QEMU CPU仿真原理 [英] principle of QEMU CPU emulation

问题描述

在QEMU中，操作系统可以在软件仿真的CPU之上运行. 如何用软件模拟CPU? 我想了解细节.

In QEMU, an operating system can run above software emulated CPU. How can be a CPU emulated by software? I want to know about detail.

如果CPU由软件仿真，寄存器是否与主机系统内存仿真?

假设有ARM汇编代码

LDRB r0, [r1], #1

如何在x86环境中进行仿真?

我的猜测是，仿真软件会保留r0(4个字节)，r1(4个字节)的内存映射空间，然后为相应的内存位置更新寄存器值...我错了吗?

My guess is that emulating software keeps memory mapping space for r0 (4 bytes), r1 (4 bytes) and then updates the register value for corresponding memory location... Am I wrong?

推荐答案

请参阅

Please see this file for the C-level modelling of the state of an ARM CPU as done by QEMU.

这很简单，而且(当然)是因为您怀疑寄存器(以及所有其他状态)都被建模为C变量.

It's pretty straight-forward, and (of course) as you suspect the registers (and all other state) are modelled as C variables.

核心结构开始:

typedef struct CPUARMState {
    /* Regs for current mode.  */
    uint32_t regs[16];
   /* Frequently accessed CPSR bits are stored separately for efficiency.
      This contains all the other bits.  Use cpsr_{read,write} to access
      the whole CPSR.  */
   uint32_t uncached_cpsr;
   uint32_t spsr;

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