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Second Level Address Translation
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. AMD has supported SLAT through the Rapid Virtualization Indexing (RVI) technology since the introduction of its third-generation Opteron processors (code name Barcelona). Intel's implementation of SLAT, known as Extended Page Table (EPT), was introduced in the Nehalem (microarchitecture), Nehalem microarchitecture found in certain Core i7, Core i5, and Core i3 processors. ARM architecture, ARM's virtualization extensions support SLAT, known as Stage-2 page-tables provided by a Stage-2 Memory_management_unit, MMU. The guest uses the Stage-1 MMU. Support was added as optional in the ARMv7ve architecture and is also supported in the ARMv8 (32-bit and 64-bit) architectures. Overview The introduction of protected mode to the x86 architecture with the Intel 80286 proce ...
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Hardware-assisted Virtualization
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. Deskto ...
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Memory Management Unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit that examines all references to computer memory, memory, and translates the memory addresses being referenced, known as virtual memory addresses, into physical addresses in main memory. In modern systems, programs generally have addresses that access the theoretical maximum memory of the computer architecture, 32 or 64 bits. The MMU maps the addresses from each program into separate areas in physical memory, which is generally much smaller than the theoretical maximum. This is possible because programs rarely use large amounts of memory at any one time. Most modern operating systems (OS) work in concert with an MMU to provide virtual memory (VM) support. The MMU tracks memory use in fixed-size blocks known as ''pages''. If a program refers to a location in a page that is not in physical memory, the MMU sends an interrupt to the operating system. The OS selects a ...
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Executable Space Protection
In computer security, executable-space protection marks memory regions as non-executable, such that an attempt to execute machine code in these regions will cause an exception. It relies on hardware features such as the NX bit (no-execute bit), or on software emulation when hardware support is unavailable. Software emulation often introduces a performance cost, or overhead (extra processing time or resources), while hardware-based NX bit implementations have no measurable performance impact. The Burroughs large systems, starting with the Burroughs 5000 introduced in 1961, implemented executable-space protection using a tagged architecture. All accesses to code and data took place through descriptors, which had memory tags preventing them from being modified; descriptors for code did not allow the code to be modified, and descriptors for data did not allow the data ta be executed as code. Today, operating systems use executable-space protection to mark writable memory areas, ...
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Zen+
Zen+ is the name for a computer processor microarchitecture by AMD. It is the successor to the first gen Zen microarchitecture, and was first released in April 2018, powering the second generation of Ryzen processors, known as Ryzen 2000 for mainstream desktop systems, Threadripper 2000 for high-end desktop setups and Ryzen 3000G (instead of 2000G) for accelerated processing units (APUs). Features Zen+ uses GlobalFoundries' 12 nm fabrication process, an optimization of the 14 nm process used for Zen, with only minor design rule changes. This means that the die sizes between Zen and Zen+ are identical as AMD chose to use the new smaller transistors to increase the amount of empty space, or " dark silicon", between the various features on the die. This was done to improve power efficiency & reduce thermal density to allow for higher clock speeds, rather than design an entirely new floorplan for a physically smaller die (which would have been significantly more work an ...
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Kaby Lake
Kaby Lake is Intel's codename for its seventh generation Core microprocessor family announced on August 30, 2016. Like the preceding Skylake, Kaby Lake is produced using a 14 nanometer manufacturing process technology. Breaking with Intel's previous " tick–tock" manufacturing and design model, Kaby Lake represents the optimized step of the newer process–architecture–optimization model. Kaby Lake began shipping to manufacturers and OEMs in the second quarter of 2016, with its desktop chips officially launched in January 2017. In August 2017, Intel announced Kaby Lake Refresh ( Kaby Lake R) marketed as the 8th generation mobile CPUs, breaking the long cycle where architectures matched the corresponding generations of CPUs and meanwhile also supporting Windows 11. Skylake was anticipated to be succeeded by the 10 nanometer Cannon Lake, but it was announced in July 2015 that Cannon Lake had been delayed until the second half of 2017. In the meantime, Intel released a fou ...
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Corner Case
In engineering, a corner case (or pathological case) involves a problem or situation that occurs only outside normal operating parameters—specifically one that manifests itself when multiple environmental variables or conditions are simultaneously at extreme levels, even though each parameter is within the specified range for that parameter. For example, a loudspeaker might distort audio, but only when played at maximum volume, maximum bass, and in a high-humidity environment. Or a computer server may be unreliable, but only with the maximum complement of 64 processors, 512 GB of memory, and 10,000 signed-on users. The investigation of corner cases is of extreme importance as it can provide engineers with valuable insight into how corner case effects can be mitigated. In the case where automotive radar fails, corner case investigation can possibly tell engineers and investigators alike what may have occurred. Corner cases form part of an engineer's lexicon—especially an ...
