Changing the target Security state of an exception

Hi,

I recently studied Arm®v8-M Architecture Reference Manual and saw the description "Secure software must ensure that when changing the target Security state of an exception, the exception is not pending or active. A change to the Security state of an exception when the exception is pending or active might lead to UNPREDICTABLE behavior." in Chapter B3.11 IQRDM

Does anyone know if the word "exception" mentioned above includes external interrupt?

If the interrupt is in the pending state, is it still inappropriate to disable first and then change the target Security state?

Many thanks! 

Parents
  • Q: Does anyone know if the word "exception" mentioned above includes external interrupt?
    A:  Yes, external interrupt is one type of exceptions.

    Q: If the interrupt is in the pending state, is it still inappropriate to disable first and then change the target Security state?

    A: If the interrupt (exception) is in the pending state, it is not suitable for the security state change.

Reply
  • Q: Does anyone know if the word "exception" mentioned above includes external interrupt?
    A:  Yes, external interrupt is one type of exceptions.

    Q: If the interrupt is in the pending state, is it still inappropriate to disable first and then change the target Security state?

    A: If the interrupt (exception) is in the pending state, it is not suitable for the security state change.

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