llvm dev - Oct 2015 - RFC: Improving license & patent issues in the LLVM community

On 19 October 2015 at 18:12, David Chisnall via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> One worry is that Apache 2 is incompatible with GPLv2 (is it incompatible
with other licenses?)
This is interesting, I did not know that...

http://www.apache.org/licenses/GPL-compatibility.html

"Despite our best efforts, the FSF has never considered the Apache
License to be compatible with GPL version 2, citing the patent
termination and indemnification provisions as restrictions not present
in the older GPL license."

It seems to be compatible with GPLv3, though. But I think most
companies that use LLVM are stuck with GPLv2 due to the patents issue.

cheers,
--renato

> On Oct 19, 2015, at 10:57 AM, Renato Golin <renato.golin at
linaro.org> wrote:
> 
> On 19 October 2015 at 18:12, David Chisnall via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> One worry is that Apache 2 is incompatible with GPLv2 (is it
incompatible with other licenses?)
> 
> This is interesting, I did not know that...
> 
> http://www.apache.org/licenses/GPL-compatibility.html
> 
> "Despite our best efforts, the FSF has never considered the Apache
> License to be compatible with GPL version 2, citing the patent
> termination and indemnification provisions as restrictions not present
> in the older GPL license."
> 
> It seems to be compatible with GPLv3, though. But I think most
> companies that use LLVM are stuck with GPLv2 due to the patents issue.
Yes, this is a known concern with the Apache 2 license, but I don’t know if
there is an actual “known” answer to this question.  DannyB or someone else can
comment for sure, but my understanding is that the terms of the GPL2 prevent
*any* license from including the sort of patent protection that we are looking
for.

FWIW, this is what the FSF has to say about the topic:
http://www.gnu.org/licenses/license-list.en.html#apache2

Note that the FSF *recommends* the Apache 2 license for permissively licensed
projects.

If you are still concerned about this issue, my question is simply: what
specific GPL2 compiler (or other user) that might want to use LLVM would be
affected?

-Chris

On Mon, Oct 19, 2015 at 1:03 PM, Chris Lattner via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
>> On Oct 19, 2015, at 10:57 AM, Renato Golin <renato.golin at
linaro.org> wrote:
>>
>> On 19 October 2015 at 18:12, David Chisnall via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>> One worry is that Apache 2 is incompatible with GPLv2 (is it
incompatible with other licenses?)
>>
>> This is interesting, I did not know that...
>>
>> http://www.apache.org/licenses/GPL-compatibility.html
>>
>> "Despite our best efforts, the FSF has never considered the Apache
>> License to be compatible with GPL version 2, citing the patent
>> termination and indemnification provisions as restrictions not present
>> in the older GPL license."
>>
>> It seems to be compatible with GPLv3, though. But I think most
>> companies that use LLVM are stuck with GPLv2 due to the patents issue.
>
> Yes, this is a known concern with the Apache 2 license, but I don’t know if
there is an actual “known” answer to this question.  DannyB or someone else can
comment for sure, but my understanding is that the terms of the GPL2 prevent
*any* license from including the sort of patent protection that we are looking
for.
>
Note: GPLV2 and GPLv3 are *also* incompatible with each other (see
http://www.gnu.org/licenses/gpl-faq.en.html#v2v3Compatibility), so you
have larger issues if you are mixing those ;-).

Besides the obvious ones, there are subtle ones:
For example, it's not okay to use an old GPLv2 version of gcc and a
new version of GPLv3 libgcc with the runtime exception, because old
compiler is not "GPL-compatible" as that license defines it.

On 19 October 2015 at 21:03, Chris Lattner <clattner at apple.com>
wrote:
> If you are still concerned about this issue, my question is simply: what
specific GPL2 compiler (or other user) that might want to use LLVM would be
affected?
I'm not. I was just pointing to the fact. :)

I remember Apple and others have stuck with GPLv2 GCC, but I don't
think there was any cross between them to warrant worry. I'm not sure
anyone would do that because of the existing problems, so it's
probably a non-issue.

cheers,
--renato

On Oct 19, 2015, at 4:03 PM, Chris Lattner via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> Yes, this is a known concern with the Apache 2 license, but I don’t know if
there is an actual “known” answer to this question.  DannyB or someone else can
comment for sure, but my understanding is that the terms of the GPL2 prevent
*any* license from including the sort of patent protection that we are looking
for.
> 
> FWIW, this is what the FSF has to say about the topic:
> http://www.gnu.org/licenses/license-list.en.html#apache2
> 
> Note that the FSF *recommends* the Apache 2 license for permissively
licensed projects.
> 
> If you are still concerned about this issue, my question is simply: what
specific GPL2 compiler (or other user) that might want to use LLVM would be
affected?

