ESXi 6.5 supports I/O drivers built and certified on ESXi 5.5 (ESXi 5.5-based), on ESXi 6.0 (ESXi 6.0-based) in addition to I/O drivers built and certified on ESXi 6.5 (ESXi 6.5-based).
The VMware Compatibility Guide lists ESXi 5.5-based, ESXi 6.0-based, and ESXi 6.5 drivers as supported with ESXi 6.5.
Note: ESXi 5.5-based and ESXi 6.0-based drivers lack support only for the new features in ESXi 6.5.
Certified features are listed in the Model Release Details page of the VMware Compatibility Guide for each driver version where applicable.
New features for I/O drivers in ESXi 6.5:
Geneve Offload
Notes: