Arria® V SX and ST SoC Errata

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ID 683370
Date 7/14/2015
Public
Document Table of Contents
Document Table of Contents x
1. Arria® V SX and ST SoC Errata
1. Arria® V SX and ST SoC Errata x
1.1. Altera-Specific SoC Errata for Arria® V SX and ST Devices 1.2. Arm* Cortex* -A9 MPCore* and L2 Cache Errata 1.3. Revision History for Arria® V SX and ST SoC Errata
1.1. Altera-Specific SoC Errata for Arria® V SX and ST Devices x
1.1.1. Hard Processor System (HPS) 1.1.2. FPGA
1.1.1. Hard Processor System (HPS) x
1.1.1.1. EMAC RMII PHY Interface is Only Supported Through the FPGA Fabric 1.1.1.2. Hard Processor System Level 2 Cache Error Correction Code 1.1.1.3. Hard Processor System PLL Lock Issue After Power-on Reset or Cold Reset 1.1.1.4. HPS TAP Controller Is Reset By Cold Reset 1.1.1.5. SPI Slave Output Signals Cannot Be Isolated When Routed to the HPS Pins
1.1.2. FPGA x
1.1.2.1. False Configuration Failure in Active Serial Multi-Device Configurations
1.2. Arm* Cortex* -A9 MPCore* and L2 Cache Errata x
1.2.1. Arm* Cortex* -A9 MPU 1.2.2. Arm* L2 Cache Controller 1.2.3. Arm* CoreSight PTM
1.2.1. Arm* Cortex* -A9 MPU x
1.2.1.1. 761319: Ordering of Read Accesses to the Same Memory Location Might Be Uncertain 1.2.1.2. 775420: Particular Data Cache Maintenance Operation Which Aborts Might Lead to Deadlock 1.2.1.3. 782772: Speculative Execution of LDREX or STREX Instruction After a Write to Strongly Ordered Memory Might Lead to Deadlock 1.2.1.4. 761320: Full Cache Line Writes to the Same Memory Region From Both Processors Might Cause Deadlock 1.2.1.5. 845369: Under Very Rare Timing Circumstances Transition into Streaming Mode Might Create Data Corruption 1.2.1.6. 740657: Global Timer Can Send Two Interrupts for the Same Event 1.2.1.7. 751476: Missed Watchpoint on the Second Part of an Unaligned Access Crossing a Page Boundary 1.2.1.8. 754322: Faulty MMU Translations Following ASID Switch 1.2.1.9. 764369: Data or Unified Cache Line Maintenance by MVA Fails on Inner-Shareable Memory 1.2.1.10. 782773: Updating a Translation Entry to Move a Page Mapping Might Erroneously Cause an Unexpected Translation Fault 1.2.1.11. 794072: A Short Loop Including DMB Instruction Might Cause a Denial of Service When the Other Processor Executes a CP15 Broadcast Operation 1.2.1.12. 794073: Speculative Instruction Fetches with MMU Disabled Might Not Comply with Architectural Requirements 1.2.1.13. 794074: A Write Request to an Uncacheable, Shareable Normal Memory Region Might be Executed Twice, Possibly Causing a Software Synchronization Issue 1.2.1.14. 725631: ISB is Counted in Performance Monitor Events 0x0C and 0x0D 1.2.1.15. 729817: MainID Register Alias Addresses Are Not Mapped on Debug APB Interface 1.2.1.16. 729818: In Debug State, the Next Instruction is Stalled When the SDABORT Flag is Set Instead of Being Discarded 1.2.1.17. 751471: DBGPCSR Format Is Incorrect 1.2.1.18. 752519: An Imprecise Abort Might Be Reported Twice on Non-Cacheable Reads 1.2.1.19. 754323: Repeated Store in the Same Cache Line Might Delay the Visibility of the Store Description Impact Workaround Category 1.2.1.20. 756421: Sticky Pipeline Advance Bit Cannot be Cleared from Debug APB Accesses 1.2.1.21. 757119: Some Unallocated Memory Hint Instructions Generate an UNDEFINED Exception Instead of Being Treated as a NOP 1.2.1.22. 761321: MRC and MCR Are Not Counted in Event 0x68 1.2.1.23. 764319: Read Accesses to DBGPRSR and DBGPRCR May Generate an Unexpected UNDEF 1.2.1.24. 771221: PLD Instructions Might Allocate Data in the Data Cache Regardless of the Cache Enable Bit Value 1.2.1.25. 771224: Visibility of Debug Enable Access Rights to Enable/Disable Tracking is Not Ensured by an ISB 1.2.1.26. 771225: Speculative Cacheable Reads to Aborting Memory Regions Clear the Internal Exclusive Monitor and May Lead to Livelock 1.2.1.27. 775419: PMU Event 0x0A Might Count Twice the LDM PC ^ Instruction with Base Address Register Write-Back 1.2.1.28. 782774: A Spurious Event 0x63 Can be Reported on an LDREX That is preceded by a Write to Strongly Ordered Memory Region
1.2.2. Arm* L2 Cache Controller x
1.2.2.1. 754670: A Continuous Write Flow Can Stall a Read Targeting the Same Memory Area 1.2.2.2. 765569: Prefetcher Can Cross 4 KB Boundary if Offset is Programmed with Value 23 1.2.2.3. 729815: The High Priority for SO and Dev Reads Feature Can Cause Quality of Service Issues to Cacheable Read Transactions
1.2.3. Arm* CoreSight PTM x
1.2.3.1. 720107: Periodic Synchronization Can Be Delayed and Cause Overflow 1.2.3.2. 711668: Configuration Extension Register Has Wrong Value Status
1. Arria® V SX and ST SoC Errata

1.2.1.19. 754323: Repeated Store in the Same Cache Line Might Delay the Visibility of the Store

Description

The Cortex* -A9 implements a small counter that ensures the external visibility of all stores in a finite amount of time, causing an eventual drain of the Merging Store Buffer. This counter is present to avoid a situation where written data could potentially remain indefinitely in the Store Buffer.

This Store Buffer has merging capabilities and continues to merge data as long as the write accesses are performed in the same cache line. The issue that causes this erratum is that the draining counter resets each time a new data merge is performed.

In the case when a code sequence loops and continues to write data in this same cache line, then the external visibility of the written data might not be ensured. A livelock situation might consequently occur if any external agent is relying on the visibility of the written data, and where the writing processor cannot be interrupted while doing its writing loop.

This erratum can only happen on Normal Memory regions. The following examples describe scenarios that might trigger this erratum:

  • The processor continues incrementing a counter, writing the same word at the same address. The external agent (possibly the other processor) polls on this address, waiting for any update of the counter value to proceed. The Store Buffer continues merging the updated value of the counter in its cache line, so that the external agent never sees any updated value, possibly leading to livelock.
  • The processor writes a value in a given word to indicate completion of its task, and then continues writing data in an adjacent word in the same cache line. The external agent continues to poll the first word memory location to check when the processor completes its task. The situation is the same in the first example, because the cache line might remain indefinitely in the merging Store Buffer, creating a possible livelock in the system.

Impact

This erratum might create performance issues, or worst case, a livelock scenario, if the external agent relies on the automatic visibility of the written data in a finite amount of time.

Workaround

The recommended workaround for this erratum is to insert a DMB operation after the faulty write operation in code sequences that this erratum might affect to ensure the visibility of the written data to any external agent.

Category

Category 3

Level Two Title