Michael Murphy (S76)

In practice, because Rust libraries are always statically-linked, the MPL-2.0 is equivalent to the LGPL in spirit. Meanwhile, because of the static linking restrictions in the LGPL, the LGPL is effectively no different from the GPL. Hence, you’re going to find a lot of open source copyleft projects from the Rust ecosystem preferring either GPL or MPL-2.0, where MPL-2.0 is used in libraries where LGPL would have used previously in C projects. Dynamic linking is essentially going the way of the Dodo.

The Linux kernel already allows proprietary modules via DKMS, and a handful of vendors have been using this for decades, so this is no different. Case in point: NVIDIA driver, and Android vendor drivers.

All source code in Rust is statically-linked when compiled, which thereby renders the LGPL no different from the GPL in practice. For Rust, the MPL-2.0 is a better license because it does not have the linking restriction.