Macbook Pro Late 2011 Ubuntu Problem

Hello guys, so i have a problem that i cant find a fix in google, basically i want install ubuntu on my mac, but i can only boot if i disable my amd gpu in grub the problem is that i dont want disable. I checked in google and all i find is problems with gpu that doesnt work properly, my gpu works fine in Windows (bootcamp) and macOS. (sorry for my bad english)