> The real question is: do other OSs send the SIGIO only if the buffer
> goes from "no room available" to "some room available", or does it
> send it when the buffer goes from "some room available" to "some more room
> available".

It seems that FreeBSD, OpenBSD, Linux and Solaris have choosen the first
option, and NetBSD the second one. 

Anyone can do more tests to confirm this?

-- 
Emmanuel Dreyfus.
Ugly one-liners -- http://gizmo.minet.net:8080/sh
p99dreyf@criens.u-psud.fr