From the below assembler snippet code, I am trying to accesses the CPU id from the register (r0), to a global variable (_cpu_id), and pass the CPU id as a parameter to a function (setup_vector_funcs(_cpu_id )). .extern setup_vector_funcs But I am unable to do it. Can any body please help me.Currently I am using the Processor: ARM7A based LS1021A _SecureException_handler_init: mrc p15,0,r0,c0,c0,5 /* Read Multiprocessor Affinity Register (MPIDR) */ and r0,r0,#0x3 /* Mask off CPU ID */ cmp r0,#0x0 /* Determine if Core 0 */ cpy r12,r13 push {r11-r12,r14,pc} sub r11,r12,#0x04 ldr sp,=_cpu_id /* get address of _cpu_id */ ldr r0,[sp] /*ro will be copied to _cpu_id */ setup_vector_funcs(_cpu_id ) /*Now call the function*/