diff --git a/sys/kern/subr_intr.c b/sys/kern/subr_intr.c
--- a/sys/kern/subr_intr.c
+++ b/sys/kern/subr_intr.c
@@ -506,6 +506,12 @@
 	vsnprintf(isrc->isrc_name, INTR_ISRC_NAMELEN, fmt, ap);
 	va_end(ap);
 
+	if (flags & INTR_ISRCF_EARLYALLOC) {
+		error = isrc_event_create(isrc);
+		if (error)
+			return (error);
+	}
+
 	mtx_lock(&isrc_table_lock);
 	error = isrc_alloc_irq(isrc);
 	if (error != 0) {
diff --git a/sys/sys/intr.h b/sys/sys/intr.h
--- a/sys/sys/intr.h
+++ b/sys/sys/intr.h
@@ -76,6 +76,7 @@
 #define INTR_ISRCF_IPI		0x01	/* IPI interrupt */
 #define INTR_ISRCF_PPI		0x02	/* PPI interrupt */
 #define INTR_ISRCF_BOUND	0x04	/* bound to a CPU */
+#define INTR_ISRCF_EARLYALLOC	0x10	/* ask for early allocation of event */
 
 struct intr_pic;