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Evdev
evdev (short for 'event device') is a generic input event interface in the Linux kernel and FreeBSD. It generalizes raw input events from device drivers and makes them available through character devices in the /dev/input/ directory. The user-space library for the kernel component evdev is called libevdev. Libevdev abstracts the evdev ioctls through type-safe interfaces and provides functions to change the appearance of the device. Libevdev shares similarities with the read system call. It sits below the process that handles input events, in between the kernel and that process. : kernel → libevdev → xf86-input-evdev → X server → X client For Weston/Wayland compositor, the stack would look like this: : kernel → libevdev → libinput → Wayland compositor Wayland is a communication protocol that specifies the communication between a display server and its clients, as well as a C library implementation of that protocol. A display server using the Wayland pr ...
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Linux API
The Linux kernel provides multiple interfaces to user-space and kernel-mode code. The interfaces can be classified as either application programming interface (API) or application binary interface (ABI), and they can be classified as either kernel–user space or kernel-internal. Linux API The Linux API includes the kernel–user space API, which allows code in user space to access system resources and services of the Linux kernel. It is composed of the system call interface of the Linux kernel and the subroutines in the C standard library. The focus of the development of the Linux API has been to provide the ''usable features'' of the specifications defined in POSIX in a way which is reasonably compatible, robust and performant, and to provide additional useful features not defined in POSIX, just as the kernel–user space APIs of other systems implementing the POSIX API also provide additional features not defined in POSIX. The Linux API, by choice, has been ...
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Wayland (display Server Protocol)
Wayland is a communication protocol that specifies the communication between a display server and its clients, as well as a C library implementation of that protocol. A display server using the Wayland protocol is called a '' Wayland compositor'', because it additionally performs the task of a compositing window manager. Wayland is developed by a group of volunteers initially led by Kristian Høgsberg as a free and open-source community-driven project with the aim of replacing the X Window System with a secure and simpler windowing system for Linux and other Unix-like operating systems. The project's source code is published under the terms of the MIT License, a permissive free software licence. As part of its efforts, the Wayland project also develops a implementation of a Wayland compositor called ''Weston''. Overview The Wayland Display Server project was started by Red Hat developer Kristian Høgsberg in 2008. Beginning around 2010, Linux desktop graphics have moved ...
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Linux Kernel
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ...
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FreeBSD
FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable home-class hardware, and has since continuously been the most commonly used BSD-derived operating system. FreeBSD maintains a complete system, delivering a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties such as GNU for system software. The FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The project includes a security team overseeing all software shipped in the base distribution. Third-party applications may be installed using the pkg package management system or from source via FreeBSD Ports. The project is supported and promoted by the FreeBSD Foundation ...
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Device Driver
In the context of an operating system, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used. A driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device (drives it). Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface. Purpose The main purpose of device drivers is to provide abstraction b ...
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Device File
In Unix-like operating systems, a device file, device node, or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an application program to interact with a device by using its device driver via standard input/output system calls. Using standard system calls simplifies many programming tasks, and leads to consistent user-space I/O mechanisms regardless of device features and functions. Overview Device files usually provide simple interfaces to standard devices (such as printers and serial ports), but can also be used to access specific unique resources on those devices, such as disk partitions. Additionally, device files are useful for accessing system resources that have no connection with any actual device, such as data sinks and random number generators. There are two general kinds of device files in Unix-like operating syst ...
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Ioctl
In computing, ioctl (an abbreviation of input/output control) is a system call for device-specific input/output operations and other operations which cannot be expressed by regular file semantics. It takes a parameter specifying a request code; the effect of a call depends completely on the request code. Request codes are often device-specific. For instance, a CD-ROM device driver which can instruct a physical device to eject a disc would provide an ioctl request code to do so. Device-independent request codes are sometimes used to give userspace access to kernel functions which are only used by core system software or still under development. The ioctl system call first appeared in Version 7 of Unix under that name. It is supported by most Unix and Unix-like systems, including Linux and macOS, though the available request codes differ from system to system. Microsoft Windows provides a similar function, named "DeviceIoControl", in its Win32 API. Background Conventional op ...
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Read (system Call)
In modern POSIX compliant operating systems, a program that needs to access data from a file stored in a file system uses the read system call. The file is identified by a file descriptor that is normally obtained from a previous call to open. This system call reads in data in bytes, the number of which is specified by the caller, from the file and stores then into a buffer supplied by the calling process. The read system call takes three arguments: # The file descriptor of the file. # The buffer where the read data is to be stored. # The number of bytes to be read from the file. POSIX usage The read system call interface is standardized by the POSIX specification. Data from a file is read by calling the read function: ssize_t read(int fd, void *buf, size_t count); The value returned is the number of bytes read (zero indicates end of file) and the file position is advanced by this number. It is not an error if this number is smaller than the number of bytes requested; this m ...
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Interfaces Of The Linux Kernel
Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Interface: A Journal for and About Social Movements'' * ''Interface'', shortened name for the ''Journal of the Royal Society Interface'', covering the interface between life sciences and physical sciences * ''Interfaces'' (journal), now ''INFORMS Journal on Applied Analytics'' Arts and entertainment * ''Interface'' (album), by Dominion, 1996 * Interface (band), an American music group * ''Interface'' (film), a 1984 American film * ''Interface'' (novel), by Stephen Bury (a pseudonym), 1994 * "Interface" (''Star Trek: The Next Generation''), an episode of the TV series * '' Interface series'', a science fiction horror story in short installments on Reddit Science and technology * Interface (computing), a shared boundary between system comp ...
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