I finished to have a full working Gentoo on my old deprecated laptop, and it was a long and hard process to get it working with a full graphical interface. But now it works like a charm and is fast. It is amazing to have a system especially tuned for my hardware.
I had to look up in the forum dozen of times for people who had the same problems/error as me and were given a solution, so I would like to give a bit thank to everyone who asked the questions and to those who answered them.
