Add an option DDB_SAFE_CONSOLE that defaults db_console to 1.

In many cases, setting db_console in /etc/rc is too late.

3 files changed, 22 insertions, 3 deletions

diff --git a/share/man/man4/options.4 b/share/man/man4/options.4
index 433be5013d4..ea47b4e3c64 100644
--- a/share/man/man4/options.4
+++ b/share/man/man4/options.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: options.4,v 1.46 2000/02/24 16:09:14 chris Exp $
+.\"	$OpenBSD: options.4,v 1.47 2000/03/02 10:50:28 art Exp $
 .\"	$NetBSD: options.4,v 1.21 1997/06/25 03:13:00 thorpej Exp $
 .\"
 .\" Copyright (c) 1998 Theo de Raadt
@@ -159,6 +159,9 @@ Compiles in a kernel debugger for diagnosing kernel problems. See
 for details.
 .Em NOTE:
 not available on all architectures.
+.It Cd option DDB_SAFE_CONSOLE
+Allows a break into the kernel debugger during boot. Useful when
+debugging problems that can cause init(8) to fail.
 .It Cd option KGDB
 Compiles in a remote kernel debugger stub for diagnosing kernel problems
 using the
diff --git a/sys/conf/GENERIC b/sys/conf/GENERIC
index 6cc6c72c7d3..ba99502ea08 100644
--- a/sys/conf/GENERIC
+++ b/sys/conf/GENERIC
@@ -1,4 +1,4 @@
-#	$OpenBSD: GENERIC,v 1.61 2000/01/09 22:00:16 itojun Exp $
+#	$OpenBSD: GENERIC,v 1.62 2000/03/02 10:50:29 art Exp $
 #
 #	Machine-independent option; used by all architectures for their
 #	GENERIC kernel
@@ -13,6 +13,7 @@ option		SWAPPAGER	# paging; REQUIRED
 option		DEVPAGER	# mmap() of devices
 
 option		DDB		# in-kernel debugger
+#option		DDB_SAFE_CONSOLE # allow break into ddb during boot
 #makeoptions	DEBUG="-g"	# compile full symbol table
 #makeoptions	PROF="-pg"	# build profiled kernel
 #option		GPROF		# kernel profiling, kgmon(8)
diff --git a/sys/kern/subr_prf.c b/sys/kern/subr_prf.c
index 0ec990f67a9..5ab131ddc8d 100644
--- a/sys/kern/subr_prf.c
+++ b/sys/kern/subr_prf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_prf.c,v 1.27 2000/02/22 19:28:04 deraadt Exp $	*/
+/*	$OpenBSD: subr_prf.c,v 1.28 2000/03/02 10:50:29 art Exp $	*/
 /*	$NetBSD: subr_prf.c,v 1.45 1997/10/24 18:14:25 chuck Exp $	*/
 
 /*-
@@ -109,9 +109,24 @@ extern	int log_open;	/* subr_log: is /dev/klog open? */
 const	char *panicstr; /* arg to first call to panic (used as a flag
 			   to indicate that panic has already been called). */
 #ifdef DDB
+/*
+ * Enter ddb on panic.
+ */
 int	db_panic = 1;
+
+/*
+ * db_console controls if we can be able to enter ddb by a special key
+ * combination (machine dependent).
+ * If DDB_SAFE_CONSOLE is defined in the kernel configuration it allows
+ * to break into console during boot. It's _really_ useful when debugging
+ * some things in the kernel that can cause init(8) to crash.
+ */
+#ifdef DDB_SAFE_CONSOLE
+int	db_console = 1;
+#else
 int	db_console = 0;
 #endif
+#endif
 
 /*
  * v_putc: routine to putc on virtual console