1. A method of controlling an operational mode for a logical partition on a computing system, the method comprising: receiving, in a hypervisor installed on the computing system, a processor compatibility mode for the logical partition and a firmware compatibility mode for the logical partition, the processor compatibility mode specifying a processor architecture version configured for the logical partition, and the firmware compatibility mode specifying a firmware architecture version configured for the logical partition; providing, by the hypervisor for the logical partition, a firmware interface in dependence upon the firmware compatibility mode; and providing, by the hypervisor for the logical partition, a processor interface in dependence upon the processor compatibility mode.