X11 users can change the overscan margins using xrandr, but if you are running the raspberry pi console without x11 that won't work, and the config.txt method is hard to fine tune. This can be run after boot and allows semi-interactive fine tuning. It works with KMS out of the box, or fkms with a simple comment/uncomment swap.
What do I need?
You need a GCC compiler, GDM, EGL, and GLES libraries. The GCC compiler is already included in the Raspbian image. To install the other libraries, simply run:
sudo apt-get install libegl1-mesa-dev libgbm-dev libgles2-mesa-devYou will also need to connect your Raspberry Pi to a screen. The boot config from /boot/config.txt that I have used for my tests, if it helps in any way:
dtoverlay=vc4-kms-v3d
max_framebuffers=2
hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=81How do I try it?
Copy or download the margin.c file onto your Raspberry Pi. Using terminal, write the following commands to compile the source file:
gcc -o margin margin.c -ldrm -lgbm -lEGL -lGLESv2 -I/usr/include/libdrm -I/usr/include/GLES2
To run the executable, type the following:
margin 100 # all the same
margin 50 100 #top/bottom and left/right the same
margin 20 10 15 15 # all custom,
Failed to get EGL version! Error:
Your EGL might be faulty! Make sure you are using the libraries provided by Raspbian and not the ones installed through apt-get or other package managers. Use the ones in the /opt/vc/lib folder. If that does not work, try reinstalling your Raspberry Pi OS.
I get "Error! The glViewport/glGetIntegerv are not working! EGL might be faulty!" What should I do?
Same as above.
Do whatever you want.
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