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53-592: Prior to version 3.0, the ISA is divided into several categories. Processors implement a set of these categories as required for their task. Different classes of processors are required to implement certain categories, for example a server-class processor includes the categories: Base , Server , Floating-Point , 64-Bit , etc. All processors implement the Base category. Power ISA is a RISC load/store architecture . It has multiple sets of registers : Instructions up to version 3.0 have

106-681: A random number generator , hardware-assisted garbage collection and hardware-enforced trusted computing. The spec was revised in March 2017 to the Power ISA v.3.0 B spec, and revised again to v3.0C in May 2020. One major change from v3.0 to v3.0B is the removal of support for hardware assisted garbage collection. The key difference between v3.0B and v3.0C is that the Compliancy Levels listed in v3.1 were also added to v3.0C. The specification for Power ISA v.3.1

159-533: A (physical) computer with an operating system. The software or firmware that creates a virtual machine on the host hardware is called a hypervisor or virtual machine monitor . Software executed on these virtual machines is separated from the underlying hardware resources. For example, a computer that is running Arch Linux may host a virtual machine that looks like a computer with the Microsoft Windows operating system; Windows-based software can be run on

212-434: A hypervisor (a piece of software) imitates a particular piece of computer hardware or the entire computer. Furthermore, a hypervisor is not the same as an emulator ; both are computer programs that imitate hardware, but their domain of use in language differs. Hardware-assisted virtualization (or accelerated virtualization; Xen calls it hardware virtual machine (HVM), and Virtual Iron calls it native virtualization)

265-634: A hypervisor in paravirtualized mode. The first appearance of paravirtualization support in Linux occurred with the merge of the ppc64 port in 2002, which supported running Linux as a paravirtualized guest on IBM pSeries (RS/6000) and iSeries (AS/400) hardware. At the USENIX conference in 2006 in Boston, Massachusetts , a number of Linux development vendors (including IBM, VMware, Xen, and Red Hat) collaborated on an alternative form of paravirtualization, initially developed by

318-910: A length of 32 bits, with the exception of the VLE (variable-length encoding) subset that provides for higher code density for low-end embedded applications, and version 3.1 which introduced prefixing to create 64-bit instructions. Most instructions are triadic , i.e. have two source operands and one destination. Single- and double-precision IEEE-754 compliant floating-point operations are supported, including additional fused multiply–add (FMA) and decimal floating-point instructions. There are provisions for single instruction, multiple data (SIMD) operations on integer and floating-point data on up to 16 elements in one instruction. Power ISA has support for Harvard cache , i.e. split data and instruction caches , and support for unified caches. Memory operations are strictly load/store, but allow for out-of-order execution . There

371-401: A non-virtualized environment. The paravirtualization provides specially defined 'hooks' to allow the guest(s) and host to request and acknowledge these tasks, which would otherwise be executed in the virtual domain (where execution performance is worse). A successful paravirtualized platform may allow the virtual machine monitor (VMM) to be simpler (by relocating execution of critical tasks from

424-526: A private system. This simulation was comprehensive, and was based on the Principles of Operation manual for the hardware. It thus included such elements as an instruction set, main memory, interrupts, exceptions, and device access. The result was a single machine that could be multiplexed among many users. Hardware-assisted virtualization first appeared on the IBM System/370 in 1972, for use with VM/370 ,

477-431: A series of virtual machines , operating systems , processes or containers. Virtualization began in the 1960s with IBM CP/CMS . The control program CP provided each user with a simulated stand-alone System/360 computer. In hardware virtualization , the host machine is the machine that is used by the virtualization and the guest machine is the virtual machine. The words host and guest are used to distinguish

530-483: A single central processing unit (CPU). This parallelism tends to reduce overhead costs and differs from multitasking, which involves running several programs on the same OS. Using virtualization, an enterprise can better manage updates and rapid changes to the operating system and applications without disrupting the user. " Ultimately, virtualization dramatically improves the efficiency and availability of resources and applications in an organization. Instead of relying on

