1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 .. _kernel_licensing: 3 .. _kernel_licensing:
4 4
5 Linux kernel licensing rules 5 Linux kernel licensing rules
6 ============================ 6 ============================
7 7
8 The Linux Kernel is provided under the terms o 8 The Linux Kernel is provided under the terms of the GNU General Public
9 License version 2 only (GPL-2.0), as provided 9 License version 2 only (GPL-2.0), as provided in LICENSES/preferred/GPL-2.0,
10 with an explicit syscall exception described i 10 with an explicit syscall exception described in
11 LICENSES/exceptions/Linux-syscall-note, as des 11 LICENSES/exceptions/Linux-syscall-note, as described in the COPYING file.
12 12
13 This documentation file provides a description 13 This documentation file provides a description of how each source file
14 should be annotated to make its license clear 14 should be annotated to make its license clear and unambiguous.
15 It doesn't replace the Kernel's license. 15 It doesn't replace the Kernel's license.
16 16
17 The license described in the COPYING file appl 17 The license described in the COPYING file applies to the kernel source
18 as a whole, though individual source files can 18 as a whole, though individual source files can have a different license
19 which is required to be compatible with the GP 19 which is required to be compatible with the GPL-2.0::
20 20
21 GPL-1.0+ : GNU General Public License v1 21 GPL-1.0+ : GNU General Public License v1.0 or later
22 GPL-2.0+ : GNU General Public License v2 22 GPL-2.0+ : GNU General Public License v2.0 or later
23 LGPL-2.0 : GNU Library General Public Li 23 LGPL-2.0 : GNU Library General Public License v2 only
24 LGPL-2.0+ : GNU Library General Public Li 24 LGPL-2.0+ : GNU Library General Public License v2 or later
25 LGPL-2.1 : GNU Lesser General Public Lic 25 LGPL-2.1 : GNU Lesser General Public License v2.1 only
26 LGPL-2.1+ : GNU Lesser General Public Lic 26 LGPL-2.1+ : GNU Lesser General Public License v2.1 or later
27 27
28 Aside from that, individual files can be provi 28 Aside from that, individual files can be provided under a dual license,
29 e.g. one of the compatible GPL variants and al 29 e.g. one of the compatible GPL variants and alternatively under a
30 permissive license like BSD, MIT etc. 30 permissive license like BSD, MIT etc.
31 31
32 The User-space API (UAPI) header files, which 32 The User-space API (UAPI) header files, which describe the interface of
33 user-space programs to the kernel are a specia 33 user-space programs to the kernel are a special case. According to the
34 note in the kernel COPYING file, the syscall i 34 note in the kernel COPYING file, the syscall interface is a clear boundary,
35 which does not extend the GPL requirements to 35 which does not extend the GPL requirements to any software which uses it to
36 communicate with the kernel. Because the UAPI 36 communicate with the kernel. Because the UAPI headers must be includable
37 into any source files which create an executab 37 into any source files which create an executable running on the Linux
38 kernel, the exception must be documented by a 38 kernel, the exception must be documented by a special license expression.
39 39
40 The common way of expressing the license of a 40 The common way of expressing the license of a source file is to add the
41 matching boilerplate text into the top comment 41 matching boilerplate text into the top comment of the file. Due to
42 formatting, typos etc. these "boilerplates" ar 42 formatting, typos etc. these "boilerplates" are hard to validate for
43 tools which are used in the context of license 43 tools which are used in the context of license compliance.
44 44
45 An alternative to boilerplate text is the use 45 An alternative to boilerplate text is the use of Software Package Data
46 Exchange (SPDX) license identifiers in each so 46 Exchange (SPDX) license identifiers in each source file. SPDX license
47 identifiers are machine parsable and precise s 47 identifiers are machine parsable and precise shorthands for the license
48 under which the content of the file is contrib 48 under which the content of the file is contributed. SPDX license
49 identifiers are managed by the SPDX Workgroup 49 identifiers are managed by the SPDX Workgroup at the Linux Foundation and
50 have been agreed on by partners throughout the 50 have been agreed on by partners throughout the industry, tool vendors, and
51 legal teams. For further information see http 51 legal teams. For further information see https://spdx.org/
52 52
53 The Linux kernel requires the precise SPDX ide 53 The Linux kernel requires the precise SPDX identifier in all source files.
