Identification of faults in data paths and functional units of a central processing unit by a systematic execution of test instructions

• US 5,712,972 A
• Filed: 06/07/1995
• Issued: 01/27/1998
• Est. Priority Date: 06/07/1995
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Kakkar, Sunil
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): Wright, Norman M.
• Application Number:
  US08/483,604
• Time in Patent Office: 965 Days
• Field of Search: 395/183.02, 395/182.03, 395/183.04, 395/183.06, 395/183.07, 395/183.19, 395/183.16, 395/182.08, 395/185.01, 371/16.1
• US Class Current: 714/26
• CPC Class Codes: G06F 11/22 Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing
• CPC Class Codes: G06F 11/221 to test buses, lines or interfaces, e.g. stuck-at or open line faults

Abstract

A systematically structured diagnostic for detecting, isolating, analyzing and reporting problems or faults in a central processing unit. The diagnostic causes the central processing unit to execute instructions, the instructions being selected such that the central processing unit, in executing the instructions, must use every data path and functional unit therein. Errors caused by particular instructions are correlated with the functional units or datapaths used by those instructions, to produce a list of possibly faulty datapaths and functional units. Test procedures, specifically designed to the possibly faulty datapaths and functional units, are then applied to the central processing unit to isolate which of the possibly faulty data paths or functional units are in fact faulty, which are then reported. The instructions, test procedures and other information used by the diagnostic are stored in databases, so that the diagnostic has a modular and data-driven structure which permits evolution of the diagnostic over time as the central processing unit layout changes and the diagnostic is upgraded to provide higher levels of fault-detection functionality.

Claims

1. A diagnostic method for locating faulty functional units and data paths in a central processing unit of a data processing circuit, said central processing unit having signal input and output terminals, said data paths connecting signals from and between said terminals and said functional units, said functional units modifying signals received though said data paths, comprising

providing a first database of instructions, said instructions, when input as signals to terminals of said central processing unit, causing said central processing unit to use every data path and functional unit in said central processing unit,

providing a second database correlating groups of said instructions to functional units and datapaths of said central processing unit which must be operating correctly to avoid an error during said groups of instructions,

providing a third database of test procedures, each test procedure, when input as electrical signals to terminals of said central processing unit, causing the central processing unit to use specific data paths and functional units, and including a test for determining whether a data path or functional unit used by the central processing unit in response to said test procedure is faulty, said third database correlating said test procedures with specific data paths and functional units used in response to said test procedure,

executing, in said central processing unit, each of said instructions in said first database by providing electrical signals corresponding to said instructions to terminals of said central processing unit, and forming a first log of errors identifying data paths and functional units which were found to be faulty during execution of said instructions,

correlating groups of instructions which produced errors identified in said first log to said second database to form a second log of possibly faulty functional units and data paths in said central processing unit,

selecting test procedures from said third database which are correlated to possibly faulty functional units and data paths identified by said second log, and

performing, in said central processing unit, test procedures selected in the preceding step by providing electrical signals corresponding to said test procedures to terminals of said central processing unit, and forming a third log of those functional units and data paths indicated to be faulty by tests performed by said test procedures.

2. The method of claim 1 wherein

said first database further comprises expected values indicating results which would be generated by a non-faulty central processing unit in response to instructions in said first database,

said executing step includes comparing said expected values to electrical signals at terminals of said central processing unit indicative of results produced by said central processing unit in response to instructions in said first database, and if said values and results are not consistent, adding an error to said first log.

3. The method of claim 2 wherein said executing step forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

4. The method of claim 3 further comprising

providing a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit,

selecting error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and

reporting said error messages.

5. The method of claim 4 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

6. The method of claim 1 wherein said executing step forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

7. The method of claim 6 further comprising

providing a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit,

selecting error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and

reporting said error messages.

8. The method of claim 7 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

9. The method of claim 1 further comprising

providing a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit,

selecting error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and

reporting said error messages.

10. The method of claim 9 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

11. Apparatus for locating faulty functional units and data paths in a central processing unit of a data processing circuit, said central processing unit having signal input and output terminals, said data paths connecting signals from and between said terminals and said functional units, said functional units modifying signals received through said data paths, comprising

storage maintaining a first database of instructions, said instructions, when input as signals to terminals of said central processing unit, causing said central processing unit to use every data path and functional unit in said central processing unit,

storage maintaining a second database correlating groups of said instructions to functional units and datapaths of said central processing unit which must be operating correctly to avoid an error during said groups of instructions,

storage maintaining a third database of test procedures, each test procedure, when input as electrical signals to terminals of said central processing unit, causing the central processing unit to use specific data paths and functional units, and including a test for determining whether a data path or functional unit used by the central processing unit in response to said test procedure is faulty, said third database correlating said test procedures with specific data paths and functional units used in response to said test procedure,

a diagnostic control circuit, said diagnostic control circuit

causing said central processing unit to execute each of said instructions in said first database, by providing electrical signals corresponding to said instructions to terminals of said central processing unit, forming a first log of errors identifying data paths and functional units which were found to be faulty during execution of said instructions,

correlating groups of instructions which produced errors identified in said first log to said second database to form a second log of possibly faulty functional units and data paths in said central processing unit,

selecting test procedures from said third database which are correlated to possibly faulty functional units and data paths identified by said second log, and causing said central processing unit to perform test procedures selected in the preceding step, by providing electrical signals corresponding to said test procedures to terminals of said central processing unit, and

forming a third log of those functional units and data paths indicated to be faulty by tests performed by said test procedures.

12. The apparatus of claim 11 wherein

said first database further comprises expected values indicating results which would be generated by a non-faulty central processing unit in response to instructions in said first database,

said diagnostic control circuit compares said expected values to electrical signals at terminals of said central processing unit indicative of results produced by said central processing unit in response to instructions in said first database, and if said values and results are not consistent, adds an error to said first log.

13. The apparatus of claim 12 wherein diagnostic control circuit forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

14. The apparatus of claim 13 further comprising

storage maintaining a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, and wherein

said diagnostic control circuit selects error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reports said error messages.

15. The apparatus of claim 14 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

16. The apparatus of claim 11 wherein diagnostic control circuit forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

17. The apparatus of claim 16 further comprising

storage maintaining a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, and wherein

said diagnostic control circuit selects error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reports said error messages.

18. The apparatus of claim 17 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

19. The apparatus of claim 11 further comprising

storage maintaining a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, and wherein

said diagnostic control circuit selects error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reports said error messages.

20. The apparatus of claim 19 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

21. The apparatus of claim 11 wherein said diagnostic control circuit comprises circuitry separate from and communicating with said central processing unit.