I have an old computer of mine with Sabayon Linux installed. It used to work perfectly until Nvidia decided to remove the support of my GeForce GT 555M from the latest version of their driver and to move it to their 39X driver series. I discovered this when I updated Sabayon and X11 was not starting anymore. Sabayon recognized the 430.26 driver as a valid update for my driver and installed it.
At first, I fixed the problem manually after updating the system, but it was a nuisance doing it every time. So I searched for a way to prevent the update of the Nvidia Drivers to a certain version.
I found this wiki page that helped me: link.
I edited /etc/entropy/packages and added:
At the bottom of the file.
By the way, to install the supported version:
equo install x11-drivers/nvidia-userspace-390.87 equo install x11-drivers/nvidia-drivers-390.87