Buildroot

OpenWrt Buildroot

Usage and documentation by Thomas Petazzoni. Contributions from - Karsten Kruse, Ned Ludd, Martin Herren.

Usage and documentation by Felix Fietkau and Waldemar Brodkorb, based on uClibc Buildroot + documentation by Thomas Petazzoni. Contributions from Karsten Kruse, + Ned Ludd, Martin Herren.

Last modification : $Id$

About Buildroot
Obtaining Buildroot
Using Buildroot
About OpenWrt Buildroot
Obtaining OpenWrt Buildroot
Using OpenWrt Buildroot
Customizing the target filesystem
Customizing the Busybox configuration
Customizing the uClibc configuration
How Buildroot works
How OpenWrt Buildroot works
Using the uClibc toolchain
Using the uClibc toolchain outside of Buildroot
Location of downloaded packages
Extending Buildroot with more - Software
Extending OpenWrt with more Software
Ressources

About Buildroot

About OpenWrt Buildroot

Buildroot is a set of Makefiles and patches that allows to easily +

OpenWrt Buildroot is a set of Makefiles and patches that allows to easily generate both a cross-compilation toolchain and a root filesystem for your - target. The cross-compilation toolchain uses uClibc (http://www.uclibc.org/), a tiny C standard library.

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 have on his PC. It can be PowerPC - processors, MIPS processors, ARM processors, etc.

A compilation toolchain is the set of tools that allows to compile code for your system. It consists of a compiler (in our case, gcc), binary utils like assembler and linker @@ -68,7 +63,7 @@ toolchain is called the "host compilation toolchain", and more generally, the machine on which it is running, and on which you're working is called the "host system". The compilation toolchain is - provided by your distribution, and Buildroot has nothing to do + provided by your distribution, and OpenWrt Buildroot has nothing to do with it.

As said above, the compilation toolchain that comes with your system @@ -76,66 +71,35 @@ embedded system has a different processor, you need a cross-compilation toolchain: it's a compilation toolchain that runs on your host system but that generates code for your target system (and target processor). For - example, if your host system uses x86 and your target system uses ARM, the + example, if your host system uses x86 and your target system uses MIPS, the regular compilation toolchain of your host runs on x86 and generates code for x86, while the cross-compilation toolchain runs on x86 and generates - code for ARM.

- -

Even if your embedded system uses a x86 processor, you might interested - in Buildroot, for two reasons:

- -

The compilation toolchain of 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 it for - you.
Buildroot automates the building of a root filesystem with all needed - tools like busybox. It makes it much easier than doing it by hand.

+ code for MIPS.

You might wonder why such a tool is needed when you can compile gcc, binutils, uClibc and all the tools by hand. Of course, doing so is possible. But dealing with all configure options, with all problems of every gcc or binutils - version it very time-consuming and uninteresting. Buildroot automates this + version is very time-consuming and uninteresting. OpenWrt Buildroot automates this process through the use of Makefiles, and has a collection of patches for each gcc and binutils version to make them work - on most architectures.

- -

Obtaining Buildroot

- -

Buildroot is available as daily CVS snapshots or directly using - CVS.

+ on the MIPS architecture of most Wireless Routers.

The latest snapshot is always available at http://uclibc.org/downloads/snapshots/buildroot-snapshot.tar.bz2, - and previous snapshots are also available at http://uclibc.org/downloads/snapshots/.

Obtaining OpenWrt Buildroot

To download Buildroot using CVS, you can simply follow - the rules described on the "Accessing CVS"-page (http://www.uclibc.org/cvs_anon.html) - of the uClibc website (http://www.uclibc.org), and download the - buildroot CVS module. For the impatient, here's a quick - recipe:

- -

- $ cvs -d:pserver:anonymous@uclibc.org:/var/cvs login
- $ cvs -z3 -d:pserver:anonymous@uclibc.org:/var/cvs co buildroot
+    OpenWrt Buildroot is available via CVS - Concurrent Version System.
+    For any kind of development you should get the latest version from cvs via:
++ $ cvs -d:pserver:anonymous@openwrt.org:/openwrt co openwrt
 
