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15 <h1>OpenWrt Buildroot
</h1>
18 <p>Usage and documentation by Felix Fietkau and Waldemar Brodkorb, based on uClibc Buildroot
19 documentation by Thomas Petazzoni. Contributions from Karsten Kruse,
20 Ned Ludd, Martin Herren. OpenWrt Kernel Module Creation Howto by Markus Becker.
</p>
22 <p><small>Last modification : $Id$
</small></p>
25 <li><a href=
"#about">About OpenWrt Buildroot
</a></li>
26 <li><a href=
"#download">Obtaining OpenWrt Buildroot
</a></li>
27 <li><a href=
"#using">Using OpenWrt Buildroot
</a></li>
28 <li><a href=
"#custom_targetfs">Customizing the target filesystem
</a></li>
29 <li><a href=
"#custom_busybox">Customizing the Busybox
30 configuration
</a></li>
31 <li><a href=
"#custom_uclibc">Customizing the uClibc
32 configuration
</a></li>
33 <li><a href=
"#buildroot_innards">How OpenWrt Buildroot works
</a></li>
34 <li><a href=
"#using_toolchain">Using the uClibc toolchain
</a></li>
35 <li><a href=
"#toolchain_standalone">Using the uClibc toolchain
36 outside of Buildroot
</a></li>
37 <li><a href=
"#downloaded_packages">Location of downloaded packages
</a></li>
38 <li><a href=
"#add_software">Extending OpenWrt with more Software
</a></li>
39 <li><a href=
"#links">Ressources
</a></li>
41 <li><a href=
"#about_module">About OpenWrt Kernel Module Compilation
</a></li>
42 <li><a href=
"#kernel">Enable the kernel options
</a></li>
43 <li><a href=
"#buildroot_option">Create a buildroot option
</a></li>
44 <li><a href=
"#binary">Define the binary files for the kernel module
</a></li>
45 <li><a href=
"#control">Specify the ipkg control file
</a></li>
46 <li><a href=
"#compile">Compile the kernel module
</a></li>
50 <h2><a name=
"about" id=
"about"></a>About OpenWrt Buildroot
</h2>
52 <p>OpenWrt Buildroot is a set of Makefiles and patches that allows to easily
53 generate both a cross-compilation toolchain and a root filesystem for your
54 Wireless Router. The cross-compilation toolchain uses uClibc (
<a href=
55 "http://www.uclibc.org/">http://www.uclibc.org/
</a>), a tiny C standard
58 <p>A compilation toolchain is the set of tools that allows to
59 compile code for your system. It consists of a compiler (in our
60 case,
<code>gcc
</code>), binary utils like assembler and linker
61 (in our case,
<code>binutils
</code>) and a C standard library (for
62 example
<a href=
"http://www.gnu.org/software/libc/libc.html">GNU
63 Libc
</a>,
<a href=
"http://www.uclibc.org">uClibc
</a> or
<a
64 href=
"http://www.fefe.de/dietlibc/">dietlibc
</a>). The system
65 installed on your development station certainly already has a
66 compilation toolchain that you can use to compile application that
67 runs on your system. If you're using a PC, your compilation
68 toolchain runs on an x86 processor and generates code for a x86
69 processor. Under most Linux systems, the compilation toolchain
70 uses the GNU libc as C standard library. This compilation
71 toolchain is called the
"host compilation toolchain", and more
72 generally, the machine on which it is running, and on which you're
73 working is called the
"host system". The compilation toolchain is
74 provided by your distribution, and OpenWrt Buildroot has nothing to do
77 <p>As said above, the compilation toolchain that comes with your system
78 runs and generates code for the processor of your host system. As your
79 embedded system has a different processor, you need a cross-compilation
80 toolchain: it's a compilation toolchain that runs on your host system but
81 that generates code for your target system (and target processor). For
82 example, if your host system uses x86 and your target system uses MIPS, the
83 regular compilation toolchain of your host runs on x86 and generates code
84 for x86, while the cross-compilation toolchain runs on x86 and generates
87 <p>You might wonder why such a tool is needed when you can compile
88 <code>gcc
</code>,
<code>binutils
</code>, uClibc and all the tools by hand.
