README.license - platform/external/dtc - Git at Google

 Licensing and contribution policy of dtc and libfdt
 ===================================================

 This dtc package contains two pieces of software: dtc itself, and
 libfdt which comprises the files in the libfdt/ subdirectory.  These
 two pieces of software, although closely related, are quite distinct.
 dtc does not incoporate or rely on libfdt for its operation, nor vice
 versa.  It is important that these two pieces of software have
 different license conditions.

 As the copyright banners in each source file attest, dtc is licensed
 under the GNU GPL.  The full text of the GPL can be found in the file
 entitled 'GPL' which should be included in this package.  dtc code,
 therefore, may not be incorporated into works which do not have a GPL
 compatible license.

 libfdt, however, is GPL/BSD dual-licensed.  That is, it may be used
 either under the terms of the GPL, or under the terms of the 2-clause
 BSD license (aka the ISC license).  The full terms of that license are
 given in the copyright banners of each of the libfdt source files.
 This is, in practice, equivalent to being BSD licensed, since the
 terms of the BSD license are strictly more permissive than the GPL.

 I made the decision to license libfdt in this way because I want to
 encourage widespread and correct usage of flattened device trees,
 including by proprietary or otherwise GPL-incompatible firmware or
 tools.  Allowing libfdt to be used under the terms of the BSD license
 makes that it easier for vendors or authors of such software to do so.

 This does mean that libfdt code could be "stolen" - say, included in a
 proprietary fimware and extended without contributing those extensions
 back to the libfdt mainline.  While I hope that doesn't happen, I
 believe the goal of allowing libfdt to be widely used is more
 important than avoiding that.  libfdt is quite small, and hardly
 rocket science; so the incentive for such impolite behaviour is small,
 and the inconvenience caused therby is not dire.

 Licenses such as the LGPL which would allow code to be used in non-GPL
 software, but also require contributions to be returned were
 considered.  However, libfdt is designed to be used in firmwares and
 other environments with unusual technical constraints.  It's difficult
 to anticipate all possible changes which might be needed to meld
 libfdt into such environments and so difficult to suitably word a
 license that puts the boundary between what is and isn't permitted in
 the intended place.  Again, I judged encouraging widespread use of
 libfdt by keeping the license terms simple and familiar to be the more
 important goal.

 **IMPORTANT** It's intended that all of libfdt as released remain
 permissively licensed this way.  Therefore only contributions which
 are released under these terms can be merged into the libfdt mainline.


 David Gibson <david@gibson.dropbear.id.au>
 (principal original author of dtc and libfdt)
 2 November 2007
	Licensing and contribution policy of dtc and libfdt
	===================================================

	This dtc package contains two pieces of software: dtc itself, and
	libfdt which comprises the files in the libfdt/ subdirectory. These
	two pieces of software, although closely related, are quite distinct.
	dtc does not incoporate or rely on libfdt for its operation, nor vice
	versa. It is important that these two pieces of software have
	different license conditions.

	As the copyright banners in each source file attest, dtc is licensed
	under the GNU GPL. The full text of the GPL can be found in the file
	entitled 'GPL' which should be included in this package. dtc code,
	therefore, may not be incorporated into works which do not have a GPL
	compatible license.

	libfdt, however, is GPL/BSD dual-licensed. That is, it may be used
	either under the terms of the GPL, or under the terms of the 2-clause
	BSD license (aka the ISC license). The full terms of that license are
	given in the copyright banners of each of the libfdt source files.
	This is, in practice, equivalent to being BSD licensed, since the
	terms of the BSD license are strictly more permissive than the GPL.

	I made the decision to license libfdt in this way because I want to
	encourage widespread and correct usage of flattened device trees,
	including by proprietary or otherwise GPL-incompatible firmware or
	tools. Allowing libfdt to be used under the terms of the BSD license
	makes that it easier for vendors or authors of such software to do so.

	This does mean that libfdt code could be "stolen" - say, included in a
	proprietary fimware and extended without contributing those extensions
	back to the libfdt mainline. While I hope that doesn't happen, I
	believe the goal of allowing libfdt to be widely used is more
	important than avoiding that. libfdt is quite small, and hardly
	rocket science; so the incentive for such impolite behaviour is small,
	and the inconvenience caused therby is not dire.

	Licenses such as the LGPL which would allow code to be used in non-GPL
	software, but also require contributions to be returned were
	considered. However, libfdt is designed to be used in firmwares and
	other environments with unusual technical constraints. It's difficult
	to anticipate all possible changes which might be needed to meld
	libfdt into such environments and so difficult to suitably word a
	license that puts the boundary between what is and isn't permitted in
	the intended place. Again, I judged encouraging widespread use of
	libfdt by keeping the license terms simple and familiar to be the more
	important goal.

	IMPORTANT It's intended that all of libfdt as released remain
	permissively licensed this way. Therefore only contributions which
	are released under these terms can be merged into the libfdt mainline.


	David Gibson <david@gibson.dropbear.id.au>
	(principal original author of dtc and libfdt)
	2 November 2007