After upgraded the BIOS and NIC drivers the BIOS ‘upgrade’ has disabled some essential features of the CPU. When verifying the EVC mode of the Production cluster, the CPUs are missing from host:
Reproduced the error and identified the following change in BIOS version 1.39 caused the issue.
In BIOS version 1.39, Monitor/Mwait setting is set to Disable by default, but EVC needs this setting to be enabled.
To solve this problem, follow the below steps to enable this setting:
1. Enter BIOS setup menu by pressing Del key during the system booting
2. In BIOS setup menu, select Advanced\Intel RC Group\Processor Configuration
3. Set Monitor/Mwait to Enable, press F10 to save the change.
The reason of the change is we set CPU power saving mode to disable by default from this version, leave it as an option for customer to enable it when needed. Monitor/Mwait is a relevant setting for this change, so it is set to disable also after upgrading the BIOS.