 
-    Using Buildroot
+    Using OpenWrt Buildroot
 
-    Buildroot has a nice configuration tool similar to the one you can find
-    in the Linux Kernel (http://www.kernel.org/) or in Busybox
-    (http://www.busybox.org/). Note that
-    you can run 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
+    
OpenWrt Buildroot has a nice configuration tool similar to the one you can find
+    in the Linux Kernel (http://www.kernel.org/)
+    or in Busybox (http://www.busybox.org/).
+    Note that you can run everything as a normal user. There is no need to be root to
+    configure and use the Buildroot. The first step is to run the configuration
     assistant:
 
 @@ -156,12 +120,24 @@
 
 
     This command will download, configure and compile all the selected
-    tools, and finally generate a target filesystem. The target filesystem will
-    be named root_fs_ARCH.EXT where ARCH is your
-    architecture and EXT depends on the type of target filesystem
-    selected in the Target options section of the configuration
-    tool.
-
+    tools, and finally generate target firmware images and additional packages
+    (depending on your selections in make menuconfig.
+    All the target files can be found in the bin/ subdirectory.
+    You can compile firmware images containing two different filesystem types:
+    
+        jffs2
+        squashfs
+    
+    jffs2 contains a writable root filesystem, which will expand to
+    the size of your flash image. Note: if you use the generic firmware image, you 
+    need to pick the right image for your flash size, because of different
+    eraseblock sizes.
+    
+    squashfs contains a read-only root filesystem using a modified 
+    squashfs filesystem with LZMA compression. When booting it, you can
+    create a writable second filesystem, which will contain your modifications to
+    the root filesystem, including the packages you install.
+    
     
Customizing the
     target filesystem
 
@@ -170,55 +146,27 @@
     
       Customize the target filesystem directly, and rebuild the image. The
       target filesystem is available under build_ARCH/root/ where
-      ARCH is the chosen target architecture. 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 toolchain and
-      tools, these changes will be lost.
+      ARCH is the chosen target architecture, usually mipsel.
+      You can simply make your changes here, and run make target_install afterwards, 
+      which will rebuild the target filesystem image. This method allows to do
+      everything on the target filesystem, but if you decide to rebuild your toolchain,
+      tools or packages, these changes will be lost.
 
       Customize the target filesystem skeleton, available under
       target/default/target_skeleton/. You can customize
       configuration files or other stuff here. However, the full file hierarchy
       is not yet present, because it's created during the compilation process.
       So you can't do everything on this target filesystem skeleton, but
-      changes to it remains even you completely rebuild the cross-compilation
+      changes to it remains even when you completely rebuild the cross-compilation
       toolchain and the tools.

-      You can also customize the target/default/device_table.txt
-      file which is used by the tools that generate the target filesystem image
-      to properly set permissions and create device nodes. The
-      target/default/skel.tar.gz file contains the main
-      directories of a root filesystem and there is no obvious reason for which
-      it should be changed. These main directories are in an tarball inside of
-      inside the skeleton because it contains symlinks that would be broken
-      otherwise.
     
 
     Customizing the
     Busybox configuration
 
-    Busybox is very configurable, and you may want to customize it. You can
-    follow these simple steps to do it. It's not an optimal way, but it's
-    simple and it works.
-
-    
-      Make a first compilation of buildroot with busybox without trying to
-      customize it.
-
-      Go into build_ARCH/busybox/ and run make
-      menuconfig. The nice configuration tool appears and you can
-      customize everything.
-
-      Copy the .config file to
-      package/busybox/busybox.config so that your customized
-      configuration will remains even if you remove the cross-compilation
-      toolchain.
-
-      Run the compilation of buildroot again.
-    
-
-    Otherwise, you can simply change the
-    package/busybox/busybox.config file if you know the options
-    you want to change without using the configuration tool.
+    Busybox is very configurable, and you may want to customize it.
+    Its configuration is completely integrated into the main menuconfig system.
+    You can find it under "OpenWrt Package Selection" => "Busybox Configuration"
 
     Customizing the uClibc
     configuration
@@ -239,17 +187,17 @@
       Go into the directory
       toolchain_build_ARCH/uClibc/ and run make
       menuconfig. The nice configuration assistant, similar to
-      the one used in the Linux Kernel or in Buildroot appears. Make
+      the one used in the Linux Kernel appears. Make
       your configuration as appropriate.
 
