"ACPI Warning: FADT (revision x) is longer than ACPI x.x version" message in the ESXi VMkernel log

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• In the /var/log/vmkernel.log file, there are entries similar to:
  
  ACPI Warning (tbfadt-0326): FADT (revision 5) is longer than ACPI 2.0 version, truncating length 0x10c to 0xf4TSC: 4944994616 cpu0:0) [20080926]
  
  ACPI Warning: FADT (revision 6) is longer than ACPI 5.0 version, truncating length 276 to 2680:00:00:00.164 cpu0:1) (20120215/tbfadt-399)

Environment

VMware vSphere ESXi 6.0
VMware vSphere ESXi 5.1
VMware vSphere ESXi 6.5

Cause

This message occurs when the physical server has firmware that provides an ACPI FADT table that is compliant with a newer version of the ACPI specification than ESXi requires.

In general, operating system software that was designed for older versions of the ACPI specification is compatible with hardware that implements newer versions of the specification. In particular, when the ACPI FADT table is changed in newer versions of the specification, the new specification only adds fields to the end of the table. It does not change or remove the existing fields. Therefore, when firmware provides ESXi with a newer version of the FADT than ESXi requires, ESXi simply ignores the added fields and continues to operate correctly.

Resolution

This is expected behavior and the warning message can be safely ignored.

In future releases of ESXi the warning message will be removed.

Additional Information

ESXi 5.1 の VMkernel ログファイルに次の警告メッセージが出力される：ACPI Warning (tbfadt-0326) : FADT (revision 5) is longer than ACPI 2.0 version, truncating length 0x10c to 0xf4TSC