Timeline of virtualization development

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The following is a timeline of virtualization development. In computing, virtualization is the use of a computer to simulate another computer. Through virtualization, a host simulates a guest by exposing virtual hardware devices, which may be done through software or by allowing access to a physical device connected to the machine.



Note: This timeline is missing data for important historical systems, including: Atlas Computer (Manchester), GE 645, Burroughs B5000.

Year 1960

In the mid-1960s, IBM's Cambridge Scientific Center developed CP-40, the first version of CP/CMS. It went into production use in January 1967. From its inception, CP-40 was intended to implement full virtualization. Doing so required hardware and microcode customization on a S/360-40, to provide the necessary address translation and other virtualization features. Experience on the CP-40 project provided input to the development of the IBM System/360 Model 67, announced in 1965 (along with its ill-starred operating system, TSS/360). CP-40 was re-implemented for the S/360-67 as CP-67, and by April 1967, both versions were in daily production use. CP/CMS was made generally available to IBM customers in source code form, as part of the unsupported IBM Type-III Library, in 1968.

Year 1964

Year 1965

Year 1966

Year 1967

Year 1968

Year 1971

Year 1970

IBM announced the System/370 in 1970. To the disappointment of CP/CMS users – as with the System/360 announcement – the series would not include virtual memory. In 1972, IBM changed direction, announcing that the option would be made available on all S/370 models, and also announcing several virtual storage operating systems, including VM/370. By the mid-1970s, CP/CMS, VM, and the maverick VP/CSS were running on numerous large IBM mainframes. By the late 80s, there were reported to be more VM licenses than MVS licenses.

Year 1972

Year 1973

Year 1977

Year 1979

Year 1985

Year 1987

Year 1988

Year 1991

Year 1994

Year 1997

Year 1998

Year 1999

On February 8, 1999, VMware introduced the first x86 virtualization product for the Intel IA-32 architecture, known as VMware Virtual Platform, based on earlier research by its founders at Stanford University.

VMware Virtual Platform was based on software emulation with Guest/Host OS design that required all Guest environments be stored as files under the host OS filesystem.

Year 2000

Year 2001

Year 2003

Year 2005

Year 2006

Year 2007

Year 2008

Year 2013

Docker, Inc. releases Docker, a series of platform as a service (PaaS) products that use OS-level virtualization.

Year 2014

Sep 8, 2014 Initially designed by Google, the first public build of Kubernetes was released. [7] When Kubernetes first debuted, it offered a number of advantages over Docker, the most popular containerization platform at the time. The purpose of Kubernetes was to make it simple for users to deploy containerized applications across a sizable cluster of container hosts. In order to offer more features and functionality for managing containerized applications at scale, Kubernetes was created to complement Docker rather than to completely replace it. [8] [9]

Overview of Virtualization

As an overview, there are three levels of virtualization

Application virtualization

Application virtualization solutions such as VMware ThinApp, Softricity, and Trigence attempt to separate application-specific files and settings from the host operating system, thus allowing them to run in more-or-less isolated sandboxes without installation and without the memory and disk overhead of full machine virtualization. Application virtualization is tightly tied to the host OS and thus does not translate to other operating systems or hardware. VMware ThinApp and Softricity are Intel Windows centric, while Trigence supports Linux and Solaris. Unlike machine virtualization, Application virtualization does not use code emulation or translation so CPU-related benchmarks run with no changes, though filesystem benchmarks may experience some performance degradation. On Windows, VMware ThinApp and Softricity essentially work by intercepting filesystem and registry requests by an application and redirecting those requests to a preinstalled isolated sandbox, thus allowing the application to run without installation or changes to the local PC. Though VMware ThinApp and Softricity both began independent development around 1998, behind the scenes VMware ThinApp and Softricity are implemented using different techniques:

