CP-67 is a hypervisor , or Virtual Machine Monitor, from IBM for its System/360 Model 67 computer.
58-433: A hypervisor , also known as a virtual machine monitor ( VMM ) or virtualizer , 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
116-662: A S/360-40 modified at the Cambridge Scientific Center to support dynamic address translation , a feature that enabled virtualization. Prior to this time, computer hardware had only been virtualized to the extent to allow multiple user applications to run concurrently, such as in CTSS and IBM M44/44X . With CP-40, the hardware's supervisor state was virtualized as well, allowing multiple operating systems to run concurrently in separate virtual machine contexts. Programmers soon implemented CP-40 (as CP-67 ) for
174-555: A hypervisor is a microkernel implementing virtualization infrastructure that must run in kernel-space for technical reasons, such as Intel VMX . Microkernels implementing virtualization mechanisms are also referred to as microhypervisor . Applying this terminology to Linux , KVM is a hypervisor and QEMU or Cloud Hypervisor are VMMs utilizing KVM as hypervisor. In his 1973 thesis, "Architectural Principles for Virtual Computer Systems," Robert P. Goldberg classified two types of hypervisor: The distinction between these two types
232-532: A provider and accessed over the Internet . The process of developing software involves several stages. The stages include software design , programming , testing , release , and maintenance . Software quality assurance and security are critical aspects of software development, as bugs and security vulnerabilities can lead to system failures and security breaches. Additionally, legal issues such as software licenses and intellectual property rights play
290-509: A vulnerability . Software patches are often released to fix identified vulnerabilities, but those that remain unknown ( zero days ) as well as those that have not been patched are still liable for exploitation. Vulnerabilities vary in their ability to be exploited by malicious actors, and the actual risk is dependent on the nature of the vulnerability as well as the value of the surrounding system. Although some vulnerabilities can only be used for denial of service attacks that compromise
348-520: A web application —had become the primary method that companies deliver applications. Software companies aim to deliver a high-quality product on time and under budget. A challenge is that software development effort estimation is often inaccurate. Software development begins by conceiving the project, evaluating its feasibility, analyzing the business requirements, and making a software design . Most software projects speed up their development by reusing or incorporating existing software, either in
406-457: A change request. Frequently, software is released in an incomplete state when the development team runs out of time or funding. Despite testing and quality assurance , virtually all software contains bugs where the system does not work as intended. Post-release software maintenance is necessary to remediate these bugs when they are found and keep the software working as the environment changes over time. New features are often added after
464-486: A code's correct and efficient behavior, its reusability and portability , or the ease of modification. It is usually more cost-effective to build quality into the product from the beginning rather than try to add it later in the development process. Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and easier to maintain . Software failures in safety-critical systems can be very serious including death. By some estimates,
522-698: A further requirement for small memory-size and low overhead. Finally, in contrast to the ubiquity of the x86 architecture in the PC world, the embedded world uses a wider variety of architectures and less standardized environments. Support for virtualization requires memory protection (in the form of a memory management unit or at least a memory protection unit) and a distinction between user mode and privileged mode , which rules out most microcontrollers . This still leaves x86 , MIPS , ARM and PowerPC as widely deployed architectures on medium- to high-end embedded systems. As manufacturers of embedded systems usually have
580-412: A global view of scheduling and power management, and fine-grained control of information flows. The use of hypervisor technology by malware and rootkits installing themselves as a hypervisor below the operating system, known as hyperjacking , can make them more difficult to detect because the malware could intercept any operations of the operating system (such as someone entering a password) without
638-443: A legal regime where liability for software products is significantly curtailed compared to other products. Source code is protected by copyright law that vests the owner with the exclusive right to copy the code. The underlying ideas or algorithms are not protected by copyright law, but are often treated as a trade secret and concealed by such methods as non-disclosure agreements . Software copyright has been recognized since
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#1732787953979696-503: A properly configured System/360 as a single-user system without CP-67." The minimum configuation for CP-67 is: Disks to be used by CP have to be formatted by a standalone utility called FORMAT , loaded from tape or punched cards . CP disks are formatted with fixed-length 829 byte records. Following formatting, a second stand-alone utility, DIRECT , partitions the disk space between permanent (system and user files) and temporary (paging and spooling) space. DIRECT also creates
