diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index 5458380b6ef8..262292729fc4 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -48,5 +48,6 @@ extern DECLARE_BITMAP(used_vectors, NR_VECTORS);
 extern int vector_used_by_percpu_irq(unsigned int vector);
 
 extern void init_ISA_irqs(void);
+extern int nr_legacy_irqs;
 
 #endif /* _ASM_X86_IRQ_H */
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 409f4943dc1a..1a30587a6bc2 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -94,8 +94,6 @@ struct mpc_intsrc mp_irqs[MAX_IRQ_SOURCES];
 /* # of MP IRQ source entries */
 int mp_irq_entries;
 
-/* Number of legacy interrupts */
-static int nr_legacy_irqs __read_mostly = NR_IRQS_LEGACY;
 /* GSI interrupts */
 static int nr_irqs_gsi = NR_IRQS_LEGACY;
 
@@ -140,27 +138,10 @@ static struct irq_pin_list *get_one_free_irq_2_pin(int node)
 
 /* irq_cfg is indexed by the sum of all RTEs in all I/O APICs. */
 #ifdef CONFIG_SPARSE_IRQ
-static struct irq_cfg irq_cfgx[] = {
+static struct irq_cfg irq_cfgx[NR_IRQS_LEGACY];
 #else
-static struct irq_cfg irq_cfgx[NR_IRQS] = {
+static struct irq_cfg irq_cfgx[NR_IRQS];
 #endif
-	[0]  = { .vector = IRQ0_VECTOR,  },
-	[1]  = { .vector = IRQ1_VECTOR,  },
-	[2]  = { .vector = IRQ2_VECTOR,  },
-	[3]  = { .vector = IRQ3_VECTOR,  },
-	[4]  = { .vector = IRQ4_VECTOR,  },
-	[5]  = { .vector = IRQ5_VECTOR,  },
-	[6]  = { .vector = IRQ6_VECTOR,  },
-	[7]  = { .vector = IRQ7_VECTOR,  },
-	[8]  = { .vector = IRQ8_VECTOR,  },
-	[9]  = { .vector = IRQ9_VECTOR,  },
-	[10] = { .vector = IRQ10_VECTOR, },
-	[11] = { .vector = IRQ11_VECTOR, },
-	[12] = { .vector = IRQ12_VECTOR, },
-	[13] = { .vector = IRQ13_VECTOR, },
-	[14] = { .vector = IRQ14_VECTOR, },
-	[15] = { .vector = IRQ15_VECTOR, },
-};
 
 void __init io_apic_disable_legacy(void)
 {
@@ -185,8 +166,14 @@ int __init arch_early_irq_init(void)
 		desc->chip_data = &cfg[i];
 		zalloc_cpumask_var_node(&cfg[i].domain, GFP_NOWAIT, node);
 		zalloc_cpumask_var_node(&cfg[i].old_domain, GFP_NOWAIT, node);
-		if (i < nr_legacy_irqs)
-			cpumask_setall(cfg[i].domain);
+		/*
+		 * For legacy IRQ's, start with assigning irq0 to irq15 to
+		 * IRQ0_VECTOR to IRQ15_VECTOR on cpu 0.
+		 */
+		if (i < nr_legacy_irqs) {
+			cfg[i].vector = IRQ0_VECTOR + i;
+			cpumask_set_cpu(0, cfg[i].domain);
+		}
 	}
 
 	return 0;
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index d5932226614f..fce55d532631 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -84,24 +84,7 @@ static struct irqaction irq2 = {
 };
 
 DEFINE_PER_CPU(vector_irq_t, vector_irq) = {
-	[0 ... IRQ0_VECTOR - 1] = -1,
-	[IRQ0_VECTOR] = 0,
-	[IRQ1_VECTOR] = 1,
-	[IRQ2_VECTOR] = 2,
-	[IRQ3_VECTOR] = 3,
-	[IRQ4_VECTOR] = 4,
-	[IRQ5_VECTOR] = 5,
-	[IRQ6_VECTOR] = 6,
-	[IRQ7_VECTOR] = 7,
-	[IRQ8_VECTOR] = 8,
-	[IRQ9_VECTOR] = 9,
-	[IRQ10_VECTOR] = 10,
-	[IRQ11_VECTOR] = 11,
-	[IRQ12_VECTOR] = 12,
-	[IRQ13_VECTOR] = 13,
-	[IRQ14_VECTOR] = 14,
-	[IRQ15_VECTOR] = 15,
-	[IRQ15_VECTOR + 1 ... NR_VECTORS - 1] = -1
+	[0 ... NR_VECTORS - 1] = -1,
 };
 
 int vector_used_by_percpu_irq(unsigned int vector)
@@ -116,6 +99,9 @@ int vector_used_by_percpu_irq(unsigned int vector)
 	return 0;
 }
 
+/* Number of legacy interrupts */
+int nr_legacy_irqs __read_mostly = NR_IRQS_LEGACY;
+
 void __init init_ISA_irqs(void)
 {
 	int i;
@@ -142,6 +128,19 @@ void __init init_ISA_irqs(void)
 
 void __init init_IRQ(void)
 {
+	int i;
+
+	/*
+	 * On cpu 0, Assign IRQ0_VECTOR..IRQ15_VECTOR's to IRQ 0..15.
+	 * If these IRQ's are handled by legacy interrupt-controllers like PIC,
+	 * then this configuration will likely be static after the boot. If
+	 * these IRQ's are handled by more mordern controllers like IO-APIC,
+	 * then this vector space can be freed and re-used dynamically as the
+	 * irq's migrate etc.
+	 */
+	for (i = 0; i < nr_legacy_irqs; i++)
+		per_cpu(vector_irq, 0)[IRQ0_VECTOR + i] = i;
+
 	x86_init.irqs.intr_init();
 }
 
diff --git a/arch/x86/kernel/vmiclock_32.c b/arch/x86/kernel/vmiclock_32.c
index 1268d993e9ca..2f1ca5614292 100644
--- a/arch/x86/kernel/vmiclock_32.c
+++ b/arch/x86/kernel/vmiclock_32.c
@@ -235,6 +235,8 @@ void __init vmi_time_init(void)
 
 	vmi_time_init_clockevent();
 	setup_irq(0, &vmi_clock_action);
+	for_each_possible_cpu(cpu)
+		per_cpu(vector_irq, cpu)[vmi_get_timer_vector()] = 0;
 }
 
 #ifdef CONFIG_X86_LOCAL_APIC