One of the things that you will probably have noticed if you are running Debian via HDMI is the fact that there is a large black border, and if you are running a graphical user interface, you can’t set the resolution to 1920×1080.

You can change this behaviour (and more) by editing the text fail /boot/config.txt.

There are currently two ways to do this:

  1. From Debian Wheezy (15/07/2012), run the utility raspi-config. This is the text menu that pops up immediately after you boot your Raspberry Pi after booting a newly installed disk image. You can run this at any time by running the command “sudo raspi-config” from the command line.
  2. By editing the file /boot/config.txt with a suitable text editor (say, nano).

Changes come into effect after a reboot; this can be done from the menu or from the command line (“sudo reboot”).

More details on the config file can be found here: http://elinux.org/RPi_config.txt

Example: Get rid of the black borders (overscan)

Edit the config file in nano. Note this will create a new file if one doesn’t already exist.

sudo nano /boot/config.txt

Then amend (or add) the following line:

disable_overscan=1

After rebooting the Pi you will have access to the whole screen area.