Visible to Intel only — GUID: fnn1487885510938
Ixiasoft
3.1. 843819: Memory Locations May be Accessed Speculatively Due to Instruction Fetches When HCR.VM is Set
3.2. 845719: A Load May Read Incorrect Data
3.3. 855871: ETM Does Not Report IDLE State When Disabled Using OSLOCK
3.4. 855872: A Store-Exclusive Instruction May Pass When it Should Fail
3.5. 711668: Configuration Extension Register Has Wrong Value Status
3.6. 720107: Periodic Synchronization Can Be Delayed and Cause Overflow
3.7. 855873: An Eviction Might Overtake a Cache Clean Operation
3.8. 853172: ETM May Assert AFREADY Before All Data Has Been Output
3.9. 836870: Non-Allocating Reads May Prevent a Store Exclusive From Passing
3.10. 836919: Write of the JMCR in EL0 Does Not Generate an UNDEFINED Exception
3.11. 845819: Instruction Sequences Containing AES Instructions May Produce Incorrect Results
3.12. 851672: ETM May Trace an Incorrect Exception Address
3.13. 851871: ETM May Lose Counter Events While Entering WFx Mode
3.14. 852071: Direct Branch Instructions Executed Before a Trace Flush May be Output in an Atom Packet After Flush Acknowledgment
3.15. 852521: A64 Unconditional Branch May Jump to Incorrect Address
3.16. 855827: PMU Counter Values May Be Inaccurate When Monitoring Certain Events
3.17. 855829: Reads of PMEVCNTR<n> are not Masked by HDCR.HPMN
3.18. 855830: Loads of Mismatched Size May not be Single-Copy Atomic
Visible to Intel only — GUID: fnn1487885510938
Ixiasoft
3.3. 855871: ETM Does Not Report IDLE State When Disabled Using OSLOCK
Description
The OS Lock feature in the Embedded Trace Macrocell (ETM) allows software running on the Cortex*-A53 MPCore* to disable external debug access and save the register state before powering down the ETM. Software must follow a defined sequence to ensure that the register state is stable and all trace data is output before the system is powered-down. Because of this erratum, when the OS Lock mechanism is used, the ETM never indicates to software that it is safe to be powered-off. This erratum occurs when:- The ETM is enabled (TRCPRGCTLR.EN = 1)
- The OS Lock feature disables the ETM (TRCOSLAR.OSLK = 1)
Impact
When the OS lock feature is enabled and software polls TRCSTATR.IDLE, it remains high even after the ETM is disabled and drained of trace data. If the ETM is already disabled by clearing the TRCPRGCTLR.EN bit then a software save and restore sequence behaves correctly.
Workaround
To execute the disable sequence properly:
- Disable the ETM by setting the TRCOSLAR.OSLK bit.
- Save the state of the TRCPRGCTLR.EN bit.
- Clear the TRCPRGCTLR.EN bit.