89 Of course, doing so is possible. But dealing with all configure options,
90 with all problems of every
<code>gcc
</code> or
<code>binutils
</code>
91 version is very time-consuming and uninteresting. OpenWrt Buildroot automates this
92 process through the use of Makefiles, and has a collection of patches for
93 each
<code>gcc
</code> and
<code>binutils
</code> version to make them work
94 on the MIPS architecture of most Wireless Routers.
</p>
96 <h2><a name=
"download" id=
"download"></a>Obtaining OpenWrt Buildroot
</h2>
98 <p>OpenWrt Buildroot is available via CVS - Concurrent Version System.
99 For any kind of OpenWrt development you should get the latest version from cvs via:
</p>
101 $ cvs -d:pserver:anonymous@openwrt.org:/openwrt co openwrt
103 <p>If you only like to create your own custom firmware images and pakages we
104 strongely suggest to use the CVS branch of the stable version (whiterussian):
107 $ cvs -d:pserver:anonymous@openwrt.org:/openwrt co -rwhiterussian openwrt
111 <h2><a name=
"using" id=
"using"></a>Using OpenWrt Buildroot
</h2>
113 <p>OpenWrt Buildroot has a nice configuration tool similar to the one you can find
114 in the Linux Kernel (
<a href=
"http://www.kernel.org/">http://www.kernel.org/
</a>)
115 or in Busybox (
<a href=
"http://www.busybox.org/">http://www.busybox.org/
</a>).
116 Note that you can run everything as a normal user. There is no need to be root to
117 configure and use the Buildroot. The first step is to run the configuration
124 <p>For each entry of the configuration tool, you can find associated help
125 that describes the purpose of the entry.
</p>
127 <p>Once everything is configured, the configuration tool has generated a
128 <code>.config
</code> file that contains the description of your
129 configuration. It will be used by the Makefiles to do what's needed.
</p>
137 <p>This command will download, configure and compile all the selected
138 tools, and finally generate target firmware images and additional packages
139 (depending on your selections in
<code>make menuconfig
</code>.
140 All the target files can be found in the
<code>bin/
</code> subdirectory.
141 You can compile firmware images containing two different filesystem types:
146 <p><code>jffs2
</code> contains a writable root filesystem, which will expand to
147 the size of your flash image. Note: if you use the generic firmware image, you
148 need to pick the right image for your flash size, because of different
149 eraseblock sizes.
</p>
151 <p><code>squashfs
</code> contains a read-only root filesystem using a modified
152 <code>squashfs
</code> filesystem with LZMA compression. When booting it, you can
153 create a writable second filesystem, which will contain your modifications to
154 the root filesystem, including the packages you install.
156 <h2><a name=
"custom_targetfs" id=
"custom_targetfs"></a>Customizing the
157 target filesystem
</h2>
159 <li>You can customize the target filesystem skeleton, available under
160 <code>package/base-files/default/
</code>. You can change
161 configuration files or other stuff here. However, the full file hierarchy
162 is not yet present, because it's created during the compilation process.
163 So you can't do everything on this target filesystem skeleton, but
164 changes to it remains even when you completely rebuild the cross-compilation
165 toolchain and the tools.
<br />
167 <h2><a name=
"custom_busybox" id=
"custom_busybox"></a>Customizing the
168 Busybox configuration
</h2>
170 <p>Busybox is very configurable, and you may want to customize it.
171 Its configuration is completely integrated into the main menuconfig system.
172 You can find it under
"OpenWrt Package Selection" =
> "Busybox Configuration"</p>
174 <h2><a name=
"custom_uclibc" id=
"custom_uclibc"></a>Customizing the uClibc
177 <p>Just like
<a href=
"#custom_busybox">BusyBox
</a>,
<a
178 href=
"http://www.uclibc.org">uClibc
</a> offers a lot of
179 configuration options. They allow to select various
180 functionalities, depending on your needs and limitations.
