CXL Memory Firmware Error Record Persistence
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Solution Overview
Problem
Existing Compute Express Link (CXL) devices face data loss and operational disruptions due to error records being lost when powered down or switched between hosts, as previous approaches rely on passive error detection and do not effectively preserve error logs across device resets or host changes.
Innovation Solution
The implementation of Coherent Device Attribute Table (CDAT) interface to record and communicate error information within the CXL device firmware, allowing error records to persist across power cycles and host changes, enabling CXL Memory Block Error Synchronization (CMBES) for masking invalid memory units and preventing system-wide disabling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error records are stored in volatile memory of CXL device, then error detection is fast and simple, but error records are lost when device is powered down or switched between hosts
Solution Approach 1:
The patent applies preliminary action by proactively copying error records from volatile memory to persistent storage (firmware or non-volatile memory) before the device is powered down or switched between hosts. This ensures that error information is preserved in advance, preventing data loss when the volatile memory is cleared during power cycles or host transitions.
Solution Approach 2:
The patent implements the copying principle by creating a duplicate copy of error records from volatile memory and storing it in persistent storage media such as firmware or non-volatile memory. This copy mechanism ensures that error information survives power cycles and host switches, allowing the new host to retrieve and continue error logging without loss.
2Reliability
If passive error detection is used in previous approaches, then system complexity is reduced, but error records cannot be preserved across device resets or host changes
Solution Approach 1:
The patent introduces an intermediary mechanism (error record copying process involving firmware or non-volatile storage) that bridges the gap between volatile error logging and persistent error preservation. This intermediary layer enables error records to survive power cycles and host switches while maintaining a relatively simple overall system architecture that builds upon existing passive error detection frameworks.
3Adaptability or versatility
If CXL device is switched between hosts, then device versatility and adaptability are improved, but error records are lost and require re-detection
Solution Approach 1:
The patent applies preliminary action by copying error records to persistent storage before the device is switched to a new host. This advance preparation ensures that when the device connects to a new host, the error records are already preserved and can be immediately retrieved, eliminating the need for time-consuming re-detection processes and enabling continuous error monitoring across host transitions.
4Productivity
If error records are not preserved, then device reusability is reduced, but storage complexity and power consumption are minimized
Solution Approach 1:
The patent implements copying by creating a duplicate of error records in persistent storage only when needed for preservation, rather than continuously maintaining elaborate error logging systems. This selective copying approach enables device reusability across hosts while minimizing ongoing power consumption, as the persistent storage is only actively accessed during error record transfer operations rather than requiring continuous power for complex error management hardware.
Data Source
AI summary
Provided is a method comprising obtaining information about a detected memory error in a memory device, the memory device being connected to a first host via a compute express link, CXL, interface. The method comprises further recording the memory error information into a firmware of the memory device.