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X86 Virtualization
x86 virtualization is the use of hardware-assisted virtualization capabilities on an x86/x86-64 CPU. In the late 1990s x86 virtualization was achieved by complex software techniques, necessary to compensate for the processor's lack of hardware-assisted virtualization capabilities while attaining reasonable performance. In 2005 and 2006, both Intel ( VT-x) and AMD ( AMD-V) introduced limited hardware virtualization support that allowed simpler virtualization software but offered very few speed benefits. Greater hardware support, which allowed substantial speed improvements, came with later processor models. Software-based virtualization The following discussion focuses only on virtualization of the x86 architecture protected mode. In protected mode the operating system kernel runs at a higher privilege such as ring 0, and applications at a lower privilege such as ring 3. In software-based virtualization, a host OS has direct access to hardware while the guest OSs have limit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypervisor
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 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 a single kernel, though the guest operating systems can differ in user space, such as different Linux distributions with the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardware Virtualization
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 emulates the hardware environment of its host architecture, allowing multiple OSes to run unmodified and in isolation. 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. Concept The term "virtualization" was coined in the 1960s to refer to a virtual machine (sometimes called "pseudo machine"), a term which itself dates from the experimental IBM M44/44X system. The creation and management of virtual machines has also been called "platform virtualization", or "server virtualization", more recently. Platform virtualization is performed on a given hardware platform by ''host'' software (a ''control program''), which creates a simulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shadow Memory
In computing, shadow memory is a technique used to track and store information on computer memory used by a computer program, program during its execution. Shadow memory consists of shadow bytes that map to individual bits or one or more bytes in main memory. These shadow bytes are typically invisible to the original program and are used to record information about the original piece of data. Technique The technique is utilized by memory-error checkers that can store information on which parts of memory have been allocated to the program being checked. This shadow memory is then used for detecting and reporting incorrect accesses of memory, even though the program may not be crashing due to a segmentation fault or similar. An error checker may also store additional information on memory such as which bits have been defined and which ones do not. Memcheck, part of the Valgrind suite, uses this to detect undefined behavior resulting from acting on or printing undefined memory values. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paravirtualization
In computing, virtualization (abbreviated v12n) is a series of technologies that allows dividing of physical computing resources into 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 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 v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L4 Microkernel Family
L4 is a family of second-generation microkernels, used to implement a variety of types of operating systems (OS), though mostly for Unix-like, ''Portable Operating System Interface'' (POSIX) compliant types. L4, like its predecessor microkernel #L3, L3, was created by Germany, German computer scientist Jochen Liedtke as a response to the poor performance of earlier microkernel-based OSes. Liedtke felt that a system designed from the start for high performance, rather than other goals, could produce a microkernel of practical use. His original implementation in hand-coded Intel i386-specific assembly language code in 1993 created attention by being 20 times faster than Mach (kernel), Mach. The follow-up publication two years later was considered so influential that it won the 2015 ACM SIGOPS Hall of Fame Award. Since its introduction, L4 has been developed to be Cross-platform software, cross-platform and to improve Computer security, security, isolation, and Robustness (computer s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denali (operating System)
The Denali operating system is "an IA-32 virtual machine monitor, that allows for untrusted services to be run in isolated (protected) domains." Denali makes use of paravirtualization to support high performance virtual machines, even on the notoriously uncooperative x86 architecture (see x86 virtualization). The envisioned usage model for the original Denali was to support virtual machines running lightweight single application operating systems for internet services. A later revision of Denali () includes support for running full-featured operating systems. References "Lightweight virtual machines for distributed and networked systems" Developer's page. University of Washington. "Scale and performance in the Denali isolation kernel" Association for Computing Machinery The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Conference On Architectural Support For Programming Languages And Operating Systems
The International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS) is an annual interdisciplinary computer science conference organized by the Association for Computing Machinery (ACM). Reflecting its focus, sponsorship of the conference is made up of 50% by the ACM's Special Interest Group on Computer Architecture (SIGARCH) and 25% by each of the Special Interest Group on Programming Languages (SIGPLAN) and the Special Interest Group on Operating Systems ( SIGOPS). It is a high-impact conference in computer architecture and operating systems, but less so in programming languages/software engineering. See also * List of computer science conferences This is a list of academic conferences in computer science. Only conferences with separate articles are included; within each field, the conferences are listed alphabetically by their short names. General * FCRC – Federated Computing Resear ... References {{Authority control ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Popek And Goldberg Virtualization Requirements
The Popek and Goldberg virtualization requirements are a set of conditions sufficient for a computer architecture to support system virtualization efficiently. They were introduced by Gerald J. Popek and Robert P. Goldberg in their 1974 article "Formal Requirements for Virtualizable Third Generation Architectures". Even though the requirements are derived under simplifying assumptions, they still represent a convenient way of determining whether a computer architecture supports efficient virtualization and provide guidelines for the design of virtualized computer architectures. VMM definition System virtual machines are capable of virtualizing a full set of hardware resources, including a processor (or processors), memory and storage resources and peripheral devices. A virtual machine monitor (VMM, also called hypervisor) is the piece of software that provides the abstraction of a virtual machine. There are three properties of interest when analyzing the environment created by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM System/370
The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the IBM System/360, System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement. Early 370 systems differed from the 360 largely in their internal circuitry, moving from the Solid Logic Technology hybrid integrated circuits containing separate transistors to more modern monolithic integrated circuits containing multiple transistors per integrated circuit, which IBM referred to as Monolithic System Technology, or MST. The higher density packaging allowed several formerly optional features from the 360 line to be included as standard features of the machines, floating-point support for instance. The 370 also added a small number of new instructions. At the time of its introduction, the development of virtual mem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emulator
In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run software or use peripheral devices designed for the guest system. Emulation refers to the ability of a computer program in an electronic device to emulate (or imitate) another program or device. Many printer (computing), printers, for example, are designed to emulate Hewlett-Packard, HP LaserJet printers because a significant amount of software is written specifically for HP models. If a non-HP printer emulates an HP printer, any software designed for an actual HP printer will also function on the non-HP device, producing equivalent print results. Since at least the 1990s, many video game enthusiasts and hobbyists have used emulators to play classic arcade games from the 1980s using the games' original 1980s machine code and data, which is in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
