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    SubjectSerial: bug in 8250.c when handling PCI or other level triggers
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    The receive_chars function is designed to handle the case where the port
    is jammed full on by aborting after 256 characters in one IRQ.
    Unfortunately the author of this code forgot that some systems are level
    triggered. On these systems the IRQ simply gets invoked again and the
    count loop just makes the problem take longer to clear.

    In the non level case it appears that a jam could leave the IRQ jammed
    forever and ignored - the remaining bytes never appearing.

    As far as I can see the code would actually need to clear the interrupt
    enable and then restore it on a timer event or similar in order to get
    the intended effect.

    Alan

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