</p>
182 <p>The easiest way to modify the configuration of uClibc is to
183 follow these steps :
</p>
187 <li>Make a first compilation of buildroot without trying to
188 customize uClibc.
</li>
190 <li>Go into the directory
191 <code>toolchain_build_ARCH/uClibc/
</code> and run
<code>make
192 menuconfig
</code>. The nice configuration assistant, similar to
193 the one used in the Linux Kernel appears. Make
194 your configuration as appropriate.
</li>
196 <li>Copy the
<code>.config
</code> file to
197 <code>toolchain/uClibc/uClibc.config
</code> or
198 <code>toolchain/uClibc/uClibc.config-locale
</code>. The former
199 is used if you haven't selected locale support in the Buildroot
200 configuration, and the latter is used if you have selected
203 <li>Run the compilation again.
</li>
207 <p>Otherwise, you can simply change
208 <code>toolchain/uClibc/uClibc.config
</code> or
209 <code>toolchain/uClibc/uClibc.config-locale
</code> without running
210 the configuration assistant.
</p>
212 <h2><a name=
"buildroot_innards" id=
"buildroot_innards"></a>How OpenWrt Buildroot
215 <p>As said above, OpenWrt is basically a set of Makefiles that download,
216 configure and compiles software with the correct options. It also includes
217 some patches for various software, mainly the ones involved in the
218 cross-compilation tool chain (
<code>gcc
</code>,
<code>binutils
</code> and
221 <p>There is basically one Makefile per software, and they are named
<code>Makefile
</code>.
222 Makefiles are split into three sections:
</p>
225 <li><b>package
</b> (in the
<code>package/
</code> directory) contains the
226 Makefiles and associated files for all user-space tools that Buildroot
227 can compile and add to the target root filesystem. There is one
228 sub-directory per tool.
</li>
230 <li><b>toolchain
</b> (in the
<code>toolchain/
</code> directory) contains
231 the Makefiles and associated files for all software related to the
232 cross-compilation toolchain :
<code>binutils
</code>,
<code>ccache
</code>,
233 <code>gcc
</code>,
<code>gdb
</code>,
<code>kernel-headers
</code> and
234 <code>uClibc
</code>.
</li>
236 <li><b>target
</b> (in the
<code>target
</code> directory) contains the
237 Makefiles and associated files for software related to the generation of
238 the target root filesystem image and the linux kernel for the different
239 system on a chip boards, used in the Wireless Routers.
240 Two types of filesystems are supported
241 : jffs2 and squashfs.
244 <p>Each directory contains at least
2 files :
</p>
247 <li><code>Makefile
</code> is the Makefile that downloads, configures,
248 compiles and installs the software
<code>something
</code>.
</li>
250 <li><code>Config.in
</code> is a part of the configuration tool
251 description file. It describes the option related to the current
255 <p>The main Makefile do the job through the following steps (once the
256 configuration is done):
</p>
259 <li>Create the download directory (
<code>dl/
</code> by default). This is
260 where the tarballs will be downloaded. It is interesting to know that the
261 tarballs are in this directory because it may be useful to save them
262 somewhere to avoid further downloads.
</li>
264 <li>Create the build directory (
<code>build_ARCH/
</code> by default,
265 where
<code>ARCH
</code> is your architecture). This is where all
266 user-space tools while be compiled.
</li>
268 <li>Create the toolchain build directory
269 (
<code>toolchain_build_ARCH/
</code> by default, where
<code>ARCH
</code>
270 is your architecture). This is where the cross compilation toolchain will
273 <li>Setup the staging directory (
<code>staging_dir_ARCH/
</code> by
274 default). This is where the cross-compilation toolchain will be
275 installed. If you want to use the same cross-compilation toolchain for
276 other purposes, such as compiling third-party applications, you can add
277 <code>staging_dir_ARCH/bin
</code> to your PATH, and then use
278 <code>arch-linux-gcc
</code> to compile your application. In order to
279 setup this staging directory, it first removes it, and then it creates
280 various subdirectories and symlinks inside it.
