Index: include/cpu.h
===================================================================
RCS file: /cvs/src/sys/arch/alpha/include/cpu.h,v
retrieving revision 1.54
diff -u -p -r1.54 cpu.h
--- include/cpu.h	17 Dec 2014 15:23:42 -0000	1.54
+++ include/cpu.h	23 Jun 2015 23:58:26 -0000
@@ -199,6 +199,7 @@ struct cpu_info {
 	struct device *ci_dev;		/* pointer to our device */
 	u_long ci_want_resched;		/* preempt current process */
 	u_long ci_intrdepth;		/* interrupt trap depth */
+	int ci_handled_intr_level;
 	struct trapframe *ci_db_regs;	/* registers for debuggers */
 
 #if defined(MULTIPROCESSOR)
Index: alpha/interrupt.c
===================================================================
RCS file: /cvs/src/sys/arch/alpha/alpha/interrupt.c,v
retrieving revision 1.35
diff -u -p -r1.35 interrupt.c
--- alpha/interrupt.c	19 May 2015 20:28:14 -0000	1.35
+++ alpha/interrupt.c	23 Jun 2015 23:58:26 -0000
@@ -258,13 +258,25 @@ interrupt(unsigned long a0, unsigned lon
 	case ALPHA_INTR_DEVICE:	/* I/O device interrupt */
 	    {
 		struct scbvec *scb;
+		int curipl = alpha_pal_rdps() & ALPHA_PSL_IPL_MASK;
+		int floor;
 
 		KDASSERT(a1 >= SCB_IOVECBASE && a1 < SCB_SIZE);
 
+		/*
+		 * Depending on the system, hardware interrupts may occur
+		 * either at level 3 or level 4.
+		 */
+		if (curipl == ALPHA_PSL_IPL_IO - 1)
+			curipl = ALPHA_PSL_IPL_IO;
+
 		atomic_add_ulong(&ci->ci_intrdepth, 1);
 		atomic_add_int(&uvmexp.intrs, 1);
 		scb = &scb_iovectab[SCB_VECTOIDX(a1 - SCB_IOVECBASE)];
+		floor = ci->ci_handled_intr_level;
+		ci->ci_handled_intr_level = curipl;
 		(*scb->scb_func)(scb->scb_arg, a1);
+		ci->ci_handled_intr_level = floor;
 		atomic_sub_ulong(&ci->ci_intrdepth, 1);
 		break;
 	    }
@@ -606,6 +618,7 @@ _splraise(int s)
 void
 splassert_check(int wantipl, const char *func)
 {
+	struct cpu_info *ci = curcpu();
 	int curipl = alpha_pal_rdps() & ALPHA_PSL_IPL_MASK;
 
 	/*
@@ -617,11 +630,14 @@ splassert_check(int wantipl, const char 
 
 	if (curipl < wantipl) {
 		splassert_fail(wantipl, curipl, func);
+	}
+
+	if (ci->ci_handled_intr_level > wantipl) {
 		/*
-		 * If splassert_ctl is set to not panic, raise the ipl
-		 * in a feeble attempt to reduce damage.
+		 * XXX - need to show difference between what's blocked and
+		 * what's running.
 		 */
-		alpha_pal_swpipl(wantipl);
+		splassert_fail(wantipl, ci->ci_handled_intr_level, func);
 	}
 }
 #endif