diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index ec4e874..37482fe 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -69,7 +69,7 @@
 #include <asm/xen/pci.h>
 
 #include <asm/xen/pci.h>
-
+#include <linux/kernel.h>
 #define __apicdebuginit(type) static type __init
 #define for_each_irq_pin(entry, head) \
 	for (entry = head; entry; entry = entry->next)
@@ -486,6 +486,11 @@ __ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
 void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
 {
 	unsigned long flags;
+	if (pin == 1 || pin == 0xc) {
+		printk(KERN_INFO "Reprogramming PIN%d, dest=%d\n", pin, e.dest);
+		if (e.dest > 1)
+			dump_stack();
+	}
 	spin_lock_irqsave(&ioapic_lock, flags);
 	__ioapic_write_entry(apic, pin, e);
 	spin_unlock_irqrestore(&ioapic_lock, flags);
@@ -1198,6 +1203,7 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
 	if (old_vector) {
 		cpumask_and(tmp_mask, mask, cpu_online_mask);
 		cpumask_and(tmp_mask, cfg->domain, tmp_mask);
+		printk(KERN_INFO "old_vector: %d  mask: %x\n", old_vector, tmp_mask->bits[0]);
 		if (!cpumask_empty(tmp_mask)) {
 			free_cpumask_var(tmp_mask);
 			return 0;
@@ -1214,6 +1220,8 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
 
 		vector = current_vector;
 		offset = current_offset;
+		printk(KERN_INFO "vector: %d, mask: %x, cpu: %d per_cpu:%x\n",
+			vector, tmp_mask->bits[0], cpu, per_cpu(vector_irq, cpu)[vector]);
 next:
 		vector += 8;
 		if (vector >= first_system_vector) {
@@ -1237,8 +1245,11 @@ next:
 			cfg->move_in_progress = 1;
 			cpumask_copy(cfg->old_domain, cfg->domain);
 		}
-		for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask)
+		for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask) {
 			per_cpu(vector_irq, new_cpu)[vector] = irq;
+			printk(KERN_WARNING "__assign_irq_vector: setting vector_irq[%d]=%d for cpu=%d\n",
+				vector, irq, new_cpu);
+			}
 		cfg->vector = vector;
 		cpumask_copy(cfg->domain, tmp_mask);
 		err = 0;
@@ -1304,6 +1315,8 @@ void __setup_vector_irq(int cpu)
 		if (!cpumask_test_cpu(cpu, cfg->domain))
 			continue;
 		vector = cfg->vector;
+		printk(KERN_INFO "%s: vector: %d on CPU %d set to IRQ: %d\n",
+				__FUNCTION__, vector, cpu, irq);
 		per_cpu(vector_irq, cpu)[vector] = irq;
 	}
 	/* Mark the free vectors */
@@ -1313,8 +1326,11 @@ void __setup_vector_irq(int cpu)
 			continue;
 
 		cfg = irq_cfg(irq);
-		if (!cpumask_test_cpu(cpu, cfg->domain))
+		if (!cpumask_test_cpu(cpu, cfg->domain)) {
+			printk(KERN_INFO "%s: vector %d on CPU %d reset b/c not in affinity mask (%d)\n",
+					__FUNCTION__, vector, cpu, cfg->domain->bits[0]);
 			per_cpu(vector_irq, cpu)[vector] = -1;
+		}
 	}
 }
 
@@ -1452,7 +1468,20 @@ int setup_ioapic_entry(int apic_id, int irq,
 		entry->mask = 1;
 	return 0;
 }
-
+static void dump_vectors(const char *prefix) {
+	int cpu;
+	int vector;
+
+	for (vector = 0x30; vector < 0x3f; vector++) {
+ 		for_each_cpu_and(cpu, 0xff, cpu_online_mask) {
+			if (per_cpu(vector_irq, cpu)[vector] != -1)
+				printk(KERN_INFO "%s [vec:%d,cpu:%d] = irq:%d\n",
+					prefix,
+					vector, cpu,
+					per_cpu(vector_irq, cpu)[vector]);
+		}
+	}
+}
 static void setup_IO_APIC_irq(int apic_id, int pin, unsigned int irq, struct irq_desc *desc,
 			      int trigger, int polarity)
 {
@@ -1465,10 +1494,15 @@ static void setup_IO_APIC_irq(int apic_id, int pin, unsigned int irq, struct irq
 
 	cfg = desc->chip_data;
 
+	printk(KERN_WARNING "setup_IO_APIC_irq: cfg->domain=%d (vector: %d)\n", cfg->domain->bits[0], cfg->vector);
+
+	dump_vectors("PRE");
 	if (assign_irq_vector(irq, cfg, apic->target_cpus()))
 		return;
+	dump_vectors("PAST");
 
 	dest = apic->cpu_mask_to_apicid_and(cfg->domain, apic->target_cpus());
+	printk(KERN_WARNING "setup_IO_APIC_irq: dest=%d\n", dest);
 
 	apic_printk(APIC_VERBOSE,KERN_DEBUG
 		    "IOAPIC[%d]: Set routing entry (%d-%d -> 0x%x -> "