Always good to see progress towards people getting to own their own hardware.

> MIT for all original code. The kernel excerpt (kernel/mem.c) retains its GPL-2.0 license and copyright notices.

One small tweak needed here.

GPL 2.0? Has this bit:

> You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.

"under the terms of [this License]."

It is viral. Copying the code, and distributing it, as done here, means that GPL 2.0 is meant to apply to everything. The only carveout, is if your code didn't depend on the kernel excerpt at all. But... It does.

> If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission.

In this particular case it is not viral. All MIT-licensed code can be "licensed as a whole at no charge to all third parties under" GPL 2. The point of the MIT license is that it can be freely relicensed.

You actually have more rights with that file than with the others; the GPL doesn't restrict non-GPL'd code distributed with it, it requires that that code be licensed in a way that allows it to be distributed under GPL 2. For example, I myself can take this code and redistribute the entire thing under GPL 2 without an exception for ./kernel/mem.c (as long as I include any acknowledgement required by MIT, such as a copy of the MIT license and a copyright notice.)

You're overcomplicating things and (maybe accidentally) spreading FUD. MIT was specifically designed to be compatible with anything from copyleft to proprietary.