Operating system hang detection and correction

A system for detecting an operating system hang condition within a computer system, the computer system operated in accordance with an operating system having an operating system kernel, the system comprising:

• a processor;
• a status register coupled to the processor, the status register for storing a status flag;
• a timer coupled to the status register and the processor, the timer configured to set the status flag to a first value and generate an operating system interrupt to an interrupt handler within the operating system kernel in response to an overflow of the timer;
• a watchdog timer coupled to the processor, the watchdog timer configured to periodically generate a system BIOS interrupt to a watchdog timer handler within a system BIOS of the computer system, the system BIOS interrupt generated independent of and transparent to the operating system;
• a watchdog counter, coupled to the processor, for storing a counter value;
• a first memory unit coupled to the processor, the first memory unit for storing the interrupt handler instructions which when executed by the processor cause the processor to operate so as to:
• reset the status flag to a second value if the operating system kernel is responding to the operating system interrupt;
• and
• a second memory unit coupled to the processor, the second memory unit for storing the watchdog timer handler instructions which when executed by the processor cause the processor to operate so as to:
• read the value of the status flag;
• increment the counter value stored within the watchdog counter in response to the status flag having the first value;
• clear the counter value stored within the watchdog counter in response to the status flag having the second value;
• and
• determine that the operating system hang condition has occurred in response to the counter value exceeding a threshold value.

An apparatus for detecting the occurrence of an operating system hang condition within a computer system, the apparatus comprising:

• a memory device for storing instructions which when executed by a processor cause the processor to operate so as to:
• periodically read a status flag that is set to a first value in response to an overflow of a timer and reset to a second value in response to execution of an operating system interrupt handler, the execution of the operating system interrupt handler being dependent upon whether an operating system kernel of the computer system is responding to operating system interrupts;
• increment a counter in response to the status flag having the first value;
• clear the counter in response to the status flag having the second value;
• and
• determine that the operating system hang condition has occurred in response to the counter exceeding a threshold value.