/stand/arch/vers/kmods works in rump (and that the result is usable ;).
On i386 this "just works". For amd64, due to -mcmodel=kernel,
things are a little more complicated. We must have the entire rump
kernel loaded in the lower 2GB. Currently, this can be done either
by using the non-PIC version for the rump kernel compiled with
-mcmodel=small, or, as njoly pointed out, using netbsd32, which
causes vm_default_addr() to give something in the lower 2GB and
therefore shared libs "magically" getting loaded there. I guess
it would be possible to put a suggested vaddr into the rump kernel
libs and make ld.elf_so map memory from the suggested address if
present ... but that's another show.
Also thanks to tron for access to an amd64 so that I could verify
the test works.
pooka