diff --git a/sys/x86/include/intr_machdep.h b/sys/x86/include/intr_machdep.h
--- a/sys/x86/include/intr_machdep.h
+++ b/sys/x86/include/intr_machdep.h
@@ -151,6 +151,7 @@
 int	intr_remove_handler(void *cookie);
 void	intr_resume(bool suspend_cancelled);
 void	intr_suspend(void);
+void	intr_enable_src(u_int irq);
 void	intr_reprogram(void);
 void	intrcnt_add(const char *name, u_long **countp);
 void	nexus_add_irq(u_long irq);
diff --git a/sys/x86/x86/intr_machdep.c b/sys/x86/x86/intr_machdep.c
--- a/sys/x86/x86/intr_machdep.c
+++ b/sys/x86/x86/intr_machdep.c
@@ -405,6 +405,15 @@
 	mtx_unlock(&intrpic_lock);
 }
 
+void
+intr_enable_src(u_int irq)
+{
+	struct intsrc *is;
+
+	is = interrupt_sources[irq];
+	is->is_pic->pic_enable_source(is);
+}
+
 static int
 intr_assign_cpu(void *arg, int cpu)
 {