Sleep state transitioning

• US 20040225907A1
• Filed: 06/08/2004
• Published: 11/11/2004
• Est. Priority Date: 11/05/1999
• Status: Abandoned Application

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Cho, Sung-Soo, Jain, Satchit
• Application Number:
  US10/862,946
• Publication Number:
  US 20040225907A1
• Time in Patent Office: Days
• US Class Current: 713/320
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3237 by disabling clock generation or distribution
• CPC Class Codes: G06F 1/3287 by switching off individual functional units in the computer system
• CPC Class Codes: G06F 9/4418 Suspend and resume; Hibernate and awake
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A system has a processor with multiple states, including an awake state and a sleep state, a memory subsystem including a memory controller and memory devices, and a second memory. The system uses software in the second memory to initialize the memory controller upon a transition from a sleep state to an awake state. The system detects a wake event trigger, and in response to the wake event trigger, executes software stored in the second memory to initialize the memory controller, and then executes software out of the first memory after the initialization.

Claims

1. In a system comprising a processor, a first memory, a first memory controller, and a second memory, a method for transitioning between an awake state and a sleep state comprising:

detecting a trigger to transition from the sleep state to the awake state;

initializing the first memory controller in response to the detecting, the initializing comprising executing software in the second memory; and

executing software in the first memory after the initializing.

2. The method of claim 1 further comprising:

preparing, under control of software stored in the first memory, for a transition from the awake state to the sleep state; and

transitioning to the sleep state.

3. The method of claim 2 wherein the software stored in the first memory comprises operating system software.

4. The method of claim 2 wherein the first memory comprises RDRAM.

5. The method of claim 4 wherein the first memory controller resides in the same chip as the processor.

6. The method of claim 5 wherein the software in the second memory comprises BIOS software.

7. The method of claim 5 wherein the software in the second memory comprises software inaccessible by the operating system.

8. The method of claim 5 wherein the software in the second memory comprises system management mode software.

9. The method of claim 1 wherein the processor and memory controller have inputs for receiving respective clock signals, the method further comprising preventing the receiving of the respective clock signals prior to the detecting.

10. The method of claim 2 wherein the preparing comprises:

configuring the processor to execute the software stored in the second memory in response to a sleep trigger signal from the operating system;

receiving a first sleep trigger signal from the operating system;

executing the software stored in the second memory in response to the receiving;

reconfiguring the processor to transition to the sleep state in response to a sleep trigger signal; and

receiving a second sleep trigger signal.

11. The method of claim 10 wherein the software stored in the second memory comprises system management mode software, the method further comprising generating a system management interrupt in response to the receiving of the first sleep trigger.

12. The method of claim 10 wherein the initializing executes the software stored in the second memory at the instruction following the last instruction executed before transitioning to the sleep state.

13. The method of claim 2 wherein the transitioning transitions the processor into an S1 state.

14. The method of claim 2 wherein the transitioning transitions the processor into an S2 state.

15. The method of claim 2 wherein the preparing comprises flushing a cache.

16. The method of claim 2 further comprising resetting the processor prior to the initializing.

17. In a system comprising a processor, a first memory, a first memory controller, and a second memory, wherein the processor and memory controller have inputs for receiving respective clock signals, and the first memory stores operating system software, a method for transitioning between an awake state and a sleep state comprising:

preparing, under control of the operating system software, for a transition from the awake state to the sleep state, the preparing including configuring the address space mapping to point to the second memory following the detecting;

preventing the receiving of the respective clock signals;

transitioning to the sleep state;

detecting a trigger to transition from the sleep state to the awake state;

initializing the first memory controller in response to the detecting, the initializing comprising executing BIOS software in the second memory;

executing operating system software after the initializing.

18. The method of claim 17 further comprising:

storing a BIOS resume address in the first memory; and

transferring control from the BIOS to the operating system following the initializing using the resume address stored in the first memory.

19. The method of claim 18 further comprising powering down the first memory controller prior to the detecting.

20. A system comprising:

a processor having an awake state and a sleep state;

a first memory;

a first memory controller;

a second memory; and

software stored in the second memory that executes to initialize the first memory controller responsive to a trigger signal signaling a transition from the sleep state to the awake state.

21. The system of claim 20 wherein:

the first memory stores operating system software;

the second memory is nonvolatile memory;

the second memory stores BIOS software; and

the operating system software is configured to control a transition from the awake state to the sleep state.

22. The system of claim 21 wherein:

the operating system stores a BIOS resume address in the first memory prior to a transition from the awake state to the sleep state; and

the BIOS software returns control to the operating system using the stored BIOS resume address after the memory controller is initialized.

23. The system of claim 21 wherein the first memory comprises RDRAM.

24. The system of claim 21 wherein the second memory comprises RAM.

25. The system of claim 21 further comprising system management mode software, the system management mode software being inaccessible by the operating system, and wherein the system management mode software initializes the first memory.

26. The system of claim 20 wherein the processor, first memory, and first memory controller have clock inputs, the system comprising clock disable circuitry preventing the internal clocking of the processor, first memory, and first memory controller.

27. The system of claim 20 wherein the processor and first memory controller reside within a common chip.

28. The system of claim 20 further comprising cache residing in the same chip as the processor and first memory controller and wherein the operating system is configured to flush the cache prior to the transition from the awake state to the sleep state.

29. A portable computer system comprising:

a power storage medium;

a display;

a processor;

a processor clock;

a first memory;

a first memory controller;

a second memory;

wherein the system includes an awake state and a sleep state;

wherein the processor and first memory controller are not clocked in the sleep state; and

wherein software in the second memory initializes the first memory controller responsive to a transition from the sleep state to the awake state.

30. The system of claim 29 further comprising circuitry to disable the flow of power internal to the processor, first memory controller, and first memory.