System and method for optimizing a device driver by incorporating debugging and tracing

• US 6,526,567 B1
• Filed: 08/16/1999
• Issued: 02/25/2003
• Est. Priority Date: 03/24/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Cobbett, Michael, Wong, Yuk-Lun, Duffin, Paul Andrew
• Primary Examiner(s): Khatri, Anil
• Application Number:
  US09/375,063
• Time in Patent Office: 1,289 Days
• Field of Search: 717/124, 717/127, 717/128, 717/136, 717/139, 717/151, 717/106, 717/122, 702/119, 714/799
• US Class Current: 717/124
• CPC Class Codes: G06F 11/3624 by performing operations on the source code, e.g. via a compiler
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 11/366 using diagnostics G06F11/0703 takes precedence
• CPC Class Codes: G06F 8/54 Link editing before load time

Abstract

The invention relates to a method for executing, in a computer system 5, a device driver 10 which is used by a number of applications running on that system. A first 12 and second version 11 of the device driver are provided, with the first version being optimised and the second version containing debug code for providing trace information. Upon discovering a problem with the device driver, it is possible to selectively switch to the debug version of the code without any of the applications already using the device driver being aware of the switch. Having gathered the necessary trace data, it is then possible to transparently switch back to the optimised version. Conventionally, device drivers form part of the operating system within a computer and so are difficult to remove and re-load without taking the whole system down and re-booting. The invention however affords continuous service to any application already using the device driver and does not require a time-wasting reboot which may in any event remove the error condition.

Claims

1. A method for executing a software component in a computer system, wherein said software component is used by one or more applications running on the computer system, and wherein said method comprises:

providing a first and second version of said software component, wherein said first version of the software component is optimised and said second version contains debug code for providing trace information; and

selectively switching between- the first and second versions of said software component, said switching being transparent to any applications already using the software component.

2. The method of claim 1 wherein said software component is a device driver.

3. The method of claim 2 wherein an application using the device driver first establishes communication therewith by making an appropriate call to the computer operating system.

4. The method of claim 1 wherein said first version is used by default by an application upon the execution of said software component.

5. The method of claim 1 wherein said switching between the first and second versions of said software component occurs in response to a system call.

6. The method of claim 5 wherein said system call sets a boolean flag and wherein the value of said boolean flag determines which version of said software component is executed.

7. The method of claim 1, wherein said software component provides a plurality of corresponding functions in both versions, the function names in one version differing from the function names in the other version.

8. The method of claim 7 wherein the function names in one version can be distinguished from the function names in other version by an identifier.

9. The method of claim 7, wherein said step of selectively switching comprises:

selecting a sub-set of functions from within the version containing debug code; and

selecting the remaining functions from the other version.

10. The method of claim 9, wherein said sub-set selection occurs in response to a system call, said system call setting a plurality of boolean flags, wherein the value of said plurality of flags determines which functions within the debug version are executed.

11. A method for constructing a software component, comprising the steps of:

creating source code;

preprocessing said source code to produce two versions of said code, wherein said second version differs from said first version in that said second version contains debug code for providing trace information;

combining said first and second versions to construct the software component.

12. The method of claim 11 wherein said software component is a device driver.

13. The method of claim 11 wherein said preprocessing step comprises the step of generating one version automatically from the other version by copying.

14. The method of claim 11, wherein said software component provides a plurality of corresponding functions in both versions, the function names in one version differing from the function names in the other version.

15. The method of claim 14 wherein the step of pre-processing further comprises modifying the function names of one version with an identifier, wherein said identifier serves to distinguish the function names in one version from the other version.

16. The method of claim 11 wherein said pre-processing further comprises the step of removing all debug code from the second version in order to produce the first version.

17. The method of claim 11 wherein combining said first and second versions to construct the software component comprises:

compiling said first and second versions separately to produce two object modules; and

linking both object modules with a third object module to produce said executable software component.

18. The method of claim 17 wherein said third object module includes control information, having a boolean flag used to determine which version of said software component is executed.

19. The method of claim 18 wherein said boolean flag has a default value, said default value providing the first software version for initial execution.

20. A software component for use in a computer system, wherein said software component is used by applications running on the computer system, and wherein said software component comprises:

a first and a second version, wherein said first version of the software component is optimised and said second version contains debug code for providing trace information, and

means for selectively switching between the first and second versions of said software component, said switching being transparent to the applications already using the software component.

21. The software component of claim 20 wherein said software component is a device driver.

22. The software component of claim 21 wherein said application using the device driver first establishes communication therewith by making an appropriate call to the computer operating system.

23. The software component of claim 20 wherein the first version is used by default upon the execution of said software component.

24. The software component of claim 20 wherein said switching between the first and second versions of said software component occurs in response to a system call external to the software component.

25. The software component of claim 24 wherein said switching means includes a boolean flag which determines which version of said software component is executed, and wherein said system call sets the value of the boolean flag.

26. The software component of claim 20, wherein said software component provides a plurality of corresponding functions in both versions, the function names in one version differing from the function names in the other version.

27. The software component of claim 26 wherein the function names in one version can be distinguished from the function names in other version by an identifier.

28. The software component of claim 26, wherein said step of selectively switching comprises:

selecting a sub-set of functions from within the version containing debug code; and

selecting the remaining functions from the other version.

29. The software component of claim 28, wherein said sub-set selection occurs in response to a system call, said system call setting a plurality of boolean flags, wherein the value of said plurality of flags determines which functions within the debug version are executed.

30. A computer system for executing a software component, wherein said software component is used by applications running on the computer system, and wherein said computer system comprises:

means for providing a first and second version of said software component, wherein said first version of the software component is optimised and said second version contains debug code for providing trace information, and wherein said computer system further comprises;

means for selectively switching between the first and second versions of said software component, said switching being transparent to those applications already using the software component.

31. The computer system of claim 30 wherein said software component is a device driver.

32. The computer system of claim 31 wherein said application using the device driver first establishes communication therewith by making an appropriate call to the computer operating system.

33. The computer system of claim 30 further comprising means for using said first version by default upon the execution of said software component.

34. The computer system of claim 30 wherein said switching between the first and second versions of said software component occurs in response to a system call external to the software component.

35. The computer system of claim 34 wherein said switching means includes a boolean flag which determines which version of said software component is executed, and wherein said system call sets the value of the boolean flag.

36. The computer system of claim 30, wherein said software component provides a plurality of corresponding functions in both versions, the function names in one version differing from the function names in the other version.

37. The computer system of claim 36 wherein the function names in one version can be distinguished from the function names in other version by an identifier.

38. The computer system of claim 36, wherein said step of selectively switching comprises:

selecting a sub-set of functions from within the version containing debug code; and

selecting the remaining functions from the other version.

39. The computer system of claim 38, wherein said sub-set selection occurs in response to a system call, said system call setting a plurality of boolean flags, wherein the value of said plurality of flags determines which functions within the debug version are executed.