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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 system used by NAPI is an example of the hardware-based approach: the system (driver) starts in interrupt enabled state, and the Interrupt handler then disables the interrupt and lets a thread/task handle the event(s) and then task polls the device, processing some number of events and enabling the interrupt.
The system treats every signal( ) to wake one thread as a broadcast( ) to wake all of them, thus breaking any possibly expected 1:1 relationship between signals and wakeup. [1] If ten threads are waiting, only one will win and the other nine will experience spurious wakeup.
INT is an x86 instruction that triggers a software interrupt, and 13 hex is the interrupt number (as a hexadecimal value) being called. Modern computers come with both BIOS INT 13h and UEFI functionality that provides the same services and more, with the exception of UEFI Class 3 that completely removes CSM thus lacks INT 13h and other interrupts.
The 8259 combines multiple interrupt input sources into a single interrupt output to the host microprocessor, extending the interrupt levels available in a system beyond the one or two levels found on the processor chip. The 8259A was the interrupt controller for the ISA bus in the original IBM PC and IBM PC AT.
IRQ 2/9 is the traditional interrupt line for an MPU-401 MIDI port, but this conflicts with the ACPI system control interrupt (SCI is hardwired to IRQ9 on Intel chipsets); [6] this means ISA MPU-401 cards with a hardwired IRQ 2/9, and MPU-401 device drivers with a hardcoded IRQ 2/9, cannot be used in interrupt-driven mode on a system with ACPI ...
In a modern operating system, upon entry the execution context of a hardware interrupt handler is subtle. For reasons of performance, the handler will typically be initiated in the memory and execution context of the running process, to which it has no special connection (the interrupt is essentially usurping the running context—proces
BIOS interrupt calls perform hardware control or I/O functions requested by a program, return system information to the program, or do both. A key element of the purpose of BIOS calls is abstraction - the BIOS calls perform generally defined functions, and the specific details of how those functions are executed on the particular hardware of the system are encapsulated in the BIOS and hidden ...