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Unikernel
A unikernel is a specialised, single address space machine image constructed by using library operating systems. A developer selects, from a modular stack, the minimal set of libraries which correspond to the OS constructs required for the application to run. These libraries are then compiled with the application and configuration code to build sealed, fixed-purpose images (unikernels) which run directly on a hypervisor or hardware without an intervening OS such as Linux or Windows. The first such systems were Exokernel and Nemesis in the late 1990s. Design In a library operating system, protection boundaries are pushed to the lowest hardware layers, resulting in: # a set of libraries that implement mechanisms such as those needed to drive hardware or talk network protocols; # a set of policies that enforce access control and isolation in the application layer. The library OS architecture has several advantages and disadvantages compared with conventional OS designs. One ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unikernel Mirage Example
A unikernel is a specialised, single address space machine image constructed by using library operating systems. A developer selects, from a modular stack, the minimal set of libraries which correspond to the OS constructs required for the application to run. These libraries are then compiled with the application and configuration code to build sealed, fixed-purpose images (unikernels) which run directly on a hypervisor or hardware without an intervening OS such as Linux or Windows. The first such systems were Exokernel and Nemesis in the late 1990s. Design In a library operating system, protection boundaries are pushed to the lowest hardware layers, resulting in: # a set of libraries that implement mechanisms such as those needed to drive hardware or talk network protocols; # a set of policies that enforce access control and isolation in the application layer. The library OS architecture has several advantages and disadvantages compared with conventional OS designs. One ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IncludeOS
IncludeOS is a minimal, open source, unikernel operating system for cloud services and IoT. IncludeOS allows users to run C++ applications in the cloud without any operating system. IncludeOS adds operating system functionality to an application allowing oneself to create a 'virtual machine' for an application. IncludeOS applications boot in tens of milliseconds and require only a few megabytes of disk and memory. Architecture The minimalist architecture of IncludeOS means that it does not have any virtual memory space. In turn, therefore, there is no concept of system calls nor user space. References {{reflist , refs= {{cite web , author= Stig Øyvann , date= November 12, 2018 , df= ymd , url= https://www.zdnet.com/article/iot-security-and-linux-why-includeos-thinks-it-has-the-edge/ , title= IoT security and Linux: Why IncludeOS thinks it has the edge , website= ZDNet ZDNET is a business technology news website owned and operated by Red Ventures. The brand was founde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose personal computer operating system is Microsoft Windows with a market share of around 74.99%. macOS by Apple Inc. is in second place (14.84%), and ... [...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 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Hardware
Computer hardware includes the physical parts of a computer, such as the computer case, case, central processing unit (CPU), Random-access memory, random access memory (RAM), Computer monitor, monitor, Computer mouse, mouse, Computer keyboard, keyboard, computer data storage, graphics card, sound card, Computer speakers, speakers and motherboard. By contrast, software is the set of instructions that can be stored and run by hardware. Hardware is so-termed because it is "Hardness, hard" or rigid with respect to changes, whereas software is "soft" because it is easy to change. Hardware is typically directed by the software to execute any command or Instruction (computing), instruction. A combination of hardware and software forms a usable computing system, although Digital electronics, other systems exist with only hardware. Von Neumann architecture The template for all modern computers is the Von Neumann architecture, detailed in a First Draft of a Report on the EDVAC, 1945 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exokernel
Exokernel is an operating system kernel developed by the MIT Parallel and Distributed Operating Systems group, and also a class of similar operating systems. Operating systems generally present hardware resources to applications through high-level abstractions such as (virtual) file systems. The idea behind exokernels is to force as few abstractions as possible on application developers, enabling them to make as many decisions as possible about hardware abstractions. Exokernels are tiny, since functionality is limited to ensuring protection and multiplexing of resources, which is considerably simpler than conventional microkernels' implementation of message passing and monolithic kernels' implementation of high-level abstractions. Implemented abstractions are called library operating systems; they may request specific memory addresses, disk blocks, etc. The kernel only ensures that the requested resource is free, and the application is allowed to access it. This low-level hardwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nemesis (operating System)
