[llvm-dev] Relicensing: Revised Developer Policy

Chris Lattner via llvm-dev llvm-dev at lists.llvm.org
Thu Aug 10 13:54:03 PDT 2017 

This has already been discussed extensively in the public.  The threads are available in the archives.

-Chris

> On Aug 10, 2017, at 1:05 PM, Rafael Avila de Espindola <rafael.espindola at gmail.com> wrote:
> 
> Sorry, but I really don't think a private conversation is appropriate
> for such discussions.
> 
> If the motive cannot be explained in public I have no choice but to decide
> based on what I know.
> 
> Cheers,
> Rafael
> 
> Chris Lattner <clattner at llvm.org> writes:
> 
>> Hi Rafael,
>> 
>> We’ve discussed why a license change is preferable over the span of several years now.  I’m happy to explain over the phone, contact me off list and we can talk.
>> 
>> -Chris
>> 
>>> On Aug 10, 2017, at 8:33 AM, Rafael Avila de Espindola <rafael.espindola at gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> I still don't see any justification in the text why a license change is
>>> required over having a contributor agreement including whatever patent
>>> wording we want.
>>> 
>>> As such, I don't agree with it.
>>> 
>>> Cheers,
>>> Rafael
>>> 
>>> Chris Lattner via llvm-dev <llvm-dev at lists.llvm.org> writes:
>>> 
>>>> Hi all,
>>>> 
>>>> Now that we’ve settled on the license legalese to get to, we need to start the process of relicensing.  We’re still sorting through all of the details of what this will take, but the first step is clear: new contributions to LLVM will need to be under both the old license structure and the new one (until the old structure is completely phased out).  From a mechanical perspective, this is pretty simple, but I want to make sure that the community is aware of this and has time to digest and discuss any concerns.
>>>> 
>>>> In order to spell out what this will look like, we’ve gone ahead and revised http://llvm.org/docs/DeveloperPolicy.html to reflect what the new structure will look like.  While the license text is the canonical truth, the DeveloperPolicy serves a few purposes: it explains to non-lawyers what the license means, provides rationale for the design, and deals with relicensing process topics.
>>>> 
>>>> I’ve attached a draft of the revised document below.  Please take a look and let me know if anything should be further clarified or if you have any other questions and comments.  Thanks!
>>>> 
>>>> -Chris
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> Copyright, License, and Patents
>>>> ===============================
>>>> 
>>>> .. note::
>>>> 
>>>>  This section deals with legal matters but does not provide legal advice.  We
>>>>  are not lawyers --- please seek legal counsel from a licensed attorney.
>>>> 
>>>> This section addresses the issues of copyright, license and patents for the LLVM
>>>> project.  The copyright for the code is held by the contributors of
>>>> the code.  The code is licensed under permissive `open source licensing terms`_,
>>>> namely the Apache 2 license, which includes a copyright and `patent license`_.
>>>> When you contribute code to the LLVM project, you license it under these terms.
>>>> 
>>>> If you have questions or comments about these topics, please contact the
>>>> `LLVM Developer's Mailing List <mailto:llvm-dev at lists.llvm.org>`_.  However,
>>>> please realize that most compiler developers are not lawyers, and therefore you
>>>> will not be getting official legal advice.
>>>> 
>>>> Copyright
>>>> ---------
>>>> 
>>>> The LLVM project does not collect copyright assignments, which means that the
>>>> copyright for the code in the project is held by the respective contributors.
>>>> Because you (or your company)
>>>> retain ownership of the code you contribute, you know it may only be used under
>>>> the terms of the open source license you contributed it under: the license for
>>>> your contributions cannot be changed in the future without your approval.
>>>> 
>>>> Because the LLVM project does not require copyright assignments, changing the
>>>> LLVM license requires tracking down the
>>>> contributors to LLVM and getting them to agree that a license change is
>>>> acceptable for their contributions.  We feel that a high burden for relicensing
>>>> is good for the project, because contributors do not have to fear that their
>>>> code will be used in a way with which they disagree.
