Unrecognised Instruction Flushda Error

Hi,everybody.I encountered a error as the following when i compilered the uclinux kernel. I followed the steps like:

http://www.nioswiki.com/installnios2linux

My OS is ubuntu9.04

gcc is 4.2

Platform is DE2_70

Could anybody help to fix it,

Thanks.:)

----------------------------------------------------------

LD usr/built-in.o

CC arch/nios2/mm/memory.o

{standard input}: Assembler messages:

{standard input}:96: Error: unrecognised instruction flushda

{standard input}:232: Error: unrecognised instruction flushda

{standard input}:364: Error: unrecognised instruction flushda

{standard input}:427: Error: unrecognised instruction flushda

make[3]: *** [arch/nios2/mm/memory.o] Error 1

make[2]: *** [arch/nios2/mm] Error 2

make[1]: *** [sub-make] Error 2