Messages in this thread | | | From | Gabriel Paubert <> | Date | Wed, 24 Mar 2004 16:50:40 +0100 | Subject | Re: spurious 8259A interrupt |
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On Wed, Mar 24, 2004 at 03:28:00PM +0000, Jamie Lokier wrote: > Richard B. Johnson wrote: > > It isn't CPU-specific. It's motherboard glitch specific. If there > > is ground-bounce on the motherboard or excessive induced > > coupling, the CPU may occasionally get hit with a logic-level > > that it "thinks" is an interrupt, even though no controller > > actually generated it. > > That doesn't seem plausible on an otherwise reliable computer. > > Why would interrupt lines suffer ground-bounce logic glitches yet all > the data, address and control lines be fine?
Two reasons at least: - the data/address lines are always driven by a buffer when there a transfer is taking place, while the interrupt lines are permanently monitored but most of the time only held by passive pull-ups of a much higher impedance.
- board designers know that the timing of data and addresses are critical and take care during the layout. Interrupt lines come last and are routed where there is room left, after all these are low frequency signals...
Regards, Gabriel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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