54 The valid identifiers used in the kernel are e 54 The valid identifiers used in the kernel are explained in the section
55 `License identifiers`_ and have been retrieved 55 `License identifiers`_ and have been retrieved from the official SPDX
56 license list at https://spdx.org/licenses/ alo 56 license list at https://spdx.org/licenses/ along with the license texts.
57 57
58 License identifier syntax 58 License identifier syntax
59 ------------------------- 59 -------------------------
60 60
61 1. Placement: 61 1. Placement:
62 62
63 The SPDX license identifier in kernel files 63 The SPDX license identifier in kernel files shall be added at the first
64 possible line in a file which can contain a 64 possible line in a file which can contain a comment. For the majority
65 of files this is the first line, except for 65 of files this is the first line, except for scripts which require the
66 '#!PATH_TO_INTERPRETER' in the first line. 66 '#!PATH_TO_INTERPRETER' in the first line. For those scripts the SPDX
67 identifier goes into the second line. 67 identifier goes into the second line.
68 68
69 | 69 |
70 70
71 2. Style: 71 2. Style:
72 72
73 The SPDX license identifier is added in for 73 The SPDX license identifier is added in form of a comment. The comment
74 style depends on the file type:: 74 style depends on the file type::
75 75
76 C source: // SPDX-License-Identifier: <S 76 C source: // SPDX-License-Identifier: <SPDX License Expression>
77 C header: /* SPDX-License-Identifier: <S 77 C header: /* SPDX-License-Identifier: <SPDX License Expression> */
78 ASM: /* SPDX-License-Identifier: <S 78 ASM: /* SPDX-License-Identifier: <SPDX License Expression> */
79 scripts: # SPDX-License-Identifier: <SP 79 scripts: # SPDX-License-Identifier: <SPDX License Expression>
80 .rst: .. SPDX-License-Identifier: <S 80 .rst: .. SPDX-License-Identifier: <SPDX License Expression>
81 .dts{i}: // SPDX-License-Identifier: <S 81 .dts{i}: // SPDX-License-Identifier: <SPDX License Expression>
82 82
83 If a specific tool cannot handle the standa 83 If a specific tool cannot handle the standard comment style, then the
84 appropriate comment mechanism which the too 84 appropriate comment mechanism which the tool accepts shall be used. This
85 is the reason for having the "/\* \*/" styl 85 is the reason for having the "/\* \*/" style comment in C header
86 files. There was build breakage observed wi 86 files. There was build breakage observed with generated .lds files where
87 'ld' failed to parse the C++ comment. This 87 'ld' failed to parse the C++ comment. This has been fixed by now, but
88 there are still older assembler tools which 88 there are still older assembler tools which cannot handle C++ style
89 comments. 89 comments.
90 90
91 | 91 |
92 92
93 3. Syntax: 93 3. Syntax:
94 94
95 A <SPDX License Expression> is either an SP 95 A <SPDX License Expression> is either an SPDX short form license
96 identifier found on the SPDX License List, 96 identifier found on the SPDX License List, or the combination of two
97 SPDX short form license identifiers separat 97 SPDX short form license identifiers separated by "WITH" when a license
98 exception applies. When multiple licenses a 98 exception applies. When multiple licenses apply, an expression consists
99 of keywords "AND", "OR" separating sub-expr 99 of keywords "AND", "OR" separating sub-expressions and surrounded by
100 "(", ")" . 100 "(", ")" .
101 101
102 License identifiers for licenses like [L]GP 102 License identifiers for licenses like [L]GPL with the 'or later' option
103 are constructed by using a "+" for indicati 103 are constructed by using a "+" for indicating the 'or later' option.::
104 104
105 // SPDX-License-Identifier: GPL-2.0+ 105 // SPDX-License-Identifier: GPL-2.0+
106 // SPDX-License-Identifier: LGPL-2.1+ 106 // SPDX-License-Identifier: LGPL-2.1+