  • VMware ThinApp works by packaging an application into a single "packaged" EXE which includes the runtime plus the application data files and registry. VMware ThinApp's runtime is loaded by Windows as a normal Windows application, from there the runtime replaces the Windows loader, filesystem, and registry for the target application and presents a merged image of the host PC as if the application had been previously installed. VMware ThinApp replaces all related API functions for the host application, for example the ReadFile API supplied to the application must pass through VMware ThinApp before it reaches the operating system. If the application is reading a virtual file, VMware ThinApp handles the request itself otherwise the request will be passed on to the operating system. Because VMware ThinApp is implemented in user-mode without device drivers and it does not have a client that is preinstalled, applications can run directly from USB Flash or network shares without previously needing elevated security privileges.
  • Softricity (acquired by Microsoft) operates on a similar principle using device drivers to intercept file requests in ring0 at a level closer to the operating system. Softricity installs a client in Administrator mode which can then be accessed by restricted users on the machine. An advantage of virtualizing at the kernel level is the Windows Loader (responsible for loading EXE and DLL files) does not need to be re-implemented and greater application compatibility can be achieved with less work (Softricity claims to support most major applications). A disadvantage of ring0 implementation is that it requires elevated security privileges to be installed and crashes or security defects can occur system-wide rather than being isolated to a specific application.

Because Application Virtualization runs all application code natively, it can only provide security guarantees as strong as the host OS is able to provide. Unlike full machine virtualization, Application virtualization solutions currently do not work with device drivers and other code that runs at ring0 such as virus scanners. These special applications must be installed normally on the host PC to function.

Managed runtimes

Another technique sometimes referred to as virtualization, is portable byte code execution using a standard portable native runtime (aka Managed Runtimes). The two most popular solutions today include Java and .NET. These solutions both use a process called JIT (Just in time) compilation to translate code from a virtual portable Machine Language into the local processor's native code. This allows applications to be compiled for a single architecture and then run on many different machines. Beyond machine portable applications, an additional advantage to this technique includes strong security guarantees. Because all native application code is generated by the controlling environment, it can be checked for correctness (possible security exploits) prior to execution. Programs must be originally designed for the environment in question or manually rewritten and recompiled to work for these new environments. For example, one cannot automatically convert or run a Windows / Linux native app on .NET or Java. Because portable runtimes try to present a common API for applications for a wide variety of hardware, applications are less able to take advantage of OS-specific features. Portable application environments also have higher memory and CPU overheads than optimized native applications, but these overheads are much smaller compared with full machine virtualization. Portable Byte Code environments such as Java have become very popular on the server where a wide variety of hardware exists and the set of OS-specific APIs required is standard across most Unix and Windows flavors. Another popular feature among managed runtimes is garbage collection, which automatically detects unused data in memory and reclaims the memory without the developer having to explicitly invoke "free" operations.

Neutral view of application virtualization

Given the industry bias of the past, to be more neutral, there are also two other ways to look at the Application Level:

  • The first type is application packagers (VMware ThinApp, Softricity) whereas the other is application compilers (Java and .NET). Because it is a packager, it can be used to stream applications without modifying the source code, whereas the latter can only be used to compile the source code.
  • Another way to look at it is from the Hypervisor point of view. The first one is "hypervisor" in user mode, whereas the other is "hypervisor" in runtime mode. The hypervisor was put in quotation, because both of them have similar behavior in that they intercept system calls in a different mode: user mode; and runtime mode. The user mode intercepts the system calls from the runtime mode before going to kernel mode. The real hypervisor only needs to intercept the system call using hypercall in kernel mode. Hopefully, once Windows has a Hypervisor, Virtual machine monitor, there may even be no need for JRE and CLR. Moreover, in the case of Linux, maybe the JRE can be modified to run on top of the Hypervisor as a loadable kernel module running in kernel mode, instead of having slow legacy runtime in user mode. Now, if it were running on top of the Linux Hypervisor directly, then it should be called Java OS, not just another runtime mode JIT.
  • Mendel Rosenblum [10] called the runtime mode a High-level language virtual machine in August 2004. However, at that time, the first type, intercepting system calls in user mode, was irresponsible and unthinkable, so he didn't mention it in his article. Hence, Application Streaming was still mysterious in 2004. [11] Now, when the JVM, no longer High-level language virtual machines, becomes Java OS running on Linux Hypervisor, then Java Applications will have a new level of playing field, just as Windows Applications already has with Softricity.
  • In summary, the first one is virtualizing the Binary Code so that it can be installed once and run anywhere, whereas the other is virtualizing the source code using Byte code or Managed code so that it can be written once and run anywhere. Both of them are actually partial solutions to the twin portability problems of: application portability; and source code portability. Maybe it is time to combine the two problems into one complete solution at the hypervisor level in the kernel mode.

