METHOD AND APPARATUS FOR RECONFIGURING MEMORY IN A MULTIPRCESSOR SYSTEM WITH SHARED MEMORY

Multiple instances of operating systems execute cooperatively in a single multiprocessor computer wherein all processors and resources are electrically connected together. The single physical machine with multiple physical processors and resources is subdivided by software into multiple partitions, each with the ability to run a distinct copy, or instance, of an operating system. At different times, different operating system instances may be loaded on a given partition. Resources, such as CPUs and memory, can be dynamically assigned to different partitions and used by instances of operating systems running within the machine by modifying the configuration. The partitions themselves can also be changed without rebooting the system by modifying the configuration tree. Memory may be reconfigured into or out of a partition or community under software control. In general, memory may be in one of three states: private, shared, or unowned. Memory is private if it is "owned" by a single system partition. Memory is shared if it is owned by partitions which are members of a community. Otherwise, it is unowned. Memory is placed in an "unowned" state by an operating system instance and console software, reflected in the system configuration tree, before the memory can be reconfigured into or out of a system.