Is it possible to run a virtual machine inside an emulator?

From what I gather a virtual machine makes use of a technology provided by the CPU; a technology called V.T., or "Virtualization Technology" in certain designs of Intel processors. I don't know how this works or how virtualization programs can use this exactly, but I was wondering this:

Say I run Windows 7 inside of Bochs, an x86-64 emulator, or the such. Inside Windows 7 I download VirtualBox, VMware, etc. Will they work? Can a virtual machine work running on a guest emulated OS in an emulator on the host architecture which does not support it? Would there be any issues?

I don't know if any x86-64 emulators support Intel's virtual features, but assuming one did, how feasible could this be in theory?

NOTE: Not a v.m. in a v.m.; a v.m. in an emulator, which has a host CPU that doesn't support V.T.

Think of it this way: program emulates V.T. which also emulates x86-64/etc. Guest OS is running on that, and VirtualBox/etc. can be "tricked" into working on an emulated virtual technology within the emulator's platform, but with a real host CPU that does not support it. Is it possible to emulate virtualization?

user371494

Posted 2014-09-23T18:50:39.590

Reputation:

1You made my brain hurt. – fixer1234 – 2014-09-23T18:55:23.577

1Good thing you don't live inside mine then. – None – 2014-09-23T18:55:50.643

Give it a shot, if it isn't supported it's likely that the system will fail to boot. – Adam – 2014-09-23T18:59:44.443

Seems easy enough to try it..."Is it possible to emulate virtualization?" no its not. – Ramhound – 2014-09-23T19:00:08.813

@Ramhound What's impossible about it? – None – 2014-09-23T19:03:30.600

@Adam What system and why fail to boot? – None – 2014-09-23T19:03:58.230

It depends on how good the emulator is. – Daniel R Hicks – 2014-09-23T19:09:09.873

I don't think any x86-64 emulator can top Bochs, but maybe I've missed one. – None – 2014-09-23T19:12:06.063

And to add, I mean emulate virtualization technology, and not emulate the virtualization itself. The PS3 emulator, RPCS3, is emulating 7 SPUs, a whole GPU, and 24 threads on a single four or eight-core i5/i7. This tells me that there's some hint of possibility that V.T. can be possibly emulated (and that current CPUs could handle it somewhat), but the power to do it and get it working perfectly is probably insane. – None – 2014-09-23T19:15:16.740

Answers

In theory this ought to be possible.

Logic dictates that if the emulator emulates the entire x64 environment perfectly, including Vt-x features, it should be indistinguishable from the real thing and thus support running a VM inside the OS running on the emulator.

Performance would probably be awful though.

I don't know if there is any real emulator out there that has the capability.
I strongly suspect Intel has one for internal use, that they can use as "virtual CPU" to simulate/test/verify new instructions, before making any real hardware with those instruction.

Tonny

Posted 2014-09-23T18:50:39.590

Reputation: 19 919

It could work, but it would be deathly slow.

Firstly Boshs is a virtual machine, just like VirtualBox or VMware Player. The difference is that it emulates 100% of it's hardware. A virtual machine is just a non-physical computer.

It doesn't provide any CPU virtualization features

http://en.wikipedia.org/wiki/Bochs

While Boshs does emulate CPUs that natively provide virtualization support, BoshS doesn't include that function in it's emulation.

It's also worth noting that in Boshs you must specify which features you want the cpu to have from a list of available ones. See: http://bochs.sourceforge.net/cgi-bin/topper.pl?name=New+Bochs+Documentation&url=http://bochs.sourceforge.net/doc/docbook/user/index.html

Virtualization suppport is not a requirement of all virtual machine programs. Some versions of Virtual PC will run without it, as will VirtualBox.

Robin Hood

Posted 2014-09-23T18:50:39.590

Reputation: 3 192

"Virtualization suppport is not a requirement of all virtual machine programs. Some versions of Virtual PC will run without it, as will VirtualBox." Elaborate? – None – 2014-09-23T19:20:38.087

https://www.virtualbox.org/manual/ch01.html#hostossupport read section 1.3 , and https://www.virtualbox.org/manual/ch10.html#hwvirt section 10.3 . hardware virtualization assistance is required for 64bit guests, but not 32bit. Performance does improve with support thought. – Robin Hood – 2014-09-23T19:27:54.430

I did not know that. Thanks! This info will help others as well. – None – 2014-09-23T19:28:38.090

What you call it VT may not be supported in all systems but They run VMware. HOW? They use software processing, I mean a program takes the role of processing VM's data.

ALso VT is a technology to use hardware directly in VMs, If your motherboard supports it, then you should have more speed on inner VM (second i mean).

About problems, No I dont think any problem will occur, Just speed is the issue ...

UltraDEVV

Posted 2014-09-23T18:50:39.590

Reputation: 459