memset(&ss, 0, sizeof ss);
	ss.ss_sp = signalStack;
	ss.ss_flags = 0;
	ss.ss_size = CSIGSTKSZ;
	if (sigaltstack(&ss, &oss) < 0) {
		perror("sigaltstack");
		abort();
	}
}

static void restoreSignalStack(void) {
#if (defined(__x86_64__) || defined(__i386__)) && defined(__APPLE__)
	// The Darwin C library enforces a minimum that the kernel does not.
	// This is OK since we allocated this much space in mpreinit,