</li>
282 <li>Create the target directory (
<code>build_ARCH/root/
</code> by
283 default) and the target filesystem skeleton. This directory will contain
284 the final root filesystem. To set it up, it first deletes it, then it
285 copies the skeleton available in
<code>target/default/target_skeleton
</code>
286 and then removes useless
<code>CVS/
</code> directories.
</li>
288 <li>Call the
<code>prepare
</code>,
<code>compile
</code> and
<code>install
</code>
289 targets for the subdirectories
<code>toolchain
</code>,
<code>package
</code>
290 and
<code>target
</code></li>
293 <h2><a name=
"using_toolchain" id=
"using_toolchain"></a>Using the
294 uClibc toolchain
</h2>
296 <p>You may want to compile your own programs or other software
297 that are not packaged in OpenWrt. In order to do this, you can
298 use the toolchain that was generated by the Buildroot.
</p>
300 <p>The toolchain generated by the Buildroot by default is located in
301 <code>staging_dir_ARCH
</code>. The simplest way to use it
302 is to add
<code>staging_dir_ARCH/bin/
</code> to your PATH
303 environment variable, and then to use
304 <code>arch-linux-gcc
</code>,
<code>arch-linux-objdump
</code>,
305 <code>arch-linux-ld
</code>, etc.
</p>
307 <p>For example, you may add the following to your
308 <code>.bashrc
</code> (considering you're building for the MIPS
309 architecture and that Buildroot is located in
310 <code>~/openwrt/
</code>) :
</p>
313 export PATH=$PATH:~/openwrt/staging_dir_mipsel/bin/
316 <p>Then you can simply do :
</p>
319 mipsel-linux-uclibc-gcc -o foo foo.c
322 <p><b>Important
</b> : do not try to move the toolchain to an other
323 directory, it won't work. There are some hard-coded paths in the
324 <i>gcc
</i> configuration. If the default toolchain directory
325 doesn't suit your needs, please refer to the
<a
326 href=
"#toolchain_standalone">Using the uClibc toolchain outside of
327 buildroot
</a> section.
</p>
329 <h2><a name=
"toolchain_standalone" id=
"toolchain_standalone"></a>Using the
330 uClibc toolchain outside of buildroot
</h2>
332 <p>By default, the cross-compilation toolchain is generated inside
333 <code>staging_dir_ARCH/
</code>. But sometimes, it may be useful to
334 install it somewhere else, so that it can be used to compile other programs
335 or by other users. Moving the
<code>staging_dir_ARCH/
</code>
336 directory elsewhere is
<b>not possible
</b>, because they are some hardcoded
337 paths in the toolchain configuration.
</p>
339 <p>If you want to use the generated toolchain for other purposes,
340 you can configure Buildroot to generate it elsewhere using the
341 option of the configuration tool :
<code>Build options -
>
342 Toolchain and header file location
</code>, which defaults to
343 <code>staging_dir_ARCH/
</code>.
</p>
345 <h2><a name=
"downloaded_packages"
346 id=
"downloaded_packages"></a>Location of downloaded packages
</h2>
348 <p>It might be useful to know that the various tarballs that are
349 downloaded by the
<i>Makefiles
</i> are all stored in the
350 <code>DL_DIR
</code> which by default is the
<code>dl
</code>
351 directory. It's useful for example if you want to keep a complete
352 version of Buildroot which is known to be working with the
353 associated tarballs. This will allow you to regenerate the
354 toolchain and the target filesystem with exactly the same
357 <h2><a name=
"add_software" id=
"add_software"></a>Extending OpenWrt with
360 <p>This section will only consider the case in which you want to
361 add user-space software.
</p>
363 <h3>Package directory
</h3>
365 <p>First of all, create a directory under the
<code>package
</code>
366 directory for your software, for example
<code>foo
</code>.
