METHOD AND APPARATUS FOR PROVIDING DATA ACCESS

• US 20100146160A1
• Filed: 12/04/2008
• Published: 06/10/2010
• Est. Priority Date: 12/01/2008
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Piekarski, Marek
• Granted Patent: US 9,880,954 B2
• Time in Patent Office: Days
• US Class Current: 710/28
• CPC Class Codes: G06F 13/105 where the programme performs an input/output emulation function
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence

Abstract

A method of providing access to first data stored at a first device to a second device, the first device storing the first data in a memory accessible to said second device. The method comprises, at a control element distinct from each of said first and second devices accessing the stored first data in said memory accessible to said second device before said first data is accessed in said memory accessible to said second device by said second device.

Claims

1. A method of providing access to first data stored at a first device to a second device, the first device storing the first data in a memory accessible to said second device, the method comprising, at a control element distinct from each of said first and second devices:

accessing the stored first data in said memory accessible to said second device before said first data is accessed in said memory accessible to said second device by said second device.

2. A method according to claim 1, wherein said accessing the stored first data further comprises modifying said first data in said memory accessible to said second device before said first data is accessed in said memory accessible to said second device by said second device.

3. A method according to claim 2, further comprising, at the control element:

receiving a message from said first device and accessing and modifying the stored first data in response to receipt of said message.

4. A method according to claim 3, wherein said message is a command intended to initiate access by said second device to said memory accessible to said second device.

5. A method according to claim 3, wherein said message is directed from said first device to said second device and redirected to said control element at a switching device.

6. A method according to claim 5, wherein said message is contained within a data packet and the method further comprises:

determining at the switching device whether a received data packet satisfies a predetermined criterion, and forwarding said data packet to said control element if but only if it is determined that the data packet satisfies the predetermined criterion.

7. A method according to claim 6, wherein said predetermined criterion is based upon a type of transaction with which said data packet is associated.

8. A method according to claim 6, wherein said predetermined criterion is that said data packet comprises a command.

9. A method according to claim 6, further comprising:

if it is determined that said data packet does not satisfy the predetermined criterion, forwarding said data packet from said switching device to an attached device.

10. A method according to claim 3, wherein said message comprises data indicating said stored first data to be accessed and modified.

11. A method according to claim 10, wherein said data indicating said stored data to be accessed and modified comprises data indicating further data stored at said first device, said further data indicating said stored first data to be accessed and modified.

12. A method according to claim 11, further comprising copying said further data to a memory accessible by said control element.

13. A method according to claim 2, wherein said stored first data comprises data defined with reference to said first device, and said modifying modifies said data defined with reference to said first device to be defined with reference to said second device.

14. A method according to claim 13, wherein the data defined with reference to said first device comprises an identifier used by said first device to reference said second device.

15. A method according to claim 13, wherein the data defined with reference to said first device is a logical identifier of said second device.

16. A method according to claim 13, wherein modifying the data defined with reference to said first device so as to be defined with reference to said second device comprises modifying said data to indicate a physical identifier of said second device.

17. A method according to claim 13, further comprising:

reading said data defined with reference to said first device;

determining corresponding data defined with reference to said second device; and

modifying said data defined with reference to said first device based upon said corresponding data.

18. A method according to claim 17, further comprising:

storing data in a memory accessible to said control element defining relationships between said data defined with reference to said first device and said data defined with reference to said second device.

19. A method according to claim 1, wherein said stored first data comprises a plurality of data packets.

20. A method according to claim 17, wherein said modifying comprises modifying a field in a header of at least one of said plurality of data packets.

21. A method according to claim 19, wherein said modifying comprising modifying a part of at least one of said plurality of data packets defined by an offset relative to a start of the data packet.

22. A method according to claim 2, further comprising, at the second device, reading data from said memory accessible to said second device after said modification.

23. A method according to claim 1, wherein the first device is a computing device, the memory accessible to said second device is a memory of the computing device and the second device accesses the memory of the computing device using direct memory access.

24. A control element comprising:

a memory storing processor readable instructions; and

a processor arranged to read and execute instructions stored in said program memory;

wherein said processor readable instructions comprise instructions arranged to cause the processor to carry out a method according to claim 1.

25. A control element according to claim 24 in communication with a switching device, wherein the switching device comprises:

a first interface for communication with said first device;

a second interface for communication with said second device;

a third interface for communication with said control element; and

a processor arranged to process data packets passing between said first device and said second device, and to forward a processed data packet to said control element if but only if a predetermined criterion defined with reference to the processed data packets is satisfied.

