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 user manual of Ironclad is provided under the Free Documentation License (FDL) 1.3.
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.
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.
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 legaly tested way is the GPL.
The code and documentation for the kernel and some userland utilities are available under the aforementioned licenses at our Codeberg Organization.
Due to Ironclad’s GPL, we can only accept contributions to Ironclad that comply with the base license. That is, GPL code itself, or more permissive, GPL-compatible licenses like the MIT, or most BSD varieties. The licensing status of contributions should be clearly delineated by using license headers.
We do not require a CLA or anything of the sort for Ironclad, we instead require a DCO for any major contribution.
The DCO is a statement created by the Linux Foundation in 2004 that shifts the responsibility for the licensing from the project to the user, as to protect the project from license fraud or legal repercusions. Unlike a CLA, this makes no copyright transfer, and the developer keeps their copyright and legal ownership permanently. The text of the DCO is:
Developer’s Certificate of Origin 1.1
By making a contribution to this project, I certify that:
(a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or
(b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or
(c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it.
(d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved.
Our version management software, git, provides an easy and convenient way
to sign the DCO with the -s command-line switch.