the second timer stage; the second stage will reset the computer if the fault cannot be corrected before the timer elapses. Watchdog timers are sometimes used to trigger the recording of system state information—which may be useful during fault recovery—or debug information (which may be useful for determining the cause of the fault) onto a persistent medium. In such cases, a second timer—which is started when the first timer elapses—is typically used to reset the computer later, after allowing sufficient time for data recording to complete. This allows time for the information to be saved, but ensures that the computer will be reset even if the recording process fails. For example, the above diagram shows a likely configuration for a two-stage watchdog timer. During normal operation the computer regularly kicks Stage1 to prevent a timeout. If the computer fails to kick Stage1 (e.g., due to a hardware fault or programming error), Stage1 will eventually timeout. This event will start the Stage2 timer and, simultaneously, notify the computer (by means of a non-maskable interrupt) that a reset is imminent. Until Stage2 times out, the computer may attempt to record state information, debug information, or both. The computer will be reset upon Stage2 timeout. Fault detection A watchdog timer provides automatic detection of catastrophic malfunctions that prevent the computer from kicking it. However, computers often have other, less-severe types of faults which do not interfere with kicking, but which still require watchdog oversight. To support these, a computer system is typically designed so that its watchdog timer will be kicked only if the computer deems the system functional. The computer determines whether the system is functional by conducting one or more fault detection tests and will kick the watchdog only if all tests have passed. In computers that are running an operating system and multiple processes, a single, simple test might be insufficient to guarantee normal operation, as it could fail to detect a subtle fault condition and therefore allow the watchdog to be kicked even though a fault condition exists. For example, in the case of the Linux operating system, a user-space watchdog daemon may simply kick the watchdog periodically without performing any tests. As long as the daemon runs normally, the system will be protected against serious system crashes such as a kernel panic. To detect less severe faults, the daemon can be configured to perform tests that cover resource