Multiple firmware levels in a partitionable multi-processor system

A baseboard management controller in a multi-processor system may perform operations including: identifying a partitioning mode (partitioned state or unified state) to implement on the multi-processor system having first and second central processing units (CPUs) located on a single motherboard; accessing, in response to the partitioned state, a first partitioned node configuration (P1C) for a first partitioned node (P1) and a second partitioned node configuration (P2C) for a second partitioned node (P2), wherein P1C identifies a first firmware interface level (F1L) and a first operating system to be used by P1, and wherein P2C identifies a second firmware interface level (F2L) and a second operating system to be used by P2; and causing the first CPU to load a first firmware interface having the identified F1L identified in the P1C and causing the second CPU to load a second firmware interface having the F2L identified in the P2C.