I've been trying to build optimized kernels for my relatively ancient
IBM ThinkPad 760XD.  It has an early-generation pentium-mmx 166MHz CPU.

When I build a kernel with any CPU-specific optimization flags
(-march=pentium-mmx, -march=pentium or even just -mcpu=pentium-mmx,
-mcpu=pentium which should produce i386-compatible code), the resulting
kernel hangs immediately upon loading.

As long as the kernel is built with no cpu-optimizations, it boots and
runs just fine, although probably non-optimally.

Has anyone else experienced a problem like this?  Any clues on what may
be causing this behavior or ways to build cpu-optimized kernels that will
run?

Thanks.

-- 
John D. Baker, KN5UKS                    NetBSD     Darwin/MacOS X
jdbaker(at)mylinuxisp(dot)com                 OpenBSD            FreeBSD
BSD -- It just sits there and _works_!