System and method for maintaining persistent state data

• US 7,392,429 B2
• Filed: 12/22/2004
• Issued: 06/24/2008
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Westerinen, William J., Frank, Alexander, Light, Mark C.
• Primary Examiner(s): LE, DIEU MINH T
• Application Number:
  US11/020,329
• Publication Number:
  US 20060139069A1
• Time in Patent Office: 1,280 Days
• Field of Search: 714/14, 714/22, 714/24, 714 5- 6, 714/13, 713/300, 713/340
• US Class Current: 714/24
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24
• CPC Class Codes: G06F 11/1441 Resetting or repowering

Abstract

A system and method for maintaining persistent data during an unexpected power loss uses a memory controller and a supplemental power source. An entity running on the computer, for example, an application program, a utility, the operating system or other entity, may identify data for preservation using an application program interface. The application program interface may be provided by the memory controller. A sensor determines when an unexpected power loss has occurred and signals the memory controller. Using power from the supplemental power source, i.e. a battery or capacitor, the memory controller copies the identified data to a non-volatile memory. The memory controller may set a flag to indicate that preserved data is available for later recovery.

Claims

1. A method of preserving a data in a computer when a power loss occurs comprising:

designating a range of system memory containing the data to be preserved in the event of the power loss by an application program via a software application program interface;

determining when the power loss has occurred;

copying the data to a non-volatile memory responsive to determining that the power loss has occurred; and

receiving an AddMemoryObj([in]MemoryRange) call via the software application program interface.

2. The method of claim 1, further comprising retrieving the data when the power loss is ended.

3. The method of claim 2, wherein the retrieving the data further comprises retrieving the data using the application program interface.

4. The method of claim 1, further comprising setting a flag when the power loss has occurred and clearing the flag when the data has been retrieved, the flag comprising one of an indication of the power loss and an indication of successful copying the data to the non-volatile memory.

5. The method of claim 1, wherein copying the data to a non-volatile memory further comprises copying the data to a non-volatile memory after a main processor has been disabled due to the power loss.

6. The method of claim 1, wherein the designating the data to be preserved comprises designating at least one pre-determined memory location.

7. A computer adapted for preserving data upon a power loss comprising:

a main power supply for receiving a line power and supplying energy to the computer;

a first memory comprising a first data, the first data being a range of system memory;

a non-volatile memory;

a memory controller coupled to the first memory and the non-volatile memory for storing the first data in the non-volatile memory responsive to the signal, the memory controller supporting a software application program interface for receiving a designation of the first data, the software application program interface supporting an AddMemoryObj([in]MemoryRange) call;

a sensor coupled to the main power supply and the memory controller, the sensor for sending a signal when the line power to the main power supply is interrupted; and

a supplemental power source, the supplemental power source providing energy, at least temporarily, to one of the first memory, the non-volatile memory and the memory controller when the line power to the main power supply is interrupted.

8. The computer of claim 7, wherein the first data occupies less than 10% of the first memory.

9. The computer of claim 7, further comprising:

a second memory for storing a second data, the second data comprising information about the first data.

10. The computer of claim 9 wherein the second memory is comprised by one of the memory controller, the first memory, and the non-volatile memory.

11. The computer of claim 9, further comprising an application program interface for programming the second data, the second data for determining a location of the first data.

12. The computer of claim 7, further comprising:

a processor coupled to the supplemental power source, the processor implementing the memory controller.

13. A memory controller for use in a computer adapted for preserving data upon a power loss, the memory controller comprising:

a logic unit;

a first input for receiving a signal indicative of the power loss;

a second input for receiving supplemental power during the power loss;

an application program interface for configuring an information corresponding to a first data to be preserved upon the power loss, the application program interface supporting receipt of an AddMemoryObj([in]MemoryRange) call designating a range of system memory as the data for preserving during a power loss; and

a memory for storing the information.

14. The memory controller of claim 13 wherein the logic unit provides the application program interface.

15. The memory controller of claim 13 wherein the information corresponding to the first data is a range of memory comprising the first data.

16. The memory controller of claim 13 wherein the logic unit, responsive to receiving the signal, uses the information corresponding to the first data to store a copy of the first data in a non-volatile memory.

17. The memory controller of claim 16 wherein the logic unit, responsive to receiving the signal, uses the information corresponding to the first data to store an encrypted copy of the first data in the non-volatile memory.

18. The memory controller of claim 13 wherein the memory further comprises a location wherein the logic unit sets a flag at the location indicating when the first data has been preserved.

19. The memory controller of claim 18 wherein the application program interface further comprises a routine for determining when the flag is set and for recovering the first data from the non-volatile memory.