>>>> 
>>>> Relicensing
>>>> -----------
>>>> 
>>>> The last paragraph notwithstanding, the LLVM Project is in the middle of a large
>>>> effort to change licenses, which aims to solve several problems:
>>>> 
>>>> * The old licenses made it difficult to move code from (e.g.) the compiler to
>>>> runtime libraries, because runtime libraries used a different license from the
>>>> rest of the compiler.
>>>> * Some contributions were not submitted to LLVM due to concerns that
>>>> the patent grant required by the project was overly broad.
>>>> * The patent grant was unique to the LLVM Project, not written by a lawyer, and
>>>> was difficult to determine what was protection was provided (if any).
>>>> 
>>>> The scope of relicensing is all code that is considered part of the LLVM
>>>> project, including the main LLVM repository, runtime libraries (compiler_rt,
>>>> OpenMP, etc), Polly, and all other subprojects.  There are a few exceptions:
>>>> 
>>>> * Code imported from other projects (e.g. Google Test, Autoconf, etc) will
>>>> remain as it is.  This code isn't *developed* as part of the LLVM project, it
>>>> is *used* by LLVM.
>>>> * Some subprojects are impractical or uninteresting to relicense (e.g. llvm-gcc
>>>> and dragonegg). These will be split off from the LLVM project (e.g. to
>>>> separate Github projects), allowing interested people to continue their
>>>> development elsewhere.
>>>> 
>>>> To relicense LLVM, we will be seeking approval from all of the copyright holders
>>>> of code in the repository, or potentially remove/rewrite code if we cannot.
>>>> This is a large
>>>> and challenging project which will take a significant amount of time to
>>>> complete.  In the interim, **all contributions to the project will be made under
>>>> the terms of both the new license and the legacy license scheme** (each of which
>>>> is described below).  The exception to this is the legacy patent grant, which
>>>> will not be required for new contributions.
>>>> 
>>>> When all of the code in the project has been converted to the new license or
>>>> removed, we will drop the requirement to contribute under the legacy license.
>>>> This will achieve the goal of having
>>>> a single standardized license for the entire codebase.
>>>> 
>>>> If you are a prior contributor to LLVM and have not done so already, please do
>>>> *TODO* to allow us to use your code. *Add a link to a separate page here, which
>>>> is probably a click through web form or something like that.  Details to be
>>>> determined later*.
>>>> 
>>>> 
>>>> .. _open source licensing terms:
>>>> 
>>>> New LLVM Project License Framework
>>>> ----------------------------------
>>>> 
>>>> Contributions to LLVM are licensed under the `Apache License, Version 2.0
>>>> <https://www.apache.org/licenses/LICENSE-2.0>`_, with two limited
>>>> exceptions intended to ensure that LLVM is very permissively licensed.
>>>> Collectively, the name of this license is "Apache 2.0 License with LLVM
>>>> exceptions".  The exceptions read:
>>>> 
>>>> ::
>>>> 
>>>>  ---- LLVM Exceptions to the Apache 2.0 License ----
>>>> 
>>>>  As an exception, if, as a result of your compiling your source code, portions
>>>>  of this Software are embedded into an Object form of such source code, you
>>>>  may redistribute such embedded portions in such Object form without complying
>>>>  with the conditions of Sections 4(a), 4(b) and 4(d) of the License.
>>>> 
>>>>  In addition, if you combine or link compiled forms of this Software with
>>>>  software that is licensed under the GPLv2 ("Combined Software") and if a
>>>>  court of competent jurisdiction determines that the patent provision (Section
>>>>  3), the indemnity provision (Section 9) or other Section of the License
>>>>  conflicts with the conditions of the GPLv2, you may retroactively and
>>>>  prospectively choose to deem waived or otherwise exclude such Section(s) of
>>>>  the License, but only in their entirety and only with respect to the Combined
>>>>  Software.
