> > In addition to amd64/i386, it occurs to me that sparc64/sparc32 is > > another case; IIRC it's possible to take sparc64 hardware and build a > > (special? not sure) kernel that runs sparc32 userland. I've never > > tried it; I don't know whether sparc32 and sparc64 are as freely > > mixable at runtime as amd64 and i386 are under amd64 kernels. > > Yes, that's what compat/netbsd32 is for. (Of course, there are still a > few things like mount I never bothered to get working across ABIs.)
there are a few supported cases here: 32 bit kernel on 64 bit cpu (32 bit userland only). 64 bit kernel with either size userland. eeh - matt@ fixed mount compat a few years ago, as well as a lot of the remaining edge cases we'd never gotten to. it was necessary to run full n32 userland on n64 kernel (we still build all the kvm-on-running-kernel-using programs as n64.) so that generally works fine now.. .mrg.
