x86: change FIRST_SYSTEM_VECTOR to a variable

The SGI UV system needs several more system vectors than a vanilla
x86_64 system.  Rather than burden the other archs with extra system
vectors that they don't use, change FIRST_SYSTEM_VECTOR to a variable,
so that it can be dynamic.

Signed-off-by: Alan Mayer <ajm@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index a40d54f..0ae4a9d 100644
--- a/arch/x86/kernel/io_apic_32.c
+++ b/arch/x86/kernel/io_apic_32.c
@@ -83,6 +83,10 @@
 
 static int disable_timer_pin_1 __initdata;
 
+int first_system_vector = 0xfe;
+
+char system_vectors[NR_VECTORS] = { [0 ... NR_VECTORS-1] = SYS_VECTOR_FREE};
+
 /*
  * Rough estimation of how many shared IRQs there are, can
  * be changed anytime.
@@ -1176,7 +1180,7 @@
 	offset = current_offset;
 next:
 	vector += 8;
-	if (vector >= FIRST_SYSTEM_VECTOR) {
+	if (vector >= first_system_vector) {
 		offset = (offset + 1) % 8;
 		vector = FIRST_DEVICE_VECTOR + offset;
 	}
@@ -2269,7 +2273,7 @@
 	int i;
 
 	/* Reserve all the system vectors. */
-	for (i = FIRST_SYSTEM_VECTOR; i < NR_VECTORS; i++)
+	for (i = first_system_vector; i < NR_VECTORS; i++)
 		set_bit(i, used_vectors);
 
 	enable_IO_APIC();