diff -Nru linux-2.6.10-adeos-orig/arch/ppc/kernel/adeos.c linux-2.6.10-adeos-work/arch/ppc/kernel/adeos.c
--- linux-2.6.10-adeos-orig/arch/ppc/kernel/adeos.c	2005-05-25 21:22:41.289901000 +0300
+++ linux-2.6.10-adeos-work/arch/ppc/kernel/adeos.c	2005-05-25 23:23:17.954761000 +0300
@@ -65,6 +65,11 @@
 
 struct pt_regs __adeos_irq_regs;
 
+#ifdef CONFIG_POWER4
+extern struct irqaction k2u3_cascade_action;
+extern int openpic2_get_irq(struct pt_regs *regs);
+#endif
+
 /* Current reload value for the decrementer. */
 unsigned long __adeos_decr_ticks;
 
@@ -346,7 +351,7 @@
 
 {
     irq_desc_t *desc = irq_desc + irq;
-
+    
     if (desc->handler->ack != NULL)
 	{
 	unsigned long adflags;
@@ -364,7 +369,19 @@
 	preempt_disable();
 #endif /* CONFIG_PREEMPT */
 	spin_lock(&desc->lock);
-	desc->handler->ack(irq);
+	desc->handler->ack(irq); 
+#ifdef CONFIG_POWER4
+	/* if it is a k2u3 cascaded irq, acknowledge it, also */
+	if (desc->action == &k2u3_cascade_action) {
+	    struct pt_regs regs;
+	    int irq2 = openpic2_get_irq(&regs);
+	    if (irq2 != -1) {
+                irq_desc_t *desc2 = irq_desc + irq2;
+		if (desc2->handler->ack)
+		    desc2->handler->ack(irq2);
+	    }
+	}
+#endif
 	spin_unlock(&desc->lock);
 #ifdef CONFIG_PREEMPT
 	preempt_enable_no_resched();
@@ -565,6 +582,14 @@
 	return 1;
 	}
 
+#ifdef CONFIG_POWER4
+    /* On 970 CPUs DEC cannot be disabled, and without setting DEC
+     * here, DEC interrupt would be triggered as soon as interrupts are
+     * enabled in __adeos_sync_stage 
+     */
+    set_dec(0x7fffffff);
+#endif
+    
     __adeos_irq_regs.msr = regs->msr; /* for do_timer() */
 
     __adeos_handle_irq(ADEOS_TIMER_VIRQ,regs);
diff -Nru linux-2.6.10-adeos-orig/arch/ppc/platforms/pmac_pic.c linux-2.6.10-adeos-work/arch/ppc/platforms/pmac_pic.c
--- linux-2.6.10-adeos-orig/arch/ppc/platforms/pmac_pic.c	2004-12-24 23:35:28.000000000 +0200
+++ linux-2.6.10-adeos-work/arch/ppc/platforms/pmac_pic.c	2005-05-25 23:09:37.535483000 +0300
@@ -387,7 +387,12 @@
 	return IRQ_HANDLED;
 }
 
+#ifdef CONFIG_ADEOS_CORE
+/* this is used in kernel/adeos.c adeos_acknowledge_irq */
+struct irqaction k2u3_cascade_action = {
+#else /* !CONFIG_ADEOS_CORE */
 static struct irqaction k2u3_cascade_action = {
+#endif /* CONFIG_ADEOS_CORE */
 	.handler	= k2u3_action,
 	.flags		= 0,
 	.mask		= CPU_MASK_NONE,