Copyleft-next and the kernel [LWN.net]
The Linux kernel is, as a whole, licensed under the GPLv2, but various parts and pieces are licensed under other compatible licenses and/or dual-licensed. That picture was much murkier only a few years back, before the SPDX in the kernel project cleaned up the licensing information in most of the kernel source by specifying the licenses, by name rather than boilerplate text, directly in the files. A recent move to add yet another license into the mix is encountering some headwinds, but the license in question was already being used in a few kernel files, and has been for four years at this point.