583-505: A virtual machine that does not implement the hard-to-virtualize parts of the actual x86 instruction set. In 2005, VMware proposed a paravirtualization interface, the Virtual Machine Interface (VMI), as a communication mechanism between the guest operating system and the hypervisor. This interface enabled transparent paravirtualization in which a single binary version of the operating system can run either on native hardware or on

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636-408: Is a way of improving overall efficiency of hardware virtualization using help from the host processors. A full virtualization is used to emulate a complete hardware environment, or virtual machine , in which an unmodified guest operating system (using the same instruction set as the host machine) effectively executes in complete isolation. Hardware-assisted virtualization was first introduced on

689-487: Is also support for both big and little-endian addressing with separate categories for moded and per-page endianness, and support for both 32-bit and 64-bit addressing. Different modes of operation include user, supervisor and hypervisor. The Power ISA specification is divided into five parts, called "books": New in version 3 of the Power ISA is that you don't have to implement the entire specification to be compliant. The sprawl of instructions and technologies has made

742-821: Is based on the former PowerPC ISA v.2.02 in POWER5 + and the Book E extension of the PowerPC specification. The Book I included five new chapters regarding auxiliary processing units like DSPs and the AltiVec extension. The specification for Power ISA v.2.04 was finalized in June 2007. It is based on Power ISA v.2.03 and includes changes primarily to the Book III-S part regarding virtualization , hypervisor functions, logical partitioning and virtual page handling. The specification for Power ISA v.2.05

795-420: Is simply updated on the server, and the desktop gets the updated version when it reboots. It also enables centralized control over what applications the user is allowed to have access to on the workstation. Moving virtualized desktops into the cloud creates hosted virtual desktops (HVDs), in which the desktop images are centrally managed and maintained by a specialist hosting firm. Benefits include scalability and

848-453: Is the concept of separating the logical desktop from the physical machine. Operating-system-level virtualization, also known as containerization , refers to an operating system feature in which the kernel allows the existence of multiple isolated user-space instances. The usual goal of virtualization is to centralize administrative tasks while improving scalability and overall hardware-resource utilization. A form of virtualization

901-614: The IBM 308X processors in 1980, with the Start Interpretive Execution (SIE) instruction. It was added to x86 processors ( Intel VT-x , AMD-V or VIA VT ) in 2005, 2006 and 2010 respectively. IBM offers hardware virtualization for its IBM Power Systems hardware for AIX , Linux and IBM i , and for its IBM Z mainframes . IBM refers to its specific form of hardware virtualization as "logical partition", or more commonly as LPAR . Hardware-assisted virtualization reduces

954-810: The OpenPOWER ISA Workgroup . Note that it is not strictly necessary to join the OpenPOWER Foundation to submit RFCs. The EABI specifications predate the announcement and creation of the Compliancy subsets. Regarding the Linux Compliancy subset having VSX (SIMD) optional: in 2003–4, 64-bit EABI v1.9 made SIMD optional, but in July 2015, to improve performance for IBM POWER9 systems, SIMD was made mandatory in EABI v2.0. This discrepancy between SIMD being optional in

1007-525: The Popek and Goldberg virtualization requirements to achieve "classical virtualization": This made it difficult to implement a virtual machine monitor for this type of processor. Specific limitations included the inability to trap on some privileged instructions. Therefore, to compensate for these architectural limitations, designers accomplished virtualization of the x86 architecture through two methods: full virtualization or paravirtualization . Both create

1060-472: The x86 architecture called Intel VT-x and AMD-V, respectively. On the Itanium architecture, hardware-assisted virtualization is known as VT-i. The first generation of x86 processors to support these extensions were released in late 2005 early 2006: Hardware virtualization (or platform virtualization) pools computing resources across one or more virtual machines . A virtual machine implements functionality of

