Minimal OS for running virtual machines [closed]

Is there a minimalistic operating system built purely for the purpose of running virtual machines (preferrably open source / otherwise free)?

If not, let's say I decided to do something like Linux From Scratch. What is the minimum I could get away with while still being able to run something like Virtual Box (or your recommended virtual machine middleware)?

The intention is to have a machine that I can use purely for the purpose of running virtual machines for test configurations on software (parallel or otherwise) in development. I would like to do this without having to run a full-fledged generic-use OS underneath the virtual machines, if possible (trying to get as much performance as possible for each virtual machine).

Solution 1:

NetBSD is often considered quite "minimalist" as it comes with very little extra software pre-installed, and yet I find it to be excellent for running Xen to virtualize many different Operating Systems, including MS-Windows.

Here's a free, step-by-step guide that I wrote which explains how to get virtualization technology running with free, open source software (including an alternative to MS-Windows that is also free and open source, and is not WINE):

  Step-by-step guide to installing Xen on NetBSD
  http://www.lumbercartel.ca/library/xen/

Many people have also given me feedback (and a few suggestions; credits are included at the end of the guide) on this. So far, my guide has greatly simplified the process of installing Xen and getting it running for most people. (I also use this guide when installing Xen for my clients who need virtualization on Unix because it saves me time.)

I do hope you find this guide useful.

Solution 2:

Have a look at Hyper-V Server from Microsoft.