摘要:
Non-intrusive techniques have been developed to dynamically and selectively alter address translations performed by, or for, a processor. For example, in some embodiments, a memory management unit is configured to map from effective addresses in respective effective (or virtual) address spaces to physical addresses in the memory, wherein the mappings performed by the memory management unit are based on address translation entries of an address translation table. For a subset of less than all processes, entry selection logic selects from amongst plural alternative mappings coded in respective ones of the address translation entries. For at least some effective addresses mapped for a particular process of the subset, selection of a particular address translation entry is based on an externally sourced value. In some embodiments, only a subset of effective addresses mapped for the particular process are subject to dynamic runtime alteration of the address translation entry selection.
摘要:
Non-intrusive techniques have been developed to dynamically and selectively alter address translations performed by, or for, a processor. For example, in some embodiments, a memory management unit is configured to map from effective addresses in respective effective (or virtual) address spaces to physical addresses in the memory, wherein the mappings performed by the memory management unit are based on address translation entries of an address translation table. For a subset of less than all processes, entry selection logic selects from amongst plural alternative mappings coded in respective ones of the address translation entries. For at least some effective addresses mapped for a particular process of the subset, selection of a particular address translation entry is based on an externally sourced value. In some embodiments, only a subset of effective addresses mapped for the particular process are subject to dynamic runtime alteration of the address translation entry selection.
摘要:
A data processing system includes a processor having a multi-way cache which has a first and a second way. The second way is configurable to either be redundant to the first way or to operate as an associative way independent of the first way. The system may further include a memory, where the processor, in response to a read address missing in the cache, provides the read address to the memory. The second way may be dynamically configured to be redundant to the first way during operation of the processor in response to an error detection signal. In one aspect, when the second way is configured to be redundant, in response to the read address hitting in the cache, data addressed by an index portion of the read address is provided from both the first and second way and compared to each other to determine if a comparison error exists.
摘要:
Method and apparatus for performing access censorship in a data processing system (10). In one embodiment, a digital data processing system (10) has a sub-system (34) that can be protected against intrusions, yet is still accessible and/or alterable under certain defined conditions. In a non-volatile storage portion (48) of the data processing system (10), censorship information is stored to enable an access control mechanism. Access control information (42) to selectively disable the access control mechanism is programmably generated. Additional access control information (44) can be employed to reprogram a data processing system (10) containing access protected data in a secure mode.
摘要:
A method and apparatus for performing atomic accesses in a data processing system (10). In one embodiment, a small number of control signals (e.g. 100-102; or 103-104; or 105-108 from FIG. 3 ) are used to provide information regarding the status of reservations between bus masters (e.g. 80), bus interfaces (e.g. 84, 86, and 92), and snoop logic (e.g. 82,88, and 90). Snoop logic (e.g. 40 in FIG. 2) is required if multiple bus masters (12 and 46) are used. The control signals allow atomic accesses to be performed in a multi-master data processing system (10), while minimizing the circuitry required to be built on-board each bus master integrated circuit processor (e.g. 152 in FIG. 3). The result is lower cost processors (152) which can operate in multi-processor systems, but which are optimized for use in single-processor systems.
摘要:
The present invention relates in general to a data processing system (10), and more particularly to a method and apparatus for controlling showcycles in a data processing system (10) to provide user control over the tradeoff between internal bus visibility and operating performance. In one embodiment, the functionality of one or more register control bits (100, 102) can be combined with the functionality of one or more externally provided signals (78) to allow the user to have a wide range of control over the show cycles provided on external bus 12. The user is thus able to continuously select and change which information is provided by way of show cycles on external bus 12. As a result, the difficulty of debugging software program code can potentially be reduced.
摘要:
A method for tracking alteration of a non-volatile storage includes receiving a request to modify a tracked region of the non-volatile storage. In response to the request, it is determined whether or not a modification of data stored in a non-erasable one-time programmable (NEOTP) alteration log region has occurred. In response to determining that the modification of the data stored in the NEOTP alteration log region has occurred, the tracked region of non-volatile storage is modified in response to the request. In response to determining that the modification of the data stored in the NEOTP alteration log region has not occurred, the request to modify the tracked region of the non-volatile memory is denied.
摘要:
A data processing system (20) has a central processing unit (CPU) (22) and a memory (30) for storing an exception table. The exception table is mapped in the memory (30) in consecutive segments, with each segment for storing a predetermined number of instructions for executing the exception. By asserting a control bit, the exception table can be relocated, or remapped, and compressed into a jump table. The jump table stores only jump instruction for branching to the exception routines, which are relocated to other memory locations. The jump table is generated from the starting addresses of the exception routines. Relocating the exception routines allows for more efficient use of internal memory space of the data processing system (20).
摘要:
A master device (11) can access slave devices (12) either speculatively or non-speculatively. The slave devices (12) can be either non-hazardous devices or hazardous devices which exhibit status changes on reading. The master device (11) issues an access request including information as to whether the request is speculative or non-speculative, the slave device (12) then responds to the master device (11) with a negative acknowledgment that access is denied if the access request is speculative and the slave device (12) is hazardous. Otherwise, if the slave device (12) can deal with the request, a positive acknowledgment is sent. If the master device (11) receives a negative acknowledgment, it continues to reissue updated access requests until a positive acknowledgment is received.
摘要:
A bus protocol is provided for pipelined and/or split transaction buses (18,48) which have in-order data bus termination and which do not require data bus arbitration. The present invention solves the problem of matching the initial address request by a bus master (12, 13, 42) to the corresponding data response from a bus slave (14, 15, 44) when the bus (18, 48) used for master-slave communication is a split-transaction bus and/or a pipelined bus. Each bus master (12, 13, 42) and each bus slave (14, 15, 44) has a counter (30-33, 75-76) which is used to store a current pipe depth value (21, 51) from a central pipe counter (16, 72). A transaction start signal (20, 50) and a transaction end signal (22, 52) are used to selectively increment and decrement the counters (30-33, 75-76).