On Tue, 20 May 1997 13:40:26 -0700 (PDT) 
 wrstuden@loki.stanford.edu (Bill Studenmund) wrote:

 > 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.

...err, why?  If you just handle HDLC in zstty, then you can use
any line discipline ith it, yes?  Then localtalk is a line discipline
like ppp...

 > 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
 > protection.

...we don't special case for "dialer lines", so why for HDLC?  If processes
want to avoid collision like that, they should be using TIOCEXCL.

Jason R. Thorpe                                       thorpej@nas.nasa.gov
NASA Ames Research Center                               Home: 408.866.1912
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