This article describes why the ELBE project was born.
early embedded Linux devices
Well, first we should look at embedded devices to see what they used to look like and how some of them look like today.
The first devices, that were initially called embedded Linux, had about 4MiB flash and around 16MiB of RAM. With these constrains in mind people started to hack a root file system for their devices. If they had bad luck you had to start with building a cross toolchain first.
Once that part was over you could focus on the user land. Busybox is a good tool to start with since it contains most of the required programs in a small single binary. Those programs and a few configurations files on top and you were done. Maybe you had to compile your “added value” binary or something else that was not part of busybox but that was it.
Cross-build Toolkits
Now sum up the single steps which were required to create a root file from scratch and create a tool to ease your life. This is when tools like OpenEmbedded, EDLK were born. Those tools are still good as long as they are well maintained. They aren’t just projects that are that small these days. A lot of them are getting very complex. This includes hardware that has much more RAM and a GiBs of NAND flash if not replaced by a disk or mmc card and the software, that is used, is more extensive.
Rootfilesystems are getting bigger and bigger
A lot of libraries are used to ease the development of a system. A toolkit for GUI development, several libraries for multimedia support just to name a few.
Depending on the build environment that is used, it is more or less difficult to add a package that is not yet included. It depends on the scripting language that is used, the format keeping the build instructions and the user’s ability to understand it and make changes.
Adding Debuging Tools is not that easy
Adding a debug version of a package to the root file system means a rebuild or restart of the build process to create this piece of the rootfile system assuming that a debug version can be selected (and not added to the build process). Even then the debug version isn’t installed in a jiffy.
There is usually one person in charge of the root file system and a few others that are developing the application or a component of the application. One of the application developers has a problem and wants just to install a debug version of the library in question or replace it with a later version of it or a substitute library just to see if his problem goes away or not. He doesn’t necessarily know how to handle the build environment to make such changes. So he has to ask the person in charge of the root filesystem to make this change and send him the new filesystem.
The application developer never did this kind of work because the Linux distribution on his desktop computer takes care of these things for him. The same distribution runs a test suite (if available) of the package after it has been built to spot problems in the compiled binaries which can’t be run if the package is cross compiled.
No Bugtracking Informations available
Another missing feature is the bug tracking against all packages in the root file system including security updates. This can be a full time job for one person even just by looking after 10 packages with a reasonable size. So why try to do a lot of work alone while this work is already done by large communities around Linux distribution like Debian?
Debian for embedded?
Instead of doing the work again we tried to figure out how Debian could be reused in a way that will fulfill our needs.
Continue reading ELBE Overview.