When I debug by arm-elf-gdb or OCD Commander. I can’t access the register of ther NS7520 except the basic register such as R0 - R15. When I type “x 0xffb00000” in the gdb,the result show “0xffb00000: Cannot access memory at address 0xffb00000”. How can I read the register ? 0xffb00000 is the address of System Control register of the NS7520?