hald/linux/acpi.[ch] dual-license?

[David Zeuthen]

On Mon, 2007-04-09 at 22:55 +0200, Danny Kukawka wrote: 
> I'm not sure what this imply for the leagal/license side. Are both licenses 
> compatible (IMO there are several differences)? What are the advantages of 
> AFL against GPL and why do we need to licenses in HAL?

Historically, I chose dual license because that's what D-Bus did.

The point of two licenses ("AFL 2.1" and "GPLv2 or later") is that you
can choose what license you want to distribute HAL under; the licenses
don't have to be compatible - you just choose one of them. So either you
distribute HAL under the AFL 2.1 or you distribute HAL under the GPLv2;
that's your choice as a distributor.

However, for a number of reasons, I later chose to make the Linux
backend GPLv2 only. So any Linux distributor shipping "HAL + HAL Linux
backend" is forced to choose GPLv2 (and thereby give changes back).
Which is fine, it's in the spirit of Linux since the same applies to the
Linux kernel. I didn't, however, want to make that choice for other back
ends and operating systems. Which I think is only fair. That's why all
the non-Linux specific code is, and will continue to be in the future,
available under both AFL2.1 and GPLv2.

Anyway, as I understand, the Solaris backend is AFL2.1 so Sun can choose
to use AFL2.1 for distributing "HAL + HAL Solaris backend". That's why
they're asking to relicense this code so it can be included in their
tree and still retain the option to choose AFL2.1 for "HAL + HAL Solaris
backend". 

FWIW, I personally don't think relicensing this particular piece code
should be a problem or concern.. that's why I gave my permission to do
it right away. But all the copyright holders needs to give their OK.

Hope this clarifies. Thanks.

     David