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I've used serial console on Redhat before, and all I did was direct grub to put the output to the serial port, I was wondering if anyone has done this on FreeBSD or by chance knows some sites that would help make this possible.

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already pointed to the Handbook; the notes below are a short, practical follow‑up that fills in common gotchas people hit when the basic steps seem to do nothing (as discovered).

Serial device names and what to look for

  • FreeBSD uses different device names depending on version and hardware: legacy UARTs are typically ttyuN/cuauN, USB device‑mode ports appear as ttyUN/cuaUN, and there are .init and .lock siblings you can use to set or lock defaults. Check what the kernel actually saw during boot (it will mention uart and the console speed) and list the device nodes to confirm names. (docs.freebsd.org)

Quick checks (run as root)

# grep -i uart /var/run/dmesg.boot
# ls -l /dev/ttyu* /dev/ttyU* /dev/cu*
# stty -a -f /dev/ttyu0

These show which UART was probed, what device name to use, and the current port settings. (docs.freebsd.org)

How to test a live connection and the init/lock behavior

  • From the other machine use cu, tip, screen or minicom to open the serial line (example: cu -l /dev/cuaU0 -s 115200 or screen /dev/ttyu0 115200). If the port opens but login is funky, check the .init file (FreeBSD restores settings from it when the device is reopened) or write to the .lock device to prevent apps from changing speed. Use stty -f /dev/ttyu0.init … to set defaults. (docs.freebsd.org)

Advanced gotchas and boot console notes

  • The boot loader and kernel console selection are controlled by loader settings (e.g., the console/speed tunables) so verify loader config if you never see boot output. Using a serial port other than the standard sio0 for the boot blocks requires rebuilding boot blocks/kernel and setting the appropriate build variable — multiport cards usually won’t work as the boot console. If boot messages don’t appear, check those two places first. (man.freebsd.org)

Short checklist

  • Confirm kernel probed a UART (grep uart /var/run/dmesg.boot).
  • Match device name (ttyu vs ttyU vs cuau/cuaU) and use the correct /dev path.
  • Use stty -f ...init to set defaults and cu/screen to test the link.

These steps address the usual surprises after the Handbook basics. (docs.freebsd.org)

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Member Avatar for blud

Thanks, I thought I looked, but maybe I was busy doing other things and forgot!

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