754-487: A quick web search . Most creative professionals have switched to software-based tools such as computer-aided design , 3D modeling , digital image editing , and computer animation . Almost every complex device is controlled by software. CP-67 CP-67 is the control program portion of CP/CMS , a virtual machine operating system developed by IBM's Cambridge Scientific Center in Cambridge, Massachusetts . It
812-541: A series of disputed and bitter battles, time-sharing lost out to batch processing through IBM political infighting, and VM remained IBM's "other" mainframe operating system for decades, losing to MVS . It enjoyed a resurgence of popularity and support from 2000 as the z/VM product, for example as the platform for Linux on IBM Z . As mentioned above, the VM control program includes a hypervisor-call handler that intercepts DIAG ("Diagnose", opcode x'83') instructions used within
870-495: A significant role in the distribution of software products. The first use of the word software is credited to mathematician John Wilder Tukey in 1958. The first programmable computers, which appeared at the end of the 1940s, were programmed in machine language . Machine language is difficult to debug and not portable across different computers. Initially, hardware resources were more expensive than human resources . As programs became complex, programmer productivity became
928-447: A single kernel, though the guest operating systems can differ in user space , such as different Linux distributions with the same kernel. The term hypervisor is a variant of supervisor , a traditional term for the kernel of an operating system : the hypervisor is the supervisor of the supervisors, with hyper- used as a stronger variant of super- . The term dates to circa 1970; IBM coined it for software that ran OS/360 and
986-514: A specific version of the software, downloaded, and run on hardware belonging to the purchaser. The rise of the Internet and cloud computing enabled a new model, software as a service (SaaS), in which the provider hosts the software (usually built on top of rented infrastructure or platforms ) and provides the use of the software to customers, often in exchange for a subscription fee . By 2023, SaaS products—which are usually delivered via
1044-415: A system's availability, others allow the attacker to inject and run their own code (called malware ), without the user being aware of it. To thwart cyberattacks, all software in the system must be designed to withstand and recover from external attack. Despite efforts to ensure security, a significant fraction of computers are infected with malware. Programming languages are the format in which software
1102-463: A virtual machine. This provides fast-path non-virtualized execution of file-system access and other operations (DIAG is a model-dependent privileged instruction, not used in normal programming, and thus is not virtualized. It is therefore available for use as a signal to the "host" operating system). When first implemented in CP/CMS release 3.1, this use of DIAG provided an operating system interface that
1160-402: Is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the machine language specific to the hardware. The introduction of high-level programming languages in 1958 allowed for more human-readable instructions, making software development easier and more portable across different computer architectures . Software in a programming language
1218-720: Is heavily discouraged, because Integrity VM implements its own memory management, scheduling and I/O policies that are tuned for virtual machines and are not as effective for normal applications. HPE also provides more rigid partitioning of their Integrity and HP9000 systems by way of VPAR and nPar technology, the former offering shared resource partitioning and the latter offering complete I/O and processing isolation. The flexibility of virtual server environment (VSE) has given way to its use more frequently in newer deployments. IBM provides virtualization partition technology known as logical partitioning (LPAR) on System/390 , zSeries , pSeries and IBM AS/400 systems. For IBM's Power Systems,
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#17327879539791276-514: Is not always clear. For instance, KVM and bhyve are kernel modules that effectively convert the host operating system to a type-1 hypervisor. The first hypervisors providing full virtualization were the test tool SIMMON and the one-off IBM CP-40 research system, which began production use in January 1967 and became the first version of the IBM CP/CMS operating system. CP-40 ran on
1334-414: Is run through a compiler or interpreter to execute on the architecture's hardware. Over time, software has become complex, owing to developments in networking , operating systems , and databases . Software can generally be categorized into two main types: The rise of cloud computing has introduced the new software delivery model Software as a Service (SaaS). In SaaS, applications are hosted by
1392-453: Is written. Since the 1950s, thousands of different programming languages have been invented; some have been in use for decades, while others have fallen into disuse. Some definitions classify machine code —the exact instructions directly implemented by the hardware—and assembly language —a more human-readable alternative to machine code whose statements can be translated one-to-one into machine code—as programming languages. Programs written in
