- without COMPAT_43, the kernel wouldn't link. This was not detected
     automagically by $TOOLDIR/bin/nbconfig, so something must've been
     wrong.

why didn't it link?
   
   - fdtwo floppy device must not be configured, or the kernel won't even
     "nbmake depend". This appears to be a known issue; I found a post
     dated September'01 describing it, giving me the impression that
     it's simply b0rken on Sparc64.

there is no floppy support on sparc64.