Documentation/process/license-rules.rst

1 .. SPDX-License-Identifier: GPL-2.0
8 The Linux Kernel is provided under the terms of the GNU General Public
9 License version 2 only (GPL-2.0), as provided in LICENSES/preferred/GPL-2.0,
11 LICENSES/exceptions/Linux-syscall-note, as described in the COPYING file.
19 which is required to be compatible with the GPL-2.0::
21     GPL-1.0+  :  GNU General Public License v1.0 or later
22     GPL-2.0+  :  GNU General Public License v2.0 or later
23     LGPL-2.0  :  GNU Library General Public License v2 only
24     LGPL-2.0+ :  GNU Library General Public License v2 or later
25     LGPL-2.1  :  GNU Lesser General Public License v2.1 only
26     LGPL-2.1+ :  GNU Lesser General Public License v2.1 or later
28 Aside from that, individual files can be provided under a dual license,
32 The User-space API (UAPI) header files, which describe the interface of
33 user-space programs to the kernel are a special case.  According to the
34 note in the kernel COPYING file, the syscall interface is a clear boundary,
40 The common way of expressing the license of a source file is to add the
45 An alternative to boilerplate text is the use of Software Package Data
48 under which the content of the file is contributed.  SPDX license
59 -------------------------
65    of files this is the first line, except for scripts which require the
73    The SPDX license identifier is added in form of a comment.  The comment
76       C source:	// SPDX-License-Identifier: <SPDX License Expression>
77       C header:	/* SPDX-License-Identifier: <SPDX License Expression> */
78       ASM:	/* SPDX-License-Identifier: <SPDX License Expression> */
79       scripts:	# SPDX-License-Identifier: <SPDX License Expression>
80       .rst:	.. SPDX-License-Identifier: <SPDX License Expression>
81       .dts{i}:	// SPDX-License-Identifier: <SPDX License Expression>
85    is the reason for having the "/\* \*/" style comment in C header
95    A <SPDX License Expression> is either an SPDX short form license
99    of keywords "AND", "OR" separating sub-expressions and surrounded by
105       // SPDX-License-Identifier: GPL-2.0+
106       // SPDX-License-Identifier: LGPL-2.1+
108    WITH should be used when there is a modifier to a license needed.
111       // SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
112       // SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note
116       // SPDX-License-Identifier: GPL-2.0 WITH mif-exception
117       // SPDX-License-Identifier: GPL-2.0+ WITH GCC-exception-2.0
124    OR should be used if the file is dual licensed and only one license is
125    to be selected.  For example, some dtsi files are available under dual
128       // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
130    Examples from the kernel for license expressions in dual licensed files::
132       // SPDX-License-Identifier: GPL-2.0 OR MIT
133       // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
134       // SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
135       // SPDX-License-Identifier: GPL-2.0 OR MPL-1.1
136       // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) OR MIT
137       // SPDX-License-Identifier: GPL-1.0+ OR BSD-3-Clause OR OpenSSL
140    apply to use the file. For example, if code is inherited from another
144       // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) AND MIT
147    adhered to is::
149       // SPDX-License-Identifier: GPL-1.0+ AND LGPL-2.1+
152 -------------------
173       LICENSES/preferred/GPL-2.0
185    - Valid-License-Identifier:
189      this is a single valid identifier, but e.g. for licenses with the 'or
192    - SPDX-URL:
197    - Usage-Guidance:
203    - License-Text:
205      All text after this tag is treated as the original license text
209       Valid-License-Identifier: GPL-2.0
210       Valid-License-Identifier: GPL-2.0+
211       SPDX-URL: https://spdx.org/licenses/GPL-2.0.html
212       Usage-Guide:
217 	  SPDX-License-Identifier: GPL-2.0
219 	  SPDX-License-Identifier: GPL-2.0+
220       License-Text:
225       SPDX-License-Identifier: MIT
226       SPDX-URL: https://spdx.org/licenses/MIT.html
227       Usage-Guide:
231 	  SPDX-License-Identifier: MIT
232       License-Text:
258       LICENSES/deprecated/GPL-1.0
269       Valid-License-Identifier: ISC
270       SPDX-URL: https://spdx.org/licenses/ISC.html
271       Usage-Guide:
272         Usage of this license in the kernel for new code is discouraged
278 	  SPDX-License-Identifier: ISC
279       License-Text:
284 3. Dual Licensing Only
286    These licenses should only be used to dual license code with another
290       LICENSES/dual/
300       LICENSES/dual/MPL-1.1
305       LICENSES/dual/Apache-2.0
317       Valid-License-Identifier: MPL-1.1
318       SPDX-URL: https://spdx.org/licenses/MPL-1.1.html
319       Usage-Guide:
320         Do NOT use. The MPL-1.1 is not GPL2 compatible. It may only be used for
321         dual-licensed files where the other license is GPL2 compatible.
327       SPDX-License-Identifier: MPL-1.1
328       License-Text:
346       LICENSES/exceptions/Linux-syscall-note
349    file of the Linux kernel, which is used for UAPI header files.
350    e.g. /\* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note \*/::
352       LICENSES/exceptions/GCC-exception-2.0
356    with this exception. This is required for creating runnable executables
357    from source code which is not compatible with the GPL.
363    - SPDX-Exception-Identifier:
368    - SPDX-URL:
373    - SPDX-Licenses:
378    - Usage-Guidance:
384    - Exception-Text:
386      All text after this tag is treated as the original exception text
390       SPDX-Exception-Identifier: Linux-syscall-note
391       SPDX-URL: https://spdx.org/licenses/Linux-syscall-note.html
392       SPDX-Licenses: GPL-2.0, GPL-2.0+, GPL-1.0+, LGPL-2.0, LGPL-2.0+, LGPL-2.1, LGPL-2.1+
393       Usage-Guidance:
394         This exception is used together with one of the above SPDX-Licenses
395 	to mark user-space API (uapi) header files so they can be included
396 	into non GPL compliant user-space application code.
398 	identifiers in the SPDX-Licenses tag:
399 	  SPDX-License-Identifier: <SPDX-License> WITH Linux-syscall-note
400       Exception-Text:
405       SPDX-Exception-Identifier: GCC-exception-2.0
406       SPDX-URL: https://spdx.org/licenses/GCC-exception-2.0.html
407       SPDX-Licenses: GPL-2.0, GPL-2.0+
408       Usage-Guidance:
409         The "GCC Runtime Library exception 2.0" is used together with one
410 	of the above SPDX-Licenses for code imported from the GCC runtime
413 	identifiers in the SPDX-Licenses tag:
414 	  SPDX-License-Identifier: <SPDX-License> WITH GCC-exception-2.0
415       Exception-Text:
420 in the LICENSES subdirectories. This is required to allow tool
422 and extract right from the source, which is recommended by various FOSS
426 -----------------
428    Loadable kernel modules also require a MODULE_LICENSE() tag. This tag is
430    (SPDX-License-Identifier) nor in any way relevant for expressing or
432    is provided.
434    The sole purpose of this tag is to provide sufficient information
435    whether the module is free software or proprietary for the kernel
441     "GPL"			  Module is licensed under GPL version 2. This
443 				  GPL-2.0-only or GPL-2.0-or-later. The exact
452 				  module source is dual licensed under a
456     "Dual MIT/GPL"		  The correct way of expressing that the
457 				  module is dual licensed under a GPL v2
460     "Dual BSD/GPL"		  The module is dual licensed under a GPL v2
466     "Dual MPL/GPL"		  The module is dual licensed under a GPL v2
473     "Proprietary"		  The module is under a proprietary license.
474 				  This string is solely for proprietary third