Further development

Microsoft bought Softricity on July 17, 2006, and popularized Application Streaming, giving traditional Windows applications a level playing field with Web and Java applications with respect to the ease of distribution (i.e. no more setup required, just click and run). Soon every JRE and CLR can run virtually in user mode, without kernel mode drivers being installed, such that there can even be multiple versions of JRE and CLR running concurrently in RAM.

The integration of the Linux Hypervisor into the Linux Kernel and that of the Windows Hypervisor into the Windows Kernel may make rootkit techniques such as the filter driver [12] obsolete[ failed verification ]. This may take a while as the Linux Hypervisor is still waiting for the Xen Hypervisor and VMware Hypervisor to be fully compatible with each other as Oracle impatiently pounding at the door to let the Hypervisor come into the Linux Kernel so that it can full steam ahead with its Grid Computing life. Meanwhile, Microsoft have decided to be fully compatible with the Xen Hypervisor . IBM, of course, doesn't just sit idle as it is working with VMware for the x86 servers, and possibly helping Xen to move from x86 into Power ISA using the open source rHype. Now, to make the Hypervisor party into a full house, Intel VT-x and AMD-V are hoping to ease and speed up para-virtualization so that a guest OS can be run unmodified. [ needs update ][ clarification needed ]

See also

Related Research Articles

In computing, a virtual machine (VM) is the virtualization or emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two. Virtual machines differ and are organized by their function, shown here:

<span class="mw-page-title-main">History of operating systems</span> Aspect of computing history

Computer operating systems (OSes) provide a set of functions needed and used by most application programs on a computer, and the links needed to control and synchronize computer hardware. On the first computers, with no operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for peripheral devices like printers and punched paper card readers. The growing complexity of hardware and application programs eventually made operating systems a necessity for everyday use.

<span class="mw-page-title-main">Xen</span> Type-1 hypervisor

Xen is a free and open-source type-1 hypervisor, providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently. It was originally developed by the University of Cambridge Computer Laboratory and is now being developed by the Linux Foundation with support from Intel, Citrix, Arm Ltd, Huawei, AWS, Alibaba Cloud, AMD, Bitdefender and epam.

<span class="mw-page-title-main">UEFI</span> Operating system and firmware specification

Unified Extensible Firmware Interface is a specification that defines the architecture of the platform firmware used for booting the computer hardware and its interface for interaction with the operating system. Examples of firmware that implement the specification are AMI Aptio, Phoenix SecureCore, TianoCore EDK II, InsydeH2O. UEFI replaces the BIOS which was present in the boot ROM of all personal computers that are IBM PC compatible, although it can provide backwards compatibility with the BIOS using CSM booting. Intel developed the original Extensible Firmware Interface (EFI) specification. Some of the EFI's practices and data formats mirror those of Microsoft Windows. In 2005, UEFI deprecated EFI 1.10.

A hypervisor is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called a host machine, and each virtual machine is called a guest machine. The hypervisor presents the guest operating systems with a virtual operating platform and manages the execution of the guest operating systems. Unlike an emulator, the guest executes most instructions on the native hardware. Multiple instances of a variety of operating systems may share the virtualized hardware resources: for example, Linux, Windows, and macOS instances can all run on a single physical x86 machine. This contrasts with operating-system–level virtualization, where all instances must share a single kernel, though the guest operating systems can differ in user space, such as different Linux distributions with the same kernel.

In computing, paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical, to the underlying hardware–software interface.

<span class="mw-page-title-main">QEMU</span> Free virtualization and emulation software

QEMU is a free and open-source emulator. It emulates a computer's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest operating systems. It can interoperate with Kernel-based Virtual Machine (KVM) to run virtual machines at near-native speed. QEMU can also do emulation for user-level processes, allowing applications compiled for one architecture to run on another.

Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic information about platform virtualization hypervisors.

OS-level virtualization is an operating system (OS) virtualization paradigm in which the kernel allows the existence of multiple isolated user space instances, called containers, zones, virtual private servers (OpenVZ), partitions, virtual environments (VEs), virtual kernels, or jails. Such instances may look like real computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources of that computer. However, programs running inside of a container can only see the container's contents and devices assigned to the container.