1113-437: The Linux Compliancy level but mandatory in EABI v2.0 cannot be rectified without considerable effort: backwards incompatibility for Linux distributions is not a viable option. At present this leaves new OpenPOWER implementors wishing to run standard Linux distributions having to implement a massive 962 instructions. By contrast, RISC-V RV64GC, the minimum to run Linux, requires only 165. The specification for Power ISA v.2.03

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1166-543: The POWER7 processor and e500-mc core . One significant new feature is vector-scalar floating-point instructions ( VSX ). Book III-E also includes significant enhancement for the embedded specification regarding hypervisor and virtualisation on single and multi core implementations. The spec was revised in November 2010 to the Power ISA v.2.06 revision B spec, enhancing virtualization features. The specification for Power ISA v.2.07

1219-862: The Xen group, called "paravirt-ops". The paravirt-ops code (often shortened to pv-ops) was included in the mainline Linux kernel as of the 2.6.23 version, and provides a hypervisor-agnostic interface between the hypervisor and guest kernels. Distribution support for pv-ops guest kernels appeared starting with Ubuntu 7.04 and RedHat 9. Xen hypervisors based on any 2.6.24 or later kernel support pv-ops guests, as does VMware's Workstation product beginning with version 6. Hybrid virtualization combines full virtualization techniques with paravirtualized drivers to overcome limitations with hardware-assisted full virtualization. A hardware-assisted full virtualization approach uses an unmodified guest operating system that involves many VM traps producing high CPU overheads limiting scalability and

1272-570: The changing needs of the user and business. Another form, session virtualization, allows multiple users to connect and log into a shared but powerful computer over the network and use it simultaneously. Each is given a desktop and a personal folder in which they store their files. With multiseat configuration , session virtualization can be accomplished using a single PC with multiple monitors, keyboards, and mice connected. Thin clients , which are seen in desktop virtualization, are simple and/or cheap computers that are primarily designed to connect to

1325-468: The complete specification unwieldy, so the OpenPOWER Foundation have decided to enabled tiered compliancy. These levels include optional and mandatory requirements, however one common misunderstanding is that there is nothing stopping an implementation from being compliant at a lower level but having additional selected functions from higher levels and custom extensions. It is however recommended that an option be provided to disable any added functions beyond

1378-432: The data center. For users, this means they can access their desktop from any location, without being tied to a single client device. Since the resources are centralized, users moving between work locations can still access the same client environment with their applications and data. For IT administrators, this means a more centralized, efficient client environment that is easier to maintain and able to more quickly respond to

1431-528: The design's declared subset level. A design must be compliant at its declared subset level to make use of the Foundation's protection regarding use of intellectual property , be it patents or trademarks . This is explained in the OpenPOWER EULA. A compliant design must: If the extension is general-purpose enough, the OpenPOWER Foundation asks that implementors submit it as a Request for Comments (RFC) to

1484-419: The efficiency of server consolidation. The hybrid virtualization approach overcomes this problem. Desktop virtualization separates the logical desktop from the physical machine. One form of desktop virtualization, virtual desktop infrastructure (VDI), can be thought of as a more advanced form of hardware virtualization. Rather than interacting with a host computer directly via a keyboard, mouse, and monitor,

1537-489: The first virtual machine operating system. IBM added virtual memory hardware to the System/370 series in 1972 which is not the same as Intel VT-x Rings providing a higher privilege level for Hypervisor to properly control Virtual Machines requiring full access to Supervisor and Program or User modes. With the increasing demand for high-definition computer graphics (e.g. CAD ), virtualization of mainframes lost some attention in

1590-598: 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. This approach was pioneered in 1966 with the IBM CP-40 and CP-67 , predecessors of the VM family. In binary translation , instructions are translated to match the emulated hardware architecture. A piece of hardware imitates another while in hardware assisted virtualization,

1643-428: The guest operating system communicate with the hypervisor. By allowing the guest operating system to indicate its intent to the hypervisor, each can cooperate to obtain better performance when running in a virtual machine. The intent of the modified interface is to reduce the portion of the guest's execution time spent performing operations which are substantially more difficult to run in a virtual environment compared to

