[$] Copyleft-next and the kernel

The Linux kernel is, as a whole, licensed under the GPLv2, but variousparts and pieces are licensed under other compatible licenses and/ordual-licensed. That picture was much murkier only a few years back, beforethe SPDX in the kernel project cleaned up the licensing information in most of the kernel source by specifyingthe licenses, by name rather than boilerplate text, directlyin the files. A recent move to add yetanother license into the mix is encountering some headwinds, but thelicense in question was already being used in a few kernel files, and hasbeen for four years at this point.