</p>
368 <h3><code>Config.in
</code> file
</h3>
370 <p>Then, create a file named
<code>Config.in
</code>. This file
371 will contain the portion of options description related to our
372 <code>foo
</code> software that will be used and displayed in the
373 configuration tool. It should basically contain :
</p>
376 config BR2_PACKAGE_FOO
377 tristate
"foo - some nice tool"
378 default m if CONFIG_DEVEL
380 This is a comment that explains what foo is.
383 <p>If you depend on other software or library inside the Buildroot, it
384 is important that you automatically select these packages in your
385 <code>Config.in
</code>. Example if foo depends on bar library:
388 config BR2_PACKAGE_FOO
389 tristate
"foo - some nice tool"
390 default m if CONFIG_DEVEL
391 select BR2_PACKAGE_LIBBAR
393 This is a comment that explains what foo is.
396 <p>Of course, you can add other options to configure particular
397 things in your software.
</p>
399 <h3><code>Config.in
</code> in the package directory
</h3>
401 <p>To add your package to the configuration tool, you need
402 to add the following line to
<code>package/Config.in
</code>,
403 please add it to a section, which fits the purpose of foo:
407 source
"package/foo/Config.in"
410 <h3><code>Makefile
</code> in the package directory
</h3>
412 <p>To add your package to the build process, you need to edit
413 the Makefile in the
<code>package/
</code> directory. Locate the
414 lines that look like the following:
</p>
417 package-$(BR2_PACKAGE_FOO) += foo
420 <p>As you can see, this short line simply adds the target
421 <code>foo
</code> to the list of targets handled by OpenWrt Buildroot.
</p>
423 <p>In addition to the default dependencies, you make your package
424 depend on another package (e.g. a library) by adding a line:
427 foo-compile: bar-compile
430 <h3>The ipkg control file
</h3>
431 <p>Additionally, you need to create a control file which contains
432 information about your package, readable by the
<i>ipkg
</i> package
433 utility. It should be created as file:
434 <code>package/foo/ipkg/foo.control
</code></p>
436 <p>The file looks like this
</p>
442 4 Maintainer: Foo Software
<foo@foosoftware.com
>
443 5 Source: http://foosoftware.com
445 7 Description: Package Description
448 <p>You can skip the usual
<code>Version:
</code> and
<code>Architecture
</code>
449 fields, as they will be generated by the
<code>make-ipkg-dir.sh
</code> script
450 called from your Makefile. The Depends field is important, so that ipkg will
451 automatically fetch all dependend software on your target system.
</p>
453 <h3>The real
<i>Makefile
</i></h3>
455 <p>Finally, here's the hardest part. Create a file named
456 <code>Makefile
</code>. It will contain the
<i>Makefile
</i> rules that
457 are in charge of downloading, configuring, compiling and installing
458 the software. Below is an example that we will comment afterwards.
</p>
463 3 include $(TOPDIR)/rules.mk
468 8 PKG_MD5SUM:=
4584f226523776a3cdd2fb6f8212ba8d
470 10 PKG_SOURCE_URL:=http://www.foosoftware.org/downloads
471 11 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
474 14 PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)-$(PKG_VERSION)
475 15 PKG_INSTALL_DIR:=$(PKG_BUILD_DIR)/ipkg-install
477 17 include $(TOPDIR)/package/rules.mk
479 19 $(eval $(call PKG_template,FOO,foo,$(PKG_VERSION)-$(PKG_RELEASE),$(ARCH)))
481 21 $(PKG_BUILD_DIR)/.configured:
482 22 (cd $(PKG_BUILD_DIR); \
483 23 $(TARGET_CONFIGURE_OPTS) \
484 24 CFLAGS=
"$(TARGET_CFLAGS)" \
486 26 --target=$(GNU_TARGET_NAME) \
487 27 --host=$(GNU_TARGET_NAME) \
488 28 --build=$(GNU_HOST_NAME) \
490 30 --sysconfdir=/etc \
491 31 --with-bar=
"$(STAGING_DIR)/usr" \
495 35 $(PKG_BUILD_DIR)/.built:
496 36 rm -rf $(PKG_INSTALL_DIR)
