device/</code>, named
after your company or organization</li>
<p>If <u>another</u> project uses the same packages, but with
a different configuration,these packages will <u>not</u> be rebuilt,
and the root file system for the new project will be populated
with files from the build of the <u>first</u> project</p>
<li>Add a line <code>source
"target/device/yourcompany/Config.in"</code> in
<code>target/device/Config.in</code> so that your board appears
in the configuration system</li>
<p>If multiple project are built, and a specific package
needs two different configuration, then the user must
delete the package from the
<code>&quot;build_&lt;ARCH&gt;&quot;</code> directory
before rebuilding the new project.<p>
<li>In <code>target/device/yourcompany/</code>, create a
directory for your project. This way, you'll be able to store
several projects of your company/organization inside
Buildroot.</li>
<p>A long term solution is to edit the package makefile and move
the build of the configurable packages from
<code>&quot;build_&lt;ARCH&gt;&quot;</code> to
<code>&quot;project_build_&lt;ARCH&gt;/&lt;project name&gt;&quot;</code>
and send a patch to the buildroot mailing list.
<li>Create a <code>target/device/yourcompany/Config.in</code>
file that looks like the following:
<li>Naming conventions</li>
<pre>
menuconfig BR2_TARGET_COMPANY
bool "Company projects"
<p>Names of resulting binaries should reflect the
&quot;project name&quot;
if BR2_TARGET_COMPANY
<li>Generating File System binaries</li>
<p>
Packages which needs to be installed with the &quot;root&quot;
as owner, will generate a
<code>&quot;.fakeroot.&lt;package&gt;&quot;</code> file
which will be used for the final build of the root file system binary. </p>
config BR2_TARGET_COMPANY_PROJECT_FOOBAR
bool "Support for Company project Foobar"
help
This option enables support for Company project Foobar
<p>This was previously located in the
<code>&quot;$(STAGING_DIR)&quot;</code> directory, but was
recently moved to the
<code>&quot;$(PROJECT_BUILD_DIR)&quot;</code> directory. </p>
endif
</pre>
<p>Currently only three packages:
<code>&quot;at&quot;</code>,
<code>&quot;ltp-testsuite&quot;</code> and
<code>&quot;nfs-utils&quot;</code>
requests fakeroot. <p>
Of course, customize the different values to match your
company/organization and your project. This file will create a
menu entry that contains the different projects of your
company/organization.</li>
<p>The makefile fragments for each file system type like
<code>&quot;ext2&quot;</code>,
<code>&quot;jffs2&quot;</code> or
<code>&quot;squashfs&quot;</code>
will, when the file system binary is generated,
collect all present
<code>&quot;.fakeroot.&lt;package&gt;&quot;</code> files
to a single <code>&quot;_fakeroot.&lt;file system&gt;&quot;</code>
file and call fakeroot.</p>
<code>&quot;.fakeroot.&lt;package&gt;&quot;</code>
files are deleted as the last action of the Buildroot Makefile. </p>
<li>Create a <code>target/device/yourcompany/Makefile.in</code>
file that looks like the following:
<p>It needs to be evaluated if any further action for the
file system binary build is needed. </p>
<pre>
ifeq ($(BR2_TARGET_COMPANY_PROJECT_FOOBAR),y)
include target/device/yourcompany/project-foobar/Makefile.in
endif
</pre>
</li>
</ol>
<li>Now, create the
<code>target/device/yourcompany/project-foobar/Makefile.in</code>
file. It is first recommended to define a
<code>BOARD_PATH</code> variable set to
<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>$(BOARD_PATH)/target_skeleton</code>, so that the target
skeletonn is stored in the board specific directory.</li>
<li><code>TARGET_DEVICE_TABLE</code> to a file that contains
the target device table, i.e the list of device files (in
<code>/dev/</code>) created by the root filesystem building
procedure. If this variable is defined, the given device table
will be used instead of the default one. If defined, the
convention is to define it to
<code>$(BOARD_PATH)/target_device_table.txt</code>. See
<code>target/generic/device_table.txt</code> for an example
file.</li>
</ul>
</li>
<li>Then, in the
<code>target/device/yourcompany/project-foobar/</code>
directory, you can store different files:
<ul>
<li>One or more Buildroot configurations, under file named
<code>something_defconfig</code>. Your users will then be able
to run <code>make something_defconfig</code> and get the right
configuration for your project</li>
<li>Configuration files for the kernel, for Busybox or
uClibc. These files can then be referenced by the Buildroot
configuration described above</li>
</ul>
</li>
</ol>
<h2><a name="using_toolchain" id="using_toolchain"></a>Using the
uClibc toolchain outside Buildroot</h2>
generated toolchain outside Buildroot</h2>
<p>You may want to compile 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 by default is located in
<code>build_ARCH/staging_dir/</code>. The simplest way to use it
is to add <code>build_ARCH/staging_dir/usr/bin/</code> to your PATH
<code>output/staging/</code>. The simplest way to use it
is to add <code>output/staging/usr/bin/</code> to your PATH
environnement variable, and then to use
<code>arch-linux-gcc</code>, <code>arch-linux-objdump</code>,
<code>arch-linux-ld</code>, etc. </p>
<code>ARCH-linux-gcc</code>, <code>ARCH-linux-objdump</code>,
<code>ARCH-linux-ld</code>, etc. </p>
<p>For example, you may add the following to your
<code>.bashrc</code> (considering you're building for the MIPS
architecture and that Buildroot is located in
<code>~/buildroot/</code>) :</p>
<pre>
export PATH=&quot;$PATH:~/buildroot/build_mips/staging_dir/usr/bin/&quot;
</pre>
<p>Then you can simply do :</p>
<pre>
mips-linux-gcc -o foo foo.c
</pre>
<p>The easiest way is of course to add the
<code>output/staging/usr/bin/</code> directory to your PATH
environment variable.</p>
<p><b>Important</b> : do not try to move a gcc-3.x toolchain to an other
directory, it won't work. There are some hardcoded paths in the
@ -815,8 +692,8 @@ mips-linux-gcc -o foo foo.c
might be cumbersome.</p>
<p>It is also possible to generate the Buildroot toolchain in
another directory than <code>build_ARCH/staging_dir</code> using
the <code>Build options -&gt; Toolchain and header file
another directory than <code>build/staging</code> using the
<code>Build options -&gt; Toolchain and header file
location</code> option. This could be useful if the toolchain
must be shared with other users.</p>
@ -890,22 +767,6 @@ It allows to generate 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="adapting_rootfs" id="adapting_rootfs">Adapting the rootfs
for own binaries</h2>
<p>When using BR2 in an environment where own software binaries or
static data should be part of the generated rootfs package, the
<code>BR2_ROOTFS_POST_BUILD_SCRIPT</code> feature might interest
you. You can specify a command here which is called <i>after</i> BR2
built all the selected software, but <i>before</i> the the rootfs
packages are assembled. The destination rootfs folder is given as
first argument. You can add own components here, change
default configurations and remove unwanted files.</p>
<p>You should, however, use that feature with care. Whenever you
find that a certain package generates wrong or unneeded files, you
should rather fix than package than working around it with a
cleanup script.</p>
<h2><a name="add_software" id="add_software"></a>Extending Buildroot with
more software</h2>
@ -992,7 +853,7 @@ endif
<p>On <a href="#ex1line9">line 9</a>, we tell Buildroot to install
the application to the staging directory. The staging directory,
located in <code>build_ARCH/staging_dir/</code> is the directory
located in <code>output/staging/</code> is the directory
where all the packages are installed, including their
documentation, etc. By default, packages are installed in this
location using the <code>make install</code> command.</p>