10.2. Synchronous and asynchronous exceptions

In AArch64, exceptions may be either synchronous, or asynchronous. An exception is described as synchronous if it is generated as a result of execution or attempted execution of the instruction stream, and where the return address provides details of the instruction that caused it. An asynchronous exception is not generated by executing instructions, while the return address might not always provide details of what caused the exception.

Sources of asynchronous exceptions are IRQ (normal priority interrupt), FIQ (fast interrupt) or SError (System Error). System errors have a number of possible causes, the most common being asynchronous Data Aborts (for example, an abort triggered by writeback of dirty data from a cache line to external memory).

There are a number of sources of Synchronous exceptions:

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