Index: head/sys/amd64/include/intr_machdep.h
===================================================================
--- head/sys/amd64/include/intr_machdep.h
+++ head/sys/amd64/include/intr_machdep.h
@@ -83,7 +83,7 @@
 
 #ifndef LOCORE
 
-typedef void inthand_t(u_int cs, u_int ef, u_int esp, u_int ss);
+typedef void inthand_t(void);
 
 #define	IDTVEC(name)	__CONCAT(X,name)
 
Index: head/sys/amd64/include/md_var.h
===================================================================
--- head/sys/amd64/include/md_var.h
+++ head/sys/amd64/include/md_var.h
@@ -36,9 +36,6 @@
 
 extern  uint64_t *vm_page_dump;
 
-/* XXX */
-typedef void alias_for_inthand_t(u_int cs, u_int ef, u_int esp, u_int ss);
-
 struct	savefpu;
 
 void	amd64_db_resume_dbreg(void);
Index: head/sys/i386/include/intr_machdep.h
===================================================================
--- head/sys/i386/include/intr_machdep.h
+++ head/sys/i386/include/intr_machdep.h
@@ -83,7 +83,7 @@
 
 #ifndef LOCORE
 
-typedef void inthand_t(u_int cs, u_int ef, u_int esp, u_int ss);
+typedef void inthand_t(void);
 
 #define	IDTVEC(name)	__CONCAT(X,name)
 
Index: head/sys/i386/include/md_var.h
===================================================================
--- head/sys/i386/include/md_var.h
+++ head/sys/i386/include/md_var.h
@@ -46,7 +46,6 @@
 #endif
 extern	uint32_t *vm_page_dump;
 
-typedef void alias_for_inthand_t(u_int cs, u_int ef, u_int esp, u_int ss);
 struct	segment_descriptor;
 union savefpu;
 
Index: head/sys/x86/include/x86_var.h
===================================================================
--- head/sys/x86/include/x86_var.h
+++ head/sys/x86/include/x86_var.h
@@ -86,6 +86,13 @@
 struct  dbreg;
 struct	dumperinfo;
 
+/*
+ * The interface type of the interrupt handler entry point cannot be
+ * expressed in C.  Use simplest non-variadic function type as an
+ * approximation.
+ */
+typedef void alias_for_inthand_t(void);
+
 void	*alloc_fpusave(int flags);
 void	busdma_swi(void);
 bool	cpu_mwait_usable(void);