diff --git a/sys/amd64/amd64/local_apic.c b/sys/amd64/amd64/local_apic.c
index c8f60f0..cfb27bf 100644
--- a/sys/amd64/amd64/local_apic.c
+++ b/sys/amd64/amd64/local_apic.c
@@ -908,6 +908,42 @@ apic_alloc_vector(u_int apic_id, u_int irq)
 	return (0);
 }
 
+/* Request a free IDT vector to be used by the specified IRQ. */
+u_int
+apic_alloc_vector_broadcast(u_int irq)
+{
+	u_int apic_id;
+	u_int vector;
+
+	KASSERT(irq < NUM_IO_INTS, ("Invalid IRQ %u", irq));
+
+	/*
+	 * Search for a free vector.  Currently we just use a very simple
+	 * algorithm to find the first free vector.
+	 */
+	mtx_lock_spin(&icu_lock);
+	for (vector = 0; vector < APIC_NUM_IOINTS; vector++) {
+		for (apic_id = 0; apic_id < LVT_MAX; apic_id++) {
+			if (!lapics[apic_id].la_present)
+				continue;
+			if (lapics[apic_id].la_ioint_irqs[vector] != -1)
+				break;
+		}
+		if (apic_id < LVT_MAX)
+			continue;
+		for (apic_id = 0; apic_id < LVT_MAX; apic_id++) {
+			if (!lapics[apic_id].la_present)
+				continue;
+			lapics[apic_id].la_ioint_irqs[vector] = irq;
+		}
+		mtx_unlock_spin(&icu_lock);
+		printf("apic_alloc_vector_broadcast: vector %u for irq %u\n",
+		    vector + APIC_IO_INTS, irq);
+		return (vector + APIC_IO_INTS);
+	}
+	mtx_unlock_spin(&icu_lock);
+	return (0);
+}
 /*
  * Request 'count' free contiguous IDT vectors to be used by 'count'
  * IRQs.  'count' must be a power of two and the vectors will be
diff --git a/sys/amd64/include/apicvar.h b/sys/amd64/include/apicvar.h
index 91bba99..7093692 100644
--- a/sys/amd64/include/apicvar.h
+++ b/sys/amd64/include/apicvar.h
@@ -186,6 +186,7 @@ extern vm_paddr_t lapic_paddr;
 extern int apic_cpuids[];
 
 u_int	apic_alloc_vector(u_int apic_id, u_int irq);
+u_int	apic_alloc_vector_broadcast(u_int irq);
 u_int	apic_alloc_vectors(u_int apic_id, u_int *irqs, u_int count,
 	    u_int align);
 void	apic_disable_vector(u_int apic_id, u_int vector);