[Firmware Bug]: CPU52: APIC id mismatch. Firmware: 34 APIC: 40

This document (000019947) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12 SP4 (LTSS)
Microsoft Azure Virtual Machines

Situation

System is running on top of  Microsoft Azure and these messages can be seen in the logs:
2020-11-08T09:32:59.603656+00:00 hec45v122410 kernel: [0.004000] [Firmware Bug]: CPU52: APIC id mismatch. Firmware: 34 APIC: 40
2020-11-08T09:32:59.603656+00:00 hec45v122410 kernel: [0.120329] #53
2020-11-08T09:32:59.603657+00:00 hec45v122410 kernel: [0.004000] [Firmware Bug]: CPU53: APIC id mismatch. Firmware: 35 APIC: 41
2020-11-08T09:32:59.603660+00:00 hec45v122410 kernel: [0.125622] #54
2020-11-08T09:32:59.603661+00:00 hec45v122410 kernel: [0.004000] [Firmware Bug]: CPU54: APIC id mismatch. Firmware: 36 APIC: 42
2020-11-08T09:32:59.603661+00:00 hec45v122410 kernel: [0.130967] #55
2020-11-08T09:32:59.603661+00:00 hec45v122410 kernel: [0.004000] [Firmware Bug]: CPU55: APIC id mismatch. Firmware: 37 APIC: 43
2020-11-08T09:32:59.603662+00:00 hec45v122410 kernel: [0.134924] #56
2020-11-08T09:32:59.603662+00:00 hec45v122410 kernel: [0.004000] [Firmware Bug]: CPU56: APIC id mismatch. Firmware: 38 APIC: 44

Resolution

The reported kernel messages are harmless.

Cause

These errors are benign and can be ignored:
 [Firmware Bug]: CPU52: APIC id mismatch. Firmware: 34 APIC: 40
They occur in any Azure VM that has multiple NUMA nodes and where the number of vCPUs in a NUMA node is not a power of 2.
In this case the M208ms_v2 VM size has 208 vCPUs, with 52 vCPUs in each of 4 NUMA nodes. 52 is not a power of 2, so the errors are generated.
The root cause is the way Hyper-V sets up some ACPI tables in the guest VM.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:000019947
  • Creation Date: 20-Apr-2021
  • Modified Date:21-Apr-2021
    • SUSE Linux Enterprise Server

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