Index: ./lib/libc/sys/ptrace.2
===================================================================
RCS file: /cvsroot/src/lib/libc/sys/ptrace.2,v
retrieving revision 1.80
diff -u -r1.80 ptrace.2
--- ./lib/libc/sys/ptrace.2	30 Jul 2019 20:18:11 -0000	1.80
+++ ./lib/libc/sys/ptrace.2	9 Oct 2019 12:51:06 -0000
@@ -1,7 +1,7 @@
 .\"	$NetBSD: ptrace.2,v 1.80 2019/07/30 20:18:11 mgorny Exp $
 .\"
 .\" This file is in the public domain.
-.Dd July 11, 2019
+.Dd October 9, 2019
 .Dt PTRACE 2
 .Os
 .Sh NAME
@@ -252,6 +252,35 @@
 had been used with
 .Dv SIGKILL
 given as the signal to be delivered.
+The
+.Fa addr
+and
+.Fa data
+arguments are ignored.
+The difference is that
+.Dv PT_KILL
+can be used for a non-stopped tracee.
+.It Dv PT_STOP
+The traced process stops, as if
+.Xr kill
+had been used with
+.Dv SIGSTOP
+given as the signal to be delivered.
+The difference is that
+.Dv PT_STOP
+will set the waited flag to 0 and child will be waiting for
+.Xr wait 2
+call.
+The
+.Fa addr
+and
+.Fa data
+arguments are ignored.
+The
+.Dv PT_CONTINUE
+call cannot be used as a general replacement for
+.Dv PT_STOP
+as it will error for a running child.
 .It Dv PT_ATTACH
 This request allows a process to gain control of an otherwise unrelated
 process and begin tracing it.