Re: ttyS1 hangs, cua1 works fine

mlord (mlord@pobox.com)
Sat, 28 Mar 1998 17:31:07 -0500

> mlord wrote:
> > /dev/ttyS1 works *once* after each boot,
> > but when I then kill pppd, it never works again.
> > /dev/cua1 doesn't care -- always works fine.
...
> > Maybe killing pppd has something to do with it.
>
> I think so. It could be a problem with the CLOCAL being cleared (because
> pppd needs to know if DCD drops), and old settings not being restored when
> you kill pppd.
...
> > Is the kernel not cleaning up properly on close of /dev/ttyS1 ??

Okay, here's all that I have to do to lock up /dev/ttyS1 (my serial modem port):

1. Boot Linux 2.1.91.
2. run chat+pppd to connect to my ISP.
3. kill pppd.
4. /dev/ttyS1 is no longer usable, /dev/cua1 works perfectly.

eg. stty </dev/ttyS1 ## this hangs.. does nothing.

Here is stty -a </dev/ttyS1 from just after booting:

speed 9600 baud; rows 45; columns 80; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W;
lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 hupcl -cstopb cread clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff
-iuclc -ixany -imaxbel
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
echoctl echoke

Here it is again while pppd is running:

speed 115200 baud; rows 45; columns 80; line = 3;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W;
lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 hupcl -cstopb cread -clocal crtscts
ignbrk -brkint ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff
-iuclc -ixany -imaxbel
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0
ff0
-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop
-echoprt -echoctl -echoke

After stopping pppd, I can no longer examine the ttyS1 settings.

?????

/dev/cua1 still works perfectly in all scenarios.

-- 
mlord@pobox.com
The Linux IDE guy


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