Sun Microsystems 3.0.0 user manual Features overview

1 Introduction

Warning: Do not run other hypervisors (open-source or commercial virtu- alization products) together with VirtualBox! While several hypervisors can normally be installed in parallel, do not attempt to run several virtual ma- chines from competing hypervisors at the same time. VirtualBox cannot track what another hypervisor is currently attempting to do on the same host, and especially if several products attempt to use hardware virtualization features such as VT-x, this can crash the entire host.

In addition to “plain” hardware virtualization, your processor may also support ad- ditional sophisticated techniques:1

•A newer feature called “nested paging” implements some memory management in hardware, which can greatly accelerate hardware virtualization since these tasks no longer need to be performed by the virtualization software.

On AMD processors, nested paging has been available starting with the Barcelona (K10) architecture; Intel added support for nested paging, which they call “extended page tables” (EPT), with their Core i7 (Nehalem) processors.

Nested paging is still disabled by default even for new machines, but it can be enabled for each virtual machine individually in the machine settings.

If your system supports nested paging (AMD-V) or EPT (VT-x), then you can expect a significant performance increase by enabling hardware virtualization and the nested paging feature

•Another hardware feature called “Virtual Processor Identifiers” (VPIDs) can greatly accelerate context switching by reducing the need for expensive flushing of the processor’s Translation Lookaside Buffers (TLBs). To enable this feature for a VM, you need to use the command line; see chapter 8.5, VBoxManage modifyvm, page 107.

1.3 Features overview

Here’s a brief outline of VirtualBox’s main features:

•Portability. VirtualBox runs on a large number of 32-bit and 64-bit host op- erating systems (Windows, Linux, Mac OS X and Solaris; see chapter 1.4, Sup- ported host operating systems, page 16 for details). Virtual machines can easily be imported and exported using the industry-standard Open Virtualization Format (OVF, see chapter 3.8, Importing and exporting virtual machines, page 56). Since the file and image formats used are identical on all the platforms, this works between all supported host operating systems.

1VirtualBox 2.0 added support for AMD’s nested paging; support for Intel’s EPT and VPIDs was added with version 2.1.

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