>>>> 
>>>> 
>>>> We intend to keep LLVM perpetually open source and available under a permissive
>>>> license - this fosters the widest adoption of LLVM by
>>>> **allowing commercial products to be derived from LLVM** with few restrictions
>>>> and without a requirement for making any derived works also open source.  In
>>>> particular, LLVM's license is not a "copyleft" license like the GPL.
>>>> 
>>>> The "Apache 2.0 License with LLVM exceptions" allows you to:
>>>> 
>>>> * freely download and use LLVM (in whole or in part) for personal, internal, or
>>>> commercial purposes.
>>>> * include LLVM in packages or distributions you create.
>>>> * combine LLVM with code licensed under every other major open source
>>>> license (including BSD, MIT, GPLv2, GPLv3...).
>>>> * make changes to LLVM code without being required to contribute it back
>>>> to the project - contributions are appreciated though!
>>>> 
>>>> However, it imposes these limitations on you:
>>>> 
>>>> * You must retain the copyright notice if you redistribute LLVM: You cannot
>>>> strip the copyright headers off or replace them with your own.
>>>> * Binaries that include LLVM must reproduce the copyright notice (e.g. in an
>>>> included README file or in an "About" box), unless the LLVM code was added as
>>>> a by-product of compilation.  For example, if an LLVM runtime library like
>>>> compiler_rt or libc++ was automatically included into your application by the
>>>> compiler, you do not need to attribute it.
>>>> * You can't use our names to promote your products (LLVM derived or not) -
>>>> though you can make truthful statements about your use of the LLVM code,
>>>> without implying our sponsorship.
>>>> * There's no warranty on LLVM at all.
>>>> 
>>>> We want LLVM code to be widely used, and believe that this provides a model that
>>>> is great for contributors and users of the project.  For more information about
>>>> the Apache 2.0 License, please see the `Apache License FAQ
>>>> <http://www.apache.org/foundation/license-faq.html>`_, maintained by the
>>>> Apache Project.
>>>> 
>>>> 
>>>> .. note::
>>>> 
>>>>  The LLVM Project includes some really old subprojects (dragonegg,
>>>>  llvm-gcc-4.0, and llvm-gcc-4.2), which are licensed under **GPL
>>>>  licenses**.  This code is not actively maintained - it does not even
>>>>  build successfully.  This code is cleanly separated into distinct SVN
>>>>  repositories from the rest of LLVM, and the LICENSE.txt files specifically
>>>>  indicate that they contain GPL code.  When LLVM transitions from SVN to Git,
>>>>  we plan to drop these code bases from the new repository structure.
>>>> 
>>>> 
>>>> .. _patent license:
>>>> 
>>>> Patents
>>>> -------
>>>> 
>>>> Section 3 of the Apache 2.0 license is a patent grant under which
>>>> contributors of code to the project contribute the rights to use any of
>>>> their patents that would otherwise be infringed by that code contribution
>>>> (protecting uses of that code).  Further, the patent grant is revoked
>>>> from anyone who files a patent lawsuit about code in LLVM - this protects the
>>>> community by providing a "patent commons" for the code base and reducing the
>>>> odds of patent lawsuits in general.
>>>> 
>>>> The license specifically scopes which patents are included with code
>>>> contributions.  To help explain this, the `Apache License FAQ
>>>> <http://www.apache.org/foundation/license-faq.html>`_ explains this scope using
>>>> some questions and answers, which we reproduce here for your convenience (for
>>>> reference, the "ASF" is the Apache Software Foundation, the guidance still
>>>> holds though)::
>>>> 
>>>>  Q1: If I own a patent and contribute to a Work, and, at the time my
>>>>  contribution is included in that Work, none of my patent's claims are subject
>>>>  to Apache's Grant of Patent License, is there a way any of those claims would
>>>>  later become subject to the Grant of Patent License solely due to subsequent
>>>>  contributions by other parties who are not licensees of that patent.
