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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 time from when a hardware interrupt is generated to when the interrupt is serviced is called the interrupt latency. Switching between two processes in a single address space operating system can be faster than switching between two processes in an operating system with private per-process address spaces.
The IRR specifies which interrupts are pending acknowledgement, and is typically a symbolic register which can not be directly accessed. The ISR register specifies which interrupts have been acknowledged, but are still waiting for an end of interrupt (EOI). The IMR specifies which interrupts are to be ignored and not acknowledged.
The job of a FLIH is to quickly service the interrupt, or to record platform-specific critical information which is only available at the time of the interrupt, and schedule the execution of a SLIH for further long-lived interrupt handling. [2] FLIHs cause jitter in process execution. FLIHs also mask interrupts.
Message Signaled Interrupts (MSI) are a method of signaling interrupts, using special in-band messages to replace traditional out-of-band signals on dedicated interrupt lines. While message signaled interrupts are more complex to implement in a device, they have some significant advantages over pin-based out-of-band interrupt signalling, such ...
During this time, the process was not performing useful work, but still maintained complete control of the CPU. With the advent of interrupts and preemptive multitasking, these I/O bound processes could be "blocked", or put on hold, pending the arrival of the necessary data, allowing other processes to utilize the CPU.
For the "interrupt acknowledge" method, the external device gives the CPU an interrupt handler number. The interrupt acknowledge method is used by the Intel Pentium and many older microprocessors. [8] When the CPU is affected by an interrupt, it looks up the interrupt handler in the interrupt vector table, and transfers control to it.
A part of the preservation process is automatically handled by the MPU when it acknowledges the interrupt, as it will push the program counter (and program bank in the 65C816/65C802) and status register to the stack prior to executing the ISR. At the completion of the ISR, when the RTI instruction is executed, the MPU will reverse the process ...