I am having a problem with FreeBSD, wherein I cannot get the text to be constrained within the area of a TV (composite). I have been using framebuffer_height and framebuffer_width in /boot/msdos/config.txt to get the right size but overscan_left, _right, etc. does not seem to be consistent. The size of the TV screen is approx. 11.5 wide x 8.5 high (inches). There are no real controls on the TV for the size of the viewing area as far as I can tell. The TV is manufactured in 1985, it is a Montgomery Ward TV.

Everything else with this FreeBSD-10.1-RELEASE-arm-armv6-RPI-B.img image seems to work fine. It seems with this image I cannot extract the ports tree but I had done that earlier with another image.

I have also tried using a config.txt generated from a debian system on the same TV, which set the framebuffer at 720x480 and the overscan settings all at 16, the only other thing in the file was disable_overscan=0... that was not commented out.

1 Answer 1


I don't know FreeBSD but I used the following to calibrate my display on Raspbian


  • The script referenced looks to be a useful tool although I don't think it will work on FreeBSD.
    – eh-five
    Dec 19, 2014 at 6:22
  • @eh-five overscan.c is actually the meat of that; it looks to be POSIX and should at least compile on FreeBSD. It's all just about the creation of a dev node and an ioctl() call -- which may or may not be linux specific, but if you know someone else running FreeBSD with a good grasp of system programming they might get a good clue from that. The script would probably work too (for creating the dev node, etc.) except it uses whiptail which is a bit of an oddity. However, the script itself is not strictly necessary.
    – goldilocks
    Dec 19, 2014 at 18:21
  • Well, the problem really seems to be that I get no response from using the overscan settings, rather I get a change but not really predictable. The screen will be garbled in the initial stages with some settings although when I get to the login prompt it will be clear.
    – eh-five
    Dec 20, 2014 at 6:03
  • I think the problem is that the settings are rather unusual. I found trying to do them manually didn't produce the results I wanted (and it was SLOOW). If you can't get this to work on FreeBSD, you could try on Raspbian and copy settings. Have you set sdtv_mode sdtv_aspect
    – Milliways
    Dec 20, 2014 at 6:10
  • I agree, many layers of interpretation it seems. Of the video information. I have tried sdtv settings, the most success I had was with solely framebuffer settings. I was thinking that I should take the settings from a raspi-config generated config.txt too. @miliways, thanks
    – eh-five
    Dec 20, 2014 at 6:24

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