<span class="mw-page-title-main">Full virtualization</span> Computing technique involving instances of an environment

In computer science, full virtualization (fv) is a modern virtualization technique developed in late 1990s. It is different from simulation and emulation. Virtualization employs techniques that can create instances of a virtual environment, as opposed to simulation, which models the environment; and emulation, which replicates the target environment with certain kinds of virtual environments called emulation environments for virtual machines. Full virtualization requires that every salient feature of the hardware be reflected into one of several virtual machines – including the full instruction set, input/output operations, interrupts, memory access, and whatever other elements are used by the software that runs on the bare machine, and that is intended to run in a virtual machine. In such an environment, any software capable of execution on the raw hardware can be run in the virtual machine and, in particular, any operating systems. The obvious test of full virtualization is whether an operating system intended for stand-alone use can successfully run inside a virtual machine.

<span class="mw-page-title-main">Kernel-based Virtual Machine</span> Virtualization module in the Linux kernel

Kernel-based Virtual Machine (KVM) is a free and open-source virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. It was merged into the mainline Linux kernel in version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules.

<span class="mw-page-title-main">VirtualBox</span> Open-source x86 virtualization application

Oracle VM VirtualBox is a type-2 hypervisor for x86 virtualization developed by Oracle Corporation. VirtualBox was originally created by InnoTek Systemberatung GmbH, which was acquired by Sun Microsystems in 2008, which was in turn acquired by Oracle in 2010.

Hardware virtualization is the virtualization of computers as complete hardware platforms, certain logical abstractions of their componentry, or only the functionality required to run various operating systems. Virtualization hides the physical characteristics of a computing platform from the users, presenting instead an abstract computing platform. At its origins, the software that controlled virtualization was called a "control program", but the terms "hypervisor" or "virtual machine monitor" became preferred over time.

<span class="mw-page-title-main">Hyper-V</span> Native hypervisor by Microsoft

Microsoft Hyper-V, codenamed Viridian, and briefly known before its release as Windows Server Virtualization, is a native hypervisor; it can create virtual machines on x86-64 systems running Windows. Starting with Windows 8, Hyper-V superseded Windows Virtual PC as the hardware virtualization component of the client editions of Windows NT. A server computer running Hyper-V can be configured to expose individual virtual machines to one or more networks. Hyper-V was first released with Windows Server 2008, and has been available without additional charge since Windows Server 2012 and Windows 8. A standalone Windows Hyper-V Server is free, but has a command-line interface only. The last version of free Hyper-V Server is Hyper-V Server 2019, which is based on Windows Server 2019.

Sun xVM was a product line from Sun Microsystems that addressed virtualization technology on x86 platforms. One component was discontinued before the Oracle acquisition of Sun; the remaining two continue under Oracle branding.

Oracle VM Server for x86 is the server virtualization offering from Oracle Corporation. Oracle VM Server for x86 incorporates the free and open-source Xen hypervisor technology, supports Windows, Linux, and Solaris guests and includes an integrated Web based management console. Oracle VM Server for x86 features fully tested and certified Oracle Applications stack in an enterprise virtualization environment.

libvirt Management tool

libvirt is an open-source API, daemon and management tool for managing platform virtualization. It can be used to manage KVM, Xen, VMware ESXi, QEMU and other virtualization technologies. These APIs are widely used in the orchestration layer of hypervisors in the development of a cloud-based solution.

Second Level Address Translation (SLAT), also known as nested paging, is a hardware-assisted virtualization technology which makes it possible to avoid the overhead associated with software-managed shadow page tables.

In computing, a system virtual machine is a virtual machine (VM) that provides a complete system platform and supports the execution of a complete operating system (OS). These usually emulate an existing architecture, and are built with the purpose of either providing a platform to run programs where the real hardware is not available for use, or of having multiple instances of virtual machines leading to more efficient use of computing resources, both in terms of energy consumption and cost effectiveness, or both. A VM was originally defined by Popek and Goldberg as "an efficient, isolated duplicate of a real machine".


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  12. File System Filter Driver