From b41e0f0f56e729972814d4be35bf380f7d349a17 Mon Sep 17 00:00:00 2001
From: Marcel Moolenaar <marcel@FreeBSD.org>
Date: Mon, 12 Jul 2004 04:43:58 +0000
Subject: [PATCH] Document the new PT_LWPINFO request. In fact, the request is
 so new it hasn't even been implemented yet. I just wanted to be the first to
 try a new approach to development ;-)

---
 lib/libc/sys/ptrace.2 | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/libc/sys/ptrace.2 b/lib/libc/sys/ptrace.2
index 18683faf89aa..a8910d7466a6 100644
--- a/lib/libc/sys/ptrace.2
+++ b/lib/libc/sys/ptrace.2
@@ -278,6 +278,25 @@ it loads the traced process's debug registers from the
 .In machine/reg.h )
 pointed to by
 .Fa addr .
+.It Dv PT_LWPINFO
+This request can be used to obtain information about the kernel thread,
+also known as light-weight process, that caused the traced process to stop.
+The
+.Fa addr
+argument specifies a pointer to a
+.Vt "struct ptrace_lwpinfo" ,
+which is defined as follows:
+.Bd -literal
+struct ptrace_lwpinfo {
+	lwpid_t pl_lwpid;	/* LWP described. */
+	int	pl_event;	/* Event received. */
+};
+.Ed
+.Pp
+The
+.Fa data
+argument is to be set to the size of the structure known to the caller.
+This allows the structure to grow without affecting older programs.
 .El
 .Pp
 Additionally, machine-specific requests can exist.