Understanding Simulation, Virtualization & Emulation

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When working with Software/Android development, especially in automotive projects, you’ll often hear terms like emulation, virtualization, simulation. These concepts often overlap in practice, but each one has a distinct meaning. They can be painful if we don’t understand them properly. I will try my best to explain them in simple words.

1. Simulation

Creating a model that mimics how something behaves, but it’s not the real thing. It reproduces the system’s logic and interactions at a higher level without what is actually under the hood

In Android context:

  • For example: When you design a layout in Android Studio’s XML Layout Preview, it’s not running a real Android OS or rendering pipeline. Instead, it just simulates how your layout might look on a device by estimating rendering.
  • Another example could be a real flight or F1 or train Simulator or think of Simulation based games. They mimic real-world behavior without running the same code

2. Emulation

Emulation means reproducing the hardware environment of another system. This includes translating CPU instructions from one architecture to another.

In Android context:

  • If you run an ARM Android image on your x86_64 laptop, you are running in emulation.
  • Tools like QEMU (Quick Emulator) come into play. QEMU takes ARM instructions and dynamically translates them into x86_64 instructions that your laptop CPU understands.
  • This process is slower because every instruction has to be translated.

Note:

  • When you emulate, QEMU provides virtual hardware drivers (for graphics, networking, storage, etc.). If the vendor doesn’t provide a QEMU-compatible driver, the emulated hardware can’t function properly.

3. Virtualization

Virtualization is about running multiple operating systems on the same physical hardware, sharing resources, without translating instructions. Instead, a special software layer called a hypervisor manages this.

In Android context:

  • If you run an x86_64 Android image on your x86_64 laptop, but instead of QEMU you use KVM (Kernel-based Virtual Machine) or HAXM (Intel’s Hardware Accelerated Execution Manager), you are doing virtualization.
  • No instruction translation is needed because both guest (Android) and host (Linux/Windows) are x86_64.
  • The hypervisor just partitions resources: CPU, RAM, GPU, etc.

This is why virtualization is much faster than emulation.

Another example could be VirtualBox running Ubuntu on Windows.

Why is Android an emulator and iOS is a Simulator?

mindblown
  • Android emulates real hardware based in your systems architecture where as iOS does not emulate the iPhone hardware
  • Android runs its actual OS but iOS only simulates using macOS frameworks
  • That’s why Android works on multiple platform and iOS doesn’t

Summary

  • Simulation: Like playing a flight simulator game. You’re not actually flying, but the behavior looks real.
  • Emulation: Like hiring a translator to help you speak a foreign language. Communication is possible but slower.
  • Virtualization: Like two people speaking the same language but sharing a house. They divide resources (rooms, food, chores) efficiently.

Final words

All the above information are human typed (me) and not AI. I want to improve my English Vocabulary and share what I learn. Hope you can also take away something and I’ll be happy 🙂