Apparatus and Method for Microprocessor File System Protection
First Claim
1. A method of protecting a processor system by the use of a state machine to control a the shutting down of power and the restoration of power comprising the steps of:
- a. providing a means for supplying a backup power source, andb. providing a means for selectively supplying power to said protected processor system from said backup power source, from the normal external power source, from both power sources, or from neither, andc. providing a means for determining that external power to a protected processor is failed, failing or is about to fail, andd. providing a means for shutdown signaling to said protected processor that shutdown is imminent on said indication that the external power is failed, failing or about to fail to allow said processor to begin an orderly shutdown, ande. providing provision within the code of said protected processor for conducting an orderly shutdown of said protected processor, andf. providing a means for receiving from said protected processor an indication that said orderly shutdown is complete after said shutdown signaling, andg. providing a means for removing power from said protected processor on receipt of said indication that said orderly shutdown is complete or that a predetermined time has elapsed after said shutdown signaling without said indication that said orderly shutdown is complete, andh. providing a means after said removing power from said protected processor for a fixed time for determining that said external power has been restored, andi. providing a means for orderly restoring power to said protected processor after said determination that said external power has been restored,whereby said protected processor is protected against unsafe operation.
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Accused Products
Abstract
A system for providing protection to a processor system from the problems associated with power failures in the middle of processor operations is described. On detection of a power failure in the main power source, the processor power is maintained by means of a short-term secondary power source. Either immediately or after a momentary pause to override glitches, if power remains off the processor is notified that power will soon be removed and that an orderly shutdown is to take place. Once the protected system has completed its orderly shutdown, or after a length of time indicating that the orderly shutdown is improbable, power is removed from the system for a defined period and the system removes power from the protected processor system for at least a defined period of time, providing an assured hard restart. When external power is restored a normal running state is resumed after any power up sequencing. The orderly shutdown and hard reset can take place by command from the protected processor or system. A state machine is used to sequence the states in this process and control the transitions between states.
32 Citations
15 Claims
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1. A method of protecting a processor system by the use of a state machine to control a the shutting down of power and the restoration of power comprising the steps of:
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a. providing a means for supplying a backup power source, and b. providing a means for selectively supplying power to said protected processor system from said backup power source, from the normal external power source, from both power sources, or from neither, and c. providing a means for determining that external power to a protected processor is failed, failing or is about to fail, and d. providing a means for shutdown signaling to said protected processor that shutdown is imminent on said indication that the external power is failed, failing or about to fail to allow said processor to begin an orderly shutdown, and e. providing provision within the code of said protected processor for conducting an orderly shutdown of said protected processor, and f. providing a means for receiving from said protected processor an indication that said orderly shutdown is complete after said shutdown signaling, and g. providing a means for removing power from said protected processor on receipt of said indication that said orderly shutdown is complete or that a predetermined time has elapsed after said shutdown signaling without said indication that said orderly shutdown is complete, and h. providing a means after said removing power from said protected processor for a fixed time for determining that said external power has been restored, and i. providing a means for orderly restoring power to said protected processor after said determination that said external power has been restored, whereby said protected processor is protected against unsafe operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A machine for protecting a processor system comprising:
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a. a normal protected processor system power supply with a means for disconnecting said normal power supply from said protected processor system, and b. a backup power supply capable of maintaining a switchable power to said protected processor system in a manner such that said backup power source is not drained while said normal protected processor system power supply is operating in a normal fashion, and c. a power supply monitor capable of determining if said normal protected system power supply power is failed, failing or about to fail, and d. a state machine with at least the following states and state transitions; i. a startup state where said normal protected processor system power supply and said backup power supply are turned on in a controlled manner after which the running state is entered, and ii. a running state where said normal protected processor system power supply and said backup power supply are on, and transitioning to the shutdown state occurs when said monitor of said protected system power supply determines said protected system power supply power is failed, failing or about to fail, and iii. a shutdown state where at least the following steps are taken; 1. said backup power supply remains on, and 2. an irreversible shutdown handshaking sequence between said state machine and said protected processor system is initiated comprising the following steps; a. said state machine signals said protected processor that a power shutdown is imminent, and b. after an orderly shutdown said protected processor signals said state machine that said protected processor has completed an orderly shutdown, and c. after receipt of said signal that said protected processor has completed an orderly shutdown, or a defined period has passed from said state machine signaling said protected processor that a power shutdown is imminent the state machine turns off both said normal protected processor system power supply and said backup power supply, and after a predetermined time the state machine transitions to the powerdown state, and iv. a powerdown state where both said normal protected processor system power supply and said backup power supply are off and the state machine monitors said protected system power supply monitor to determine that said protected system power supply is no longer failed or failing, in which case said state machine transitions to said startup state, whereby said protected processor is protected against premature shutdown. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification