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What happens if an interrupt occurs as it is already disabled

Manyam

for ARMv7 architecture:What happens if an interrupt occurs as it is already disabled

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  • +1 Arm Employee Badge

    If an interrupt is masked in the CPSR then the short answer is nothing - the processor will simply ignore any interrupts which arrive when the interrupt is masked.

    However, in most cases interrupts are not transient signals - most peripherals will keep their interrupt line asserted until it is cleared by explicit action (e.g. a device driver clears the interrupt). This means that even though the CPU does not take the interrupt when it is first asserted, the peripheral will keep the interrupt line active and the interrupt will be taken when the CPU eventually unmasks IRQ or FIQ (depending which interrupt type it is associated with).

    HTH,
    Pete

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  • +1 Arm Employee Badge

    If an interrupt is masked in the CPSR then the short answer is nothing - the processor will simply ignore any interrupts which arrive when the interrupt is masked.

    However, in most cases interrupts are not transient signals - most peripherals will keep their interrupt line asserted until it is cleared by explicit action (e.g. a device driver clears the interrupt). This means that even though the CPU does not take the interrupt when it is first asserted, the peripheral will keep the interrupt line active and the interrupt will be taken when the CPU eventually unmasks IRQ or FIQ (depending which interrupt type it is associated with).

    HTH,
    Pete

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