Method, apparatus and system for allocating and accessing memory-mapped facilities within a data processing system

摘要

Within a data processing system, a pool of facilities are allocated to an operating system, where each facility within the pool of facilities has an associated real address. The operating system allocates from the pool at least one bypass facility to a first process that the first process is permitted to directly access by its associated real address without first obtaining translation of a non-real address. The operating system also allocates from the pool at least one protected facility to a second process that the second process accesses only by translation of a non-real address to obtain the real address associated with the protected facility. Accesses to the facilities are either protected or unprotected based upon the state of a bypass field within a request address.