I've talked about a few of the enhancements that came in version 12.2.1 over the past few weeks. The last one is a new generic architecture class for newer systems that gives you new migration options for logical domains.
Some new systems - Oracle SPARC T4 servers, Oracle M5 and M6 servers, and Fujitsu M10 servers - have a class1 architecture. When you start a guest domain on one of these systems, Ops Center recognizes the architecture, and you can migrate the guest to systems with other CPU architectures without losing any LDOM capabilities.
Take a look at the Oracle VM Server for SPARC chapter in the Feature Reference Guide for more information about CPU architectures and other Logical Domain configuration options.