I'm currently installing Gentoo on a Dell Inspiron 15 (3521 - Celeron 1007u CPU, 4 GB RAM, and an Intel X25-M [gen 2] 80 GB SSD with the same InsydeH2O uEFI interface {that suspiciously looks like a plain old BIOS interface) with secure boot on. Once I figured out how to give it the parameters that InsydeH2O wants / needs, I was able to leave secure boot on, enable the custom settings, and set up 3 devices that the laptop is allowed to boot from: (1) The HD (2) My USB drive with SystemRescueCD (a uEFI compatible live CD that is based on Gentoo, so perfect for use in installing Gentoo) (3) A Windows 10 USB made using the Media Creation tool I'm actually in the middle of that install, so I cannot reboot at the moment to take pictures, but as soon as I am able to, I'll make a full post on what you need to do, and where you need to do it, so that you'll then be able to keep secure boot on and boot Ubuntu. Getting the HD to boot Gentoo is a bit trickier, thus far, as I am also using rEFInd as a bootmanager for...