       Copy the .config file to
       toolchain/uClibc/uClibc.config or
       toolchain/uClibc/uClibc.config-locale. The former
-      is used if you haven't selected locale support in Buildroot
+      is used if you haven't selected locale support in the Buildroot
       configuration, and the latter is used if you have selected
       locale support.
 
-      Run the compilation of Buildroot again
+      Run the compilation again.
 
     
 
@@ -258,18 +206,17 @@
     toolchain/uClibc/uClibc.config-locale without running
     the configuration assistant.
 
-    How Buildroot
+    
How OpenWrt Buildroot
     works
 
-    As said above, Buildroot is basically a set of Makefiles that download,
+    
As said above, OpenWrt is basically a set of Makefiles that download,
     configure and compiles software with the correct options. It also includes
     some patches for various software, mainly the ones involved in the
     cross-compilation tool chain (gcc, binutils and
     uClibc).
 
-    There is basically one Makefile per software, and they are named with
-    the .mk extension. Makefiles are split into three
-    sections:
+    There is basically one Makefile per software, and they are named Makefile.
+    Makefiles are split into three sections:
 
     
       package (in the package/ directory) contains the
@@ -285,27 +232,21 @@
 
       
target (in the target 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's a
-      sub-directory with the required files. There is also a
-      default/ directory that contains the target filesystem
-      skeleton.
+      the target root filesystem image and the linux kernel for the different 
+      system on a chip boards, used in the Wireless Routers. 
+      Two types of filesystems are supported
+      : jffs2 and squashfs. 
     
 
-    Each directory contains at least 3 files :
+    Each directory contains at least 2 files :
 
     
-      something.mk is the Makefile that downloads, configures,
+      
Makefile is the Makefile that downloads, configures,
       compiles and installs the software something.
 
       Config.in is a part of the configuration tool
       description file. It describes the option related to the current
       software.
-
-      Makefile.in is a part of Makefile that sets various
-      variables according to the configuration given through the configuration
-      tool. For most tools it simply involves adding the name of the tool to
-      the TARGETS variable.
     
 
     The main Makefile do the job through the following steps (once the
@@ -326,55 +267,53 @@
       is your architecture). This is where the cross compilation toolchain will
       be compiled.
 
-      
Setup the staging directory (build_ARCH/staging_dir/ by
+      
Setup the staging directory (staging_dir_ARCH/ 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
-      build_ARCH/staging_dir/bin to your PATH, and then use
+      staging_dir_ARCH/bin to your PATH, and then use
       arch-linux-gcc 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.
 
       Create the target directory (build_ARCH/root/ 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 target/default/skel.tar.gz file to create the
-      main subdirectories and symlinks, copies the skeleton available in
-      target/default/target_skeleton and then removes useless
-      CVS/ directories.
-
-      Make the TARGETS dependency. This is where all the job
-      is done : all Makefile.in files "subscribe" targets into
-      this global variable, so that the needed tools gets compiled.
+      the final root filesystem. To set it up, it first deletes it, then it
+      copies the skeleton available in  target/default/target_skeleton
+      and then removes useless CVS/ directories.
+
+      Call the prepare, compile and install
+      targets for the subdirectories toolchain, package
+      and target
     
 
     Using the
     uClibc toolchain
 
     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.
+    that are not packaged in OpenWrt. In order to do this, you can
+    use the toolchain that was generated by the Buildroot.
 
-    The toolchain generated by Buildroot by default is located in
-    build_ARCH/staging_dir/. The simplest way to use it
-    is to add build_ARCH/staging_dir/bin/ to your PATH
-    environnement variable, and then to use
+    
The toolchain generated by the Buildroot by default is located in
+    staging_dir_ARCH. The simplest way to use it
+    is to add staging_dir_ARCH/bin/ to your PATH
+    environment variable, and then to use
     arch-linux-gcc, arch-linux-objdump,
     arch-linux-ld, etc.
 
