diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 21fc029..128ae25 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -344,7 +344,9 @@ static void __init acpi_sci_ioapic_setup(u32 gsi, u16 polarity, u16 trigger)
 	 * stash over-ride to indicate we've been here
 	 * and for later update of acpi_gbl_FADT
 	 */
+	printk(KERN_INFO "%s: %d -> %d (%d, %d)\n", __FUNCTION__, acpi_sci_override_gsi, gsi, trigger, polarity);
 	acpi_sci_override_gsi = gsi;
+	
 	return;
 }
 
diff --git a/arch/x86/xen/pci.c b/arch/x86/xen/pci.c
index f999ad8..4cee777 100644
--- a/arch/x86/xen/pci.c
+++ b/arch/x86/xen/pci.c
@@ -69,7 +69,41 @@ int xen_register_gsi(u32 gsi, int triggering, int polarity)
 	}
 	return irq;
 }
+static int xen_sci_override = 0;
+static int xen_sci_trigger = ACPI_ACTIVE_LOW;
+static int xen_sci_polarity = ACPI_EDGE_SENSITIVE;
 
+static int __init
+xen_sci_override_func(char *str)
+{
+	int val;
+
+	while (*str) {
+		if (!strncmp(str, "level", 5)) {
+			xen_sci_trigger = ACPI_LEVEL_SENSITIVE;
+			str+=5;
+		}
+		if (!strncmp(str, "edge", 4)) {
+			xen_sci_trigger = ACPI_EDGE_SENSITIVE;
+			str+=4;
+		}
+		if (!strncmp(str, "high", 4)) {
+			xen_sci_polarity = ACPI_ACTIVE_HIGH;
+			str+=4;
+		}
+		if (!strncmp(str, "low", 3)) {
+			xen_sci_polarity = ACPI_ACTIVE_LOW;
+			str+=3;
+		}
+		str = strpbrk(str, ",");
+		if (!str)
+			break;
+		str++; /* skip ',' */
+	}
+	xen_sci_override = 1;
+	return 0;
+}
+__setup("xen_sci=", xen_sci_override_func);
 void __init xen_setup_pirqs(void)
 {
 	int irq;
@@ -84,13 +118,56 @@ void __init xen_setup_pirqs(void)
 	for (irq = 0; irq < NR_IRQS_LEGACY; irq++) {
 		int trigger, polarity;
 
-		if (acpi_get_override_irq(irq, &trigger, &polarity) == -1)
+		if (acpi_get_override_irq(irq, &trigger, &polarity) == -1) {
+			printk(KERN_INFO "%s: skipping %d\n", __FUNCTION__, irq);
 			continue;
+		}
+		xen_register_gsi(irq,
+			trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE,
+			polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH);
+	}
+	/* For SCI that is above NR_IRQS_LEGACY or xen_sci_override is turned on*/
+	if ((acpi_gbl_FADT.sci_interrupt > NR_IRQS_LEGACY) || 
+	    (acpi_sci_override_gsi > NR_IRQS_LEGACY) ||
+	    (xen_sci_override)) {
+
+		int trigger, polarity;
+	
+		irq = acpi_gbl_FADT.sci_interrupt;
+
+		if ((acpi_sci_override_gsi > NR_IRQS_LEGACY) &&
+		    (acpi_gbl_FADT.sci_interrupt <= NR_IRQS_LEGACY))
+			irq = acpi_sci_override_gsi;
+
+		if ((acpi_sci_override_gsi <= NR_IRQS_LEGACY) &&
+		    (acpi_gbl_FADT.sci_interrupt > NR_IRQS_LEGACY))
+			irq = acpi_gbl_FADT.sci_interrupt;
 
+		printk(KERN_INFO "%s: FADT.SCI: %d ACPI.SCI:%d. Using IRQ %d.\n",
+			__FUNCTION__,
+			acpi_gbl_FADT.sci_interrupt, acpi_sci_override_gsi, irq);
+
+		if (acpi_get_override_irq(irq, &trigger, &polarity) == -1) {
+			printk(KERN_INFO "%s: acpi_get_override_irq fails for %d. \n", __FUNCTION__, irq);
+		}
+		if (xen_sci_override) {
+#define trig2str(x) (x == ACPI_LEVEL_SENSITIVE) ? "level" : "edge"
+#define pol2str(x) (x == ACPI_ACTIVE_LOW) ? "low" : "high"
+			printk(KERN_INFO "%s: SCI override: trigger: %s->%s, polarity: %s->%s\n",
+				__FUNCTION__,
+				trig2str(trigger), trig2str(xen_sci_trigger),
+				pol2str(polarity), pol2str(xen_sci_polarity));
+#undef trig2str
+#undef pol2str
+			trigger =  xen_sci_trigger;
+			polarity =  xen_sci_polarity;
+		}
 		xen_register_gsi(irq,
 			trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE,
 			polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH);
+
 	}
+
 }
 
 #ifdef CONFIG_PCI_MSI
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 7411915..82d60a4 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -688,6 +688,7 @@ void __init acpi_early_init(void)
 		 * update it with result from INT_SRC_OVR parsing
 		 */
 		acpi_gbl_FADT.sci_interrupt = acpi_sci_override_gsi;
+		printk(KERN_INFO "%s: FADT.SCI = %d\n", __FUNCTION__,acpi_sci_override_gsi);
 	}
 #endif