On Sat, 25 Jul 1998, Eduardo E. Horvath wrote:

: AFIK the current model of MACHINE and MACHINE_ARCH doesn't work very well
: where one architecture is a superset of another atchitecture.  A mips64
: machine should be able to run mips32 binaries, but not the other way
: around.  So what happens?  Does MACHINE_ARCH become `mips' and `mips64'
: and the two are wholely incompatible?  Does a mips64 machine use a mips32
: userland?

That depends on what the userland is, as this is where the ambiguity comes
into question.  Kernel builds can specify a different compiler/toolchain
option for an output target, but userland has a lot more than just the
NetBSD source tree to deal with.

If, for example, the sparc64 port had a fully 64-bit ELF userland, I'd say
it should have its own MACHINE_ARCH as well.  Though it could run sparc
architecture binaries, its native toolchain and binary format would not be
compatible with the baseline MACHINE_ARCH "sparc."

-- 
-- Todd Vierling (Personal tv@pobox.com; Bus. todd_vierling@xn.xerox.com)