Licensing of the code

This page explains the licensing model of the project, the motivation behind it, and details on all the open-source licenses used for code provided by the Ironclad project.

Kernel licensing

The Ironclad kernel is free software, licensed under the GNU General Public License (GPL) 3. This only applies to kernel code. Anything not statically linked with the kernel (like userland applications, or distributions) is not subject to this license.

The GPL is one of the most popular open-source licenses. One of its stipulations is that changes and “derived code” must again be licensed under the GPL to the users of the program, this does not include use without modification or distribution of the code to non-users, if Ironclad code is being used as part of a paid distribution.

This only applies to kernel code. We feel like the Linux syscall note for the GPL is not necessary as copyright legislation already implies it. Developers should proceed as if any use of syscalls or other Ironclad interfaces from userland does not constitute a derivative work of Ironclad, thus, no licensing requirements.

Some of our drivers are licensed under more liberal licenses than the GPL under the idea of them being of use to other embedded projects. For details on the licensing of the driver in question, consult the file headers on the code.

Why the GPL?

We intend for Ironclad to always be free, and for it to be always available for developers to study, use, modify, and share modifications, while making sure that no entity can just glob up our work and deny these rights to their users. The only license family that guarantees that in a legally tested way is the GPL.

Userland support software licensing

Userland support libraries and programs like util-ironclad are provided under more liberal licenses than the kernel, under the idea that such licenses will help their use and further the idea that only the kernel has licensing requirements, not the userland. The license we default to for these utilities is The MIT License.

Documentation licensing

The user manual of Ironclad and all other documentation we have is provided under the Free Documentation License (FDL) 1.3.