Note: this section only corresponds to the official eCos 1.3.1 release. eCos sources from anonymous CVS are covered by a different licence which is a modified version of the GPL. Future releases will also be covered by this licence.

eCos is released under a new license, the Red Hat eCos Public License or RHEPL for short.

You can use eCos to develop products without paying anybody anything, no matter how many developers are working on the product or how many units you expect to ship. This applies not only to the core system itself but also to any changes anybody makes to the core system.

A key aspect of the eCos public license is that it is intended to protect the eCos user community as a whole. It should prevent any company or individual contributing code to the system and then claim that all eCos users are now guilty of copyright or patent infringements and have to pay royalties. It should also prevent any company from making some small improvements, calling the result a completely new system, and releasing this under a new and less generous license.

The license does impose one obligation on application developers: you must include a notice with your product indicating that it makes use of eCos.

No. Your application source code is your own, to do with as you please. As far as the eCos public license is concerned you are under no obligation to reveal a single line of your source code to Red Hat or to anybody else. In fact you do not even have to tell Red Hat about the existence of your project, although we would love to know about all the different products that use eCos.

If you make a change to the core eCos system then we believe that the entire user community should have the opportunity to benefit from that change. This does not necessarily mean that your changes will become part of the core system, since there are fairly strict criteria that have to be satisfied before any contribution will be incorporated. However any such decisions will be made by the eCos maintainers, not by the person making the changes.

eCos is designed to be the component framework for the embedded systems industry. An eCos release consists of a number of different packages including the kernel, the C library, and a uITRON compatibility layer. All the packages that go into such a release and the associated documentation constitute the core system, and the license describes this using the term "Original Code".

Another way of looking at this is from a purely practical perspective. At the end of the day building an application involves linking together some application-specific object files with some libraries. The current eCos build system will produce a library libtarget.a, containing all the packages that the user has selected. All the source code that goes into the building of this library is part of the core system and is covered by the eCos public license. Anything which goes into the application-specific object files is not part of the core system and is not covered by the public license. Note that this is not a legally binding definition - in particular you cannot get around the public license simply by copying bits of eCos sources and making them part of your application code.

Typically other packages will end up as other libraries that need to be linked with the application code. These other packages may be covered by different licenses, and application developers should make sure that the requirements for all licenses are satisfied.

Some companies or organizations may release packages that are not open source or freely available. Instead the application developer may have to pay a one-off license fee or quite possibly per-unit royalties if the application uses such a package. Not only is this perfectly legal, Red Hat would very much like other companies to make money by providing such packages.

Some packages may be released under the eCos public license without becoming part of the core system. Typically this will happen if the eCos maintainers believe that they would be unable to maintain such a package themselves, for example because it relies on special hardware.

There are two possibilities. If the new package is derived in large part from some existing software then it is likely that there are existing license restrictions that will apply. For example if you create a new eCos device driver by copying an existing one and editing it then this would constitute a modification to existing code and the eCos public license would apply to the new device driver. If you create a new device driver from scratch then you can decide for yourself what license should apply. If you want the package to be freely available to the entire eCos community then we recommend the eCos public license, but the choice is yours.

Balancing the needs and desires of all the companies, organizations, and individuals involved with eCos is difficult. The most important requirement is that the freedom of all eCos users is protected: it must be impossible for anybody, even Red Hat, to impose restrictions on how the system can be used now or in the future. Some existing licenses such as the X11 license do not provide this.

It is also desirable that all enhancements are made available to the community as a whole, thus improving the system and making it even more attractive to potential users. Some existing licenses such as the BSD license do not provide this.

The GNU Public License does meet these requirements, but it goes further: all applications that get linked with GPL'd code are also covered by the GPL, which means in practice that application developers have to make the sources available. In the embedded systems market this requirement is generally considered unacceptable and many companies refuse to use any GPL'd code as a result. This would reduce the uptake of eCos, and we want as many people as possible to use the system.

The Netscape Public License came closest to meeting the requirements. There were some modifications to reflect the needs of embedded system developers, and the result was the eCos public license.

Hopefully yes, but there may be situations that we have missed. If you have any queries about the license and how it applies to your situation, please contact us. There are both public and private channels of communication available, depending on your requirements. We are always interested in suggested improvements to the license that are compatible with our overall goals.