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Interrupt handlers are initiated by hardware interrupts, software interrupt instructions, or software exceptions, and are used for implementing device drivers or transitions between protected modes of operation, such as system calls. The traditional form of interrupt handler is the hardware interrupt handler.
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 ...
When working with personal computer hardware, installing and removing devices, the system relies on interrupt requests. There are default settings that are configured in the system BIOS and recognized by the operating system. These default settings can be altered by advanced users.
An Interrupt Request Level (IRQL) is a hardware-independent means with which Windows prioritizes interrupts that come from the system's processors. On processor architectures on which Windows runs, hardware generates signals that are sent to an interrupt controller .
On Intel systems, the LAPIC must be enabled for the PCI (and PCI Express) MSI/MSI-X to work, even on uniprocessor (single core) systems. [ 11 ] [ 12 ] In these systems, MSIs are handled by writing the interrupt vector directly into the LAPIC of the processor/core that needs to service the interrupt.
The critical parts of the OS run in kernel mode, while other software (such as system utilities and application programs) run in user mode. This serves as the fundamental distinction between the OS and other system software. The part of the system executing in the kernel mode is called the kernel, or nucleus, of the OS. The kernel is designed ...
Software interrupt vector numbers are defined by the specific runtime environment, such as the IBM PC BIOS, DOS, or other operating systems. They are triggered by software using the INT instruction (either by applications, device drivers or even other interrupt handlers).
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.