Error: Invalid cpuid.coresPerSocket value (XX) when powering on a virtual machine on vSphere ESXi

Products

• VMware vSphere ESXi
• VMware Telco Cloud Platform

Issue/Introduction

All vSphere ESXi versions up to 7.x support a maximum of 64 vCPUs per virtual socket. This is documented in Hardware Features Available with Virtual Machine Compatibility Settings under: "Maximum number of cores (virtual CPUs) per socket".

Powering on a VM with a manually configured value for cpuid.coresPerSocket larger than 64 will result in a power on failure:

"Invalid cpuid.coresPerSocket value (XX). You must select between 1 and 64 cores per socket."

Note that when creating large virtual machines on CPUs with more than 32 cores and HyperThreading (SMT) enabled, a virtual socket topology that exactly matches the physical one might not be possible. This however does not affect the automatic vNUMA node sizing.

 

Environment

ESXi: 7.x

TCP: 3.0

Cause

vSphere ESXi versions up to 7.x support a maximum of 64 vCPUs per virtual socket. Manually configuring the cpuid.coresPerSocket parameter to a value exceeding 64 triggers a validation failure in the CPUID module during the power-on sequence.

Resolution

This configuration maximum was increased in vSphere ESXi 8.0. VMs with virtual hardware version 20 and EFI now support up to 256 vCPU per socket, with the exact number depending on the guest OS selection.