>> An idea which has occurred to me was to add a new signal,
>> SIGIFCH, analogous to SIGWINCH, which is delivered to user
>> processes expressing interest in it when the "local address set" of a
>> system changes.
>
>There are a bunch of things that one might want to signal -- window
>size changes, IP changes, wakeups following an APM sleep, etc.
>
>I wish kill() had a richer interface so one could pass data along with
>a signal and have one generic "something has changed" signal and tell
>what has changed in the passed data.  I believe the kernel can sort of
>do this right now for some signals...

make some sort of /dev/ thingee where you open it, do some sort of ioctl
on the descriptor (a la bpf programming?) and them ask the kernel for
delivery of a sigurg when something you are interested in has "changed"
and the appropriate message is present on the device?

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