> Excuse me?  Last I looked there was both a SLIP and a PPP line
> discipline.  Could you explain  what it is  you're asing that the line
> discipline mechanism doesn't give?

Um, avoiding at least one of the copies from mbuf to clist to output
silo on the way out?  And maybe the necessity of copying data out of
software silos with a character-by-character upcall on the way in?

I think the line discipline mechanism works just fine, the issue is that
the way the lower-level hardware drivers interface to a line discipline
is strongly biased towards the needs and usage characteristics of one
particular line discipline, the tty driver.  Since the tty line discipline
is no longer the predominant user of the hardware drivers this construction
seems a bit unfortunate.

Dennis Ferguson