1SPDX-License-Identifier: GPL-2.0 2 3 U-Boot is Free Software. It is copyrighted by Wolfgang Denk and 4many others who contributed code (see the actual source code and the 5git commit messages for details). You can redistribute U-Boot and/or 6modify it under the terms of version 2 of the GNU General Public 7License as published by the Free Software Foundation. Most of it can 8also be distributed, at your option, under any later version of the 9GNU General Public License -- see individual files for exceptions. 10 11 NOTE! This license does *not* cover the so-called "standalone" 12applications that use U-Boot services by means of the jump table 13provided by U-Boot exactly for this purpose - this is merely 14considered normal use of U-Boot, and does *not* fall under the 15heading of "derived work" -- see file Licenses/Exceptions for 16details. 17 18 Also note that the GPL and the other licenses are copyrighted by 19the Free Software Foundation and other organizations, but the 20instance of code that they refer to (the U-Boot source code) is 21copyrighted by me and others who actually wrote it. 22-- Wolfgang Denk 23 24 25Like many other projects, U-Boot has a tradition of including big 26blocks of License headers in all files. This not only blows up the 27source code with mostly redundant information, but also makes it very 28difficult to generate License Clearing Reports. An additional problem 29is that even the same licenses are referred to by a number of 30slightly varying text blocks (full, abbreviated, different 31indentation, line wrapping and/or white space, with obsolete address 32information, ...) which makes automatic processing a nightmare. 33 34To make this easier, such license headers in the source files will be 35replaced with a single line reference to Unique License Identifiers 36as defined by the Linux Foundation's SPDX project [1]. 37 38If a "SPDX-License-Identifier:" line references more than one Unique 39License Identifier, then this means that the respective file can be 40used under the terms of either of these licenses, i. e. with 41 42 SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause 43 44you can choose between GPL-2.0+ and BSD-3-Clause licensing. 45 46We use the SPDX Unique License Identifiers here; these are available 47at [2]. 48 49License identifier syntax 50------------------------- 51 521. Placement: 53 54 The SPDX license identifier in U-Boot files shall be added at the first 55 possible line in a file which can contain a comment. For the majority 56 or files this is the first line, except for scripts which require the 57 '#!PATH_TO_INTERPRETER' in the first line. For those scripts the SPDX 58 identifier goes into the second line. 59 60| 61 622. Style: 63 64 The SPDX license identifier is added in form of a comment. The comment 65 style depends on the file type:: 66 67 C source: // SPDX-License-Identifier: <SPDX License Expression> 68 C header: /* SPDX-License-Identifier: <SPDX License Expression> */ 69 ASM: /* SPDX-License-Identifier: <SPDX License Expression> */ 70 scripts: # SPDX-License-Identifier: <SPDX License Expression> 71 .rst: .. SPDX-License-Identifier: <SPDX License Expression> 72 .dts{i}: // SPDX-License-Identifier: <SPDX License Expression> 73 74 If a specific tool cannot handle the standard comment style, then the 75 appropriate comment mechanism which the tool accepts shall be used. This 76 is the reason for having the "/\* \*/" style comment in C header 77 files. There was build breakage observed with generated .lds files where 78 'ld' failed to parse the C++ comment. This has been fixed by now, but 79 there are still older assembler tools which cannot handle C++ style 80 comments. 81 82| 83 843. Syntax: 85 86 A <SPDX License Expression> is either an SPDX short form license 87 identifier found on the SPDX License List, or the combination of two 88 SPDX short form license identifiers separated by "WITH" when a license 89 exception applies. When multiple licenses apply, an expression consists 90 of keywords "AND", "OR" separating sub-expressions and surrounded by 91 "(", ")" . 92 93 License identifiers for licenses like [L]GPL with the 'or later' option 94 are constructed by using a "+" for indicating the 'or later' option.:: 95 96 // SPDX-License-Identifier: GPL-2.0+ 97 // SPDX-License-Identifier: LGPL-2.1+ 98 99 WITH should be used when there is a modifier to a license needed. 100 For example, the linux kernel UAPI files use the expression:: 101 102 // SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note 103 // SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note 104 105 Other examples using WITH exceptions found in the linux kernel are:: 106 107 // SPDX-License-Identifier: GPL-2.0 WITH mif-exception 108 // SPDX-License-Identifier: GPL-2.0+ WITH GCC-exception-2.0 109 110 Exceptions can only be used with particular License identifiers. The 111 valid License identifiers are listed in the tags of the exception text 112 file. 113 114 OR should be used if the file is dual licensed and only one license is 115 to be selected. For example, some dtsi files are available under dual 116 licenses:: 117 118 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause 119 120 Examples from U-Boot for license expressions in dual licensed files:: 121 122 // SPDX-License-Identifier: GPL-2.0 OR MIT 123 // SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause 124 125 AND should be used if the file has multiple licenses whose terms all 126 apply to use the file. For example, if code is inherited from another 127 project and permission has been given to put it in U-Boot, but the 128 original license terms need to remain in effect:: 129 130 // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) AND MIT 131 132 Another other example where both sets of license terms need to be 133 adhered to is:: 134 135 // SPDX-License-Identifier: GPL-1.0+ AND LGPL-2.1+ 136 137[1] http://spdx.org/ 138[2] http://spdx.org/licenses/ 139 140Full name SPDX Identifier OSI Approved File name URI 141======================================================================================================================================= 142GNU General Public License v2.0 only GPL-2.0 Y gpl-2.0.txt http://www.gnu.org/licenses/gpl-2.0.txt 143GNU General Public License v2.0 or later GPL-2.0+ Y gpl-2.0.txt http://www.gnu.org/licenses/gpl-2.0.txt 144GNU Library General Public License v2 or later LGPL-2.0+ Y lgpl-2.0.txt http://www.gnu.org/licenses/old-licenses/lgpl-2.0.txt 145GNU Lesser General Public License v2.1 or later LGPL-2.1+ Y lgpl-2.1.txt http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt 146eCos license version 2.0 eCos-2.0 eCos-2.0.txt http://www.gnu.org/licenses/ecos-license.html 147BSD 2-Clause License BSD-2-Clause Y bsd-2-clause.txt http://spdx.org/licenses/BSD-2-Clause 148BSD 3-clause "New" or "Revised" License BSD-3-Clause Y bsd-3-clause.txt http://spdx.org/licenses/BSD-3-Clause#licenseText 149IBM PIBS (PowerPC Initialization and IBM-pibs ibm-pibs.txt 150 Boot Software) license 151ISC License ISC Y isc.txt https://spdx.org/licenses/ISC 152MIT License MIT Y mit.txt https://spdx.org/licenses/MIT.html 153SIL OPEN FONT LICENSE (OFL-1.1) OFL-1.1 Y OFL.txt https://spdx.org/licenses/OFL-1.1.html 154X11 License X11 x11.txt https://spdx.org/licenses/X11.html 155