[ixp1200] Addressing I21555's Interrupt regs....

Hi, Does anyone know where in the Virtual address space of strong arm core are Primary Set IRQ and Primary clear IRQ of i21555 available (if they are?) I was trying to map the appropriate 512 MB addresses into the physical memory by changing CSR_PCIADDR_EXT variable whose lower half should be available in the virtual address space. Thanks, Himanshu