diff --git a/include/linux/irq.h b/include/linux/irq.h
index 1d73d1abb834..5f4b013624dc 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -179,7 +179,11 @@ struct irq_desc {
 	const char		*name;
 } ____cacheline_internodealigned_in_smp;
 
+#ifdef CONFIG_HAVE_DYN_ARRAY
+extern struct irq_desc *irq_desc;
+#else
 extern struct irq_desc irq_desc[NR_IRQS];
+#endif
 
 /*
  * Migration helpers for obsolete names, they will go away:
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index e9d022cf593e..e94eeca09ea9 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -48,6 +48,36 @@ handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  * Controller mappings for all interrupt sources:
  */
 int nr_irqs = NR_IRQS;
+
+#ifdef CONFIG_HAVE_DYN_ARRAY
+static struct irq_desc irq_desc_init __initdata = {
+	.status = IRQ_DISABLED,
+	.chip = &no_irq_chip,
+	.handle_irq = handle_bad_irq,
+	.depth = 1,
+	.lock = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
+#ifdef CONFIG_SMP
+	.affinity = CPU_MASK_ALL
+#endif
+};
+
+static void __init init_work(void *data)
+{
+	struct dyn_array *da = data;
+	int i;
+	struct  irq_desc *desc;
+
+	desc = *da->name;
+
+	for (i = 0; i < *da->nr; i++)
+		memcpy(&desc[i], &irq_desc_init, sizeof(struct irq_desc));
+}
+
+struct irq_desc *irq_desc;
+DEFINE_DYN_ARRAY(irq_desc, sizeof(struct irq_desc), nr_irqs, PAGE_SIZE, init_work);
+
+#else
+
 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 	[0 ... NR_IRQS-1] = {
 		.status = IRQ_DISABLED,
@@ -60,6 +90,7 @@ struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 #endif
 	}
 };
+#endif
 
 /*
  * What should we do if we get a hw irq event on an illegal vector?