107 107
108 WITH should be used when there is a modifie 108 WITH should be used when there is a modifier to a license needed.
109 For example, the linux kernel UAPI files us 109 For example, the linux kernel UAPI files use the expression::
110 110
111 // SPDX-License-Identifier: GPL-2.0 WITH 111 // SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
112 // SPDX-License-Identifier: GPL-2.0+ WIT 112 // SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note
113 113
114 Other examples using WITH exceptions found 114 Other examples using WITH exceptions found in the kernel are::
115 115
116 // SPDX-License-Identifier: GPL-2.0 WITH 116 // SPDX-License-Identifier: GPL-2.0 WITH mif-exception
117 // SPDX-License-Identifier: GPL-2.0+ WIT 117 // SPDX-License-Identifier: GPL-2.0+ WITH GCC-exception-2.0
118 118
119 Exceptions can only be used with particular 119 Exceptions can only be used with particular License identifiers. The
120 valid License identifiers are listed in the 120 valid License identifiers are listed in the tags of the exception text
121 file. For details see the point `Exceptions 121 file. For details see the point `Exceptions`_ in the chapter `License
122 identifiers`_. 122 identifiers`_.
123 123
124 OR should be used if the file is dual licen 124 OR should be used if the file is dual licensed and only one license is
125 to be selected. For example, some dtsi fil 125 to be selected. For example, some dtsi files are available under dual
126 licenses:: 126 licenses::
127 127
128 // SPDX-License-Identifier: GPL-2.0 OR B 128 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
129 129
130 Examples from the kernel for license expres 130 Examples from the kernel for license expressions in dual licensed files::
131 131
132 // SPDX-License-Identifier: GPL-2.0 OR M 132 // SPDX-License-Identifier: GPL-2.0 OR MIT
133 // SPDX-License-Identifier: GPL-2.0 OR B 133 // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
134 // SPDX-License-Identifier: GPL-2.0 OR A 134 // SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
135 // SPDX-License-Identifier: GPL-2.0 OR M 135 // SPDX-License-Identifier: GPL-2.0 OR MPL-1.1
136 // SPDX-License-Identifier: (GPL-2.0 WIT 136 // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) OR MIT
137 // SPDX-License-Identifier: GPL-1.0+ OR 137 // SPDX-License-Identifier: GPL-1.0+ OR BSD-3-Clause OR OpenSSL
138 138
139 AND should be used if the file has multiple 139 AND should be used if the file has multiple licenses whose terms all
140 apply to use the file. For example, if code 140 apply to use the file. For example, if code is inherited from another
141 project and permission has been given to pu 141 project and permission has been given to put it in the kernel, but the
142 original license terms need to remain in ef 142 original license terms need to remain in effect::
143 143
144 // SPDX-License-Identifier: (GPL-2.0 WIT 144 // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) AND MIT
145 145
146 Another other example where both sets of li 146 Another other example where both sets of license terms need to be
147 adhered to is:: 147 adhered to is::
148 148
149 // SPDX-License-Identifier: GPL-1.0+ AND 149 // SPDX-License-Identifier: GPL-1.0+ AND LGPL-2.1+
150 150
151 License identifiers 151 License identifiers
152 ------------------- 152 -------------------
153 153
154 The licenses currently used, as well as the li 154 The licenses currently used, as well as the licenses for code added to the
155 kernel, can be broken down into: 155 kernel, can be broken down into:
156 156
157 1. _`Preferred licenses`: 157 1. _`Preferred licenses`:
158 158
159 Whenever possible these licenses should be 159 Whenever possible these licenses should be used as they are known to be
160 fully compatible and widely used. These li 160 fully compatible and widely used. These licenses are available from the
161 directory:: 161 directory::
162 162
163 LICENSES/preferred/ 163 LICENSES/preferred/
164 164
165 in the kernel source tree. 165 in the kernel source tree.
166 166
167 The files in this directory contain the ful 167 The files in this directory contain the full license text and
168 `Metatags`_. The file names are identical 168 `Metatags`_. The file names are identical to the SPDX license
169 identifier which shall be used for the lice 169 identifier which shall be used for the license in source files.
