Unix-Pc Loadable Drivers

[Mike "Ford" Ditto]

In article <1140 at csustan.UUCP> jb at csustan.UUCP (john birchfield) writes:
>
>I am interested in playing around with line disciplines on the Unix PC.
>However, the only info I have with my manuals are the man page entries
>for LDDRV(1M) and MASTERUPD(1M).

Good luck!  The first thing you need to know is that lddrv's alleged
line discipline support doesn't work!  (At least it gets very confused
on my attempts to use it; but it does seem to handle the xt driver...
hmm...).

>I believe I could probably write a complete tty device driver and have it
>running eventually but I would like to know if I could write and install a
>new and unique line discipline and install that.
>
>I wonder if anyone out there could point me in the right direction.

I've been thoroughly searching every bit of Unix device driver pseudo-
documentation I can find, and it seems that SysV line disciplines are,
for all practical purposes, officially undocumented.  Now, I haven't
taken AT&T's Unix internals class, but I may do just that if I hear
there is some info on line disciplines to be found.  xt and sxt are
the only line disciplines I have ever heard of (other than the
default), and even those protocols are only documented something like
"This is only used by the {shl,layers} command so we don't need to
tell you how it works."

The closest I've seen to anything resembling documentation is in the
SCO Xenix manual (of all places) and it just lists the 8 functions
that the linesw entry contains.  Looking at driver source is more
helpful.  SCO's example tty driver, the PD pty driver, and the 3b2 tty
driver source available from AT&T all deal with line discipline
functions in some way, but not enough to really figure out what's
going on.

If I discover a source for this type of info, I'll tell everyone,
and I'd sure appreciate hearing about anything anyone else knows
about.

					-=] Ford [=-

"Once there were parking lots,		(In Real Life:  Mike Ditto)
now it's a peaceful oasis.		ford%kenobi at crash.CTS.COM
This was a Pizza Hut,			...!sdcsvax!crash!kenobi!ford
now it's all covered with daisies." -- Talking Heads