diff -pruN ../orig-linux-2.6.16.29/arch/i386/kernel/entry.S ./arch/i386/kernel/entry.S
--- ../orig-linux-2.6.16.29/arch/i386/kernel/entry.S	2006-09-19 14:05:44.000000000 +0100
+++ ./arch/i386/kernel/entry.S	2006-09-19 14:05:56.000000000 +0100
@@ -406,7 +406,7 @@ vector=0
 ENTRY(irq_entries_start)
 .rept NR_IRQS
 	ALIGN
-1:	pushl $vector-256
+1:	pushl $~(vector)
 	jmp common_interrupt
 .data
 	.long 1b
@@ -423,7 +423,7 @@ common_interrupt:
 
 #define BUILD_INTERRUPT(name, nr)	\
 ENTRY(name)				\
-	pushl $nr-256;			\
+	pushl $~(nr);			\
 	SAVE_ALL			\
 	movl %esp,%eax;			\
 	call smp_/**/name;		\
diff -pruN ../orig-linux-2.6.16.29/arch/i386/kernel/irq.c ./arch/i386/kernel/irq.c
--- ../orig-linux-2.6.16.29/arch/i386/kernel/irq.c	2006-09-12 19:02:10.000000000 +0100
+++ ./arch/i386/kernel/irq.c	2006-09-19 14:05:56.000000000 +0100
@@ -53,8 +53,8 @@ static union irq_ctx *softirq_ctx[NR_CPU
  */
 fastcall unsigned int do_IRQ(struct pt_regs *regs)
 {	
-	/* high bits used in ret_from_ code */
-	int irq = regs->orig_eax & 0xff;
+	/* high bit used in ret_from_ code */
+	int irq = ~regs->orig_eax;
 #ifdef CONFIG_4KSTACKS
 	union irq_ctx *curctx, *irqctx;
 	u32 *isp;
diff -pruN ../orig-linux-2.6.16.29/arch/x86_64/kernel/entry.S ./arch/x86_64/kernel/entry.S
--- ../orig-linux-2.6.16.29/arch/x86_64/kernel/entry.S	2006-09-12 19:02:10.000000000 +0100
+++ ./arch/x86_64/kernel/entry.S	2006-09-19 14:05:56.000000000 +0100
@@ -596,7 +596,7 @@ retint_kernel:	
  */		
 	.macro apicinterrupt num,func
 	INTR_FRAME
-	pushq $\num-256
+	pushq $~(\num)
 	CFI_ADJUST_CFA_OFFSET 8
 	interrupt \func
 	jmp ret_from_intr
diff -pruN ../orig-linux-2.6.16.29/arch/x86_64/kernel/irq.c ./arch/x86_64/kernel/irq.c
--- ../orig-linux-2.6.16.29/arch/x86_64/kernel/irq.c	2006-09-12 19:02:10.000000000 +0100
+++ ./arch/x86_64/kernel/irq.c	2006-09-19 14:05:56.000000000 +0100
@@ -96,8 +96,8 @@ skip:
  */
 asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
 {	
-	/* high bits used in ret_from_ code  */
-	unsigned irq = regs->orig_rax & 0xff;
+	/* high bit used in ret_from_ code  */
+	unsigned irq = ~regs->orig_rax;
 
 	exit_idle();
 	irq_enter();
diff -pruN ../orig-linux-2.6.16.29/arch/x86_64/kernel/smp.c ./arch/x86_64/kernel/smp.c
--- ../orig-linux-2.6.16.29/arch/x86_64/kernel/smp.c	2006-09-12 19:02:10.000000000 +0100
+++ ./arch/x86_64/kernel/smp.c	2006-09-19 14:05:56.000000000 +0100
@@ -135,10 +135,10 @@ asmlinkage void smp_invalidate_interrupt
 
 	cpu = smp_processor_id();
 	/*
-	 * orig_rax contains the interrupt vector - 256.
+	 * orig_rax contains the negated interrupt vector.
 	 * Use that to determine where the sender put the data.
 	 */
-	sender = regs->orig_rax + 256 - INVALIDATE_TLB_VECTOR_START;
+	sender = ~regs->orig_rax - INVALIDATE_TLB_VECTOR_START;
 	f = &per_cpu(flush_state, sender);
 
 	if (!cpu_isset(cpu, f->flush_cpumask))
diff -pruN ../orig-linux-2.6.16.29/include/asm-x86_64/hw_irq.h ./include/asm-x86_64/hw_irq.h
--- ../orig-linux-2.6.16.29/include/asm-x86_64/hw_irq.h	2006-09-12 19:02:10.000000000 +0100
+++ ./include/asm-x86_64/hw_irq.h	2006-09-19 14:05:56.000000000 +0100
@@ -127,7 +127,7 @@ asmlinkage void IRQ_NAME(nr); \
 __asm__( \
 "\n.p2align\n" \
 "IRQ" #nr "_interrupt:\n\t" \
-	"push $" #nr "-256 ; " \
+	"push $~(" #nr ") ; " \
 	"jmp common_interrupt");
 
 #if defined(CONFIG_X86_IO_APIC)