A kernel is the central part of an operating system. It manages the operations of the computer and the hardwaremost notably memory and CPU time. A computer user never interacts directly with the kernel.
It runs behind the scenes and cannot be seen, except for the text logs that it prints. The kernel is the most fundamental part of an operating system. It can be thought of as the program which controls all other programs on the computer. When the computer starts, it goes through some initialization booting functions, such as checking memory.
It is responsible for assigning and unassigning memory space which allows software to run. The kernel provides services so programs can request the use of the network cardthe disk or other pieces of hardware. The kernel forwards the request to special programs called device drivers which control the hardware.
It also manages the file system and sets interrupts for the CPU to enable multitasking. Many kernels are also responsible for ensuring that faulty programs do not interfere with the operation of others by denying access to memory that has not been allocated to them and restricting the amount of CPU time they can consume.
It is the heart of the operating system.
Operating systems commonly use monolithic kernels. In Linuxfor example, device drivers are often part of a kernel specifically Loadable Kernel Modules. When a device is needed, its extension is loaded and 'joined' onto the kernel making the kernel larger. Monolithic kernels can cause trouble when one of these drivers is faulty, such as if a beta driver is downloaded. Because it is part of the kernel the faulty driver can override the mechanisms that deal with faulty programs see above.
This can mean that the kernel, and thus the entire computer, can cease to function. If there are too many devices, the kernel can also run out of memory causing a system crash or making the computer very slow. Microkernels are a way of solving this problem. In a microkernel operating system, the kernel deals only with critical activities, such as controlling the memory and CPU, and nothing else. Drivers and other functions that monolithic kernels would normally include within the kernel are moved outside the kernel, where they are under control.
Instead of being an uncontrollable part of the kernel the beta driver is, therefore, no more likely to cause a crash than a beta web browser. That is, if a driver goes wrong it can simply be restarted by the kernel.
Unfortunately, creating microkernel based operating systems is very difficult and there are no common microkernel operating systems. Minix and QNX are both microkernel operating systems. From Simple English Wikipedia, the free encyclopedia. Bellevue Linux Users Group. Category : Computer science. Namespaces Page Talk. Views Read Change Change source View history.A Kernel is a computer program that is the heart and core of an Operating System.
Since the Operating System has control over the system so, the Kernel also has control over everything in the system. It is the most important part of an Operating System. Whenever a system starts, the Kernel is the first program that is loaded after the bootloader because the Kernel has to handle the rest of the thing of the system for the Operating System.
The Kernel remains in the memory until the Operating System is shut-down. The Kernel is responsible for low-level tasks such as disk management, memory management, task management, etc. It provides an interface between the user and the hardware components of the system.
When a process makes a request to the Kernel, then it is called System Call. A Kernel is provided with a protected Kernel Space which is a separate area of memory and this area is not accessible by other application programs. So, the code of the Kernel is loaded into this protected Kernel Space. Apart from this, the memory used by other applications is called the User Space.
As these are two different spaces in the memory, so communication between them is a bit slower. There are certain instructions that need to be executed by Kernel only. For example, memory management should be done in Kernel-Mode only. Monolithic Kernels are those Kernels where the user services and the kernel services are implemented in the same memory space i. By doing so, the size of the Kernel is increased and this, in turn, increases the size of the Operating System.
As there is no separate User Space and Kernel Space, so the execution of the process will be faster in Monolithic Kernels. A Microkernel is different from Monolithic kernel because in a Microkernel, the user services and kernel services are implemented into different spaces i.
As we are using User Space and Kernel Space separately, so it reduces the size of the Kernel and this, in turn, reduces the size of Operating System. As we are using different spaces for user services and kernel service, so the communication between application and services is done with the help of message parsing and this, in turn, reduces the speed of execution.
It makes the use of the speed of Monolithic Kernel and the modularity of Microkernel. Hybrid kernels are micro kernels that have some "non-essential" code in kernel-space in order for the code to run more quickly than it would be in user-space. So, some services such as network stack or filesystem are run in Kernel space to reduce the performance overhead, but still, it runs kernel code as servers in the user-space.
In a Nanokrnel, as the name suggests, the whole code of the kernel is very small i. The term nanokernel is used to describe a kernel that supports a nanosecond clock resolution.
Here in this type of kernel, the resource protection is separated from the management and this, in turn, results in allowing us to perform application-specific customization.
In the Exokernel, the idea is not to implement all the abstractions. But the idea is to impose as few abstractions as possible and by doing so the abstraction should be used only when needed. So, no force abstraction will be there in Exokernel and this is the feature that makes it different from a Monolithic Kernel and Microkernel.
