60 lines
1.9 KiB
ReStructuredText
60 lines
1.9 KiB
ReStructuredText
.. _license_guidelines:
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License Guidelines
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##################
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The Zephyr Kernel is licensed under a BSD 3-clause license. This is a
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permissive license that allows our customers to write kernel-level code
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without having to open source their code. All code linked in a Zephyr Kernel
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binary image must be permissively licensed. The source tree includes some GPL
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-licensed build tools, but those are not linked to the final binary image,
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and thus the image itself is not GPL-tainted.
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Customers are able to add GPL code to their kernel. Therefore, all
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permissively licensed code in the project must be GPL-compatible.
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.. caution::
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Some permissive licenses are not GPL-compatible).
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Acceptable Licenses
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*******************
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The following list shows all licenses that can be used without further
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considerations:
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* 2-clause BSD
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* 3-clause BSD
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* MIT
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* ISC
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* NCSA, the license for Clang and LLVM
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* True public domain
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* Creative Commons Zero (public domain) but not other CC licenses
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Licenses that Require Caution
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*****************************
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The following list shows the licenses that can be used if the special
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considerations included are taken into account:
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* GPL
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* Apache: Incompatible with GPLv2 but not GPLv3, according to the FSF.
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* Mozilla: weak copy-left. It is weaker than LGPL.
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* Microsoft public license
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* LGPL
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* OpenSSL license: permissive, but not GPL compatible.
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* BSD 4-clause: not GPL compatible. It is difficult to attribute.
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IANAL Disclaimer
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****************
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Be cautious about working with GPL code while working on permissively
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licensed code.
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Do not copy code or have a different project's code open while you re-
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implement the same code in your project.
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It is allowed to look at other project's documentation, code concepts,
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comments, and git commits while implementing new code. You may contribute
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code to unrelated GPL projects while working on permissively licensed code. |