1. A unified memory system comprising:
a memory accessed from a plurality of masters;
a speculative access control section for issuing, in response to a first access request to the memory from a CPU as one of the plurality of masters, a speculative second access request to the memory; and
a memory controller for receiving the first and second access requests and an access request to the memory from any of the plurality of masters other than the CPU and executing access to the memory,
wherein the speculative access control section issues the second access request according to speculative access information as information related to access to the memory.
2. The system of claim 1, wherein the CPU controls the speculative access control section using the speculative access information.
3. The system of claim 2, wherein the CPU uses memory access priorities of the plurality of masters as the speculative access information, and
the speculative access control section issues the second access request if the memory access priority of the CPU is higher than the memory access priority of any of the plurality of masters other than the CPU.
4. The system of claim 2, wherein the CPU determines a hit rate indicating the proportion in which data transfers already executed in response to speculative access requests were useful, as the speculative access information, and
the speculative access control section issues the second access request if the hit rate is higher than a predetermined value.
5. The system of claim 1, wherein the memory controller produces the speculative access information.
6. The system of claim 5, wherein the memory controller outputs the number of access requests from the plurality of masters as the speculative access information, and
the speculative access control section issues the second access request if the number of access requests is smaller than a predetermined value.
7. The system of claim 5, wherein the memory controller outputs the number of cycles required for completion of access to the memory as the speculative access information, and
the speculative access control section issues the second access request if no unexecuted normal access to the memory exists and the number of cycles is smaller than a predetermined value.
8. The system of claim 5, wherein the memory controller outputs requesting master information indicating a master that is under issuance of an access request to the memory, among the plurality of masters, as the speculative access information, and
the speculative access control section issues the second access request if the requesting master information does not indicate a predetermined master.
9. The system of claim 1, wherein the speculative access control section issues the second access request according to a parameter selected from a plurality of parameters as the speculative access information.
10. The system of claim 9, wherein the speculative access control section issues the second access request according to the result of weighted calculation of determination results on issuance of a second access request obtained based on a plurality of parameters selected.
11. The system of claim 1, further comprising a size determination section for setting the size of data to be transferred in response to the second access request at a value corresponding to the speculative access information.
12. The system of claim 1, wherein the speculative access control section issues a speculative third access request for accessing the memory after completion of access to the memory according to the second access request if the priority of access to the memory from the CPU is high.
13. The system of claim 12, further comprising a size determination section for setting the size of data to be transferred in response to the third access request at a value corresponding to the speculative access information.
14. The system of claim 12, wherein the speculative access control section determines a hit rate indicating the proportion in which data transfers already executed in response to speculative access requests were useful, and issues the third access request if the hit rate is higher than a predetermined value.
15. The system of claim 14, further comprising a size determination section for setting the size of data to be transferred in response to the third access request at a value corresponding to the hit rate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of detecting an unauthorized exchange of components comprising the steps of:
a control unit sending a message to a first component, said message including at least one randomly generated or not easily reproducible value used for checking said first component and a selection data field;
said first component accessing an assignment field and assigning an identification to each of said at least one randomly generated or not easily reproducible value when a defined value is transmitted in the selection data field;
said first component generating the identification on the basis of an algorithm when other values are transmitted in the selection data field;
said first component transmitting said identification back to said control unit; and
said control unit deciding, on the basis of the identification, whether the first component is a component which is authorized for use.
2. The method according to claim 1, wherein
the assignment field is a matrix from which said identification is generated on the basis of two randomly generated or not easily reproducible values.
3. The method according to claim 1, wherein:
the algorithm is filed in both the component and the control unit; and
said control unit uses said algorithm to determine whether the component is authorized.
4. The method according to claim 1, wherein the first component sends back a message to the control unit, in which the selection data field and then the determined identification are transmitted.
5. The method according to claim 1, wherein, on the basis of a function value or function result sent back by the first component using a message, the control unit carries out a comparison with the identification forwarded during a preceding message exchange, and decides therefrom whether the first component is that component which is authorized for the use in this technical system.
6. The method according to claim 1, wherein, on the basis of a message transmission from the control unit, the first component sends back the corresponding message with the identification.
7. The method according to claim 1, wherein:
the assignment field is also stored in the control unit;
the control unit uses the at least one randomly generated or not easily reproducible value to generate an identification which corresponds to the identification transmitted by said first component; and
said control unit determines whether said first component is authorized for use based on a comparison of said identifications.