There are three low-level hardware test and clear mechanisms for system logic and memory:
•Memory built-in self-test (MBIST) tests the RAM elements used to store values
•Logic BIST (LBIST) tests the logic used for control
•Scan clear removes system state
The MBIST always runs after the power-on rest (POR). The MBIST can also be initiated by the system software calling the platform management unit user firmware (PMU FW). The LBIST only runs after a POR and only if the LBIST_EN eFUSE is programmed. The PMU scan clear only runs after a POR. The LPD and FPD scan clear only works when LPD_SC and FPD_SC eFuses are programmed. If the eFuses are programmed the LPD and FPD scan clear are always running after a POR or after a secure lockdown only.
Running MBIST, LBIST, or scan clear will cause loss of state. Therefore, care must be taken when initiating BIST and clear functions during system operation.