> FASYNC == O_ASYNC which is documented to send SIGIO. That is
> what asynchronous/io is.

According to Design & Implementation of 4.4BSD OS, Async I/O is about
sending "a signal (SIGIO) when read or write becomes possible". 

In our fcntl(2) man page, we describe O_ASYNC like this: "Enable the
SIGIO signal to be sent to the process group when I/O is possible, e.g.,
upon availability of data to be read."

I do not exepct to receive SIGIO because the reader at the other end of
a pipe has readen a byte. Do you expect such a behavior? Since NetBSD
seems to be the only OS doing this, I beleive there is a real problem
here.

-- 
Emmanuel Dreyfus
p99dreyf@criens.u-psud.fr