Compatibility modes on supported servers

You can run a processor in a compatibility mode on supported servers.

On an unmanaged server, a processor that is running in a compatibility mode is compatible with a previously released processor architecture. On a managed server, a processor compatibility mode specifies the processor environment in which a logical partition can successfully operate. While POWER6 and POWER6+ are distinct LPAR processor compatibility mode settings, Linux distribution kernels operate the same in these modes. However, compilers and applications can use more instructions in the POWER6+ mode that are not available in the POWER6 mode.

For more information about processor compatibility modes, see Processor compatibility modes in the Systems Hardware Knowledge Center. This link leads to information whose navigation suggests it pertains to only the IVM (Integrated Virtualization Manager) style of system management. However, processor compatibility modes is a concept more fundamental than system management style. This information applies equally to the HMC (Hardware Management Console) management style. In addition, the link leads to information for a specific system that contains a POWER7® processor. However, newer architecture information includes information about processor compatibility modes for previous architectures.