I think the definition of math_errhandling is wrong on a couple
architectures.  C99 (7.12) says:

    If the expression math_errhandling & MATH_ERREXCEPT can be nonzero,
    the implementation shall define the macros FE_DIVBYZERO, FE_INVALID,
    and FE_OVERFLOW in <fenv.h>.

math.h always defines math_errhandling as 2 (MATH_ERREXCEPT), but
whether those FE_* macros are defined or not is architecture-dependent.
In particular, ARM only defines them if __ARM_PCS_VFP is defined, and
microblaze does not define them.

It looks like if the architecture doesn't support floating point
exceptions, math_errhandling must be MATH_ERRNO. This in turn requires
that the various math functions set errno appropriately, which it
doesn't look like musl's do.

--
Bobby Bingham