Pull sgi into release branch

arch/ia64/kernel/acpi.c

···
  */
 int acpi_register_gsi(u32 gsi, int triggering, int polarity)
 {
+	if (acpi_irq_model == ACPI_IRQ_MODEL_PLATFORM)
+		return gsi;
+
 	if (has_8259 && gsi < 16)
 		return isa_irq_to_vector(gsi);
 

arch/ia64/sn/kernel/io_acpi_init.c

···
 	u64 result;
 	s64 status;
 
+	/* SN Altix does not follow the IOSAPIC IRQ routing model */
+	acpi_irq_model = ACPI_IRQ_MODEL_PLATFORM;
+
 	acpi_bus_register_driver(&acpi_sn_hubdev_driver);
 	status = sal_ioif_init(&result);
 	if (status || result)

drivers/acpi/bus.c

···
 	case ACPI_IRQ_MODEL_IOSAPIC:
 		message = "IOSAPIC";
 		break;
+	case ACPI_IRQ_MODEL_PLATFORM:
+		message = "platform specific model";
+		break;
 	default:
 		printk(KERN_WARNING PREFIX "Unknown interrupt routing model\n");
 		return -ENODEV;

include/linux/acpi.h

···
 	ACPI_IRQ_MODEL_PIC = 0,
 	ACPI_IRQ_MODEL_IOAPIC,
 	ACPI_IRQ_MODEL_IOSAPIC,
+	ACPI_IRQ_MODEL_PLATFORM,
 	ACPI_IRQ_MODEL_COUNT
 };