AC_DEFUN([MY_FUNC_MAKECONTEXT],
[
	AC_REQUIRE([AC_CANONICAL_HOST])
	case "$host_os" in
	*darwin*)
		# ucontext appears to be broken, avoid it for now
		ac_cv_func_makecontext=no
		;;
	*)
		AC_CHECK_FUNCS(makecontext)
	esac
	case "$host_os" in
	*irix*|*solaris2.?)
		AC_DEFINE([MAKECONTEXT_SP_HIGH], 1,
			[Define if your makecontext() requires ss_sp at the top of the stack])
		;;
	esac
])