So let's take a look at OpenWrt and see how this all works.
-\subsubsection{Download openwrt}
+\subsubsection{Download OpenWrt}
This article refers to the "Kamikaze" branch of OpenWrt, which can be downloaded via
subversion using the following command:
\begin{Verbatim}
-$ svn co https://svn.openwrt.org/openwrt/trunk kamikaze
+$ svn checkout https://svn.openwrt.org/openwrt/trunk kamikaze
\end{Verbatim}
-Additionally, ther is a trac interface on \href{https://dev.openwrt.org/}{https://dev.openwrt.org/}
-which can be used to monitor svn commits and browse the sources.
+Additionally, there is a trac interface on \href{https://dev.openwrt.org/}{https://dev.openwrt.org/}
+which can be used to monitor svn commits and browse the source repository.
\subsubsection{The directory structure}
trunk and can be obtained from subversion at the following location:
\begin{Verbatim}
-$ svn co https://svn.openwrt.org/openwrt/packages ../packages
+$ svn checkout https://svn.openwrt.org/openwrt/packages packages
\end{Verbatim}
Those packages can be used to extend the functionality of the build system and need to be
$ ln -s packages/*/* kamikaze/package/
\end{Verbatim}
-
\texttt{target} refers to the embedded platform, this contains items which are specific to
a specific embedded platform. Of particular interest here is the "\texttt{target/linux}"
-directory which is broken down by platform and contains the kernel config and patches
-to the kernel for a particular platform. There's also the "\texttt{target/image}" directory
+directory which is broken down by platform \textit{<arch>} and contains the patches to the
+kernel, profile config, for a particular platform. There's also the "\texttt{target/image}" directory
which describes how to package a firmware for a specific platform.
Both the target and package steps will use the directory "\texttt{build\_\textit{<arch>}}"
\begin{itemize}
\item \texttt{package/\textit{<name>}/Makefile}
\item \texttt{package/\textit{<name>}/patches}
- \item \texttt{package/\textit{<name>}/files}
+ \item \texttt{package/\textit{<name>}/files}
\end{itemize}
The patches directory is optional and typically contains bug fixes or optimizations to
Here for example, is \texttt{package/bridge/Makefile}:
\begin{Verbatim}[frame=single,numbers=left]
-#
-# Copyright (C) 2006 OpenWrt.org
-#
-# This is free software, licensed under the GNU General Public License v2.
-# See /LICENSE for more information.
-#
# $Id: Makefile 5624 2006-11-23 00:29:07Z nbd $
include $(TOPDIR)/rules.mk
SECTION:=net
CATEGORY:=Base system
TITLE:=Ethernet bridging configuration utility
- DESCRIPTION:=\
- Manage ethernet bridging: a way to connect networks together to \\\
- form a larger network.
URL:=http://bridge.sourceforge.net/
endef
+define Package/bridge/description
+ Manage ethernet bridging:
+ a way to connect networks together to form a larger network.
+endef
+
define Build/Configure
$(call Build/Configure/Default, \
--with-linux-headers="$(LINUX_DIR)" \
will automatically show in the menu the next time you run "make menuconfig" and if selected
will be built automatically the next time "\texttt{make}" is run.
+\subsection{Creating kernel modules packages}
+
+The OpenWrt distribution makes the distinction between two kind of kernel modules, those coming along with the mainline kernel, and the others available as a separate project. We will see later that a common template is used for both of them.
+
+For kernel modules that are part of the mainline kernel source, the makefiles are located in \textit{package/kernel/modules/*.mk} and they appear under the section "Kernel modules"
+
+For external kernel modules, you can add them to the build system just like if they were software packages by defining a KernelPackage section in the package makefile.
+
+Here for instance the Makefile for the I2C subsytem kernel modules :
+
+\begin{Verbatim}[frame=single,numbers=left]
+# $Id $
+
+I2CMENU:=I2C Bus
+
+define KernelPackage/i2c-core
+ TITLE:=I2C support
+ DESCRIPTION:=Kernel modules for i2c support
+ SUBMENU:=$(I2CMENU)
+ KCONFIG:=CONFIG_I2C_CORE CONFIG_I2C_DEV
+ FILES:=$(MODULES_DIR)/kernel/drivers/i2c/*.$(LINUX_KMOD_SUFFIX)
+ AUTOLOAD:=$(call AutoLoad,50,i2c-core i2c-dev)
+endef
+$(eval $(call KernelPackage,i2c-core))
+\end{Verbatim}
+
+To group kernel modules under a common description in menuconfig, you might want to define a \textit{<description>MENU} variable on top of the kernel modules makefile.
+
+\begin{itemize}
+ \item \texttt{TITLE} \\
+ The name of the module as seen via menuconfig
+ \item \texttt{DESCRIPTION} \\
+ The description as seen via help in menuconfig
+ \item \texttt{SUBMENU} \\
+ The sub menu under which this package will be seen
+ \item \texttt{KCONFIG} \\
+ Kernel configuration option dependency. For external modules, remove it.
+ \item \texttt{FILES} \\
+ Files you want to inlude to this kernel module package, separate with spaces.
+ \item \texttt{AUTOLOAD} \\
+ Modules that will be loaded automatically on boot, the order you write them is the order they would be loaded.
+\end{itemize}
+
+After you have created your \texttt{package/kernel/modules/\textit{<name>}.mk}, the new kernel modules package
+will automatically show in the menu under "Kernel modules" next time you run "make menuconfig" and if selected
+will be built automatically the next time "\texttt{make}" is run.
\subsection{Conventions}
projects / openwrt.git / blobdiff