Fast interrupt request (FIQ) is a specialized type of
interrupt request
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 s ...
, which is a standard technique used in computer CPUs to deal with events that need to be processed as they occur, such as receiving data from a network card, or keyboard or mouse actions. FIQs are specific to the
ARM architecture, which supports two types of interrupts; FIQs for fast, low-latency interrupt handling, and standard interrupt requests (IRQs), for more general interrupts.
An FIQ takes priority over an IRQ in an ARM system. Also, only one FIQ source at a time is supported. This helps reduce interrupt latency as the interrupt service routine can be executed directly without determining the source of the interrupt. A context save is not required for servicing an FIQ since it has its own set of banked registers. This reduces the overhead of
context switching.
References
External links
Debugging ARM kernels using fast interrupts LWN.net
LWN.net is a computing webzine with an emphasis on free software and software for Linux and other Unix-like operating systems. It consists of a weekly issue, separate stories which are published most days, and threaded discussion attached to ...
, May 29, 2014, by Daniel Thompson
Interrupts
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