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The NIDEN, DBGEN, SPIDEN, and SPNIDEN input signals are either tied off to some fixed value or controlled by some external device. If software running on the processor has control over an external device that drives the authentication signals, it must change the signal value using the specified procedure.
STRinstruction might write certain values to a control register in a system peripheral.
ISBinstruction or exception entry or exception return.
Software cannot perform debug or analysis operations that depend on the new value of the authentication signals until this procedure is complete. The same rules apply when the debugger has control of the processor through the Instruction Transfer Register, EDITR, while in debug state. You can determine the relevant combinations of the DBGEN, NIDEN, SPIDEN, and SPNIDEN values by polling DBGAUTHSTATUS_EL1.