What is the booting process for ARM?

Question

As we know, for X86 architecture: After we press the power button, machine starts to execute code at 0xFFFFFFF0, then it starts to execute code in BIOS in order to do hardware i

Answer 1

After Power is ON The cpu will start executing exception mode 1st one is reset ,As Reset must run as superviser mode since CPU doesn't know the status of the register at this time of execution it cant go into the superviser mode .To achieve this small code need to be written (See at end). after this other exceptions can be handled by loading the address into PC .

.globl _start
 _start: b       reset
    ldr     pc, _undefined_instruction
    ldr     pc, _software_interrupt
    ldr     pc, _prefetch_abort
    ldr     pc, _data_abort
    ldr     pc, _not_used
    ldr     pc, _irq
    ldr     pc, _fiq

reset:
    mrs     r0,cpsr                 /* set the cpu to SVC32 mode        */
    bic     r0,r0,#0x1f             /* (superviser mode, M=10011)       */
    orr     r0,r0,#0x13
    msr     cpsr,r0