There is no reason for this ioctl at all.  Either existing
facilities provide what you need or what you want is a
protocol violation we can't do.

I agree that 99 times out of ten such a mechanism serves only as a 
massive KLUDGE to paper-over application bugs.  I'll also sadly 
point-out that such a mechanism exists in HP-UX 11.X and I suspect 
Solaris !-(  I've spent probably the last decade or so attempting to 
discourage its use in the HP-UX space, but like some daemon from hell it 
just refuses to die.

rick jones