170 170
171 Examples:: 171 Examples::
172 172
173 LICENSES/preferred/GPL-2.0 173 LICENSES/preferred/GPL-2.0
174 174
175 Contains the GPL version 2 license text and 175 Contains the GPL version 2 license text and the required metatags::
176 176
177 LICENSES/preferred/MIT 177 LICENSES/preferred/MIT
178 178
179 Contains the MIT license text and the requi 179 Contains the MIT license text and the required metatags
180 180
181 _`Metatags`: 181 _`Metatags`:
182 182
183 The following meta tags must be available i 183 The following meta tags must be available in a license file:
184 184
185 - Valid-License-Identifier: 185 - Valid-License-Identifier:
186 186
187 One or more lines which declare which Lic 187 One or more lines which declare which License Identifiers are valid
188 inside the project to reference this part 188 inside the project to reference this particular license text. Usually
189 this is a single valid identifier, but e. 189 this is a single valid identifier, but e.g. for licenses with the 'or
190 later' options two identifiers are valid. 190 later' options two identifiers are valid.
191 191
192 - SPDX-URL: 192 - SPDX-URL:
193 193
194 The URL of the SPDX page which contains a 194 The URL of the SPDX page which contains additional information related
195 to the license. 195 to the license.
196 196
197 - Usage-Guidance: 197 - Usage-Guidance:
198 198
199 Freeform text for usage advice. The text 199 Freeform text for usage advice. The text must include correct examples
200 for the SPDX license identifiers as they 200 for the SPDX license identifiers as they should be put into source
201 files according to the `License identifie 201 files according to the `License identifier syntax`_ guidelines.
202 202
203 - License-Text: 203 - License-Text:
204 204
205 All text after this tag is treated as the 205 All text after this tag is treated as the original license text
206 206
207 File format examples:: 207 File format examples::
208 208
209 Valid-License-Identifier: GPL-2.0 209 Valid-License-Identifier: GPL-2.0
210 Valid-License-Identifier: GPL-2.0+ 210 Valid-License-Identifier: GPL-2.0+
211 SPDX-URL: https://spdx.org/licenses/GPL- 211 SPDX-URL: https://spdx.org/licenses/GPL-2.0.html
212 Usage-Guide: 212 Usage-Guide:
213 To use this license in source code, pu 213 To use this license in source code, put one of the following SPDX
214 tag/value pairs into a comment accordi 214 tag/value pairs into a comment according to the placement
215 guidelines in the licensing rules docu 215 guidelines in the licensing rules documentation.
216 For 'GNU General Public License (GPL) 216 For 'GNU General Public License (GPL) version 2 only' use:
217 SPDX-License-Identifier: GPL-2.0 217 SPDX-License-Identifier: GPL-2.0
218 For 'GNU General Public License (GPL) 218 For 'GNU General Public License (GPL) version 2 or any later version' use:
219 SPDX-License-Identifier: GPL-2.0+ 219 SPDX-License-Identifier: GPL-2.0+
220 License-Text: 220 License-Text:
221 Full license text 221 Full license text
222 222
223 :: 223 ::
224 224
225 SPDX-License-Identifier: MIT 225 SPDX-License-Identifier: MIT
226 SPDX-URL: https://spdx.org/licenses/MIT. 226 SPDX-URL: https://spdx.org/licenses/MIT.html
227 Usage-Guide: 227 Usage-Guide:
228 To use this license in source code, pu 228 To use this license in source code, put the following SPDX
229 tag/value pair into a comment accordin 229 tag/value pair into a comment according to the placement
230 guidelines in the licensing rules docu 230 guidelines in the licensing rules documentation.
231 SPDX-License-Identifier: MIT 231 SPDX-License-Identifier: MIT
232 License-Text: 232 License-Text:
233 Full license text 233 Full license text
234 234
235 | 235 |
236 236
237 2. Deprecated licenses: !! 237 2. Not recommended licenses:
238 238
239 These licenses should only be used for exis 239 These licenses should only be used for existing code or for importing
240 code from a different project. These licen 240 code from a different project. These licenses are available from the
241 directory:: 241 directory::
242 242
243 LICENSES/deprecated/ !! 243 LICENSES/other/
244 244
245 in the kernel source tree. 245 in the kernel source tree.
246 246
247 The files in this directory contain the ful 247 The files in this directory contain the full license text and
248 `Metatags`_. The file names are identical 248 `Metatags`_. The file names are identical to the SPDX license
249 identifier which shall be used for the lice 249 identifier which shall be used for the license in source files.