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1696-678: The illusion of physical hardware to achieve the goal of operating system independence from the hardware but present some trade-offs in performance and complexity. Full virtualization was not fully available on the x86 platform prior to 2005. Many platform hypervisors for the x86 platform came very close and claimed full virtualization (such as Adeos , Mac-on-Linux, Parallels Desktop for Mac , Parallels Workstation , VMware Workstation , VMware Server (formerly GSX Server), VirtualBox , Win4BSD, and Win4Lin Pro ). In 2005 and 2006, Intel and AMD (working independently) created new processor extensions to

1749-431: The kernel is shared between containers. Containerization started gaining prominence in 2014, with the introduction of Docker . Virtualization, in particular, full virtualization has proven beneficial for: A common goal of virtualization is to centralize administrative tasks while improving scalability and overall hardware-resource utilization. With virtualization, several operating systems can be run in parallel on

1802-406: The late 1970s, when the upcoming minicomputers fostered resource allocation through distributed computing , encompassing the commoditization of microcomputers . The increase in compute capacity per x86 server (and in particular the substantial increase in modern networks' bandwidths) rekindled interest in data-center based computing which is based on virtualization techniques. The primary driver

1855-493: The maintenance overhead of paravirtualization as it reduces (ideally, eliminates) the changes needed in the guest operating system. It is also considerably easier to obtain better performance. Paravirtualization 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. Paravirtualization improves performance and efficiency, compared to full virtualization, by having

1908-410: The network. They may lack significant hard disk storage space , RAM or even processing power , but many organizations are beginning to look at the cost benefits of eliminating "thick client" desktops that are packed with software (and require software licensing fees) and making more strategic investments. Desktop virtualization simplifies software versioning and patch management, where the new image

1961-518: The new 64-bit prefixed instructions is the extension of immediates in branches to 34-bit. The spec was revised in September 2021 to the Power ISA v.3.1B spec. The spec was revised in May 2024 to the Power ISA v.3.1C spec. Load Load or LOAD may refer to: easuring its response Hardware-assisted virtualization In computing, virtualization (v12n) is a series of technologies that allows dividing of physical computing resources into

2014-534: The paravirtual framework. The term "paravirtualization" was first used in the research literature in association with the Denali Virtual Machine Manager. The term is also used to describe the Xen , L4 , TRANGO , VMware , Wind River and XtratuM hypervisors . All these projects use or can use paravirtualization techniques to support high performance virtual machines on x86 hardware by implementing

2067-506: The point of view of programs running in them. A computer program running on an ordinary operating system can see all resources (connected devices, files and folders, network shares , CPU power, quantifiable hardware capabilities) of that computer. However, programs running inside a container can only see the container's contents and devices assigned to the container. This provides many of the benefits that virtual machines have such as standardization and scalability, while using less resources as

2120-518: The predictability, continuity, and quality of service delivered by their converged infrastructure . For example, companies like HP and IBM provide a hybrid VDI model with a range of virtualization software and delivery models to improve upon the limitations of distributed client computing . Selected client environments move workloads from PCs and other devices to data center servers, creating well-managed virtual clients, with applications and client operating environments hosted on servers and storage in

2173-443: The reduction of capital expenditure, which is replaced by a monthly operational cost. Operating-system-level virtualization, also known as containerization , refers to an operating system feature in which the kernel allows the existence of multiple isolated user-space instances. Such instances, called containers, partitions, virtual environments (VEs) or jails ( FreeBSD jail or chroot jail ), may look like real computers from

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2226-548: The significant performance advantages of paravirtualization. For example, the Xen Windows GPLPV project provides a kit of paravirtualization-aware device drivers, that are intended to be installed into a Microsoft Windows virtual guest running on the Xen hypervisor. Such applications tend to be accessible through the paravirtual machine interface environment. This ensures run-mode compatibility across multiple encryption algorithm models, allowing seamless integration within

