The implementation is of course different, but the workaround is the same, separating the user/kernel pages tables. One key difference is that OpenBSD doesn't have to deal with 32-bit binary compatibility [0] and such, and also has made considerable effort to minimize the amount of kernel pages needed, AFAICT 6+(2*ncpus)

[0] https://marc.info/?l=openbsd-misc&m=148926149318522&w=2