The reason this seems valid, is that it takes a long time to get the full system of device drivers you need to run on anything more than just a single platform.

The reason this seems valid, is that it takes a long time to get the full system of device drivers you need to run on anything more than just a single platform. Just seems like a good starting point than reworking the entire world. Also, on the question of "how" you'd do this, I'm not a kernel hacker, but I thought it would be possible to expose FFI, i.e. the shim you talk about, that would allow drivers to be used from something like NetBSD. But you're right that it could be self-defeating in that supporting all of those interfaces might end up constraining the OS in it's attempt to deliver on these features. On a side note, it seems like it would be nice to expose POSIX FFI hooks to make porting software to a Rust OS easier.