Subject: hardware flow control problem
To: None <netbsd-bugs@NetBSD.ORG>
From: John R. Winans <winans@aps.anl.gov>
List: netbsd-bugs
Date: 01/13/1995 10:19:43
First, please let me ask a question, How do I set up the ttys so that
ixany is OFF be default?
Second, this has GOT to me a misfeature...
My Environment
--------------
NetBSD 1.0 with patches up to #5 applied. Running on a 386sx generic
motherboard, 4 16550s, and 1 IDE.
Problem Description
-------------------
If I insert the rtscts flag in my /etc/ttys file for a port that is 'on' and
log into it via modem and then run a program that looks like this:
while (1)
printf("a long line of text..........................................\n");
I get some odd behavior. The following is a description of a simple experiment:
1) Turn off tty01 in /etc/ttys
2) kill -1 1
3) I Plug in a modem to tty01.
4) Tip out to it and configure it to auto answer and use rtc/cts flow control.
5) Set tty01 to 'on rtscts' in /etc/ttys
6) kill -1 1
7) sttyflags -a
8) 'ps' and see the getty running at 38.4
9) dial in to modem and sync up at 14.4
10) log in and do a 'stty -a'
Note that tty is running at 38.4 (OK, since dte side of modem is too)
Note that ixany is on for some reason.
11) Run print-loop program
12) Observe that the modem is turning cts off and on and that NetBSD is
following along nicely.
13) During a period where the cts line of de-asserted and NetBSD is not
sending data, hit the space key on the host that dialed in.
14) Observe that NetBSD resumes transmission even though cts is still
de-asserted.
Doing an 'stty -ixany' on tty01 and rerunning the above experiment yeilds a
more desireable result. That is, no matter what, when cts is de-asserted, data
stops flowing from NetBSD and when it is asserted, it restarts again.
However, I am pretty sure that this is NOT how it is supposed to work. I
should be able to use both rtscts AND xon/xoff flow control at the same time
and ixany should also be allowed to be used w/o dorking over the rtscts.
What I would LIKE to use is '-ixon ixany -ixoff crtscts' on dial-up shell
logins, and '-ixon -ixany -ixoff crtscts' for dial-up slip.
Any information would be appreciated... I looked thru the com driver and
couldn't deciphering it since it has a miniscule amount of doc and I have no
experience with drivers that talk to the UNIX tty/line code. (I have only
done simple character device work in UNIX.)
--John