2 files changed, 6 insertions, 0 deletions

diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index 73ef4a85b861..ef2fe474f107 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -590,6 +590,9 @@ void __init acpi_numa_arch_fixup(void)
  */
 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);
 
diff --git a/arch/ia64/sn/kernel/io_acpi_init.c b/arch/ia64/sn/kernel/io_acpi_init.c
index 99d7f278612a..cb96b4ea7df6 100644
--- a/arch/ia64/sn/kernel/io_acpi_init.c
+++ b/arch/ia64/sn/kernel/io_acpi_init.c
@@ -223,6 +223,9 @@ sn_io_acpi_init(void)
         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)