497 37 mkdir -p $(PKG_INSTALL_DIR)
498 38 $(MAKE) -C $(PKG_BUILD_DIR) \
499 39 $(TARGET_CONFIGURE_OPTS) \
500 40 install_prefix=
"$(PKG_INSTALL_DIR)" \
505 46 install -d -m0755 $(IDIR_FOO)/usr/sbin
506 47 cp -fpR $(PKG_INSTALL_DIR)/usr/sbin/foo $(IDIR_FOO)/usr/sbin
507 49 $(RSTRIP) $(IDIR_FOO)
508 50 $(IPKG_BUILD) $(IDIR_FOO) $(PACKAGE_DIR)
511 53 make -C $(PKG_BUILD_DIR) clean
512 54 rm $(PKG_BUILD_DIR)/.built
515 <p>First of all, this
<i>Makefile
</i> example works for a single
516 binary software. For other software such as libraries or more
517 complex stuff with multiple binaries, it should be adapted. Look at
518 the other
<code>Makefile
</code> files in the
<code>package/
</code>
521 <p>At lines
5-
15, a couple of useful variables are defined:
</p>
524 <li><code>PKG_NAME
</code> : The package name, e.g.
<i>foo
</i>.
</li>
526 <li><code>PKG_VERSION
</code> : The version of the package that
527 should be downloaded.
</li>
529 <li><code>PKG_RELEASE
</code> : The release number that will be
530 appended to the version number of your
<i>ipkg
</i> package.
</li>
532 <li><code>PKG_MD5SUM
</code> : The md5sum of the software archive.
</li>
534 <li><code>PKG_SOURCE_URL
</code> : Space separated list of the HTTP
535 or FTP sites from which the archive is downloaded. It must include the complete
536 path to the directory where
<code>FOO_SOURCE
</code> can be
539 <li><code>PKG_SOURCE
</code> : The name of the tarball of
540 your package on the download website of FTP site. As you can see
541 <code>PKG_NAME
</code> and
<code>PKG_VERSION
</code> are used.
</li>
543 <li><code>PKG_CAT
</code> : The tool needed for extraction of the
544 software archive.
</li>
546 <li><code>PKG_BUILD_DIR
</code> : The directory into which the software
547 will be configured and compiled. Basically, it's a subdirectory
548 of
<code>BUILD_DIR
</code> which is created upon extraction of
551 <li><code>PKG_INSTALL_DIR
</code> : The directory into the software
552 will be installed. It is a subdirectory of
<code>PKG_BUILD_DIR
</code>.
</li>
556 <p>In Line
3 and
17 we include common variables and routines to simplify
557 the process of ipkg creation. It includes routines to download, verify
558 and extract the software package archives.
</p>
560 <p>Line
19 contains the magic line which automatically creates the
563 <p>Lines
21-
33 defines a target and associated rules that
564 configures the software. It depends on the previous target (the
565 hidden
<code>.prepared
</code> file) so that we are sure the software has
566 been uncompressed. In order to configure it, it basically runs the
567 well-known
<code>./configure
</code>script. As we may be doing
568 cross-compilation,
<code>target
</code>,
<code>host
</code> and
569 <code>build
</code> arguments are given. The prefix is also set to
570 <code>/usr
</code>, not because the software will be installed in
571 <code>/usr
</code> on your host system, but in the target
572 filesystem. Finally it creates a
<code>.configured
</code> file to
573 mark the software as configured.
</p>
575 <p>Lines
35-
42 defines a target and a rule that compiles the
576 software. This target will create the binary file in the
577 compilation directory, and depends on the software being already
578 configured (hence the reference to the
<code>.configured
</code>
579 file). Afterwards it installs the resulting binary into the
580 <code>PKG_INSTALL_DIR
</code>. It basically runs
581 <code>make install
</code> inside the source directory.
</p>
583 <p>Lines
44-
50 defines a target and associated rules that create
584 the
<i>ipkg
</i> package, which can optionally be embedded into
585 the resulting firmware image. It manually installs all files you
586 want to integrate in your resulting ipkg.
