When you use Oracle VM Server for SPARC, you can assign most of the memory in a SPARC T5 server to logical domains. However, a small portion of the server's memory is preassigned to software components, the hypervisor, and certain I/O devices. To determine which portions of memory are unavailable for logical domains, type this command:
# ldm ls-devices -a mem
In the output, look for rows that include _sys_ in the Bound column. Each of those portions of memory is not available for logical domains.