HelenOS sources

SIGKILL            82 uspace/lib/pcut/src/os/unix.c 	kill(child_pid, SIGKILL);
SIGKILL           130 uspace/lib/posix/include/posix/signal.h 	_TOP_SENDABLE_SIGNAL = SIGKILL,
SIGKILL           100 uspace/lib/posix/src/signal.c 	case SIGKILL:
SIGKILL           267 uspace/lib/posix/src/signal.c 	    (sig == SIGKILL || sig == SIGSTOP))) {
SIGKILL           451 uspace/lib/posix/src/signal.c 	case SIGKILL:
SIGKILL           213 uspace/lib/posix/src/string.c 		[SIGKILL] = "SIGKILL (Kill process)",
HelenOS homepage, sources at GitHub