     For example, you may add the following to your
     .bashrc (considering you're building for the MIPS
     architecture and that Buildroot is located in
-    ~/buildroot/) :
+    ~/openwrt/) :
 
 -export PATH=$PATH:~/buildroot/build_mips/bin/
+export PATH=$PATH:~/openwrt/staging_dir_mipsel/bin/
 
 
     Then you can simply do :
 
 -mips-linux-gcc -o foo foo.c
+mipsel-linux-uclibc-gcc -o foo foo.c
 
 
     Important : do not try to move the toolchain to an other
@@ -388,17 +327,17 @@ mips-linux-gcc -o foo foo.c
     uClibc toolchain outside of buildroot
 
     
By default, the cross-compilation toolchain is generated inside
-    build_ARCH/staging_dir/. But sometimes, it may be useful to
+    staging_dir_ARCH/. But sometimes, it may be useful to
     install it somewhere else, so that it can be used to compile other programs
-    or by other users. Moving the build_ARCH/staging_dir/
+    or by other users. Moving the staging_dir_ARCH/
     directory elsewhere is not possible, because they are some hardcoded
     paths in the toolchain configuration.
 
     If you want to use the generated toolchain for other purposes,
     you can configure Buildroot to generate it elsewhere using the
-    option of the configuration tool : Build options ->
+    option of the configuration tool : Build options ->
     Toolchain and header file location, which defaults to
-    $(BUILD_DIR)/staging_dir/.

+    staging_dir_ARCH/.
 
     Location of downloaded packages
@@ -407,12 +346,12 @@ mips-linux-gcc -o foo foo.c
     downloaded by the Makefiles are all stored in the
     DL_DIR which by default is the dl
     directory. It's useful for example if you want to keep a complete
-    version of Buildroot which is know to be working with the
+    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.
 
-    Extending Buildroot with
+    
Extending OpenWrt with
     more software
 
     This section will only consider the case in which you want to
@@ -432,148 +371,195 @@ mips-linux-gcc -o foo foo.c
 
 
 config BR2_PACKAGE_FOO
-        bool "foo"
-        default n
+        tristate "foo - some nice tool"
+        default m if CONFIG_DEVEL
         help
 	     This is a comment that explains what foo is.
 
 
+    If you depend on other software or library inside the Buildroot, it
+    is important that you automatically select these packages in your 
+    Config.in. Example if foo depends on bar library:
+    
++config BR2_PACKAGE_FOO
+        tristate "foo - some nice tool"
+        default m if CONFIG_DEVEL
+	select BR2_PACKAGE_LIBBAR
+        help
+        This is a comment that explains what foo is.
+
+
     Of course, you can add other options to configure particular
     things in your software.
 
-    Makefile.in file
+    Config.in in the package directory
+	
+    To add your package to the configuration tool, you need
+    to add the following line to package/Config.in,
+    please add it to a section, which fits the purpose of foo:
+
+
+comment "Networking"
+source "package/foo/Config.in"
+
+
+    Makefile in the package directory
 
-    Then, write a Makefile.in file. Basically, this is
-    a very short Makefile that adds the name of the software to
-    the list of TARGETS that Buildroot will generate. In
-    fact, the name of the software is the the identifier of the target
-    inside the real Makefile that will do everything (download,
-    compile, install), and that we study below. Back to
-    Makefile.in, here is an example :
+    To add your package to the build process, you need to edit
+    the Makefile in the package/ directory. Locate the
+    lines that look like the following:
 
 -ifeq ($(strip $(BR2_PACKAGE_FOO)),y)
-TARGETS+=foo
-endif
+package-$(BR2_PACKAGE_FOO) += foo
 
