Klaus Karcher wrote:
I know: YANAL, IANAL, but do you think it's possible to distribute my CMM (which is linked with proprietary OS APIs) under GPL?
If everything you distribute is compatible with the GPL, then yes (ie. the users do the linking to OS API's). The GPL doesn't prohibit any use of the software, just copying it, so there's no issue with end users combining GPL software with non-GPL software in any manner they like. What can't be done is combining GPL software with non-GPL software, and distributing (copying) it.
I think this case is covered by the GPL FAQ <http://www.gnu.org/copyleft/gpl-faq.html#GPLIncompatibleLibs>, but I'm not quite sure if I understood it well enough: The libraries my CMM needs are distributed with the OS, my source code does not contain them, but even if the executable does, my package is still GPL compatible? Did I get this right?
I think that this exception certainly covers your situation. In some ways it doesn't matter even if it doesn't, if you aren't providing the non-GNU components. There's nothing to stop someone creating a GPL piece of software that can't do anything without some other (3rd party) proprietary library, it just isn't very useful from a Free Software point of view. What they can't do is take some GPL software and combine/package it with a proprietary library and distribute it, since the package is a derivative work, and the license for the GNU component has the condition that derivative works be distributed under GNU compatible conditions. Graeme Gill.