250 250
251 Examples:: 251 Examples::
252 252
253 LICENSES/deprecated/ISC !! 253 LICENSES/other/ISC
254 254
255 Contains the Internet Systems Consortium li 255 Contains the Internet Systems Consortium license text and the required
256 metatags:: 256 metatags::
257 257
258 LICENSES/deprecated/GPL-1.0 !! 258 LICENSES/other/ZLib
259 259
260 Contains the GPL version 1 license text and !! 260 Contains the ZLIB license text and the required metatags.
261 261
262 Metatags: 262 Metatags:
263 263
264 The metatag requirements for 'other' licens 264 The metatag requirements for 'other' licenses are identical to the
265 requirements of the `Preferred licenses`_. 265 requirements of the `Preferred licenses`_.
266 266
267 File format example:: 267 File format example::
268 268
269 Valid-License-Identifier: ISC 269 Valid-License-Identifier: ISC
270 SPDX-URL: https://spdx.org/licenses/ISC. 270 SPDX-URL: https://spdx.org/licenses/ISC.html
271 Usage-Guide: 271 Usage-Guide:
272 Usage of this license in the kernel fo 272 Usage of this license in the kernel for new code is discouraged
273 and it should solely be used for impor 273 and it should solely be used for importing code from an already
274 existing project. 274 existing project.
275 To use this license in source code, pu 275 To use this license in source code, put the following SPDX
276 tag/value pair into a comment accordin 276 tag/value pair into a comment according to the placement
277 guidelines in the licensing rules docu 277 guidelines in the licensing rules documentation.
278 SPDX-License-Identifier: ISC 278 SPDX-License-Identifier: ISC
279 License-Text: 279 License-Text:
280 Full license text 280 Full license text
281 281
282 | 282 |
283 283
284 3. Dual Licensing Only !! 284 3. _`Exceptions`:
285 <<
286 These licenses should only be used to dual <<
287 license in addition to a preferred license. <<
288 from the directory:: <<
289 <<
290 LICENSES/dual/ <<
291 <<
292 in the kernel source tree. <<
293 <<
294 The files in this directory contain the ful <<
295 `Metatags`_. The file names are identical <<
296 identifier which shall be used for the lice <<
297 <<
298 Examples:: <<
299 <<
300 LICENSES/dual/MPL-1.1 <<
301 <<
302 Contains the Mozilla Public License version <<
303 required metatags:: <<
304 <<
305 LICENSES/dual/Apache-2.0 <<
306 <<
307 Contains the Apache License version 2.0 lic <<
308 metatags. <<
309 <<
310 Metatags: <<
311 <<
312 The metatag requirements for 'other' licens <<
313 requirements of the `Preferred licenses`_. <<
314 <<
315 File format example:: <<
316 <<
317 Valid-License-Identifier: MPL-1.1 <<
318 SPDX-URL: https://spdx.org/licenses/MPL- <<
319 Usage-Guide: <<
320 Do NOT use. The MPL-1.1 is not GPL2 co <<
321 dual-licensed files where the other li <<
322 If you end up using this it MUST be us <<
323 license using "OR". <<
324 To use the Mozilla Public License vers <<
325 tag/value pair into a comment accordin <<
326 the licensing rules documentation: <<
327 SPDX-License-Identifier: MPL-1.1 <<
328 License-Text: <<
329 Full license text <<
330 <<
331 | <<
332 <<
333 4. _`Exceptions`: <<
334 285
335 Some licenses can be amended with exception 286 Some licenses can be amended with exceptions which grant certain rights
336 which the original license does not. These 287 which the original license does not. These exceptions are available
337 from the directory:: 288 from the directory::
338 289
339 LICENSES/exceptions/ 290 LICENSES/exceptions/
340 291
341 in the kernel source tree. The files in th 292 in the kernel source tree. The files in this directory contain the full
342 exception text and the required `Exception 293 exception text and the required `Exception Metatags`_.
343 294
344 Examples:: 295 Examples::
345 296
346 LICENSES/exceptions/Linux-syscall-note 297 LICENSES/exceptions/Linux-syscall-note
347 298
348 Contains the Linux syscall exception as doc 299 Contains the Linux syscall exception as documented in the COPYING
349 file of the Linux kernel, which is used for 300 file of the Linux kernel, which is used for UAPI header files.
