right; you want a change callback, which imples that someone has to put
a hook into the change code (in this case, the arp list).
> So my question boils down to: How can user space find out asyncronously
> when a button gets pushed, without resorting to ugly stuff like polling?
who not use a _blocking_ call? it can be anything you want; ioctl,
read, touch an mmaped page, etc. your device just blocks the process
until some condition is met, then wakes it. since you control the event,
there's no issue of inserting change callbacks into extant code.
regards, mark hahn.
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