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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Hi all,

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.


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).

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?