Method and apparatus to use non-volatile read/write memory for bootstrap code and processes
AssigneeCisco Technology, Inc.
InventorsJainendra Kumar, Joseph C. Harrow, Lucy Chiu, Sami Khan, Wen Huang
Life of this patent
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Abstract
A reset pin of a non-volatile read/write memory, which stores boot code, is provided with a reset signal in response to a system reset output by a watchdog timer or other external circuitry. The reset signal causes the non-volatile read/write memory to be placed into read mode. Accordingly, even when a system reset occurs while the non-volatile read/write memory is in write mode, a hang state can be avoided since the memory will be reset to read mode before attempting to read boot code for a reboot operation.
Claims14
A method for obtaining bootstrap code in a computer system comprising:
- providing a computer system comprising a CPU coupled to a non-volatile read/write memory which stores said boot code and at least indirectly coupled to at least a first external circuit, said non-volatile read/write memory including at least a first reset pin;
- outputting at least a first system reset signal from said external circuit;
- and
- providing a reset signal at said reset pin to place said non-volatile read/write memory in read mode, without the need for a power cycle;
- and
- initiating a read operation for reading boot code from said non-volatile read/write memory after said step of providing to place said non-volatile read/write memory in said read mode.
Apparatus for obtaining bootstrap code in a computer system having a CPU coupled to a non-volatile read/write memory which stores said boot code and at least indirectly coupled to at least a first external circuit, said non-volatile read/write memory including at least a first reset pin, comprising;
- a support circuit which provides a memory reset signal at said reset pin to place said non-volatile read/write memory in read mode, at least indirectly in response to output of a first system reset signal from said external circuit, without the need for a power cycle;
- and
- wherein a read operation can be performed for reading boot code from said non-volatile read/write memory in the absence of creating a hang state.
Apparatus for obtaining bootstrap code in a computer system comprising:
- a computer system comprising a CPU coupled to a non-volatile read/write memory which stores said boot code and at least indirectly coupled to at least a first external circuit, said non-volatile read/write memory including at least a first reset pin;
- means for outputting at least a first system reset signal from said external circuit;
- means for providing a memory reset signal at said reset pin to place said non-volatile read/write memory in read mode, without the need for a power cycle;
- and
- wherein a read operation can be performed for reading boot code from said non-volatile read/write memory in the absence of creating a hang state.
A method for obtaining bootstrap code in a computer system having a CPU coupled to a non-volatile read/write memory which stores boot code and at least indirectly coupled to at least a first external circuit, the method comprising:
- performing a write operation using said non-volatile read/write memory;
- receiving a system reset signal in said CPU, from said external circuit;
- placing said non-volatile read-write memory in a read state without the need for a power cycle of said computer system;
- and
- reading said boot code from said non-volatile read/write memory, in the absence of a hang state.
A computer system with reduced occurrence of hang states comprising:
- a CPU coupled to a non-volatile read/write memory which stores boot code and at least indirectly coupled to at least a first external circuit, the computer system configured to
- perform a write operation using said non-volatile read/write memory;
- receive a system reset signal in said CPU, from said external circuit;
- place said non-volatile read-write memory in a read state, in response to said system reset signal, without the need for a power cycle of said computer system;
- and
- read said boot code from said non-volatile read/write memory, in the absence of a hang state.
Dependencies are inferred from the claim text.