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To:     Christoph Hellwig <hch@lst.de>, Jonathan Corbet <corbet@lwn.net>
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From:   Thorsten Leemhuis <linux@leemhuis.info>
Subject: Re: [PATCH v3 1/3] LICENSES: Add the CC-BY-4.0 license
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Date:   Tue, 1 Dec 2020 21:45:39 +0100
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Am 01.12.20 um 15:43 schrieb Christoph Hellwig:
> On Mon, Nov 30, 2020 at 07:51:37AM -0700, Jonathan Corbet wrote:

@Jonathan: thx for getting the ball rolling again!

>> We could also, if we saw fit, take the position that anything that has
>> been processed through the docs build is a derived product of the kernel
>> and must be GPL-licensed -

That position is totally fine for me (and in fact I think that's how 
things are in that area anyway, but I'm no licensing expect).

>> any dual-licensing would be stripped by that
>> act.  That, too, should address this concern, I think.

How to make this explicit? Right now the document I want to submit only 
mentions the license in a comment near the top. From a quick test with 
'make htmldocs' on f33 with sphinx-build 3.2.1 it seems comments are 
stripped during processing, so the license won't be visible in the 
processed document anyway. So I guess adding this as comment below the 
SPDX tag should be enough:

```

Note: Only the contents of this rst file as found in the Linux kernel 
sources are available under CC-BY-4.0, as processed versions might 
contain content taken from files that use a more restrictive license.

```


Or should we add something like this to a top-level documentation file 
to make it explicit for all of the documentation:

```
The processed Linux kernel documentation can be distributed under GPL 
v2.0; some of the files used to build the documentation are available 
under other licenses, check the Documentation/ directory in the Linux 
sources for details.
```

>> In general I'd rather see fewer licenses in Documentation/ than more.

Fully agreed, but I checked the existing licenses first and none of them 
afaics came even close to what I'd prefer to see (maybe MIT does, but 
I'm not really sure).

>>  But
>> Thorsten has put a lot of effort into this work; if he wants to
>> dual-license it in this way, my inclination is to accommodate him.

Thx for your support.

>>  But
>> that requires getting CC-BY-4.0 accepted into the LICENSES directory.
>> (That said, I believe it should go into LICENSES/dual/ rather than
>> preferred/).
> I agree with everything said above.

Fine with me also, but I guess I need a little help here. The files that 
currently resist in that directory all contain this near the top:

```
Do NOT use. The Apache-2.0 is not GPL2 compatible. It may only be used 
for dual-licensed files where the other license is GPL2 compatible. If 
you end up using this it MUST be used together with a GPL2 compatible 
license using "OR".
```

CC-BY-4.0 is GPL2 compatible afaik, so what do I write instead? 
Something like this?

```
Do NOT use for code, but it's acceptable for content like artwork or 
documentation. When using it for the latter, it's best to use it 
together with a GPL2 compatible license using "OR", as processed 
CC-BY-4.0 document might include content taken from more restrictive 
licenses.
```

Do we need more? Something like this maybe: "That's also why you might 
want to point that risk out in a comment near the SPDX tag." Or is that 
too much?

Ciao, Thorsten