KallistiOS is licensed under the terms of the "new" BSD license. We are calling our version of this license with the KOS copyright notice the KOS License. For all files that are copyrighted by the authors of KallistiOS (Megan Potter, etc), or for any file which does not otherwise specify (and does not come from a third-party package like newlib), you can assume that this text is attached to them:
This program is free software; you can redistribute it and/or modify it under the terms of the KOS License.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the KOS License (LICENSE.KOS) for more details.
You should have received a copy of the KOS License along with this program; if not, please visit Cryptic Allusion Game Dev at:
Please read LICENSE.KOS for the full license text.
Some of the software included with KallistiOS is not copyrighted by us, nor is it part of the codebase of KallistiOS. Most of that code will be found within the "utils" directory and the "addons" directory. Licenses on these pieces vary; please see the source of the program in question to be sure.
The kos-ports repository provides ports of libraries with a variety of licenses. For each, the applicable license is noted in its Makefile as the LICENSE define. This can also be verified with the original authors. Please review and be aware of these licenses if you wish to use kos-ports.
If there is ever a question or you want to ask permission to do something else with it, please contact the authors and we'll see how we can accommodate you.
The Free Software Foundation has a very good source of information on the various licenses. Please see this page if you have license compatibility questions: