Intel Agilex® 7 F-Series and I-Series Known Issue List

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ID 683584
Date 5/03/2023
Public
Document Table of Contents
Document Table of Contents x
1. About this Document 2. Known Issue List for Intel Agilex® 7 Devices 3. Arm* Cortex*-A53 MPCore* and CoreSight* Errata 4. Intel Agilex® 7 F-Series and I-Series User Guidelines 5. Document Revision History for the Intel Agilex® 7 F-Series and I-Series Known Issue List
2. Known Issue List for Intel Agilex® 7 Devices x
2.1. FPGA 2.2. Hard Processor System
2.1. FPGA x
2.1.1. Configuration and Security
2.1.1. Configuration and Security x
2.1.1.1. FPGA Reconfiguration May Cause Device to Halt 2.1.1.2. Secure Device Manager May Disable Physically Unclonable Function
2.2. Hard Processor System x
2.2.1. Write Data Can Appear at an AXI Interface before the Write Address, which can Cause a Deadlock Condition
3. Arm* Cortex*-A53 MPCore* and CoreSight* Errata x
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
1. About this Document
2. Known Issue List for Intel Agilex® 7 Devices
3. Arm* Cortex*-A53 MPCore* and CoreSight* Errata
4. Intel Agilex® 7 F-Series and I-Series User Guidelines
5. Document Revision History for the Intel Agilex® 7 F-Series and I-Series Known Issue List

3.4. 855872: A Store-Exclusive Instruction May Pass When it Should Fail

Description

The Cortex-A53 MPCore* processor implements an internal exclusive monitor to manage load-exclusive, store-exclusive, and clear-exclusive instructions. Because of this erratum, a load-exclusive instruction to cacheable memory may set the monitor to the exclusive state when the processor does not have exclusive access to the line. A subsequent store-exclusive instruction may pass when it should fail.

This erratum affects all load-exclusive and store-exclusive instructions, including load-acquire exclusive and store-release exclusive instructions.

The conditions that trigger this erratum are listed below:
  • A core executes a store to memory that is marked as both inner-writeback and outer-writeback.
  • The store is not a store-exclusive (or a store-release exclusive) or a store-release instruction.
  • The store is not followed by a DMB SY or DSB.
  • The store misses in the L1 data cache.
  • The store does not trigger a linefill. This requires one or more of the following to be true:
    • The core is in read-allocate mode
    • The memory is marked as no-write-allocate
    • The memory is marked as transient
    • The store is a STNP instruction
    • The store is triggered by a DC ZVA instruction
  • The core starts a linefill to the same address as the store. The linefill is started for one of the following:
    • A PRFM, PLD, or PLDW instruction
    • An automatic data prefetch
    • A pagewalk
  • The core executes a load-exclusive (or a load-acquire exclusive) instruction to the same address as the store
  • The store data is forwarded to the load-exclusive instruction
  • If a core starts a linefill to the same address as the store, the load-exclusive instruction retires before the linefill is serialized.

Impact

If the above conditions are met then the Cortex-A53 MPCore* processor may set the internal exclusive monitor. This behavior is incorrect because the processor is not guaranteed to have exclusive access to the line. If another master executes a load-exclusive instruction to the same address then both masters may gain access to an exclusive region of code at the same time.

Workaround

The only workaround is to avoid the conditions described above. Disabling read-allocate mode by setting CPUACTLR.RADIS to 0x3 degrades write-stream performance. Therefore, the preferred workaround is to use an appropriate store-exclusive (or a store-release exclusive) or a store-release instruction or DMB instruction.

Category

Category 2
Level Two Title