Paolo, Thanks for the reference. I will give it a good look. Bill ________________________________________ From: Paolo Bonzini [paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini [bonzini@gnu.org] Sent: Wednesday, October 20, 2010 2:13 PM To: Schwab,Wilhelm K Subject: Fwd: Re: Plug-in Licensing I found a reference to GPL-compatible vs. GPLv3 in the GCC mailing list from today. It is the same situation as you, with "GCC plugin" being your library and "GCC" being GSL in your case. Hope this helps a fellow Smalltalker. Paolo ------------------ Justin Seyster <jrseys@gmail.com> writes:
I'm getting ready to release plug-in code, and I want to have a very clear idea about licensing before I release. I'm leaning towards releasing everything as GPLv3, but I do want to know exactly what is and isn't allowed.
GPLv3 is fine.
I know this issue was debated quite intensely before plug-in support got added, but my understanding is that there was a final consensus. I can't find one document though that explains exactly what this consensus was.
The document is here: http://www.gnu.org/licenses/gcc-exception.html See also the rationale and FAQ that it links to. Basically, if you use a plugin with gcc, and the plugin is not GPL-compatible, then the resulting compiled code is covered by the GPL.
I vaguely remember a proposal that there would be no restriction on plug-in licensing but that non-free plug-ins could only be used to compile Free software, but that's not documented anywhere I can find.
That's pretty much it.
GCC itself now requires that plug-ins export a plugin_is_gpl_compatible symbol, which implies that the plug-in's license need only be compatible with the GPL. Is it ok to release LGPL- or BSD-licensed plug-ins?
Sure, both of those licenses are GPL-compatible.
My understanding is that, in general, only GPLv3 code can link against GPLv3 code, which would imply that my plug-in code must be GPLv3.
That is incorrect. You can link code under any GPL-compatible license with GPLv3 code, and the resulting executable will be covered the union of both licenses. Since GPLv3 tends to be stricter than any GPL-compatible license, this generally means that the result is under GPLv3. There is a (non-exhaustive) list of GPL-compatible licenses here: http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses Ian