2279-439: The software on-the-fly to replace instructions that "pierce the virtual machine" with a different, virtual machine safe sequence of instructions. Hardware-assisted virtualization allows guest operating systems to be run in isolation with virtually no modification to the (guest) operating system. Full virtualization requires that every salient feature of the hardware be reflected into one of several virtual machines – including

2332-452: The software that runs on the physical machine from the software that runs on the virtual machine. The software or firmware that creates a virtual machine on the host hardware is called a hypervisor or virtual machine monitor . Hardware virtualization is not the same as hardware emulation . Hardware-assisted virtualization facilitates building a virtual machine monitor and allows guest OSes to be run in isolation. Desktop virtualization

2385-553: The user interacts with the host computer using another desktop computer or a mobile device by means of a network connection, such as a LAN , Wireless LAN or even the Internet . In addition, the host computer in this scenario becomes a server computer capable of hosting multiple virtual machines at the same time for multiple users. As organizations continue to virtualize and converge their data center environment, client architectures also continue to evolve in order to take advantage of

2438-477: The virtual domain to the host domain), and/or reduce the overall performance degradation of machine execution inside the virtual guest. Paravirtualization requires the guest operating system to be explicitly ported for the para- API – a conventional OS distribution that is not paravirtualization-aware cannot be run on top of a paravirtualizing VMM. However, even in cases where the operating system cannot be modified, components may be available that enable many of

2491-509: The virtual machine. Different types of hardware virtualization include: Full virtualization employs techniques that pools physical computer resources into one or more instances; each running a virtual environment where any software or operating system capable of execution on the raw hardware can be run in the virtual machine. Two common full virtualization techniques are typically used: (a) binary translation and (b) hardware-assisted full virtualization. Binary translation automatically modifies

2544-500: Was first demonstrated with IBM's CP-40 research system in 1967, then distributed via open source in CP/CMS in 1967–1972, and re-implemented in IBM's VM family from 1972 to the present. Each CP/CMS user was provided a simulated, stand-alone computer. Each such virtual machine had the complete capabilities of the underlying machine, and (for its user) the virtual machine was indistinguishable from

2597-574: Was released in December 2007. It is based on Power ISA v.2.04 and includes changes primarily to Book I and Book III-S , including significant enhancements such as decimal arithmetic (Category: Decimal Floating-Point in Book I ) and server hypervisor improvements. The specification for Power ISA v.2.06 was released in February 2009, and revised in July 2010. It is based on Power ISA v.2.05 and includes extensions for

2650-496: Was released in May 2013. It is based on Power ISA v.2.06 and includes major enhancements to logical partition functions , transactional memory , expanded performance monitoring, new storage control features, additions to the VMX and VSX vector facilities (VSX-2), along with AES and Galois Counter Mode (GCM), SHA-224, SHA-256, SHA-384 and SHA-512 ( SHA-2 ) cryptographic extensions and cyclic redundancy check (CRC) algorithms . The spec

2703-610: Was released in May 2020. Mainly giving support for new functions introduced in Power10, but also includes the notion of optionality to the PowerISA specification. Instructions can now be eight bytes long, "prefixed instructions", compared to the usual four byte "word instructions". A lot of new functions to SIMD and VSX instructions are also added. VSX and the SVP64 extension provide hardware support for 16-bit half precision floats. One key benefit of

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2756-511: Was revised in April 2015 to the Power ISA v.2.07 B spec. The specification for Power ISA v.3.0 was released in November 2015. It is the first to come out after the founding of the OpenPOWER Foundation and includes enhancements for a broad spectrum of workloads and removes the server and embedded categories while retaining backwards compatibility and adds support for VSX-3 instructions. New functions include 128-bit quad-precision floating-point operations,

2809-475: Was the potential for server consolidation: virtualization allowed a single server to cost-efficiently consolidate compute power on multiple underutilized dedicated servers. The most visible hallmark of a return to the roots of computing is cloud computing , which is a synonym for data center based computing (or mainframe-like computing) through high bandwidth networks. It is closely connected to virtualization. The initial implementation x86 architecture did not meet

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