Do one thing, do it well.

What I can not create, I do not understand.

进程抽象由两部分组成，cpu抽象和内存抽象。

不读洛阳纸贵之书，不赴争相参观之地，不信喧嚣一时之论。以是，大器初成。

本文主要从ARM汇编的使用者角度，首先介绍各种通用和系统寄存器，接着介绍发生异常时对各种系统寄存器的使用。随后介绍了ARM的指令、调用惯例和汇编宏的使用。最后以对一个裸机启动汇编代码的分析结束了本文。

An exception is an event (other than branch or jump instructions) that causes the normal sequential execution of instructions to be modified. An interrupt is an exception that is not caused directly by program execution. Usually, hardware external to the processor core signals an interrupt, such as a button being pressed

Exceptional level is a logical separation of software execution privilege, similar to ring in x86.

Designers are more efficient and effective if they can raise their level of abstraction.

直接使用as只能在原始类型之间进行转换，但是通过unsafe块能够实现任意两种同样size的其他类型也是可以转换的。如下，

最近对rust的自动解引用以及deref coercion有点懵。