--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -476,7 +476,10 @@
 		sigacts_copy(newsigacts, p1->p_sigacts);
 		p2->p_sigacts = newsigacts;
 	}
-	if (flags & RFLINUXTHPN) 
+
+	if (flags & RFTSIGZMB)
+	        p2->p_sigparent = RFTSIGNUM(flags);
+	else if (flags & RFLINUXTHPN)
 	        p2->p_sigparent = SIGUSR1;
 	else
 	        p2->p_sigparent = SIGCHLD;
@@ -723,6 +726,9 @@
 	if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
 		return (EINVAL);
 
+	if ((flags & RFTSIGZMB) && (RFTSIGNUM(flags) > _SIG_MAXSIG))
+		return (EINVAL);
+
 	p1 = td->td_proc;
 
 	/*
--- a/sys/sys/unistd.h
+++ b/sys/sys/unistd.h
@@ -180,6 +180,11 @@
 #define	RFLINUXTHPN	(1<<16)	/* do linux clone exit parent notification */
 #define	RFSTOPPED	(1<<17)	/* leave child in a stopped state */
 #define	RFHIGHPID	(1<<18)	/* use a pid higher than 10 (idleproc) */
+#define	RFTSIGZMB	(1<<19)	/* select signal for exit parent notification */
+#define	RFTSIGSHIFT	20	/* selected signal number is in bits 20-27  */
+#define	RFTSIGMASK	0xFF
+#define	RFTSIGNUM(flags)	(((flags) >> RFTSIGSHIFT) & RFTSIGMASK)
+#define	RFTSIGFLAGS(signum)	((signum) << RFTSIGSHIFT)
 #define	RFPPWAIT	(1<<31)	/* parent sleeps until child exits (vfork) */
 #define	RFKERNELONLY	(RFSTOPPED | RFHIGHPID | RFPPWAIT)