350 e.g. /\* SPDX-License-Identifier: GPL-2.0 W 301 e.g. /\* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note \*/::
351 302
352 LICENSES/exceptions/GCC-exception-2.0 303 LICENSES/exceptions/GCC-exception-2.0
353 304
354 Contains the GCC 'linking exception' which 305 Contains the GCC 'linking exception' which allows to link any binary
355 independent of its license against the comp 306 independent of its license against the compiled version of a file marked
356 with this exception. This is required for c 307 with this exception. This is required for creating runnable executables
357 from source code which is not compatible wi 308 from source code which is not compatible with the GPL.
358 309
359 _`Exception Metatags`: 310 _`Exception Metatags`:
360 311
361 The following meta tags must be available i 312 The following meta tags must be available in an exception file:
362 313
363 - SPDX-Exception-Identifier: 314 - SPDX-Exception-Identifier:
364 315
365 One exception identifier which can be use 316 One exception identifier which can be used with SPDX license
366 identifiers. 317 identifiers.
367 318
368 - SPDX-URL: 319 - SPDX-URL:
369 320
370 The URL of the SPDX page which contains a 321 The URL of the SPDX page which contains additional information related
371 to the exception. 322 to the exception.
372 323
373 - SPDX-Licenses: 324 - SPDX-Licenses:
374 325
375 A comma separated list of SPDX license id 326 A comma separated list of SPDX license identifiers for which the
376 exception can be used. 327 exception can be used.
377 328
378 - Usage-Guidance: 329 - Usage-Guidance:
379 330
380 Freeform text for usage advice. The text 331 Freeform text for usage advice. The text must be followed by correct
381 examples for the SPDX license identifiers 332 examples for the SPDX license identifiers as they should be put into
382 source files according to the `License id 333 source files according to the `License identifier syntax`_ guidelines.
383 334
384 - Exception-Text: 335 - Exception-Text:
385 336
386 All text after this tag is treated as the 337 All text after this tag is treated as the original exception text
387 338
388 File format examples:: 339 File format examples::
389 340
390 SPDX-Exception-Identifier: Linux-syscall 341 SPDX-Exception-Identifier: Linux-syscall-note
391 SPDX-URL: https://spdx.org/licenses/Linu 342 SPDX-URL: https://spdx.org/licenses/Linux-syscall-note.html
392 SPDX-Licenses: GPL-2.0, GPL-2.0+, GPL-1. 343 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: 344 Usage-Guidance:
394 This exception is used together with o 345 This exception is used together with one of the above SPDX-Licenses
395 to mark user-space API (uapi) header f 346 to mark user-space API (uapi) header files so they can be included
396 into non GPL compliant user-space appl 347 into non GPL compliant user-space application code.
397 To use this exception add it with the 348 To use this exception add it with the keyword WITH to one of the
398 identifiers in the SPDX-Licenses tag: 349 identifiers in the SPDX-Licenses tag:
399 SPDX-License-Identifier: <SPDX-Licen 350 SPDX-License-Identifier: <SPDX-License> WITH Linux-syscall-note
400 Exception-Text: 351 Exception-Text:
401 Full exception text 352 Full exception text
402 353
403 :: 354 ::
404 355
405 SPDX-Exception-Identifier: GCC-exception 356 SPDX-Exception-Identifier: GCC-exception-2.0
406 SPDX-URL: https://spdx.org/licenses/GCC- 357 SPDX-URL: https://spdx.org/licenses/GCC-exception-2.0.html
407 SPDX-Licenses: GPL-2.0, GPL-2.0+ 358 SPDX-Licenses: GPL-2.0, GPL-2.0+
408 Usage-Guidance: 359 Usage-Guidance:
409 The "GCC Runtime Library exception 2.0 360 The "GCC Runtime Library exception 2.0" is used together with one
410 of the above SPDX-Licenses for code im 361 of the above SPDX-Licenses for code imported from the GCC runtime
411 library. 362 library.
