OEMInterruptHandlerFIQ (Compact 2013)
This function provides fast interrupt request (FIQ) support for the ARM microprocessor.
The OEM implements this function. This function must be part of the OAL for an ARM build to succeed, even if it is only a stub.
This function has a C-language calling convention with a limited stack space of 256 bytes.
If no FIQ is generated by the hardware, the function should remain empty. The FIQ is intended as a quick entry or exit interrupt. Because of this characteristic, the following limitations exist on this code:
This function cannot return a value to the kernel to invoke an IST. However, it can perform urgent processing and generate a new IRQ, which can then return a SYSINTR value.
FIQs do not nest and can interrupt any IRQ interrupt handler. Nested interrupts can be achieved with the OEMInterruptHandler function, by calling the INTERRUPTS_ON function.
An FIQ ISR might not alter memory that is updated elsewhere with the interlocked functions. To maintain performance of the FIQ handling, interlocked restart is not enabled for FIQ.