In multiprocessor environments, Sun Solaris can allow enabling or disabling Processors. This although is not something that we would do all the time but can come handy when troubleshooting hardware issues.
Sun Solaris has the psradm utility which allows enabling or disabling a Processor on the system. The psradm utility changes the operational status of processors. The legal states for the processor are on-line, offline, spare, Faulted, and no-intr. An online processor processes LWPs (lightweight processes) and can be interrupted by I/O devices in the system.