 
-   As you can see, this short Makefile simply adds the
-   target foo to the list of targets handled by Buildroot
-   if software foo was selected using the configuration tool.
+   As you can see, this short line simply adds the target 
+   foo to the list of targets handled by OpenWrt Buildroot.
+
+   In addition to the default dependencies, you make your package
+   depend on another package (e.g. a library) by adding a line:
+    
+
+foo-compile: bar-compile
+
+
+   The ipkg control file
+   Additionally, you need to create a control file which contains
+   information about your package, readable by the ipkg package
+   utility. It should be created as file:
+   package/foo/ipkg/foo.control
+   
+   The file looks like this
+
++     1  Package: foo
+     2  Priority: optional
+     3  Section: net
+     4  Maintainer: Foo Software <foo@foosoftware.com>
+     5  Source: http://foosoftware.com
+     6  Depends: libbar
+     7  Description: Package Description
+
+   
+   You can skip the usual Version: and Architecture
+   fields, as they will be generated by the make-ipkg-dir.sh script
+   called from your Makefile. The Depends field is important, so that ipkg will
+   automatically fetch all dependend software on your target system.
 
    The real Makefile
 
    Finally, here's the hardest part. Create a file named
-   foo.mk. It will contain the Makefile rules that
+   Makefile. It will contain the Makefile rules that
    are in charge of downloading, configuring, compiling and installing
-   the software. Below is an example that we will comment
-   afterwards.
+   the software. Below is an example that we will comment afterwards.
 
 -     1  #############################################################
-     2  #
-     3  # foo
-     4  #
-     5  #############################################################
-     6  FOO_VERSION:=1.0
-     7  FOO_SOURCE:=less-$(FOO_VERSION).tar.gz
-     8  FOO_SITE:=http://www.foosoftware.org/downloads
-     9  FOO_DIR:=$(BUILD_DIR)/less-$(FOO_VERSION)
-    10  FOO_BINARY:=foo
-    11  FOO_TARGET_BINARY:=usr/bin/foo
-    12
-    13  $(DL_DIR)/$(FOO_SOURCE):
-    14          $(WGET) -P $(DL_DIR) $(FOO_SITE)/$(FOO_SOURCE)
-    15
-    16  $(FOO_DIR)/.source: $(DL_DIR)/$(FOO_SOURCE)
-    17          zcat $(DL_DIR)/$(FOO_SOURCE) | tar -C $(BUILD_DIR) $(TAR_OPTIONS) -
-    18          touch $(FOO_DIR)/.source
-    19
-    20  $(FOO_DIR)/.configured: $(FOO_DIR)/.source
-    21          (cd $(FOO_DIR); \
-    22                  $(TARGET_CONFIGURE_OPTS) \
-    23                  CFLAGS="$(TARGET_CFLAGS)" \
-    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 $(FOO_DIR)/.configured;
-    32
-    33  $(FOO_DIR)/$(FOO_BINARY): $(FOO_DIR)/.configured
-    34          $(MAKE) CC=$(TARGET_CC) -C $(FOO_DIR)
-    35
-    36  $(TARGET_DIR)/$(FOO_TARGET_BINARY): $(FOO_DIR)/$(FOO_BINARY)
-    37          $(MAKE) prefix=$(TARGET_DIR)/usr -C $(FOO_DIR) install
-    38          rm -Rf $(TARGET_DIR)/usr/man
-    39
-    40  foo: uclibc ncurses $(TARGET_DIR)/$(FOO_TARGET_BINARY)
-    41
-    42  foo-source: $(DL_DIR)/$(FOO_SOURCE)
-    43
-    44  foo-clean:
-    45          $(MAKE) prefix=$(TARGET_DIR)/usr -C $(FOO_DIR) uninstall
-    46          -$(MAKE) -C $(FOO_DIR) clean
-    47
-    48  foo-dirclean:
-    49          rm -rf $(FOO_DIR)
-    50
+     1  # $Id$
+     2	
+     3  include $(TOPDIR)/rules.mk
+     4
+     5  PKG_NAME:=foo
+     6  PKG_VERSION:=1.0
+     7  PKG_RELEASE:=1
+     8  PKG_MD5SUM:=4584f226523776a3cdd2fb6f8212ba8d
+     9 
+    10  PKG_SOURCE_URL:=http://www.foosoftware.org/downloads
+    11  PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
+    12 	PKG_CAT:=zcat
+    13	
+    14	PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)-$(PKG_VERSION)
+    15	PKG_INSTALL_DIR:=$(PKG_BUILD_DIR)/ipkg-install
+    16
+    17	include $(TOPDIR)/package/rules.mk
+    18
+    19	$(eval $(call PKG_template,FOO,foo,$(PKG_VERSION)-$(PKG_RELEASE),$(ARCH)))
+    20
+    21  $(PKG_BUILD_DIR)/.configured: $(PKG_BUILD_DIR)/.prepared
+    22          (cd $(PKG_BUILD_DIR); \
+    23                  $(TARGET_CONFIGURE_OPTS) \
+    24                  CFLAGS="$(TARGET_CFLAGS)" \
+    25                  ./configure \
+    26                  --target=$(GNU_TARGET_NAME) \
+    27                  --host=$(GNU_TARGET_NAME) \
+    28                  --build=$(GNU_HOST_NAME) \
+    29                  --prefix=/usr \
+    30                  --sysconfdir=/etc \
+    31 			--with-bar="$(STAGING_DIR)/usr" \
+    32          );
+    33          touch $@
+    34
+    35  $(PKG_BUILD_DIR)/.built:
+    36      	rm -rf $(PKG_INSTALL_DIR)
+    37		mkdir -p $(PKG_INSTALL_DIR)
+    38		$(MAKE) -C $(PKG_BUILD_DIR) \
+    39 	          $(TARGET_CONFIGURE_OPTS) \
+    40            install_prefix="$(PKG_INSTALL_DIR)" \
+    41 	          all install
+    42		touch $@
+    43 
+    44  $(IPKG_FOO):
+    46		install -d -m0755 $(IDIR_FOO)/usr/sbin
+    47    	cp -fpR $(PKG_INSTALL_DIR)/usr/sbin/foo $(IDIR_FOO)/usr/sbin
+    49		$(RSTRIP) $(IDIR_FOO)
+    50		$(IPKG_BUILD) $(IDIR_FOO) $(PACKAGE_DIR)
+    51	
+    52	mostlyclean:
+    53  	make -C $(PKG_BUILD_DIR) clean
+    54    	rm $(PKG_BUILD_DIR)/.built
 
