Linux Embedded

Raycomm are a UK based, custom software and electronics design and development service company creating bespoke electronic products, mobile device software applications, backend web server software and e-commerce database software.

Embedded Linux is used to describe Linux-based operating systems that are used for embedded operating systems. Systems using embedded Linux include cell phones, personal digital assistants (PDA), network routers and access devices, Personal Media Appliances (PMA), navigation equipment and medical instruments.

It is often used as an alternative for propriety operating systems such as Windows

• The source code can be modified and redistributed
• Relatively small footprint (typically less than 2 megabytes)
• No royalty or licensing costs
• Mature and stable
• Large support base

Embedded Linux systems combine the Linux kernel with a small set of free software utilities. The C standard library (glibc) is often replaced by less resource-consuming alternatives such as dietlibc, uClibc or Newlib. There are a number of providers of commercial Linux distributions specifically targeting embedded real-time applications including MontaVista software, Red Hat, SysGo and TimeSys. Processor manufacturers often support a version of Linux from one of these providers.

Embedded Linux and the GPL Licence

The rising popularity of Linux, combined with perceived cost savings, has spurred many companies to consider a real-time Linux variant as an alternative to a traditional RTOS. This does have implications on the proprietary parts of the firmware due to the Open Source nature of Linux.

A common myth is that by using open source software you have to give away your proprietary application. In reality most open source licences protect only borrowed code and do not place any restrictions on software developed alongside it.

If you don't modify the operating system, the GPL requires only that you give credit where credit is due, do not impose any further licensing or distribution conditions upon your customers, and provide the Linux source code you used to your customers, if they request it. Those are pretty reasonable terms, by any measure.
There are many situations where you might wish to keep your code proprietary even when surrounded by Linux’s open source code. This can readily be accomplished by following these general rules.

• Start proprietary software from a clean code base
• Use only LGPL Libraries
• Don’t modify the interface to the Linux Kernel.