> ZoL maintains a clear separation from Linux proper for licensing reasons so I'd think they're "independent enough" to serve as upstream for non-Linux versions.
That would neatly solve the issue of ZoL patches never making it back to Illumos.
I suppose you could argue for having a single, explicitly OS-independent "upstream repository" rather than treating either Illumos or ZoL as upstream? I doubt there are enough developers who would want to work on ZFS generically rather than ZFS in the context of a particular OS. ZoL maintains a clear separation from Linux proper for licensing reasons so I'd think they're "independent enough" to serve as upstream for non-Linux versions.