--- rt29/kernel/irq/manage.c	2006-07-10 09:01:21.000000000 +0900
+++ rt-powerpc/kernel/irq/manage.c	2006-07-21 20:17:50.000000000 +0900
@@ -723,15 +723,24 @@ static int do_irqd(void * __desc)
 		set_current_state(TASK_INTERRUPTIBLE);
 		do_hardirq(desc);
 		cond_resched_all();
+#ifndef CONFIG_PPC_PMAC64 /* work around: to revert to patch-2.6.16-rt20 version */
 		local_irq_disable();
+#endif /* !CONFIG_PPC_PMAC64 */
 		__do_softirq();
 		local_irq_enable();
 #ifdef CONFIG_SMP
 		/*
 		 * Did IRQ affinities change?
 		 */
+#ifdef CONFIG_PPC_PMAC64 /* work around; revert to patch-2.6.16-rt20 version */
+		if (!cpu_isset(smp_processor_id(), irq_affinity[irq])) {
+			mask = cpumask_of_cpu(any_online_cpu(irq_affinity[irq]));
+			set_cpus_allowed(current, mask);
+		}
+#else
 		if (!cpus_equal(current->cpus_allowed, irq_affinity[irq]))
 			set_cpus_allowed(current, irq_affinity[irq]);
+#endif /* CONFIG_PPC_PMAC64 */
 #endif
 		schedule();
 	}