Changes to VM PCI Topology Due to New ACPI Motherboard Layout in Hardware Version 21 and later

Products

• VMware vSphere ESXi

Issue/Introduction

• When creating a VM with Hardware Version 21 or later, the pci slot number sequence may differ from that of versions 20 and earlier, resulting in different slot assignments compared to previous hardware versions.
  For example, the device “ethernet0” expected at slot 192(versions 20 and earlier) may change to a different value as per design.
  
  
• This may impact certain hardcoded configuration via templates regarding virtual devices being assigned to specific PCI slots.
  
  

Environment

Esxi 8.0.x

Cause

For VMs using EFI firmware with hardware version 21 and later, new virtual ACPI motherboard layout is implemented by design. This layout supports the vSphere 8.x Virtual NUMA Topology feature but alters the VM’s PCI topology.

Resolution

The updated ACPI motherboard layout is automatically applied to HWv21 and later EFI VMs without user control. 

Workaround:

It is recommended to avoid power-on of VM or installing any operating system during the firmware reconfiguration phase. 

1. Create a VM with the latest hardware version using BIOS firmware
2. While the VM is powered off, reconfigure to EFI firmware to retain the legacy PCI topology. (Note that this disables the vNUMA Topology feature)

Note: Hardware versions 20 and earlier is available to support legacy workloads.

Additional Information

Virtual device PCI slot changes upon upgrade from hardware version 19