diff --git a/sys/sys/ras.h b/sys/sys/ras.h
index 60b3f5a4879c..838a19fd8443 100644
--- a/sys/sys/ras.h
+++ b/sys/sys/ras.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: ras.h,v 1.11 2008/04/28 20:24:11 martin Exp $	*/
+/*	$NetBSD: ras.h,v 1.12 2008/04/29 20:50:42 scw Exp $	*/
 
 /*-
  * Copyright (c) 2002, 2004, 2007 The NetBSD Foundation, Inc.
@@ -32,6 +32,7 @@
 #ifndef _SYS_RAS_H_
 #define _SYS_RAS_H_
 
+#ifndef __ASSEMBLER__
 #include <sys/types.h>
 #include <sys/queue.h>
 
@@ -44,16 +45,21 @@ struct ras {
 #define RAS_INSTALL		0
 #define RAS_PURGE		1
 #define RAS_PURGE_ALL		2
+#else
+#include <sys/cdefs.h>
+#endif /* __ASSEMBLER__ */
 
 #ifdef _KERNEL
 
+#ifndef __ASSEMBLER__
 struct proc;
 
 void	*ras_lookup(struct proc *, void *);
 int	ras_fork(struct proc *, struct proc *);
 int	ras_purgeall(void);
+#endif /* __ASSEMBLER__ */
 
-#else
+#else /* !_KERNEL */
 
 #ifndef	RAS_DECL
 
@@ -65,6 +71,9 @@ extern void __CONCAT(name,_ras_start(void)), __CONCAT(name,_ras_end(void))
 /*
  * RAS_START and RAS_END contain implicit instruction reordering
  * barriers.  See __insn_barrier() in <sys/cdefs.h>.
+ *
+ * Note: You are strongly advised to avoid coding RASs in C. There is a
+ * good chance the compiler will generate code which cannot be restarted.
  */
 #define	RAS_START(name)							\
 	__asm volatile(".globl " ___STRING(name) "_ras_start\n"	\
@@ -80,10 +89,42 @@ extern void __CONCAT(name,_ras_start(void)), __CONCAT(name,_ras_end(void))
 #define	RAS_SIZE(name)	((size_t)((uintptr_t) __CONCAT(name,_ras_end) -	\
 				  (uintptr_t) __CONCAT(name,_ras_start)))
 
+#ifndef __ASSEMBLER__
 __BEGIN_DECLS
 int rasctl(void *, size_t, int);
 __END_DECLS
 
+#else /* __ASSEMBLER__ */
+
+/*
+ * RAS_START_ASM and RAS_END_ASM are for use within assembly code.
+ * This is the prefered method of coding a RAS.
+ */
+#define	RAS_START_ASM(name)						\
+	.globl _C_LABEL(__CONCAT(name,_ras_start));			\
+	_C_LABEL(__CONCAT(name,_ras_start)):
+
+#define	RAS_END_ASM(name)						\
+	.globl _C_LABEL(__CONCAT(name,_ras_end));			\
+	_C_LABEL(__CONCAT(name,_ras_end)):
+
+/*
+ * RAS_START_ASM_HIDDEN and RAS_END_ASM_HIDDEN are similar to the above,
+ * except that they limit the scope of the symbol such that it will not
+ * be placed into the dynamic symbol table. Thus no other module (executable
+ * or shared library) can reference it directly.
+ */
+#define	RAS_START_ASM_HIDDEN(name)					\
+	.globl _C_LABEL(__CONCAT(name,_ras_start));			\
+	.hidden _C_LABEL(__CONCAT(name,_ras_start));			\
+	_C_LABEL(__CONCAT(name,_ras_start)):
+
+#define	RAS_END_ASM_HIDDEN(name)					\
+	.globl _C_LABEL(__CONCAT(name,_ras_end));			\
+	.hidden _C_LABEL(__CONCAT(name,_ras_start));			\
+	_C_LABEL(__CONCAT(name,_ras_end)):
+#endif /* __ASSEMBLER__ */
+
 #endif /* _KERNEL */
 
 #endif /* !_SYS_RAS_H_ */