Earlier quoted context omitted.
The GPL does not prevent closed versions because of Tivoization, and SaaS. For instance, Facebook is closed, in spite of running on a mountain of GPLed stuff. A locked device may prevent the user from running a kernel image that is not signed with a certain private key, even though the vendor of the device complies with the GPL and provides the matching kernel sources and the correct toolchain to reproduce the build…
This is why we have AGPL and GPLv3. You can TiVoize the kernel, but you have to provide the user land, at minimum. In a MIT only world, you would have no source of anything. So not only you can’t build a signature-free version of the kernel for educational purposes, you can’t even have it. This is a corporation paradise.
https://sfconservancy.org/blog/2021/mar/25/install-gplv2/ https://sfconservancy.org/blog/2021/jul/23/tivoization-and-t... https://events19.linuxfoundation.org/wp-content/uploads/2017... Behan-Webster-1.pdf