ARC_RA_MSGBUF
arc_read_region(sc, ARC_RA_MSGBUF, &fwinfo, sizeof(fwinfo));
arc_write(sc, ARC_RA_MSGBUF, ARC_FWINFO_SIGNATURE_SET_CONFIG);
arc_write(sc, ARC_RA_MSGBUF+1, ccb_phys_hi);