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    SubjectRe: Input issues - key down with no key up
    Andries Brouwer wrote:
    > There are many more problems with your synthesized events.
    > Look at your "repeat delay + a bit more". Can you specify how much
    > "a bit more" is?
    >
    > In times of heavy disk activity we lose interrupts.
    > Indeed, if I copy a CD image or untar a kernel tree
    > my keyboard and mouse are dead for several seconds.
    >
    > There is no guaranteed "a bit more" within which we will see a
    > keyboard event.

    I think we can safely arrange that if the timer expires, we can be
    sure to check the 8042 for an event before synthesising one.

    > If the only events that are seen are actual events, and on rare
    > occasions we miss an event, that is not so bad. We just hit that
    > key again. But if we synthesize events, then a missed key up
    > causes autorepeat.

    You've mixed the question synthetic UP with software autorepeat. They
    are unrelated, and othogonal.

    If you use software autorepeat, you have that problem of runaway
    events _anyway_, nothing to do with UP. And if you don't use software
    autorepeat, UP doesn't create a problem.

    In fact, the synthetic UP is quite helpful if you miss real events.
    For programs which, say, grab the keyboard focus until the user lets
    go of a particular key, it is good that the program is eventually sent
    an UP. Otherwise it won't give up the focus at all. Similarly, in a
    game which does something as long as the player holds a key down,
    missing the real event results in the game assuming the key is
    perpetually held down.

    > In fact I see unwanted autorepeat - maybe once a day
    > suddenly a single keystroke causes three to five identical
    characters to appear - but I am not sure what mechanism causes this.

    Faulty laptop keyboards. I get it too, with 2.4 and 2.5 kernels.
    It's not autorepeat, it's an instant burst of events.
    Possibly bad debouncing.

    -- Jamie
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