Linux Remains Licensed Under The GNU GPL v2 And New Contributions Remain Subject To It
The Linux kernel's COPYING file got the small change adding a notice saying "All contributions to the Linux Kernel are subject to this COPYING file" during the 5.6 release cycle. There was, apparently, a risk that someone would be confused trying to understand what license bew contributions to the Linux kernel are subject to 27 years after the kernel moved from a simple three point license to the GNU General Public License v2.
- Full source must be available (and free), if not with the distribution then at least on asking for it.
- Copyright notices must be intact. (In fact, if you distribute only parts of it you may have to add copyrights, as there aren't (C)'s in all files.) Small partial excerpts may be copied without bothering with copyrights.
- You may not distibute this for a fee, not even "handling" costs.
The license was changed to "GNU copyleft" with the release of Linux 0.12 on January 16th, 1992. This was primarily done due to objections against the rule prohibiting commercial distribution.
Linux 0.99, released in July 1993, was the first to include a proper
COPYING file with the full text of the GNU General Public License Version 2. The Linux kernel has been licensed under the GNU GPL v2, and only version 2, ever since. Linus Torvalds rejected the GNU GPL v3 which has additional restrictions Torvalds did not like. Linux 0.99 was also the first version to include a
README file with begun with a helpful headline urging you to "DON'T PANIC".
COPYING file got an update in 2005 when the Free Software Foundation changed their address. It remained unchanged until the full text of the GNU GPL v2 was moved from
COPYING and to its own file in March 2018.
COPYING got new text in its place stating that:
- The Linux Kernel is provided under:
- SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
- Being under the terms of the GNU General Public License version 2 only, according with: LICENSES/preferred/GPL-2.0
Some people could apparently get confused trying to understand what license new contributions to the kernel are subject to today, 27 years after the Linux kernel switched to the GNU GPL v2. Thus, there was a need to add the following text during the Linux 5.6 release cycle:
- All contributions to the Linux Kernel are subject to this COPYING file.
The reason for that commit by Greg Kroah-Hartman was stated to be:
"Explicitly state that all contributions to the kernel source tree really are covered under this COPYING file in case someone thought otherwise. Lawyers love to be pedantic, even more so than software engineers at times, and this sentence makes them sleep easier."
The Linux Kernel is, and will always be, free software licensed under the GNU GPL v2. That will not change. The GNU GPL license clarifies that "If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation." The kernel's
COPYING file never said anything about later versions of the GNU GPL so an "upgrade" to GNU GPL v3, which Linus Torvalds is against, would require written agreements from everyone who ever contributed to the kernel. That will never happen. However, many parts of the kernel are available under other licenses even though the kernel itself is not. As an example, all the
amdgpu driver code is available under the less restrictive MIT Software License. The header will tell you what license(s) any individual file in the kernel source tree is available under.