NetBSD-Users archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Getty on USB serial port

Hello all,

I'm trying to add a secondary serial port to my Raspberry Pi 1 Model A for debugging reasons (I want to repurpose the main UART for `pppd` as an experiment). Right now, I'm stuck on trying to spawn a getty on the USB serial port.

According to dmseg, my USB-to-serial device is a Prolific device:

ucom0 at uplcom0
uplcom0 at uhub0 port 1
uplcom0: Prolific Technology Inc. (0x67b) USB 2.0 To COM Device (0x2303), rev 1.10/3.00, addr 2

According to `man uplcom` and `man ucom`, `ucom` devices are treated as `ttys` and are available under `/dev/ttyU?`, where I presume `?` matches the number assigned to `ucom?`. So, using the above `dmesg` output, I add an entry to `/etc/ttys`, expecting it to be picked up on reboot:
ttyU0   "/usr/libexec/getty default"    vt100   on secure

However, this change had no effect and I didn't see any output on the system attached at the other end of the USB serial port upon rebooting. At this point I figured it's possible that the baud rate is incorrect, but I figured I should debug from a root shell first.

However, no matter which arguments I invoke the getty program_, getty _insists_ on using the main console, to dump input and output. This leads to fun things that I had no idea were possible like, for example (when invoking using `/usr/libexec/getty default ttyU0`):

* Getting a login prompt printed over the UART associated with `console` that says "(`ttyU0`)", when `ttyU0` should be associated with the USB serial port. * Logging into said login prompt, invoking `tty` command, and the output saying my current tty is a psuedoterminal: `/dev/pts/0`

At this point I'm stumped. What would cause me to have the above conditions? And what is the proper command I should use from a root shell (after logging in over `console` UART) to spawn a login prompt over the USB serial port?

As always, thanks all for any help.


William D. Jones

Home | Main Index | Thread Index | Old Index