But the drawback of this is the complex design. The design of the Exokernel is very complex. Do share this blog with your friends to spread the knowledge.
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What is the Linux kernel?
Share this blog and spread the knowledge. Share On Facebook.A kernel is the core component of an operating system. Using interprocess communication and system calls, it acts as a bridge between applications and the data processing performed at the hardware level.
When an operating system is loaded into memory, the kernel loads first and remains in memory until the operating system is shut down again. The kernel is responsible for low-level tasks such as disk management, task management and memory management. The kernel provides and manages computer resources, allowing other programs to run and use these resources. The kernel also sets up memory address space for applications, loads files with application code into memory, sets up the execution stack for programs and branches out to particular locations inside programs for execution.
The kernel is responsible for:. Toggle navigation Menu. Kernel Last Updated: July 1, Definition - What does Kernel mean? Microkernels: Define a simple abstraction over hardware that use primitives or system calls to implement minimum OS services such as multitasking, memory management and interprocess communication. Hybrid Kernels: Run a few services in the kernel space to reduce the performance overhead of traditional microkernels where the kernel code is still run as a server in the user space.
Nano Kernels: Simplify the memory requirement by delegating services, including the basic ones like interrupt controllers or timers to device drivers. Exo Kernels: Allocate physical hardware resources such as processor time and disk block to other programs, which can link to library operating systems that use the kernel to simulate operating system abstractions. Share this:. Related Terms. Related Articles. Reinforcement Learning Vs. What is the difference between a mobile OS and a computer OS?
What is the difference between alpha testing and beta testing?The kernel is a computer program at the core of a computer's operating system with complete control over everything in the system. It is the "portion of the operating system code that is always resident in memory". On most systems, it is one of the first programs loaded on startup after the bootloader.
It handles memory and peripherals like keyboards, monitors, printers, and speakers. The critical code of the kernel is usually loaded into a separate area of memory, which is protected from access by application programs or other, less critical parts of the operating system. The kernel performs its tasks, such as running processes, managing hardware devices such as the hard diskand handling interrupts, in this protected kernel space. In contrast, application programs like browsers, word processors, or audio or video players use a separate area of memory, user space.
This separation prevents user data and kernel data from interfering with each other and causing instability and slowness,  as well as preventing malfunctioning application programs from crashing the entire operating system. The kernel's interface is a low-level abstraction layer. When a process requests a service to the kernel, it must invoke a system callusually through a wrapper function that is exposed to userspace applications by system libraries which embed the assembly code for entering the kernel after loading the CPU registers with the syscall number and its parameters e.
There are different kernel architecture designs. Monolithic kernels run entirely in a single address space with the CPU executing in supervisor modemainly for speed. Microkernels run most but not all of their services in user space,  like user processes do, mainly for resilience and modularity. Instead, the Linux kernel is monolithic, although it is also modular, for it can insert and remove loadable kernel modules at runtime. This central component of a computer system is responsible for 'running' or 'executing' programs.
The kernel takes responsibility for deciding at any time which of the many running programs should be allocated to the processor or processors. Random-access memory RAM is used to store both program instructions and data.
Often multiple programs will want access to memory, frequently demanding more memory than the computer has available.
The kernel is responsible for deciding which memory each process can use, and determining what to do when not enough memory is available. Key aspects necessary in resource management are defining the execution domain address space and the protection mechanism used to mediate access to the resources within a domain.The Linux kernel, developed by contributors worldwide, is a free and open-source  monolithicmodular i.
System administrators can tailor Linux for their specific targets and for special usage scenarios before compilation;   users who have been granted the necessary privileges can also fine-tune kernel parameters at runtime. The Linux kernel is deployed on a wide variety of computing systems, such as embedded devicesmobile devices including its use in the Android operating systempersonal computersserversmainframesand supercomputers.
The Linux kernel was conceived and created in by Linus Torvalds  for his personal computer and with no cross-platform intentions, but has since ported to a wide range of computer architectures.
Notwithstanding this, the Linux kernel is highly optimized with the use of architecture specific instructions ISA therefore portability isn't as easy as it is with other kernels e.
Linux was soon adopted as the kernel for the GNU Operating System which was created as an open source and free softwareand based on UNIX as a by-product of the fallout of the Unix wars.
The Linux ABI i. In-tree drivers that are configured to become an integral part of the kernel executable vmlinux are statically linked by the building process. There's also no guarantee of stability of source level in-kernel API and, because of this, device drivers code, as well as the code of any other kernel subsystem, must be kept updated with kernel evolution.
