Multiprocessor computer architecture with multiple operating system instances and software controlled resource allocation

This invention relates to multiprocessor computer architectures in which processors and other computer hardware resources are grouped in partitions, each of which has an operating system instance and, more specifically, to methods and apparatus for allocating computer hardware resources to partitions. 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.