generally be honored. However, some signals are explicitly unblocked:
the synchronous signals, SIGILL, SIGTRAP, SIGSTKFLT, SIGCHLD, SIGPROF,
and, on Linux, signals 32 (SIGCANCEL) and 33 (SIGSETXID)
(SIGCANCEL and SIGSETXID are used internally by glibc). Subprocesses
started by [os.Exec], or by [os/exec], will inherit the
modified signal mask.

# Changing the behavior of signals in Go programs

		// mstart(), the combined runtime can deadlock if
		// these signals are blocked. Thus, don't block these
		// signals when exiting threads.
		// - glibc: SIGCANCEL (32), SIGSETXID (33)
		// - musl: SIGTIMER (32), SIGCANCEL (33), SIGSYNCCALL (34)
		sigdelset(&res, 32)
		sigdelset(&res, 33)
		sigdelset(&res, 34)
	}

	return res
}()

		//
		// QEMU turns calls to the sigaction system call into
		// calls to the C library sigaction call; the C
		// library call rejects attempts to call sigaction for
		// SIGCANCEL (32) or SIGSETXID (33).
		//
		// QEMU rejects calling sigaction on SIGRTMAX (64).
		//
		// Just ignore the error in these case. There isn't
		// anything we can do about it anyhow.