 
     First of all, this Makefile example works for a single
     binary software. For other software such as libraries or more
     complex stuff with multiple binaries, it should be adapted. Look at
-    the other *.mk files in the package
+    the other Makefile files in the package/
     directory.
 
-    At lines 6-11, a couple of useful variables are defined :
+    At lines 5-15, a couple of useful variables are defined:
 
     
-
-     FOO_VERSION : The version of foo that
+     
PKG_NAME : The package name, e.g. foo.
+     
+     PKG_VERSION : The version of the package that
      should be downloaded.
 
-     FOO_SOURCE : The name of the tarball of
-     foo on the download website of FTP site. As you can see
-     FOO_VERSION is used.
+     PKG_RELEASE : The release number that will be
+     appended to the version number of your ipkg package.
+
+     PKG_MD5SUM : The md5sum of the software archive.
 
-     FOO_SITE : The HTTP or FTP site from which
-     foo archive is downloaded. It must include the complete
+     
PKG_SOURCE_URL : Space separated list of the HTTP
+     or FTP sites from which the archive is downloaded. It must include the complete
      path to the directory where FOO_SOURCE can be
      found.
 
-     FOO_DIR : The directory into which the software
+     
PKG_SOURCE : The name of the tarball of
+     your package on the download website of FTP site. As you can see
+     PKG_NAME and PKG_VERSION are used.
+
+     PKG_CAT : The tool needed for extraction of the 
+	software archive.
+
+     PKG_BUILD_DIR : The directory into which the software
      will be configured and compiled. Basically, it's a subdirectory
-     of BUILD_DIR which is created upon decompression of
+     of BUILD_DIR which is created upon extraction of
      the tarball.
 
-     FOO_BINARY : Software binary name. As said
-     previously, this is an example for a single binary software.
-
-     FOO_TARGET_BINARY : The full path of the binary
-     inside the target filesystem.
+     PKG_INSTALL_DIR : The directory into the software 
+     will be installed. It is a subdirectory of PKG_BUILD_DIR.
 
