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In several operating systems—Linux, Unix, [citation needed] macOS, Microsoft Windows, z/OS, DESQview and some other operating systems used in the past—interrupt handlers are divided into two parts: the First-Level Interrupt Handler (FLIH) and the Second-Level Interrupt Handlers (SLIH).
When a signal is sent, the operating system interrupts the target process' normal flow of execution to deliver the signal. Execution can be interrupted during any non-atomic instruction . If the process has previously registered a signal handler , that routine is executed.
In a computer, an interrupt request (or IRQ) is a hardware signal sent to the processor that temporarily stops a running program and allows a special program, an interrupt handler, to run instead. Hardware interrupts are used to handle events such as receiving data from a modem or network card , key presses, or mouse movements.
A hardware interrupt is a condition related to the state of the hardware that may be signaled by an external hardware device, e.g., an interrupt request (IRQ) line on a PC, or detected by devices embedded in processor logic (e.g., the CPU timer in IBM System/370), to communicate that the device needs attention from the operating system (OS) [7] or, if there is no OS, from the bare metal ...
The interrupt could arrive before the DMA write was complete, and the processor could read stale data from memory. [5] To prevent this race, interrupt handlers were required to read from the device to ensure that the DMA write had finished. This read had a moderate performance penalty. An MSI write cannot pass a DMA write, so the race is ...
The interrupt priority level (IPL) is a part of the current system interrupt state, which indicates the interrupt requests that will currently be accepted. The IPL may be indicated in hardware by the registers in a programmable interrupt controller , or in software by a bitmask or integer value and source code of threads.
Suppose a process A is running and a timer interrupt occurs. The user registers — program counter, stack pointer, and status register — of process A are then implicitly saved by the CPU onto the kernel stack of A. Then, the hardware switches to kernel mode and jumps into interrupt handler for the operating system to take over.
An interrupt vector table (IVT) is a data structure that associates a list of interrupt handlers with a list of interrupt requests in a table of interrupt vectors. Each entry of the interrupt vector table, called an interrupt vector, is the address of an interrupt handler (also known as ISR). While the concept is common across processor ...