This variable is beyond pointless. Nothing allocates a vector via
alloc_gate() below FIRST_SYSTEM_VECTOR. So nothing can change
first_system_vector.

If there is a need for a gate below FIRST_SYSTEM_VECTOR then it can be
added to the vector defines and FIRST_SYSTEM_VECTOR adjusted accordingly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/desc.h   |   11 ++---------
 arch/x86/kernel/apic/apic.c   |    2 --
 arch/x86/kernel/apic/vector.c |    2 +-
 arch/x86/kernel/idt.c         |    2 +-
 arch/x86/kernel/irq.c         |    2 +-
 5 files changed, 5 insertions(+), 14 deletions(-)

--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -408,21 +408,14 @@ static inline void set_intr_gate(unsigne
 	_set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS);
 }
 
-#ifdef CONFIG_X86_LOCAL_APIC
-extern int first_system_vector;
-#else
-#define first_system_vector		NR_VECTORS
-#endif
-
 /* used_vectors is BITMAP for irq is not managed by percpu vector_irq */
 extern unsigned long used_vectors[];
 
-static inline void alloc_system_vector(int vector)
+static inline void alloc_system_vector(unsigned int vector)
 {
+	BUG_ON(vector < FIRST_SYSTEM_VECTOR);
 	if (!test_bit(vector, used_vectors)) {
 		set_bit(vector, used_vectors);
-		if (first_system_vector > vector)
-			first_system_vector = vector;
 	} else {
 		BUG();
 	}
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -177,8 +177,6 @@ static int disable_apic_timer __initdata
 int local_apic_timer_c2_ok;
 EXPORT_SYMBOL_GPL(local_apic_timer_c2_ok);
 
-int first_system_vector = FIRST_SYSTEM_VECTOR;
-
 /*
  * Debug level, exported for io_apic.c
  */
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -166,7 +166,7 @@ static int __assign_irq_vector(int irq,
 		offset = current_offset;
 next:
 		vector += 16;
-		if (vector >= first_system_vector) {
+		if (vector >= FIRST_SYSTEM_VECTOR) {
 			offset = (offset + 1) % 16;
 			vector = FIRST_EXTERNAL_VECTOR + offset;
 		}
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -290,7 +290,7 @@ void __init idt_setup_apic_and_irq_gates
 
 	idt_setup_from_table(idt_table, apic_idts, ARRAY_SIZE(apic_idts));
 
-	for_each_clear_bit_from(i, used_vectors, first_system_vector) {
+	for_each_clear_bit_from(i, used_vectors, FIRST_SYSTEM_VECTOR) {
 		entry = irq_entries_start + 8 * (i - FIRST_EXTERNAL_VECTOR);
 		set_intr_gate(i, entry);
 	}
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -414,7 +414,7 @@ int check_irq_vectors_for_cpu_disable(vo
 		 * this w/o holding vector_lock.
 		 */
 		for (vector = FIRST_EXTERNAL_VECTOR;
-		     vector < first_system_vector; vector++) {
+		     vector < FIRST_SYSTEM_VECTOR; vector++) {
 			if (!test_bit(vector, used_vectors) &&
 			    IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector])) {
 				if (++count == this_count)