     
 
-    Lines 13-14 defines a target that downloads the tarball from
-    the remote site to the download directory
-    (DL_DIR).
-
-    Lines 16-18 defines 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 (line
-    13-14) is called before executing the rules of the current
-    target. Uncompressing is followed by touching a hidden file
-    to mark the software has having been uncompressed. This trick is
-    used everywhere in Buildroot Makefile to split steps
-    (download, uncompress, configure, compile, install) while still
-    having correct dependencies.
-
-    Lines 20-31 defines a target and associated rules that
+    
In Line 3 and 17 we include common variables and routines to simplify
+	the process of ipkg creation. It includes routines to download, verify
+	 and extract the software package archives.
+
+    Line 19 contains the magic line which automatically creates the 
+	ipkg for us.
+
+    Lines 21-33 defines a target and associated rules that
     configures the software. It depends on the previous target (the
-    hidden .source file) so that we are sure the software has
+    hidden .prepared file) so that we are sure the software has
     been uncompressed. In order to configure it, it basically runs the
     well-known ./configurescript. As we may be doing
     cross-compilation, target, host and
@@ -583,41 +569,20 @@ endif
     filesystem. Finally it creates a .configured file to
     mark the software as configured.
 
-    Lines 33-34 defines a target and a rule that compiles the
+    
Lines 35-42 defines a target and a rule that compiles 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 .configured
-    file). It basically runs make inside the source
-    directory.
+    file). Afterwards it installs the resulting binary into the 
+    PKG_INSTALL_DIR. It basically runs 
+    make install inside the source directory.
 
-    Lines 36-38 defines a target and associated rules that install
-    the software inside the target filesystem. It depends on the
-    binary file in the source directory, to make sure the software has
-    been compiled. It uses the install target of the
-    software Makefile by passing a prefix
-    argument, so that the Makefile doesn't try to install
-    the software inside host /usr but inside target
-    /usr. After the installation, the
-    /usr/man directory inside the target filesystem is
-    removed to save space.
-
-    Line 40 defines the main target of the software, the one
-    referenced in the Makefile.in file. This targets
-    should first of all depends on the dependecies of the software (in
-    our example, uclibc and ncurses), and then to the
-    final binary. This last dependency will call all previous
-    dependencies in the right order. 
-
-    Line 42 defines a simple target that only downloads the code
-    source. This is not used during normal operation of Buildroot, but
-    might be useful.
-
-    Lignes 44-46 define a simple target to clean the software build
-    by calling the Makefiles with the appropriate option.
-
-    Lines 48-49 define a simple target to completely remove the
-    directory in which the software was uncompressed, configured and
-    compiled.
+    Lines 44-50 defines a target and associated rules that create
+    the ipkg package, which can optionally be embedded into
+    the resulting firmware image. It manually installs all files you
+    want to integrate in your resulting ipkg. RSTRIP will
+    recursevily strip all binaries and libraries. 
+    Finally IPKG_BUILD is called to create the package.
 
     Conclusion
 
@@ -627,17 +592,14 @@ endif
     the software.
 
     If you package software that might be useful for other persons,
-    don't forget to send a patch to Buildroot developers !
+    don't forget to send a patch to OpenWrt developers! 
+    Use the mail address: patches@openwrt.org   
+    
 
-     Ressources
+     Resources
 
-    To learn more about Buildroot you can visit these
-    websites:
-
-    
-      http://www.uclibc.org/
-      http://www.busybox.net/
-    
+    To learn more about OpenWrt you can visit this website: 
+     http://openwrt.org/

Buildroot

OpenWrt Buildroot

About Buildroot

About OpenWrt Buildroot

Obtaining Buildroot

Obtaining OpenWrt Buildroot

Using Buildroot

Using OpenWrt Buildroot

Customizing the target filesystem

Customizing the Busybox configuration

Customizing the uClibc configuration

How Buildroot +

How OpenWrt Buildroot works

Using the uClibc toolchain

Location of downloaded packages

Extending Buildroot with +

Extending OpenWrt with more software

`Makefile.in` file

`Config.in` in the package directory

`Makefile` in the package directory

The ipkg control file

The real Makefile

Conclusion

Ressources

Resources