在虚拟机中实现 I/O 的更好方法？
我正在编写一个虚拟机 - 不是像 Virtualbox 这样的现有架构模拟器，而是像 JVM 或 BEAM 这样的东西 - 具有自己的指令集、内存模型等。最终我计划实现一个非常小且简单的（但图灵完备）高级语言可以编译成字节码，只是为了好玩。
当然，机器必须有一些 I/O 支持，但我不想将其仅限于使用 stdin/stdout 进行操作。我想象类似模块化“虚拟设备”的东西，它可以实现为共享库，以便虚拟机可以在运行时加载它们并通过标准接口与它们通信。例如，通过这种方式，我们可以拥有用于标准输入/输出、图形的“虚拟设备”（想象一个虚拟设备，让您的 VM 程序在 SDL 窗口内绘制内容）甚至网络。
问题是：为VM编写的程序应该如何与虚拟设备通信？我决定模仿实际硬件所采用的技术，并了解基于端口的 I/O 和内存映射 I/O。但是，我不确定其中哪一个更适合我的目标。您能否建议哪一个更好，或者甚至指出一种完全不同的处理输入/输出的技术？
提前致谢。
I'm writing a virtual machine - not an existing architecture emulator like Virtualbox, but rather something like the JVM or BEAM - with its own instruction set, memory model, etc. Eventually I'm planning to implement a very small and simple (but turing-complete) high-level language that would compile into its bytecode, just for fun.
Of course, the machine must have some support of I/O, but I do not want to limit it only to manipulations with stdin/stdout. I imagine something like modular "virtual devices", which can be implemented as shared libraries so that the VM can load them at runtime and communicate with them through a standard interface. This way, for example, we can have "virtual devices" for standard input/output, graphics (imagine a virtual device that lets your VM program draw stuff inside an SDL window) or maybe even network.
The question is: how should the programs written for the VM communicate with the virtual devices? I decided to mimic techniques which are employed with actual hardware and learned about port-based I/O and memory-mapped I/O. However, I'm not sure which one of them is more suitable for my goals. Can you suggest which one is better or maybe even point out a totally different technique for dealing with input/output?
Thanks in advance.
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内存映射和基于端口都不适合大多数 I/O。
带有块复制的 DMA 请求通常就是您想要的。
Both memory-mapped and port based are inappropriate for most I/O.
DMA request with block-copy is usually what you want.