412 To use this exception add it with the 363 To use this exception add it with the keyword WITH to one of the
413 identifiers in the SPDX-Licenses tag: 364 identifiers in the SPDX-Licenses tag:
414 SPDX-License-Identifier: <SPDX-Licen 365 SPDX-License-Identifier: <SPDX-License> WITH GCC-exception-2.0
415 Exception-Text: 366 Exception-Text:
416 Full exception text 367 Full exception text
417 368
418 369
419 All SPDX license identifiers and exceptions mu 370 All SPDX license identifiers and exceptions must have a corresponding file
420 in the LICENSES subdirectories. This is requir 371 in the LICENSES subdirectories. This is required to allow tool
421 verification (e.g. checkpatch.pl) and to have 372 verification (e.g. checkpatch.pl) and to have the licenses ready to read
422 and extract right from the source, which is re 373 and extract right from the source, which is recommended by various FOSS
423 organizations, e.g. the `FSFE REUSE initiative 374 organizations, e.g. the `FSFE REUSE initiative <https://reuse.software/>`_.
424 375
425 _`MODULE_LICENSE` 376 _`MODULE_LICENSE`
426 ----------------- 377 -----------------
427 378
428 Loadable kernel modules also require a MODU 379 Loadable kernel modules also require a MODULE_LICENSE() tag. This tag is
429 neither a replacement for proper source cod 380 neither a replacement for proper source code license information
430 (SPDX-License-Identifier) nor in any way re 381 (SPDX-License-Identifier) nor in any way relevant for expressing or
431 determining the exact license under which t 382 determining the exact license under which the source code of the module
432 is provided. 383 is provided.
433 384
434 The sole purpose of this tag is to provide 385 The sole purpose of this tag is to provide sufficient information
435 whether the module is free software or prop 386 whether the module is free software or proprietary for the kernel
436 module loader and for user space tools. 387 module loader and for user space tools.
437 388
438 The valid license strings for MODULE_LICENS 389 The valid license strings for MODULE_LICENSE() are:
439 390
440 ============================= ============ 391 ============================= =============================================
441 "GPL" Module is li 392 "GPL" Module is licensed under GPL version 2. This
442 does not exp 393 does not express any distinction between
443 GPL-2.0-only 394 GPL-2.0-only or GPL-2.0-or-later. The exact
444 license info 395 license information can only be determined
445 via the lice 396 via the license information in the
446 correspondin 397 corresponding source files.
447 398
448 "GPL v2" Same as "GPL 399 "GPL v2" Same as "GPL". It exists for historic
449 reasons. 400 reasons.
450 401
451 "GPL and additional rights" Historical v 402 "GPL and additional rights" Historical variant of expressing that the
452 module sourc 403 module source is dual licensed under a
453 GPL v2 varia 404 GPL v2 variant and MIT license. Please do
454 not use in n 405 not use in new code.
455 406
456 "Dual MIT/GPL" The correct 407 "Dual MIT/GPL" The correct way of expressing that the
457 module is du 408 module is dual licensed under a GPL v2
458 variant or M 409 variant or MIT license choice.
459 410
460 "Dual BSD/GPL" The module i 411 "Dual BSD/GPL" The module is dual licensed under a GPL v2
461 variant or B 412 variant or BSD license choice. The exact
462 variant of t 413 variant of the BSD license can only be
463 determined v 414 determined via the license information
464 in the corre 415 in the corresponding source files.
465 416
466 "Dual MPL/GPL" The module i 417 "Dual MPL/GPL" The module is dual licensed under a GPL v2
467 variant or M 418 variant or Mozilla Public License (MPL)
468 choice. The 419 choice. The exact variant of the MPL
469 license can 420 license can only be determined via the
470 license info 421 license information in the corresponding
471 source files 422 source files.
472 423
473 "Proprietary" The module i 424 "Proprietary" The module is under a proprietary license.
474 This string 425 This string is solely for proprietary third
475 party module 426 party modules and cannot be used for modules
476 which have t 427 which have their source code in the kernel
477 tree. Module 428 tree. Modules tagged that way are tainting
478 the kernel w 429 the kernel with the 'P' flag when loaded and
479 the kernel m 430 the kernel module loader refuses to link such
480 modules agai 431 modules against symbols which are exported
481 with EXPORT_ 432 with EXPORT_SYMBOL_GPL().
482 ============================= ============ 433 ============================= =============================================
483 434
484 435
485 436
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