1450-540: The IBM System/360-67 , the first production computer system capable of full virtualization. IBM shipped this machine in 1966; it included page-translation-table hardware for virtual memory and other techniques that allowed a full virtualization of all kernel tasks, including I/O and interrupt handling. (Note that the "official" operating system, the ill-fated TSS/360 , did not employ full virtualization.) Both CP-40 and CP-67 began production use in 1967. CP/CMS
1508-583: The POWER6 processor. LPAR and MSPP capacity allocations can be dynamically changed. Memory is allocated to each LPAR (at LPAR initiation or dynamically) and is address-controlled by the POWER Hypervisor. For real-mode addressing by operating systems ( AIX , Linux , IBM i ), the Power processors ( POWER4 onwards) have designed virtualization capabilities where a hardware address-offset is evaluated with
1566-438: The high-level programming languages used to create software share a few main characteristics: knowledge of machine code is not necessary to write them, they can be ported to other computer systems, and they are more concise and human-readable than machine code. They must be both human-readable and capable of being translated into unambiguous instructions for computer hardware. The invention of high-level programming languages
1624-745: The 1960s-era IBM S/360 line. The 1972 announcement also included VM/370 , a reimplementation of CP/CMS for the S/370. Unlike CP/CMS , IBM provided support for this version (though it was still distributed in source code form for several releases). VM stands for Virtual Machine , emphasizing that all, not just some, of the hardware interfaces are virtualized. Both VM and CP/CMS enjoyed early acceptance and rapid development by universities, corporate users, and time-sharing vendors, as well as within IBM. Users played an active role in ongoing development, anticipating trends seen in modern open source projects. However, in
1682-574: The 7090 emulator concurrently on the 360/65 and later used it for the DIAG handler of CP-67. In the earlier CP/CMS (1967) system, the term Control Program was used instead. Some literature, especially in microkernel contexts, makes a distinction between hypervisor and virtual machine monitor (VMM). There, both components form the overall virtualization stack of a certain system. Hypervisor refers to kernel-space functionality and VMM to user-space functionality. Specifically in these contexts,
1740-541: The Integrity VM hypervisor layer that allows for many important features of HP-UX to be taken advantage of and provides major differentiation between this platform and other commodity platforms - such as processor hotswap, memory hotswap, and dynamic kernel updates without system reboot. While it heavily leverages HP-UX, the Integrity VM hypervisor is really a hybrid that runs on bare-metal while guests are executing. Running normal HP-UX applications on an Integrity VM host
1798-905: The OS address-offset to arrive at the physical memory address. Input/Output (I/O) adapters can be exclusively "owned" by LPARs or shared by LPARs through an appliance partition known as the Virtual I/O Server (VIOS). The Power Hypervisor provides for high levels of reliability, availability and serviceability (RAS) by facilitating hot add/replace of many parts (model dependent: processors, memory, I/O adapters, blowers, power units, disks, system controllers, etc.) Similar trends have occurred with x86/x86-64 server platforms, where open-source projects such as Xen have led virtualization efforts. These include hypervisors built on Linux and Solaris kernels as well as custom kernels. Since these technologies span from large systems down to desktops, they are described in
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1856-483: The POWER Hypervisor (PHYP) is a native (bare-metal) hypervisor in firmware and provides isolation between LPARs. Processor capacity is provided to LPARs in either a dedicated fashion or on an entitlement basis where unused capacity is harvested and can be re-allocated to busy workloads. Groups of LPARs can have their processor capacity managed as if they were in a "pool" - IBM refers to this capability as Multiple Shared-Processor Pools (MSPPs) and implements it in servers with
1914-532: The anti-malware software necessarily detecting it (since the malware runs below the entire operating system). Implementation of the concept has allegedly occurred in the SubVirt laboratory rootkit (developed jointly by Microsoft and University of Michigan researchers) as well as in the Blue Pill malware package. However, such assertions have been disputed by others who claim that it would be possible to detect
1972-399: The bottleneck. The introduction of high-level programming languages in 1958 hid the details of the hardware and expressed the underlying algorithms into the code . Early languages include Fortran , Lisp , and COBOL . There are two main types of software: Software can also be categorized by how it is deployed . Traditional applications are purchased with a perpetual license for
2030-404: The correctness of code, while user acceptance testing helps to ensure that the product meets customer expectations. There are a variety of software development methodologies , which vary from completing all steps in order to concurrent and iterative models. Software development is driven by requirements taken from prospective users, as opposed to maintenance, which is driven by events such as
