In December 2019, VirtualBox began supporting only hardware-assisted virtualization and stopped supporting software-based virtualization.   For an Ethernet network adapter, VirtualBox virtualizes these network interface cards: § 1 Purpose of the contract. This Agreement governs the use of the Oracle VM VirtualBox Extension Pack binary software (the « Product »), which contains a number of additional features for « Oracle VM VirtualBox », which enhance the operation of multiple virtual machines (« Host ») on a single physical computer (« Host »). The product consists of executable files in machine code, script files, data files, and all documentation and updates made available to you by Oracle. VirtualBox can be installed on Windows, macOS, Linux, Solaris and OpenSolaris. There are also ports to FreeBSD and Genode.  It supports the creation and management of virtual docking machines on Windows, Linux, BSD, OS/2, Solaris, Haiku, and OSx86, as well as limited virtualization of macOS clients on Apple hardware.   For some operating systems, a Guest Additions package is available with device drivers and system applications, which typically improves performance, especially graphics performance.  Innotek GmbH also contributed to the development of OS/2 and Linux media in case of virtualization and OS/2 ports of Connectix products which were later acquired by Microsoft. In particular, Innotek developed the « Additions » code in both Windows Virtual PC and Microsoft Virtual Server, which allows different interactions between host operating systems, such as shared clipboards or dynamic viewport size changes.
Starting with version 6.1, VirtualBox only supports this method.   Until then, VirtualBox has only supported some clients (including 64-bit clients, SMP clients, and some proprietary operating systems) on hosts with hardware-assisted virtualization. [Citation required] VirtualBox Guest Additions are a set of software drivers and utilities that are delivered as a subset of the VirtualBox base package and installed in a virtual machine to ensure better performance and usability. Like the VirtualBox base pack, VirtualBox Guest Additions are licensed under GPLv2. While guest add-ons are installed in any appropriate virtual home machine, the extension package is installed on the host on which VirtualBox is running. If you use Enterprise Edition for the benefit of your business or if you need additional functionality, such use is considered commercial use and you must purchase licenses. In the absence of hardware-assisted virtualization, VirtualBox uses a software virtualization approach by default….