Re: how about mutual compatibility between Linux's GPLv2 and GPLv3?

[Alexandre Oliva <aoliva@redhat.com>]

On Jun 21, 2007, david@lang.hm wrote:

> this is standard dual-licensing, not special just becouse both
> licenses are GPL versions

No, seriously, it's not, it's quite different.

If you dual-license your code between GPLv2 and GPLv3, I could combine
your code with code under GPLv3, distribute it, and if anyone tivoized
your code, I might be able to enforce the anti-tivoization provisions
against the tivoizer.

With a mere permission to combine, I can only enforce these provisions
over my own code.


I see that, for tivoization, the end result is very much the same as
an all-GPL, although the tivoizer still has the option of removing the
GPLv3 code and hoping GPLv2's implicit anti-tivoization provisions are
not enforced.  This would be just undoing the additional cooperation
that this additional permission would have provided.

However, for other GPLv3 defenses, it would make a difference.  For
example, on the patent licenses that are implicit in GPLv2 and
explicit in GPLv3.

> and for people who don't like one or the other of the two licenses
> this will not be acceptable becouse it would allow someone else to
> take their work, modify it a bit, and release the result only under
> the license that they don't like

Which is precisely why I suggested this approach of permission to
combine, rather than as dual licensing.  Because then nobody could do
what you say.

> one of the big problems that people don't realize is that if it takes
> GPLv3+ exception to be compatible with the apache license

For the record, it doesn't, GPLv3 is going to be compatible with the
apache 2.0 license, no additional exceptions needed.

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member         http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}
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