Designing ELF modules

Permissive licences* allow distribution under GPLv2, so the code could remain available under BSD/MIT/whatever without further drama - providing sufficient care is taken to keep such code from becoming so intricately linked to (and therefore "derivative work" of) GPL-only code.

There's already a bunch of code in the kernel under BSD/MIT style licences via this mode of thinking.

* For suitable definitions of "permissive licences"