<code>RSTRIP
</code> will
587 recursevily strip all binaries and libraries.
588 Finally
<code>IPKG_BUILD
</code> is called to create the package.
</p>
590 <p>If you want other targets to be executed at
<code>compile
</code>,
591 <code>install
</code> or
<code>clean
</code> time (e.g. for installing
592 a library into the staging dir), just create the targets (usually
593 <code>install-dev
</code> and
<code>uninstall-dev
</code>) and enable
596 compile-targets: install-dev
597 clean-targets: uninstall-dev
602 <p>As you can see, adding a software to buildroot is simply a
603 matter of writing a
<i>Makefile
</i> using an already existing
604 example and to modify it according to the compilation process of
607 <p>If you package software that might be useful for other persons,
608 don't forget to send a patch to OpenWrt developers!
609 Use the mail address: openwrt-devel@openwrt.org
612 <h2><a name=
"links" id=
"links"></a>Resources
</h2>
614 <p>To learn more about OpenWrt, you can visit this website:
615 <a href=
"http://openwrt.org/">http://openwrt.org/
</a></p>
621 <h1>OpenWrt Kernel Module Creation Howto
</h1>
624 <h2><a name=
"about_module" id=
"about_module"></a>About OpenWrt Kernel Module Compilation
</h2>
626 <p>You are planning to compile a kernel module? This howto will
627 explain what you have to do, to have your kernel module installable as
630 <h2><a name=
"kernel" id=
"kernel"></a>Enable the kernel options
</h2>
632 <p>Enable the kernel options you want by modifying
633 build_mipsel/linux/.config. We are assuming, that you already had your
634 kernel compiled once here. You can do the modification by hand or by
637 $ cd build_mipsel/linux
641 And copy it, so your changes are not getting lost, when doing a 'make
642 dirclean'. Here we assume that you are compiling for Broadcom chipset
645 <pre> $ cp .config ../../../target/linux/linux-
2.4/config/brcm
</pre>
648 <h2><a name=
"buildroot_option" id=
"buildroot_option"></a>Create a buildroot option
</h2>
650 <p>Create a buildroot option by modifying/inserting into
651 target/linux/Config.in, e.g.
654 config BR2_PACKAGE_KMOD_USB_KEYBOARD
655 tristate
"Support for USB keyboards"
657 depends BR2_PACKAGE_KMOD_USB_CONTROLLER
661 <h2><a name=
"binary" id=
"binary"></a>Define the binary files for the kernel module
</h2>
663 <p>Define the binary files for the kernel module by modifying/inserting into
664 target/linux/linux-
2.4/Makefile, e.g.
667 $(eval $(call KMOD_template,USB_KEYBOARD,usb-kbd,\
668 $(MODULES_DIR)/kernel/drivers/input/input.o \
669 $(MODULES_DIR)/kernel/drivers/input/keybdev.o \
670 $(MODULES_DIR)/kernel/drivers/usb/usbkbd.o \
671 ,CONFIG_USB_KEYB,kmod-usb-core,
60,input keybdev usbkbd))
674 Where CONFIG_USB_KEYB is the kernel option, USB_KEYBOARD is the last
675 part of BR2_PACKAGE_KMOD_USB_KEYBOARD and usb-kbd is part of the
676 filename of the created ipkg.
</p>
678 <h2><a name=
"control" id=
"control"></a>Specify the ipkg control file
</h2>
680 <p>Create e.g. target/linux/control/kmod-usb-kbd.control with content similar to this:
683 Package: kmod-usb-kbd
686 Maintainer: Markus Becker
<mab@comnets.uni-bremen.de
>
687 Source: buildroot internal
688 Description: Kernel Support for USB Keyboards
692 <h2><a name=
"compile" id=
"compile"></a>Compile the kernel module
</h2>
694 <p>Enable the kernel module with
698 in TOPDIR and selecting it.
<br>
702 $ make dirclean && make