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Westmere (microarchitecture)
Westmere (formerly Nehalem-C) is the code name given to the 32 nanometer, 32 nm die shrink of ''Nehalem (microarchitecture), Nehalem''. While sharing the same CPU sockets, Westmere included Intel HD Graphics, while Nehalem did not. The first ''Westmere''-based processors were launched on January 7, 2010, by Intel Corporation. The Westmere architecture has been available under the Intel brands of List of Intel Core i3 microprocessors, Core i3, List of Intel Core i5 microprocessors, Core i5, List of Intel Core i7 microprocessors, Core i7, List of Intel Pentium microprocessors, Pentium, List of Intel Celeron microprocessors, Celeron and Xeon, and includes directX 10.1, and openGL 2.1. Technology Westmere's feature improvements from Nehalem, as reported: * Native six-core (Gulftown (microprocessor), Gulftown) and ten-core (Westmere-EX) processors. * A new set of instructions that gives over 3x the encryption and decryption rate of Advanced Encryption Standard (AES) processes co ...
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Real Mode
Real mode, also called real address mode, is an operating mode of all x86-compatible CPUs. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20- bit segmented memory address space (giving 1 MB of addressable memory) and unlimited direct software access to all addressable memory, I/O addresses and peripheral hardware. Real mode provides no support for memory protection, multitasking, or code privilege levels. Before the introduction of protected mode with the release of the 80286, real mode was the only available mode for x86 CPUs; and for backward compatibility, all x86 CPUs start in real mode when reset, though it is possible to emulate real mode on other systems when starting in other modes. History The 80286 architecture introduced protected mode, allowing for (among other things) hardware-level memory protection. Using these new features, however, required a new operating system ...
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VIA Technologies
VIA Technologies, Inc. () is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory. It was once the world's largest independent manufacturer of motherboard chipsets. As a fabless semiconductor company, VIA conducts research and development of its chipsets in-house, then subcontracts the actual (silicon) manufacturing to third-party merchant foundries such as TSMC. VIA is also the parent company of VIA Labs Inc. (VLI, ). As an independently traded subsidiary, VLI develops and markets USB 3, USB 4, USB Type-C, and USB PD controllers for computer peripherals and mobile devices. History The company was founded in 1987, in Fremont, California, USA by Cher Wang. In 1992, it was decided to move the headquarters to Taipei, Taiwan in order to establish closer partnerships with the substantial and growing IT manufacturing base in Taiwan and neighbouring China. In 1999, VIA acquired most of Cyrix, then a division of National Semiconductor. Th ...
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Core I9
Intel Core is a line of multi-core (with the exception of Core Solo and Core 2 Solo) central processing units (CPUs) for midrange, embedded, workstation, high-end and enthusiast computer markets marketed by Intel Corporation. These processors displaced the existing mid- to high-end Pentium processors at the time of their introduction, moving the Pentium to the entry level. Identical or more capable versions of Core processors are also sold as Xeon processors for the server and workstation markets. Core was launched in January 2006 as a mobile-only series, consisting of single- and dual-core models. It was then succeeded later in July by the Core 2 series, which included both desktop and mobile processors with up to four cores, and introduced 64-bit support. Since 2008, Intel began introducing the Core i3, Core i5, Core i7 and Core i9 lineup of processors, succeeding Core 2. A new naming scheme debuted in 2023, consisting of Core 3, Core 5, and Core 7 for mainstream processors ...
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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 ...
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OLTP
Online transaction processing (OLTP) is a type of database system used in transaction-oriented applications, such as many operational systems. "Online" refers to the fact that such systems are expected to respond to user requests and process them in real-time (process transactions). The term is contrasted with online analytical processing (OLAP) which instead focuses on data analysis (for example planning and management systems). Meaning of the term transaction The term "transaction" can have two different meanings, both of which might apply: in the realm of computers or database transactions it denotes an atomic change of state, whereas in the realm of business or finance, the term typically denotes an exchange of economic entities (as used by, e.g., Transaction Processing Performance Council or commercial transactions.) OLTP may use transactions of the first type to record transactions of the second type. Compared to OLAP OLTP is typically contrasted to online analytical p ...
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