SPRAD28 October 2022 AM2431 , AM2432 , AM2434 , AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P4 , AM263P4-Q1 , AM26C31 , AM26C31-EP , AM26C31M , AM26C32 , AM26C32-EP , AM26C32C , AM26C32M , AM26LS31 , AM26LS31M , AM26LS32A , AM26LS32AC , AM26LS32AM , AM26LS33A , AM26LS33A-SP , AM26LS33AM , AM26LV31 , AM26LV31E , AM26LV31E-EP , AM26LV32 , AM26LV32E , AM26LV32E-EP , AM26S10 , AM2732 , AM2732-Q1
When several exceptions occur simultaneously, they are serviced in a fixed order of priority. Each exception is handled in turn before execution of the user program continues. It is not possible for all exceptions to occur concurrently. For example, the Undefined Instruction and SVC exceptions are mutually exclusive because they are both triggered by executing an instruction. Because the Data Abort exception has a higher priority than the FIQ exception, the Data Abort is actually registered before the FIQ is handled. The Data Abort handler is entered, but control is then passed immediately to the FIQ handler. When the FIQ has been handled, control returns to the Data Abort handler. This means that the data transfer error does not escape detection as it would if the FIQ were handled first.
Exception | Priority |
---|---|
Reset | 1 (Highest) |
Data Abort | 2 |
FIQ | 3 |
IRQ | 4 |
Prefetch Abort | 5 |
SVC | 6 |
Undefined Abort | 6 (lowest) |