[OSDI] Virtualization v.s. Emulation

Often, I question myself the difference between "Virtualization" and "Emulation". Hopefully, I found a good explanation on the Internet as below:

Difference by Definition

Virtual machines make use of CPU self-virtualization, to whatever extent it exists, to provide a virtualized interface to the real hardware. Emulators emulate hardware without relying on the CPU being able to run code directly and redirect some operations to a hypervisor controlling the virtual container. -- stackoverflow (geekosaur)

It turns out the main difference is whether (part of) the code is directly run on the host machine (virtualization) or on a software-emulating hardware (emulation).

Again, from this website, we learn:

• Virtualization: involves simulating parts of a computer's hardware
• Emulation: in emulation the virtual machine simulates the complete hardware in software

Example

Virtualization

• Wine

Emulation

• Bochs
• QEMU

Reference

• http://jpc.sourceforge.net/oldsite/Emulation.html
• http://stackoverflow.com/questions/6234711/what-are-the-specific-differences-between-an-emulator-and-a-virtual-machine
• http://stackoverflow.com/questions/1584617/simulator-or-emulator-what-is-the-difference