1 files changed, 17 insertions, 18 deletions

diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index 89b9510e8030..d2f787b3de56 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();
 }