Subject: Re: autoconfiguration question
To: Gordon W. Ross <>
From: Bill Studenmund <>
List: tech-kern
Date: 05/20/1997 13:40:26
> > From: (Bill Studenmund)
> > Date: Tue, 20 May 1997 12:41:29 -0700 (PDT)
> [...]
> > Maybe something where, if multiple devices "match" at the same
> > priority, they all get attached?
> I suspect you will need zstty extended to support an HDLC mode.

You might be right, but I'd like to try to find something different.
Hacking an hdlc mode into the zstty code just looks gross, though
attaching a zshdlc to the zstty might work.

Part of my idea is to take the zs slave idea and make it work with
two slaves sharing a channel. On open, each slave looks to see if
the channel is in use. If it is in use by another type of slave, it
doesn't open. If I can somehow get the hdlc support to attach as a
different device, this (and possable autoconfig changes) are all that
has to happen to zstty.

Another things is that we run into a possable can of worms if HDLC
support is a "mode" of the async driver. I think at open you need to
indicate which way you want the hardware to behave. Thus avoiding
problems like having a program talking to a modem, and then having
another process start up and try to put the port in hdlc mode.
So different device numbers and thus different open routines provide

Plus I'd like to have ppp-on-hdlc, localtalk, raw transfer, and
(someone else's doing) X.25 (or whatever really uses HDLC
framing). Thusly overloading the line disciplines looks gross.

I can send you my expected diffs to z8530tty.c if you want (w/o
autoconfig, it's like 2 sets of 4 lines).

Take care,