Re: [List] Re: Can't seem to get serial to work

On 13/07/2026 11:29, laszlo vagner wrote:
> i always thought you needed to be in the dialer group to open com ports.
>
You need permissions to r/w the device, with by default is the user uucp 
or anyone in the dialer group. Or the root user, which is the most 
likely if you're debugging hardware. It's also possible that getty may 
be waiting on a connect on the serial port. By default it won't be but 
we don't know what Polarian has done, so good question.

Most likely the line /etc/ttys will read something like:

ttyu0   "/usr/libexec/getty 3wire"      vt100   onifconsole secure

The onifconsole option enables it IF it's designated as a console (no 
kidding!), which it might be given what Polarian is trying to do. If 
there's a line in loader.conf saying "console=comconsole" then getty 
might lock on to it. Worth checking, but he wasn't complaining about the 
lock error.

The reason I say "might" is that getty references the device as 
/dev/ttyu? which blocks in open() until it get's DCD. If you hit the 
same device as /dev/cuau? it's the call-out version, which doesn't wait 
for DCD and because getty 's attempt to open(/dev/ttyu?) will be blocked 
then cu will still be able to open it. Unless DCD is pulled active, 
depending on the wiring of the cables here. Which is why I asked for a 
loopback test before anything else :-)

Regards, Frank.