Glancing through the project list <http://llvm.org/ProjectsWithLLVM/> I
see at least one project that might be adversely affected by that
incompatibility: OpenJDK Zero. I believe OpenJDK is licensed by Oracle as
"GPLv2-only with classpath exception", and that the Zero folks have
patched OpenJDK to link in LLVM to provide a JIT on platforms that OpenJDK
doesn't natively support with its own code generator.
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On 19 October 2015 at 13:57, Renato Golin via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> On 19 October 2015 at 18:12, David Chisnall via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> One worry is that Apache 2 is incompatible with GPLv2 (is it
incompatible with other licenses?)
>
> This is interesting, I did not know that...
>
> http://www.apache.org/licenses/GPL-compatibility.html
>
> "Despite our best efforts, the FSF has never considered the Apache
> License to be compatible with GPL version 2, citing the patent
> termination and indemnification provisions as restrictions not present
> in the older GPL license."
:-(

This means that for example using llvm for jitting stuff in a gpl2
program is out. Does anyone know of a list of current gpl2 programs?
The two that come to mind are the linux kernel and git.

Does anyone know if the apache 2 is compatible with the various LGPL versions?

Cheers,
Rafael

On 20 Oct 2015, at 16:59, Rafael Espíndola <rafael.espindola at gmail.com>
wrote:
> 
> Does anyone know if the apache 2 is compatible with the various LGPL
versions?
I am not a lawyer, this is not legal advice:

LGPL does not impose any restrictions on the license of things that you link
against it, only that everyone that you distribute the binary to is able to
recompile and relink the LGPL’d part with the result.  Note: one reading of this
would indicate that iOS violates this, by not allowing end users to link their
own WebKit to the installed binaries, but this has not been tested in court and
is not the only interpretation possible.  This highlights the problem with more
complex licenses: determining exactly what is and is not allowed may require
someone to take someone else to court (possibly multiple times).

David

On 20 October 2015 at 16:59, Rafael Espíndola
<rafael.espindola at gmail.com> wrote:
> Does anyone know if the apache 2 is compatible with the various LGPL
versions?
Wait, the BPF backend runs in the kernel. I'm not sure how integrated
they are, or how relevant this is, but unlike llvm-gcc, the BPF
backend would be a *big* shame to lose.

cheers,
--renato

On Tue, Oct 20, 2015 at 8:59 AM, Rafael Espíndola
<llvm-dev at lists.llvm.org> wrote:
> On 19 October 2015 at 13:57, Renato Golin via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> On 19 October 2015 at 18:12, David Chisnall via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>> One worry is that Apache 2 is incompatible with GPLv2 (is it
incompatible with other licenses?)
>>
>> This is interesting, I did not know that...
>>
>> http://www.apache.org/licenses/GPL-compatibility.html
>>
>> "Despite our best efforts, the FSF has never considered the Apache
>> License to be compatible with GPL version 2, citing the patent
>> termination and indemnification provisions as restrictions not present
>> in the older GPL license."
>
> :-(
>
> This means that for example using llvm for jitting stuff in a gpl2
> program is out.
No it isn't.
It means you can't grab the combined memory image out of memory and
ship that to others.

You could ship the non-combined program.
IE  You can ship an llvm jit and a gpl2 program, and jit the program
on the user's machine.

;-)
> Does anyone know of a list of current gpl2 programs?
> The two that come to mind are the linux kernel and git.
Kernel is GPLv2 only as well, so for example, you have the same issue
with any GCC jit (since it's GPLv3) ;)
>
> Does anyone know if the apache 2 is compatible with the various LGPL
versions?
>
Yes, it is.