2088-400: The cost of poor quality software can be as high as 20 to 40 percent of sales. Despite developers' goal of delivering a product that works entirely as intended, virtually all software contains bugs. The rise of the Internet also greatly increased the need for computer security as it enabled malicious actors to conduct cyberattacks remotely. If a bug creates a security risk, it is called
2146-419: The cost of products. Unlike copyrights, patents generally only apply in the jurisdiction where they were issued. Engineer Capers Jones writes that "computers and software are making profound changes to every aspect of human life: education, work, warfare, entertainment, medicine, law, and everything else". It has become ubiquitous in everyday life in developed countries . In many cases, software augments
2204-452: 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 (usually called containers ) must share
2262-438: The form of commercial off-the-shelf (COTS) or open-source software . Software quality assurance is typically a combination of manual code review by other engineers and automated software testing . Due to time constraints, testing cannot cover all aspects of the software's intended functionality, so developers often focus on the most critical functionality. Formal methods are used in some safety-critical systems to prove
2320-439: The functionality of existing technologies such as household appliances and elevators . Software also spawned entirely new technologies such as the Internet , video games , mobile phones , and GPS . New methods of communication, including email , forums , blogs , microblogging , wikis , and social media , were enabled by the Internet. Massive amounts of knowledge exceeding any paper-based library are now available with
2378-816: The hypervisor (and can all run simultaneously on the same processor, as fully virtualized independent guest OSes). Wind River "Carrier Grade Linux" also runs on Sun's Hypervisor. Full virtualization on SPARC processors proved straightforward: since its inception in the mid-1980s Sun deliberately kept the SPARC architecture clean of artifacts that would have impeded virtualization. (Compare with virtualization on x86 processors below.) HPE provides HP Integrity Virtual Machines (Integrity VM) to host multiple operating systems on their Itanium powered Integrity systems. Itanium can run HP-UX , Linux, Windows and OpenVMS , and these environments are also supported as virtual servers on HP's Integrity VM platform. The HP-UX operating system hosts
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2436-818: The hypervisor simulates. This is called paravirtualization in Xen , a "hypercall" in Parallels Workstation , and a "DIAGNOSE code" in IBM VM . Some microkernels, such as Mach and L4 , are flexible enough to allow paravirtualization of guest operating systems. Embedded hypervisors , targeting embedded systems and certain real-time operating system (RTOS) environments, are designed with different requirements when compared to desktop and enterprise systems, including robustness, security and real-time capabilities. The resource-constrained nature of many embedded systems, especially battery-powered mobile systems, imposes
2494-597: The mid-1970s and is vested in the company that makes the software, not the employees or contractors who wrote it. The use of most software is governed by an agreement ( software license ) between the copyright holder and the user. Proprietary software is usually sold under a restrictive license that limits copying and reuse (often enforced with tools such as digital rights management (DRM)). Open-source licenses , in contrast, allow free use and redistribution of software with few conditions. Most open-source licenses used for software require that modifications be released under
2552-473: The multimillion-dollar range at the high end), although virtualization has also been available on some low- and mid-range systems, such as IBM pSeries servers, HP Superdome series machines, and Sun / Oracle T-series CoolThreads servers. Although Solaris has always been the only guest domain OS officially supported by Sun/Oracle on their Logical Domains hypervisor, as of late 2006, Linux (Ubuntu and Gentoo), and FreeBSD have been ported to run on top of
2610-508: The next section. X86 virtualization was introduced in the 1990s, with its emulation being included in Bochs . Intel and AMD released their first x86 processors with hardware virtualisation in 2005 with Intel VT-x (code-named Vanderpool) and AMD-V (code-named Pacifica). An alternative approach requires modifying the guest operating system to make a system call to the underlying hypervisor, rather than executing machine I/O instructions that
2668-472: The operating system) can take this saved file and execute it as a process on the computer hardware. Some programming languages use an interpreter instead of a compiler. An interpreter converts the program into machine code at run time , which makes them 10 to 100 times slower than compiled programming languages. Software is often released with the knowledge that it is incomplete or contains bugs. Purchasers knowingly buy it in this state, which has led to
2726-618: The physical world may also be part of the requirements for a software patent to be held valid. Software patents have been historically controversial . Before the 1998 case State Street Bank & Trust Co. v. Signature Financial Group, Inc. , software patents were generally not recognized in the United States. In that case, the Supreme Court decided that business processes could be patented. Patent applications are complex and costly, and lawsuits involving patents can drive up
