1. A method of determining whether a logical processor of an electronic information processing system has access to an address space of the information processing system, comprising: a) executing at least an operating system program by a processor of the information processing system to allocate a plurality of address spaces within a total address space of the information processing system to a plurality of logical processors of the information processing system, each address space having a size and a position within the total address space defined by a range of addresses which is subject to vary as a result of execution of the operating system program; b) issuing an instruction by a first processor of an electronic information processing system, the instruction referencing a target logical processor of the plurality of logical processors and a target address space of the plurality of address spaces; c) in response to the instruction, checking first information by the information processing system to determine whether the target logical processor is running; and d) when it is determined that the target logical processor is not running, checking second information by a host program of the information processing system to determine whether the target logical processor has access to the target address space, wherein when it is determined that the target logical processor is running, returning a result by the host program to the first processor that it is not known whether the target logical processor has access to the target address space and posting an interrupt to the target logical processor requiring the target logical processor to relinquish its access to the target address space.