In AprilLinus Torvaldsat the time a year-old computer science student at the University of HelsinkiFinlandstarted working on some simple ideas for an operating system. He started with a task switcher in Intel assembly language and a terminal driver. On 25 AugustTorvalds posted the following to comp. I'm doing a free operating system just a hobby, won't be big and professional like gnu for AT clones.
This has been brewing since April, and is starting to get ready. I've currently ported bash 1. This implies that I'll get something practical within a few months [ On 17 SeptemberTorvalds prepared version 0. It was not even executable since its code still needed Minix for compilation and play. On 5 OctoberLinus announced the first "official" version of Linux, version 0. It has finally reached the stage where it's even usable though may not be depending on what you wantand I am willing to put out the sources for wider distribution.
It is just version 0. After that, many people contributed code to the project, included some developers from the MINIX community. At the time, the GNU Project had created many of the components required for a free operating system, but its own kernel, GNU Hurdwas incomplete and unavailable.
The Berkeley Software Distribution had not yet freed itself from legal encumbrances. Despite the limited functionality of the early versions, Linux rapidly gained developers and users.
Torvalds assigned version 0 to the kernel to indicate that it was mainly for testing and not intended for productive use. When Torvalds released version 0. With the support of the POSIX APIs, through the libC that, whether needed, acts as an entry point to the kernel address space, Linux could run software and applications that had been developed for Unix.
On 19 Januarythe first post to the new newsgroup alt. Linux version 0. It started a versioning system for the kernel with three or four numbers separated by dots where the first represented the major release, the second was the minor releaseand the third was the revision.01. Introduction to Unix - Shell, Kernel and Architecture
The optional fourth digit indicated a set of patches to a revision. The current version numbering is slightly different from the above. The even vs.It is the core that provides basic services for all other parts of the OS. It is the main layer between the OS and hardware, and it helps with process and memory management, file systems, device control and networking. You forgot to provide an Email Address.
This email address is already registered. Please login. You have exceeded the maximum character limit. Please provide a Corporate E-mail Address. Please check the box if you want to proceed. A kernel might also include a manager for the OS' address spaces in memory or storage. The manager shares the address spaces among all components and other users of the kernel's services. Other parts of the OS, as well as application programsrequest a kernel's services through a set of program interfaces known as system calls.
Device drivers help kernels execute actions. Device drivers are pieces of code that correspond to each device and execute when devices connect to the OS or hardware through a USB or software download. Device drivers help close the gap between user applications and hardware, as well as streamline the code's inner workings. To ensure proper functionality, the kernel must have a device driver embedded for every peripheral present in the system. There are several types of device drivers.
Each addresses different data transfer types. A few main types are:. Because the OS needs the code that makes up the kernel continuously, the code is usually loaded into computer storage in an area that is protected so that it will not be overlaid with less frequently used parts of the OS. Before the kernel, developers coded actions directly to the processorinstead of relying on an OS to complete interactions between hardware and software.
The first attempt to create an OS that passed messages via kernel was in with the RC Multiprogramming System.
Programmer Per Brinch Hansen discovered it was easier to create a nucleus and then build up an OS, instead of converting existing OSes to be compatible with new hardware. This nucleus -- or kernel -- contained all source code to facilitate communications and support systems, eliminating the need to directly program on the CPU.
The goal of Unix was to create smaller utilities that do specific tasks well instead of having system utilities try to multitask. From a user standpoint, this simplifies creating shell scripts that combine simple tools.
Kernel (operating system)
Unix's structure perpetuated the idea that it was easier to build a kernel on top of an OS that reused software and had consistent hardware, instead of relying on a time-shared system that didn't require an OS.
Unix brought OSes to more individual systems, but researchers at Carnegie Mellon expanded kernel technology.
From tothey expanded work on the Mach kernel. Researchers made it binary-compatible with existing BSD software, enabling it to be available for immediate use and continued experimentation. The Mach kernel's original goal was to be a cleaner version of Unix and a more portable version of Carnegie Mellon's Accent interprocess communication IPC kernel. Over time, the kernel brought new features, such as ports and IPC-based programs, and ultimately evolved into a microkernel.
This distribution contained a microkernel-based structure, multitasking, protected mode, extended memory support and an American National Standards Institute ANSI C compiler.The kernel is the central module of an operating system OS. It is the part of the operating system that loads first, and it remains in main memory. Because it stays in memory, it is important for the kernel to be as small as possible while still providing all the essential services required by other parts of the operating system and applications.
The kernel code is usually loaded into a protected area of memory to prevent it from being overwritten by programs or other parts of the operating system. Typically, the kernel is responsible for memory management, process and task management, and disk management. The kernel connects the system hardware to the application software. Every operating system has a kernel. Stay up to date on the latest developments in Internet terminology with a free newsletter from Webopedia.
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