2784-448: The presence of a hypervisor-based rootkit. In 2009, researchers from Microsoft and North Carolina State University demonstrated a hypervisor-layer anti-rootkit called Hooksafe that can provide generic protection against kernel-mode rootkits . Software Software consists of computer programs that instruct the execution of a computer . Software also includes design documents and specifications. The history of software
2842-408: The release. Over time, the level of maintenance becomes increasingly restricted before being cut off entirely when the product is withdrawn from the market. As software ages , it becomes known as legacy software and can remain in use for decades, even if there is no one left who knows how to fix it. Over the lifetime of the product, software maintenance is estimated to comprise 75 percent or more of
2900-424: The same license, which can create complications when open-source software is reused in proprietary projects. Patents give an inventor an exclusive, time-limited license for a novel product or process. Ideas about what software could accomplish are not protected by law and concrete implementations are instead covered by copyright law . In some countries, a requirement for the claimed invention to have an effect on
2958-662: The source code to their operating systems, they have less need for full virtualization in this space. Instead, the performance advantages of paravirtualization make this usually the virtualization technology of choice. Nevertheless, ARM and MIPS have recently added full virtualization support as an IP option and has included it in their latest high-end processors and architecture versions, such as ARM Cortex-A15 MPCore and ARMv8 EL2. Other differences between virtualization in server/desktop and embedded environments include requirements for efficient sharing of resources across virtual machines, high-bandwidth, low-latency inter-VM communication,
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#17327879539793016-489: The stable main production system, and without requiring costly additional development systems. IBM announced its System/370 series in 1970 without the virtual memory feature needed for virtualization, but added it in the August 1972 Advanced Function announcement. Virtualization has been featured in all successor systems, such that all modern-day IBM mainframes, including the zSeries line, retain backward compatibility with
3074-431: The total development cost. Completing a software project involves various forms of expertise, not just in software programmers but also testing, documentation writing, project management , graphic design , user experience , user support, marketing , and fundraising. Software quality is defined as meeting the stated requirements as well as customer expectations. Quality is an overarching term that can refer to
3132-491: The user directory identifying the virtual machines (users) available in the system. For each user the directory contains identifying information, id and password, and lists the resources (core, devices, etc) that this user can access, Although a user may be allowed access to physical devices it is more common to specify virtual devices, such as a spooled card reader, card punch, and printer. A user can be allocated one or more virtual disk units, "mini disks" [sic.], which resemble
3190-507: Was a reimplementation of their earlier research system CP-40 , which ran on a one-off customized S/360-40. CP-67 was later reimplemented (again) as CP-370 , which IBM released as VM/370 in 1972, when virtual memory was added to the System/370 series. CP and CMS are usually grouped together as a unit, but the "components are independent of each other. CP-67 can be used on an appropriate configuration without CMS, and CMS can be run on
3248-715: Was analogous to the System/360 Supervisor Call instruction (SVC), but that did not require altering or extending the system's virtualization of SVC. In 1985 IBM introduced the PR/SM hypervisor to manage logical partitions (LPAR). Several factors led to a resurgence around 2005 in the use of virtualization technology among Unix , Linux , and other Unix-like operating systems: Major Unix vendors, including HP , IBM , SGI , and Sun Microsystems , have been selling virtualized hardware since before 2000. These have generally been large, expensive systems (in
3306-576: Was available to IBM customers from 1968 to early 1970s, in source code form without support. CP/CMS formed part of IBM's attempt to build robust time-sharing systems for its mainframe computers. By running multiple operating systems concurrently, the hypervisor increased system robustness and stability: Even if one operating system crashed, the others would continue working without interruption. Indeed, this even allowed beta or experimental versions of operating systems—or even of new hardware—to be deployed and debugged, without jeopardizing
3364-401: Was simultaneous with the compilers needed to translate them automatically into machine code. Most programs do not contain all the resources needed to run them and rely on external libraries . Part of the compiler's function is to link these files in such a way that the program can be executed by the hardware. Once compiled, the program can be saved as an object file and the loader (part of
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