Abstract: A data processing machine is configured to automatically keep track of hypervisor given pointers pointing to respective and newly allocated areas of memory and to automatically keep track of corresponding copies or derivatives of the given pointers. A unique allocation identifier is generated for each newly allocated area. The allocation identifier is appended to a valid ID's holding list. All pointers pointing to the allocated area are tracked by a protected pointers tracking table. Additionally, a multi-input associative cache stores entries for recently used ones of the protected pointers where the entries include the respective allocation identifiers of the pointers. All pointers to a given, de-allocated area can be invalidated by deleting their entries form the multi-input associative cache and by deleting the corresponding unique allocation identifier from the valid ID's holding list.

Abstract: A method for maintaining memory coherency in a data processing system is disclosed. The data processing system includes a memory system having a dual bus memory controller, which is coupled to a first bus through a first bus master and a second bus coupled to a second bus master. The method maintains memory coherency by snooping across either the first or second bus for attributes on an address/data multiplex bus in the data processing unit. To determine when a snoop operation is required, the system begins by requesting access to either of the two buses through the dual bus memory controller. Once the control of the bus has been granted upon request data is transferred using the master bus controller. It is upon the receipt of an invalid data signal while transferring data across the bus that the snoop activity begins. The snoop is injected only after an invalid data signal is received and a last snoop injection can occur only before a last read data is read.

Abstract: A method and system for enhanced system management operations in a superscalar data processing system. Those supervisory level instructions which execute selected privileged operations within protected memory space are first identified as not requiring a full context synchronization. Each time execution of such an instruction is initiated an enable special access (ESA) instruction is executed as an entry point to that instruction or group of instructions. A portion of the machine state register for the data processing system is stored and the machine state register is then modified as follows: a problem bit is set, changing the execution privilege state to "supervisor;" external interrupts are disabled; and access privilege state bit is set; and, a special access mode bit is set, allowing execution of special instructions. The instructions which execute the selected privileged operations within the protected memory space are then executed.

Abstract: A method and system for permitting the selective support of non-architected instructions within a superscalar processor system. A special access bit within the system machine state register is provided and set in response to each initiation of an application during which execution of non-architected instructions is desired. Thereafter, each time a non-architected instruction is decoded the status of the special access bit is determined. The non-architected instruction is executed in response to a set state of the special access bit. The illegal instruction program interrupt is issued in response to an attempted execution of a non-architected instruction if the special access bit is not set. In this manner, for example, complex instruction set computing (CISC) instructions may be selectively enabled for execution within a reduced instruction set computing (RISC) data processing system while maintaining full architectural compliance with the reduced instruction set computing (RISC) instructions.

Abstract: A method and system for efficient memory management in a data processing system which utilizes a memory management unit to translate effective addresses into real addresses within a translation lookaside buffer is disclosed. During a first mode of operation a selected number of effective address identifiers are stored in the translation lookaside buffer. In association with each virtual address identifier is a corresponding real address entry for a single memory block wherein selected virtual addresses may be translated into corresponding real addresses utilizing the translation lookaside buffer.

Abstract: A protocol and system for providing a next read address during an address phase of a write transaction in a data cache unit in a processing unit is disclosed. The processing unit includes the data cache unit and an instruction cache unit both coupled to an address bus and a data bus, respectively. The two buses are further connected to a system memory controller separate from the microprocessor. The protocol and system provide for next read address and a next transaction during the address phase in a current write transaction. The protocol loads a pre-fetched address within a current data transaction and then generates a next line fill address using the pre-fetched address which is concatenated to the current data transaction. The pre-fetched address is used to generate a next line fill address.