Add a new sysctl "debug.enter_debugger" (when the kernel is compiled

with 'options DDB').  Setting this to `ddb' or `gdb' breaks into the
kernel debugger in the corresponding mode.  This mechanism has proven
very useful at Whistle for setting breakpoints, etc., while doing
remote serial line kernel debugging.

Obtained from:	Whistle source tree

1 files changed, 77 insertions, 0 deletions

diff --git a/sys/ddb/db_sysctl.c b/sys/ddb/db_sysctl.c
new file mode 100644
index 0000000..5e067c2
--- /dev/null
+++ b/sys/ddb/db_sysctl.c
@@ -0,0 +1,77 @@
+
+/*
+ * db_sysctl.c
+ *
+ * Copyright (c) 2000 Whistle Communications, Inc.
+ * All rights reserved.
+ * 
+ * Subject to the following obligations and disclaimer of warranty, use and
+ * redistribution of this software, in source or object code forms, with or
+ * without modifications are expressly permitted by Whistle Communications;
+ * provided, however, that:
+ * 1. Any and all reproductions of the source or object code must include the
+ *    copyright notice above and the following disclaimer of warranties; and
+ * 2. No rights are granted, in any manner or form, to use Whistle
+ *    Communications, Inc. trademarks, including the mark "WHISTLE
+ *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
+ *    such appears in the above copyright notice or in the software.
+ * 
+ * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
+ * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
+ * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
+ * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
+ * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
+ * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
+ * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
+ * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
+ * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
+ * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * Author: Archie Cobbs <archie@whistle.com>
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/sysctl.h>
+#include <sys/reboot.h>
+
+#define DESCRIPTION	"Set to `ddb' or `gdb' to enter the kernel debugger"
+#define READ_MODE	""
+#define MODE_DDB	"ddb"
+#define MODE_GDB	"gdb"
+
+static int
+sysctl_debug_enter_debugger SYSCTL_HANDLER_ARGS
+{
+	char dmode[64];
+	int error;
+
+	strncpy(dmode, READ_MODE, sizeof(dmode) - 1);
+	dmode[sizeof(dmode) - 1] = '\0';
+	error = sysctl_handle_string(oidp, &dmode[0], sizeof(dmode), req);
+
+	if (error == 0 && req->newptr != NULL) {
+		if (strcmp(dmode, MODE_DDB) == 0)
+			boothowto &= ~RB_GDB;
+		else if (strcmp(dmode, MODE_GDB) == 0)
+			boothowto |= RB_GDB;
+		else
+			return EINVAL;
+		Debugger("debug.enter_debugger");
+	}
+	return error;
+}
+
+SYSCTL_PROC(_debug, OID_AUTO, enter_debugger, CTLTYPE_STRING | CTLFLAG_RW,
+    0, 0, sysctl_debug_enter_debugger, "A", DESCRIPTION);
+