27. A computer program comprising computer readable instructions arranged to cause a computer to carry out a method according to claim 1.

28. A computer readable medium carrying a computer program according to claim 27.

26. Apparatus for providing access to first data stored at a first device to a second device, the first device storing the first data in a memory accessible to said second device, the apparatus comprising, a control element distinct from each of said first and second devices, the control element further comprising:

means for accessing the stored first data in said memory accessible to said second device before said first data is accessed by said second device.

29. A method of storing data in a memory of a first device, said memory being accessible to a second device, and said data being received from said second device the method comprising, at a control element distinct from each of said first and second devices:

accessing said data in said memory accessible to said second device before said data is processed by said first device.

30. A method according to claim 29, wherein said accessing said data further comprises modifying said data in said memory accessible to said second device before said data is processed by said first device.

31. A method according to claim 30, further comprising, at the control element:

receiving a message from said second device and accessing and modifying said data in response to receipt of said message.

32. A method according to claim 31, wherein said message is an interrupt indicating that said data has been written to said memory by said second device.

33. A method according to claim 31, wherein said message is directed from said first device to said second device and redirected to said control element at a switching device.

34. A method according to claim 33, wherein said message is contained within a data packet and the method further comprises:

determining at the switching device whether a received data packet satisfies a predetermined criterion, and forwarding said data packet to said control element if but only if it is determined that the data packet satisfies the predetermined criterion.

35. A method according to claim 34, wherein said predetermined criterion is based upon a type of transaction with which said data packet is associated.

36. A method according to claim 34, wherein said predetermined criterion is that said data packet comprises a command.

37. A method according to claim 30, further comprising, at the control element:

receiving an initiation message, said initiation message being generated by said first device and indicating a part of said memory accessible to said second device to which data is to be written by said second device.

38. A method according to claim 37, wherein said data indicating a part of said memory accessible to said second device to which data is to be written indicates further data stored at said first device, said further data indicating said part of said memory accessible to said second device to which data is to be written.

39. A method according to claim 38, further comprising copying said further data to a memory accessible by said control element.

40. A method according to claim 30, wherein said second device writes data defined with reference to said second device, and said modifying modifies said data defined with reference to said second device to be defined with reference to said first device.

41. A method according to claim 40, wherein the data defined with reference to said first device comprises an identifier used by said first device to reference said second device.

42. A method according to claim 40, wherein the data defined with reference to said first device is a logical identifier of said second device.

43. A method according to claim 40, wherein modifying the data defined with reference to said second device so as to be defined with reference to said first device comprises modifying said data to indicate a logical identifier of said second device.

44. A method according to claim 30, further comprising:

reading said data defined with reference to said second device;

determining corresponding data defined with reference to said first device;

modifying said data defined with reference to said second device based upon said corresponding data.

45. A method according to claim 44, further comprising:

storing data in a memory accessible to said control element defining relationships between said data defined with reference to said first device and said data defined with reference to said second device.

46. A method according to claim 29, wherein said data stored by said second device comprises a plurality of data packets.

47. A method according to claim 46, wherein said accessing said data further comprises modifying said data in said memory accessible to said second device before said data is processed by said first device and said modifying comprises modifying a field in a header of at least one of said plurality of data packets.

48. A method according to claim 46, wherein said accessing said data further comprises modifying said data in said memory accessible to said second device before said data is processed by said first device and said modifying comprises modifying a part of at least one of said plurality of data packets defined by an offset relative to a start of the data packet.

49. A method according to claim 29, wherein the first device is a computing device, the memory accessible to said second device is a memory of the computing device and the second device accesses the memory of the computing device using direct memory access.

50. A control element comprising:

a memory storing processor readable instructions; and

a processor arranged to read and execute instructions stored in said program memory;

wherein said processor readable instructions comprise instructions arranged to cause the processor to carry out a method according to claim 29.

51. A control element according to claim 50 in communication with a switching device, wherein the switching device comprises:

a first interface for communication with said first device;

a second interface for communication with said second device;

a third interface for communication with said control element; and

a processor arranged to process data packets passing between said first device and said second device, and to forward a processed data packet to said control element if but only if a predetermined criterion defined with reference to the processed data packets is satisfied.

53. A computer program comprising computer readable instructions arranged to cause a computer to carry out a method according to claim 29.

54. A computer readable medium carrying a computer program according to claim 53.

52. Apparatus for storing data in a memory of a first device, said memory being accessible to a second device, and said data being received from said second device the apparatus comprising, a control element distinct from each of said first and second devices, the control element further comprising:

means for accessing said data in said memory accessible to said second device before said data is processed by said first device.