说明：  ARMv8-A架构参考手册。Cortex-M系列处理面向嵌入式应用，而Cortex-R系列则面向实时应用，Cortex-A，则面向广大的手机用户。这是A系列参考手册。
(Architecture Reference Manual. ARMv8, for ARMv8-A architecture profile. Cortex-M series processing is oriented to embedded applications, while Cortex-R series is oriented to real-time applications, and Cortex-A is oriented to the majority of mobile phone users. This is the A series reference manual.)