Re: Removing "or later" from Xen license, Was: [PATCH v2 3/3] add SPDX to arch/arm/*.c

[Elliott Mitchell <ehem+xen@xxxxxxx>]

On Tue, Aug 23, 2022 at 11:53:50AM -0700, Stefano Stabellini wrote:
> I changed the subject to reflect the discussion and moved George to
> "to:" to get his attention.
> 
> Also, if we are going to make any chances as described below, I think
> they should be a separate series from the SPDX series.

Also gets a second look from others who may have an opinion on the topic.

I second what is after the comma.  Adding SPDX tags and changing files
from GPLv2+ to GPLv2-only are distinct tasks and should be kept separate.


> On Tue, 23 Aug 2022, Julien Grall wrote:
> > > > I am putting some thoughts below (they can be split in a separate thread
> > > > if you prefer).
> > > > 
> > > > This is not the first time this topic is brought up and probably not the
> > > > last as long as we have file using GPLv2+.
> > > > 
> > > > IIRC from past discussion there are two broads concern with GPLv2+:
> > > >   - We are leaving the choice of which license applies to the person
> > > > copying the code. So if a new version is released that is less favorable
> > > > to the initial contributor, then we have no leverage.
> > > >   - Some companies are rather cautious to contribute code that my be
> > > > licensed under GPLv3 (would be allowed with GPLv2+).
> > > > 
> > > > The later is particularly a problem because not many people realize 
> > > > that a
> > > > fair part of Xen on Arm is GPLv2+. I never really understood why we 
> > > > chose
> > > > that (this was before my time) but this got spread as the existing
> > > > copyright was added to a new file. Admittely, the contributor should be
> > > > more cautious. But I would not say this is trivial to spot the 
> > > > difference.
> > > > 
> > > > I would like to consider to re-license all the GPLv2+ files to GPLv2.
> > > > AFAIU, this would mean we would need to ask the permission for every
> > > > comapany that contributed to the file. Do you know if this was done 
> > > > before
> > > > in Xen Project?
> > > 
> > > If I am understanding right, GPLv2+ means that someone could relicense the
> > > files to GPLv3 if he wants which is more restrictive.
> > > Why do you want to move those back to GPLv2 ?
> > The main difference between GPLv2 and GPLv3 is the patent section. This has
> > caused some concerns in the past when a stakeholder want to contribute to 
> > Xen
> > Project.
> >
> > While looking through at previous discussion, I found the original 
> > discussion
> > [1] which contains a lot more details.
> 
> 
> I agree with Julien. Also, I don't think that having GPLv2-or-later on a
> few source files is of benefit to anyone (if Xen was GPLv2-or-later as a
> whole it would be a different discussion).

I disagree here.  Having GPLv2+ on a few files hints at the contributor
community's views, though one must exercise care.

Notably if 50% of contributors prefer GPLv2+ less than 10% of files are
likely to be marked GPLv2+.  The reason being GPLv3 didn't exist until
2006 and a single GPLv2-only contributor would cause shared files to be
stuck as GPLv2-only.

So there could be a majority who prefer GPLv2+, just too many existing
files are GPLv2-only.


> Moving from GPLv2-or-later to GPLv2-only is not a relicense. The "or
> later" statement is not part of the license itself. It would be limiting
> the choice of license to a subset of what is currently allowed: i.e.
> from [GPLv2,GPLv3] to [GPLv2]. I don't think we need approval from the
> original authors from that.
> 
> The original authors already stated: "my code can be either under GPLv2
> or GPLv3". Now we are only offering it under GPLv2. Users can still get
> the older version from a past Xen release under GPLv3 if they want to.
> 
> So I think we can drop "or later" any time as long as the maintainers
> agree.
> 
> George, do you agree with the above?

I'm not an expert, but this matches my understanding as a (near-trivial)
contributor.


I'm not a significant contrbutor, but let it be hereby known my portions
are available under GPLv2+.


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