From 161778121a065368a01625f70f6b2380425c1908 Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Tue, 21 Aug 2001 20:09:05 +0000
Subject: Add a hook to mi_switch() to abort via db_error() if we attempt to
 perform a context switch from DDB.

Consulting from:	bde
---
 sys/kern/kern_synch.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index 6a20e1038f8c..e39ee45e3e7e 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -39,6 +39,7 @@
  * $FreeBSD$
  */
 
+#include "opt_ddb.h"
 #include "opt_ktrace.h"
 
 #include <sys/param.h>
@@ -58,6 +59,9 @@
 #include <sys/vmmeter.h>
 #include <vm/vm.h>
 #include <vm/vm_extern.h>
+#ifdef DDB
+#include <ddb/ddb.h>
+#endif
 #ifdef KTRACE
 #include <sys/uio.h>
 #include <sys/ktrace.h>
@@ -664,6 +668,14 @@ mi_switch()
 		    (int64_t)1000000;
 	}
 
+#ifdef DDB
+	/*
+	 * Don't perform context switches from the debugger.
+	 */
+	if (db_active)
+		db_error("Context switches not allowed in the debugger.");
+#endif
+
 #if 0
 	/*
 	 * Check if the process exceeds its cpu resource allocation.
-- 
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