Before we can explore whether embedded Linux is really free we need to define what we mean by embedded. We define an embedded system as that, used as part of a larger whole, which performs a specific task. A, truly, embedded Linux, therefore, is one which is fully customised to perform a particular job.

All designers are aware that a reduction in complexity can provide a less expensive and more reliable solution. To reduce the complexity of a Linux installation you would need to recompile the kernel to remove support for any unnecessary hardware, and possibly add support for less mainstream hardware. You may also want to remove any extraneous commands from the Linux installation. Whilst this will provide the best Linux solution for your application, as it has been customised specially for it, with the smallest footprint possible, it will have been necessary to make significant investment in securing the knowledge to make these changes.

The one remaining task to complete your system is to create and add your own application code. As this is a task that you will be required to undertake regardless of operating system (packages to help with this are available freely or commercially for most operating systems) this is a cost that must be borne and therefore may not influence operating system choice.

In a company with many product lines; a very sensible commercial approach; would you perform this customisation every time? All mature approaches reuse IP. This reduces the cost and provides a stable, previously tested and proven, foundation for subsequent designs. After all nobody redesigns the processor every time they design a new product!

Perhaps the clever method, assuming your product line is not too varied, would be to create your own Linux covering your companys portfolio.

Current desktop and server versions of Linux are available on numerous CD ROMs or even a DVD. These are obviously not suited to an embedded environment, and the reduction in footprint would be a sizeable task to undertake. Embedded versions are available which have a smaller footprint, but they may still be too generalised to fit your application.

The difference between a desktop Linux and embedded Linux mirror that of Microsoft Windows XP and Microsoft Windows XP embedded (or indeed Windows 7 and Windows Embedded Standard 7). However, the platform builder for Microsoft Windows XP embedded affords you a simplified approach to customisation.

You may be lucky enough to find an embedded Linux which includes support for your unique hardware configuration (after all this is why you are in business), and that includes all of the commands necessary for your application. The version you find may, even, be free. In which case, you are as close as any of us can be to the nadir of a free Linux.

I am sure that this will have raised the question Should I use Linux? Linux is a mature operating system that is proven as a viable operating system and can be very reliable. This is also true for your embedded system. So the answer is a positive maybe.

Armed with all of the facts, and given the knowledge of all hidden costs, you should be able to make an informed financial evaluation of all available solutions.

Put simply, in answer to the original question of whether an embedded Linux can be free, with partnerships and collaboration with companies such as Datasound Laboratories Limited, you will be able to source the correct, and most cost effective, operating system for your application.

Acknowledgments
Microsoft and Windows are registered trademarks of Microsoft Corporation in the United States and/or other countries. QNX is a registered trademark of QNX Software Systems. LINUX is a registered trademark of Linus Torvalds. All other products and trademarks mentioned are trademarks of their respective owners. Datasound Laboratories Limited has attempted to properly capitalize and punctuate trademarks, but cannot warranty that it has done so in every case.