System Control Registers in ARM Cortex-A7
When MCR or MRC instructions execute with different cRm or opt2 , then what is the status of cRn register? For example if run: asm volatile("mcr p15, 0, %0, c9, c13, 0" : : "r"(val)) or asm volatile("mcr p15, 0, %0, c9, c13, 2" : : "r"(val)) then, which register's value will be changed c9 or c13 ? and what is the role of last option(0 or 2)?. here The MCR and MRC instructions are generic coprocessor instructions. What these instructions do depends on the particular hardware you're using, what coprocessors it has, and the values of the opcode and coprocessor register operands ( opcode1 ,