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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 ...
Rather than using a hard-coded interrupt dispatch table at the hardware level, software interrupts are often implemented at the operating system level as a form of callback function. Interrupt handlers have a multitude of functions, which vary based on what triggered the interrupt and the speed at which the interrupt handler completes its task.
For example, hardware timers send interrupts to the CPU at regular intervals. Most operating systems execute a HLT instruction when there is no immediate work to be done, putting the processor into an idle state. In Windows NT, for example, this instruction is run in the "System Idle Process". On x86 processors, the opcode of HLT is 0xF4.
IRQ 9 – Advanced Configuration and Power Interface (ACPI) system control interrupt on Intel chipsets. [6] And/or left for the use of peripherals (use depends on OS) IRQ 10 – The interrupt is left for the use of peripherals (for example, SCSI or NIC) IRQ 11 – The interrupt is left for the use of peripherals (for example, SCSI or NIC)
A Deferred Procedure Call (DPC) is a Microsoft Windows operating system mechanism which allows high-priority tasks (e.g. an interrupt handler) to defer required but lower-priority tasks for later execution. This permits device drivers and other low-level event consumers to perform the high-priority part of their processing quickly, and schedule ...
MSI (first defined in PCI 2.2) permits a device to allocate 1, 2, 4, 8, 16 or 32 interrupts. The device is programmed with an address to write to (this address is generally a control register in an interrupt controller), and a 16-bit data word to identify it. The interrupt number is added to the data word to identify the interrupt. [1]
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.
When an interrupt occurs, the processor multiplies the interrupt vector by the entry size (8 for protected mode, 16 for long mode) and adds the result to the IDT base address. [4] If the address is inside the table, the DPL is checked and the interrupt is handled based on the gate type.