Re: [Qemu-devel] [PATCH V9 01/14] block: move bdrv_snapshot_find() to block/snapshot.c

[Markus Armbruster]

Kevin Wolf <address@hidden> writes:

> Am 12.03.2013 um 06:01 hat Wenchao Xia geschrieben:
>>   Oops, Since it belongs to block layer I hope it can be LGPL2. Do you
>> know how to contact Fabrice Bellard to ask for a change?
>
> Fabrice is not the only copyright owner of this file.
>
> Just copy the license as it is, changing licenses is always a nasty
> thing and as I'm not a lawyer I prefer to stay on the safe side. The MIT
> license works well enough, there's no real reason to change it.

*Relicensing* a file is indeed "nasty" in the sense that it's a huge
hassle: you have to track down all copyright holders and get their
permission.

But this isn't relicensing.  This is exercising your *right* to
incorporate permissively-licensed stuff into work covered by a
compatible, stronger license.  That right was irrevocably granted to you
by the copyright holders.  You don't have to ask anyone to exercise it.

Of course, the stronger license still has to be compatible with GPLv2,
so we can accept the result into QEMU.

If a subsystem has additional requirements on licenses, its maintainers
will explain them to you.  For what it's worth, substantial parts of the
block layer are already GPLv2+.

You don't *have* to switch to a stronger license, of course.  It's your
choice.  Myself, I prefer to protect any substantial work I do with a
strong copyleft license such as GPLv2+.