>>>> 
>>>>  A1: No.
>>>> 
>>>>  Q2: If at any time after my contribution, I am able to license other patent
>>>>  claims that would have been subject to Apache's Grant of Patent License if
>>>>  they were licenseable by me at the time of my contribution, do those other
>>>>  claims become subject to the Grant of Patent License?
>>>> 
>>>>  A2: Yes.
>>>> 
>>>>  Q3: If I own or control a licensable patent and contribute code to a specific
>>>>  Apache product, which of my patent claims are subject to Apache's Grant of
>>>>  Patent License?
>>>> 
>>>>  A3:  The only patent claims that are licensed to the ASF are those you own or
>>>>  have the right to license that read on your contribution or on the
>>>>  combination of your contribution with the specific Apache product to which
>>>>  you contributed as it existed at the time of your contribution. No additional
>>>>  patent claims become licensed as a result of subsequent combinations of your
>>>>  contribution with any other software. Note, however, that licensable patent
>>>>  claims include those that you acquire in the future, as long as they read on
>>>>  your original contribution as made at the original time. Once a patent claim
>>>>  is subject to Apache's Grant of Patent License, it is licensed under the
>>>>  terms of that Grant to the ASF and to recipients of any software distributed
>>>>  by the ASF for any Apache software product whatsoever.
>>>> 
>>>> 
>>>> Legacy License Structure
>>>> ------------------------
>>>> 
>>>> .. note::
>>>>  The code base was previously licensed under the Terms described here.
>>>>  We are in the middle of relicensing to a new approach (described above), but
>>>>  until this effort is complete, the code is also still available under these
>>>>  terms.  Once we finish the relicensing project, new versions of the code will
>>>>  not be available under these terms.  However, nothing takes away your right
>>>>  to use old versions under the licensing terms under which they were
>>>>  originally released.
>>>> 
>>>> We intend to keep LLVM perpetually open source and to use a permissive open
>>>> source license.  The code in
>>>> LLVM is available under the `University of Illinois/NCSA Open Source License
>>>> <http://www.opensource.org/licenses/UoI-NCSA.php>`_, which boils down to
>>>> this:
>>>> 
>>>> * You can freely distribute LLVM.
>>>> * You must retain the copyright notice if you redistribute LLVM.
>>>> * Binaries derived from LLVM must reproduce the copyright notice (e.g. in an
>>>> included README file).
>>>> * You can't use our names to promote your LLVM derived products.
>>>> * There's no warranty on LLVM at all.
>>>> 
>>>> We believe this fosters the widest adoption of LLVM because it **allows
>>>> commercial products to be derived from LLVM** with few restrictions and without
>>>> a requirement for making any derived works also open source (i.e. LLVM's
>>>> license is not a "copyleft" license like the GPL). We suggest that you read the
>>>> `License <http://www.opensource.org/licenses/UoI-NCSA.php>`_ if further
>>>> clarification is needed.
>>>> 
>>>> In addition to the UIUC license, the runtime library components of LLVM
>>>> (**compiler_rt, libc++, and libclc**) are also licensed under the `MIT License
>>>> <http://www.opensource.org/licenses/mit-license.php>`_, which does not contain
>>>> the binary redistribution clause.  As a user of these runtime libraries, it
>>>> means that you can choose to use the code under either license (and thus don't
>>>> need the binary redistribution clause), and as a contributor to the code that
>>>> you agree that any contributions to these libraries be licensed under both
>>>> licenses.  We feel that this is important for runtime libraries, because they
>>>> are implicitly linked into applications and therefore should not subject those
>>>> applications to the binary redistribution clause. This also means that it is ok
>>>> to move code from (e.g.)  libc++ to the LLVM core without concern, but that code
>>>> cannot be moved from the LLVM core to libc++ without the copyright owner's
>>>> permission.
>>>> 
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> llvm-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

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