[ixp1200] urgent!!!!!!!!!!

Hi, can anyone tell how i can reserve a block of sram . i tried changing linker settings.i am writing data from a script to address location 0x0:0x700 in sram .i set the sram base address to 0x700 but the ixp overwrites data while processing.Is there another way.please help!!!!!!!!!!!!!!!!! Thanks, shweta