From a608af78171a4dc3530d2f50d98ca11420e5a587 Mon Sep 17 00:00:00 2001
From: Robert Watson <rwatson@FreeBSD.org>
Date: Sat, 27 Aug 2011 22:10:45 +0000
Subject: [PATCH] Add support for alternative break-to-debugger to syscons(4). 
 While most keyboards allow console break sequences (such as ctrl-alt-esc) to
 be entered, alternative break can prove useful under virtualisation and
 remote console systems where entering control sequences can be difficult or
 unreliable.

MFC after:	3 weeks
Approved by:	re (bz)
---
 sys/dev/syscons/syscons.c | 4 ++++
 sys/dev/syscons/syscons.h | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/sys/dev/syscons/syscons.c b/sys/dev/syscons/syscons.c
index ebaa945759d..b8f328ee34c 100644
--- a/sys/dev/syscons/syscons.c
+++ b/sys/dev/syscons/syscons.c
@@ -3562,6 +3562,10 @@ next_code:
 	    /* goto next_code */
 	} else {
 	    /* regular keys (maybe MKEY is set) */
+#if !defined(SC_DISABLE_KDBKEY) && defined(KDB)
+	    if (enable_kdbkey)
+		kdb_alt_break(c, &sc->sc_altbrk);
+#endif
 	    if (!(sc->flags & SC_SCRN_BLANKED))
 		return c;
 	}
diff --git a/sys/dev/syscons/syscons.h b/sys/dev/syscons/syscons.h
index a23f88474a3..79f531bd47a 100644
--- a/sys/dev/syscons/syscons.h
+++ b/sys/dev/syscons/syscons.h
@@ -266,6 +266,9 @@ typedef struct sc_softc {
 	u_char		cursor_char;
 	u_char		mouse_char;
 
+#ifdef KDB
+	int		sc_altbrk;
+#endif
 } sc_softc_t;
 
 /* virtual screen */