diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index b3bfb38..be30cf3 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -908,6 +908,16 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domctl_t) u_domctl)
         else
             ret = pirq_deny_access(d, pirq);
 
+        printk("**DBG perms { %u, %d } = %ld\n", pirq, allow, ret);
+        if ( ret )
+        {
+            printk(" Domain %"PRId16", nr_pirqs %d\n",
+                   d->domain_id, d->nr_pirqs);
+            printk(" dom_pirq_to_irq(%d) = %d\n",
+                   pirq, domain_pirq_to_irq(d, pirq));
+            rangeset_domain_printk(d);
+        }
+
         rcu_unlock_domain(d);
     }
     break;