I'm having an awfully hard time getting Ubuntu to work on a late 2012 iMac. I partitioned, installed rEFInd, and was able to boot into Ubuntu, but the display is laggy, I get strange flickers, and I can't get my Apple Magic Trackpad to pair. In short, a lot of things are broken. Is there an up to date install guide for this iMac? All the guides I can find are outdated, and all the similar questions to this one are unanswered.