1b908c675SJens WiklanderLicensing and contribution policy of dtc and libfdt 2b908c675SJens Wiklander=================================================== 3b908c675SJens Wiklander 4b908c675SJens WiklanderThis dtc package contains two pieces of software: dtc itself, and 5b908c675SJens Wiklanderlibfdt which comprises the files in the libfdt/ subdirectory. These 6b908c675SJens Wiklandertwo pieces of software, although closely related, are quite distinct. 7*17f326ebSJerome Forissierdtc does not incorporate or rely on libfdt for its operation, nor vice 8b908c675SJens Wiklanderversa. It is important that these two pieces of software have 9b908c675SJens Wiklanderdifferent license conditions. 10b908c675SJens Wiklander 11*17f326ebSJerome ForissierAs SPDX license tags in each source file attest, dtc is licensed 12b908c675SJens Wiklanderunder the GNU GPL. The full text of the GPL can be found in the file 13b908c675SJens Wiklanderentitled 'GPL' which should be included in this package. dtc code, 14b908c675SJens Wiklandertherefore, may not be incorporated into works which do not have a GPL 15b908c675SJens Wiklandercompatible license. 16b908c675SJens Wiklander 17b908c675SJens Wiklanderlibfdt, however, is GPL/BSD dual-licensed. That is, it may be used 18b908c675SJens Wiklandereither under the terms of the GPL, or under the terms of the 2-clause 19*17f326ebSJerome ForissierBSD license (aka the ISC license). The full terms of that license can 20*17f326ebSJerome Forissierbe found are in the file entitled 'BSD-2-Clause'. This is, in 21*17f326ebSJerome Forissierpractice, equivalent to being BSD licensed, since the terms of the BSD 22*17f326ebSJerome Forissierlicense are strictly more permissive than the GPL. 23b908c675SJens Wiklander 24b908c675SJens WiklanderI made the decision to license libfdt in this way because I want to 25b908c675SJens Wiklanderencourage widespread and correct usage of flattened device trees, 26b908c675SJens Wiklanderincluding by proprietary or otherwise GPL-incompatible firmware or 27b908c675SJens Wiklandertools. Allowing libfdt to be used under the terms of the BSD license 28b908c675SJens Wiklandermakes that it easier for vendors or authors of such software to do so. 29b908c675SJens Wiklander 30b908c675SJens WiklanderThis does mean that libfdt code could be "stolen" - say, included in a 31b908c675SJens Wiklanderproprietary fimware and extended without contributing those extensions 32b908c675SJens Wiklanderback to the libfdt mainline. While I hope that doesn't happen, I 33b908c675SJens Wiklanderbelieve the goal of allowing libfdt to be widely used is more 34b908c675SJens Wiklanderimportant than avoiding that. libfdt is quite small, and hardly 35b908c675SJens Wiklanderrocket science; so the incentive for such impolite behaviour is small, 36*17f326ebSJerome Forissierand the inconvenience caused thereby is not dire. 37b908c675SJens Wiklander 38b908c675SJens WiklanderLicenses such as the LGPL which would allow code to be used in non-GPL 39b908c675SJens Wiklandersoftware, but also require contributions to be returned were 40b908c675SJens Wiklanderconsidered. However, libfdt is designed to be used in firmwares and 41b908c675SJens Wiklanderother environments with unusual technical constraints. It's difficult 42b908c675SJens Wiklanderto anticipate all possible changes which might be needed to meld 43b908c675SJens Wiklanderlibfdt into such environments and so difficult to suitably word a 44b908c675SJens Wiklanderlicense that puts the boundary between what is and isn't permitted in 45b908c675SJens Wiklanderthe intended place. Again, I judged encouraging widespread use of 46b908c675SJens Wiklanderlibfdt by keeping the license terms simple and familiar to be the more 47b908c675SJens Wiklanderimportant goal. 48b908c675SJens Wiklander 49b908c675SJens Wiklander**IMPORTANT** It's intended that all of libfdt as released remain 50b908c675SJens Wiklanderpermissively licensed this way. Therefore only contributions which 51b908c675SJens Wiklanderare released under these terms can be merged into the libfdt mainline. 52b908c675SJens Wiklander 53b908c675SJens Wiklander 54b908c675SJens WiklanderDavid Gibson <david@gibson.dropbear.id.au> 55b908c675SJens Wiklander(principal original author of dtc and libfdt) 56b908c675SJens Wiklander2 November 2007 57