OpenWRT on Ebox3300 part II

12 Sep 2014 | Comments

This part will contain getting the OpenWRT distribution and making basic build.

The OpenWRT

OpenWRT is linux distibution, which can be used on many routers. It has package system based on opkg (which is quite similar in usage as Debian’s dpkg, but intended for embedded systems) and uci configuration system. The specifics can be found on the OpenWRT homepage. Especially, I recommend reading the Documentation section as it provides good starting point.

I decided to use this distribution on my device, because it’s quite mature project, stable and there are lots of packages available. I could’ve used some more popular, general purpose distribution (like Debian), but I wanted more specialized OS (my device is meant to be router after all ;)), which is hacker-friendly and can be easily modified and adapted to my needs. Also the build system is great, based on Makefiles and kconfig (the same as used in kernel build system).

Ok, so how do we get the OpenWRT? We can just download it from the Download section of the homepage (for x86 architecture), but it won’t work. The first step is to get the sources from Development page: https://dev.openwrt.org/wiki/GetSource

There are instructions how to get the sources. I recommend getting them by git. It should be quite straightforward, we only need to install this tool. Every major linux distribution has it in its repositories. For example, in Archlinux distro (which I use) command to install it, is:

pacman -S git

so nothing fancy.

Next we just use:

git clone git://git.openwrt.org/openwrt.git

and we have the newest Bleeding Edge sources of OpenWRT in newly created openwrt directory. This project is under active development so there are many changes introduced every day. We can update our sources with git pull command.

First build

In this phase, our goal is simple: build the minimal working image for the device. This will be ramfs image of root file system and kernel, and it will be booted from µSD card. Why ramfs image? Because it’s simple and we won’t have to deal with drivers for storage controllers and more advanced filesystem. The first build is only for checking if device supports our distibution in general and to have a nice starting point for porting work.

Ok, first thing we load default configuration:

make defconfig

and after that we run the calssic menuconfig:

make menuconfig

In the menu we choose x86 as Target System and generic as Subtarget. In Target Images we mark ramdisk (we may change compression to gzip) and uncheck everything else. We don’t need any other type of image for time being. That should be enough for minimal system. Exit the menu and save new configuration. Now we just run make (with -j argument, if we want to build it on multicore systems, for example make -j 5 on 4-core machine) and it should hopefully build after some time (depending on computer, but it can take even an hour). If there are errors, we must check if we got every dependency satisfied (they are described in documentation).