Nemesis was an operating system that was designed by the University of Cambridge, the University of Glasgow, the Swedish Institute of Computer Science and Citrix Systems. Nemesis was conceived with multimedia uses in mind. It was designed with a small lightweight kernel, using shared libraries to perform functions that most operating systems perform in the kernel. This reduces the processing that is performed in the kernel on behalf of application processes, transferring the activity to the processes themselves and facilitating accounting for resource usage. The ISAs that Nemesis supports include x86 ( Intel i486, Pentium, Pentium Pro, and Pentium II), Alpha and ARM (StrongARM SA–110). Nemesis also runs on evaluation boards (21064 and 21164). See also * Exokernel Exokernel is an operating system kernel developed by the MIT Parallel and Distributed Operating Systems group, and also a class of similar operating systems. Operating systems generally present hardware re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Context Switch
In computing, a context switch is the process of storing the state of a process or thread, so that it can be restored and resume execution at a later point, and then restoring a different, previously saved, state. This allows multiple processes to share a single central processing unit (CPU), and is an essential feature of a multitasking operating system. The precise meaning of the phrase "context switch" varies. In a multitasking context, it refers to the process of storing the system state for one task, so that task can be paused and another task resumed. A context switch can also occur as the result of an interrupt, such as when a task needs to access disk storage, freeing up CPU time for other tasks. Some operating systems also require a context switch to move between user mode and kernel mode tasks. The process of context switching can have a negative impact on system performance. Cost Context switches are usually computationally intensive, and much of the design of opera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Address Space Operating System
In computer science, a single address space operating system (or SASOS) is an operating system that provides only one globally shared address space for all processes. In a single address space operating system, numerically identical (virtual memory) logical addresses in different processes all refer to exactly the same byte of data. Single address-space operating systems offer certain advantages. In a traditional OS with private per-process address space, memory protection is based on address space boundaries ("address space isolation"). Single address-space operating systems use a different approach for memory protection that is just as strong. One advantage is that the same virtual-to-physical map page table can be used with every process (and in some SASOS, the kernel as well). This makes context switches on a SASOS faster than on operating systems that must change the page table and flush the TLB caches on every context switch. SASOS projects include the following: * Amiga fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtualization
In computing, virtualization or virtualisation (sometimes abbreviated v12n, a numeronym) is the act of creating a virtual (rather than actual) version of something at the same abstraction level, including virtual computer hardware platforms, storage devices, and computer network resources. Virtualization began in the 1960s, as a method of logically dividing the system resources provided by mainframe computers between different applications. An early and successful example is IBM CP/CMS. The control program CP provided each user with a simulated stand-alone System/360 computer. Since then, the meaning of the term has broadened. Hardware virtualization ''Hardware virtualization'' or ''platform virtualization'' refers to the creation of a virtual machine that acts like a real computer with an operating system. 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 machi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attack Surface
The attack surface of a software environment is the sum of the different points (for "attack vectors") where an unauthorized user (the "attacker") can try to enter data to or extract data from an environment. Keeping the attack surface as small as possible is a basic security measure. Elements of an attack surface Worldwide digital change has accelerated the size, scope, and composition of an organization’s attack surface. The size of an attack surface may fluctuate over time, adding and subtracting assets and digital systems (e.g. websites, hosts, cloud and mobile apps, etc). Attack surface sizes can change rapidly as well. Digital assets eschew the physical requirements of traditional network devices, servers, data centers, and on-premise networks. This leads to attack surfaces changing rapidly, based on the organization’s needs and the availability of digital services to accomplish it. Attack surface scope also varies from organization to organization. With the rise of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Service Oriented Architecture
In software engineering, service-oriented architecture (SOA) is an architectural style that focuses on discrete services instead of a monolithic design. By consequence, it is also applied in the field of software design where services are provided to the other components by application components, through a communication protocol over a network. A service is a discrete unit of functionality that can be accessed remotely and acted upon and updated independently, such as retrieving a credit card statement online. SOA is also intended to be independent of vendors, products and technologies. Service orientation is a way of thinking in terms of services and service-based development and the outcomes of services. A service has four properties according to one of many definitions of SOA: # It logically represents a repeatable business activity with a specified outcome. # It is self-contained. # It is a black box for its consumers, meaning the consumer does not have to be aware of the se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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