diff -r 00cc4568f10f arch/x86_64/kernel/apic-xen.c
--- a/arch/x86_64/kernel/apic-xen.c	Tue Jul 25 21:07:37 2006 +0200
+++ b/arch/x86_64/kernel/apic-xen.c	Tue Jul 25 21:17:54 2006 +0200
@@ -174,7 +174,8 @@ asmlinkage void smp_error_interrupt(void
 	   6: Received illegal vector
 	   7: Illegal register address
 	*/
-	printk (KERN_DEBUG "APIC error on CPU%d: %02x(%02x)\n",
+	if (num_online_cpus() > 1)
+		printk (KERN_DEBUG "APIC error on CPU%d: %02x(%02x)\n",
 	        smp_processor_id(), v , v1);
 	irq_exit();
 }