One of the biggest challenges to getting started with embedded devices is that you
-cannot just install a copy of Linux and expect to be able to compile a firmware.
+cannot just install a copy of GNU+Linux and expect to be able to compile a firmware.
Even if you did remember to install a compiler and every development tool offered,
you still would not have the basic set of tools needed to produce a firmware image.
The embedded device represents an entirely new hardware platform, which is
most of the time incompatible with the hardware on your development machine, so in a process called
cross compiling you need to produce a new compiler capable of generating code for
-your embedded platform, and then use it to compile a basic Linux distribution to
+your embedded platform, and then use it to compile a basic GNU+Linux distribution to
run on your device.
The process of creating a cross compiler can be tricky, it is not something that is
\subsection{Building an image}
-OpenWrt takes a different approach to building a firmware; downloading, patching
+LibreWRT takes a different approach to building a firmware; downloading, patching
and compiling everything from scratch, including the cross compiler. To put it
-in simpler terms, OpenWrt does not contain any executables or even sources, it is an
+in simpler terms, LibreWRT does not contain any executables or even sources, it is an
automated system for downloading the sources, patching them to work with the given
platform and compiling them correctly for that platform. What this means is that
just by changing the template, you can change any step in the process.
a new firmware image -- there is no work to be done trying to track down an unmodified
copy of the existing kernel to see what changes had been made, the patches are
already provided and the process ends up almost completely transparent. This does not
-just apply to the kernel, but to anything included with OpenWrt -- It is this one
-simple understated concept which is what allows OpenWrt to stay on the bleeding edge
+just apply to the kernel, but to anything included with LibreWRT -- It is this one
+simple understated concept which is what allows LibreWRT to stay on the bleeding edge
with the latest compilers, latest kernels and latest applications.
-So let's take a look at OpenWrt and see how this all works.
+So let's take a look at LibreWRT and see how this all works.
-\subsubsection{Download OpenWrt}
+\subsubsection{Download LibreWRT}
-This article refers to the "Kamikaze" branch of OpenWrt, which can be downloaded via
+This article refers to the development branch of LibreWRT, which can be downloaded via
subversion using the following command:
\begin{Verbatim}
-$ svn checkout svn://svn.openwrt.org/openwrt/trunk kamikaze
+$ svn checkout http://svn.librewrt.org//trunk
\end{Verbatim}
-Additionally, there is a trac interface on \href{https://dev.openwrt.org/}{https://dev.openwrt.org/}
+Additionally, there is a web interface on \href{http://websvn.librewrt.org/}{http://websvn.librewrt.org/}
which can be used to monitor svn commits and browse the source repository.
\item \texttt{build\_dir/toolchain-\textit{<arch>}*}
\end{itemize}
-\texttt{package} is for exactly that -- packages. In an OpenWrt firmware, almost everything
+\texttt{package} is for exactly that -- packages. In a LibreWRT firmware, almost everything
is an \texttt{.ipk}, a software package which can be added to the firmware to provide new
features or removed to save space. Note that packages are also maintained outside of the main
trunk and can be obtained from subversion using the package feeds system:
\item \texttt{dl}
\end{itemize}
-\subsubsection{Building OpenWrt}
+\subsubsection{Building LibreWRT}
-While the OpenWrt build environment was intended mostly for developers, it also has to be
+While the LibreWRT build environment was intended mostly for developers, it also has to be
simple enough that an inexperienced end user can easily build his or her own customized firmware.
-Running the command "\texttt{make menuconfig}" will bring up OpenWrt's configuration menu
+Running the command "\texttt{make menuconfig}" will bring up LibreWRT's configuration menu
screen, through this menu you can select which platform you're targeting, which versions of
the toolchain you want to use to build and what packages you want to install into the
firmware image. Note that it will also check to make sure you have the basic dependencies for it
"\texttt{make clean}" calls.
To begin compiling the firmware, type "\texttt{make}". By default
-OpenWrt will only display a high level overview of the compile process and not each individual
+LibreWRT will only display a high level overview of the compile process and not each individual
command.
\subsubsection{Example:}
\subsection{Creating packages}
-One of the things that we've attempted to do with OpenWrt's template system is make it
-incredibly easy to port software to OpenWrt. If you look at a typical package directory
-in OpenWrt you'll find several things:
+One of the things that we've attempted to do with LibreWRT's template system is make it
+incredibly easy to port software to LibreWRT. If you look at a typical package directory
+in LibreWRT you'll find several things:
\begin{itemize}
\item \texttt{package/\textit{<name>}/Makefile}
reduce the size of the executable. The package makefile is the important item, provides
the steps actually needed to download and compile the package.
-The files directory is also optional and typicall contains package specific startup scripts or default configuration files that can be used out of the box with OpenWrt.
+The files directory is also optional and typicall contains package specific startup scripts or default configuration files that can be used out of the box with LibreWRT.
Looking at one of the package makefiles, you'd hardly recognize it as a makefile.
Through what can only be described as blatant disregard and abuse of the traditional
The \texttt{PKG\_*} variables define where to download the package from;
\texttt{@SF} is a special keyword for downloading packages from sourceforge. There is also
-another keyword of \texttt{@GNU} for grabbing GNU source releases. If any of the above mentionned download source fails, the OpenWrt mirrors will be used as source.
+another keyword of \texttt{@GNU} for grabbing GNU source releases. If any of the above mentionned download source fails, the LibreWRT mirrors will be used as source.
The md5sum (if present) is used to verify the package was downloaded correctly and
\texttt{PKG\_BUILD\_DIR} defines where to find the package after the sources are
The reason that some of the defines are prefixed by "\texttt{Package/\textit{<name>}}"
and others are simply "\texttt{Build}" is because of the possibility of generating
-multiple packages from a single source. OpenWrt works under the assumption of one
+multiple packages from a single source. LibreWRT works under the assumption of one
source per package Makefile, but you can split that source into as many packages as
desired. Since you only need to compile the sources once, there's one global set of
"\texttt{Build}" defines, but you can add as many "Package/<name>" defines as you want
\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.
+The LibreWRT 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"
\subsection{Using build environments}
-OpenWrt provides a means of building images for multiple configurations
+LibreWRT provides a means of building images for multiple configurations
which can use multiple targets in one single checkout. These \emph{environments}
store a copy of the .config file generated by \texttt{make menuconfig} and the contents
of the \texttt{./files} folder.
projects / librewrt / .git / blobdiff