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Those were the only messages before the reboot, and they occurred at least 23 hours earlier, which means the problem is not due to a kernel oops, or any other atypical event that the kernel could detect. It is just the good ol' situation where there seems to be a very small but finite possibly possibility that a PC104 interrupt can be missed, and not retriggered, even though the PC104 IRQ interrupt line is high, such that the interrupt handler is never again called.
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