I want to make this very clear: Dual-booting with UEFI is entirely possible, provided that your hardware allows entering EFI vars manually, in a SIGNED OS ENVI

I want to make this very clear: Dual-booting with UEFI is entirely possible, provided that your hardware allows entering EFI vars manually, in a SIGNED OS ENVIRONMENT. Every comment I've seen thus far doesn't seem to grasp that this is MANDATORY before you have the ability to finish installing a new bootloader. This is how UEFI protects itself from unauthorized OS signing! I have my own custom EFI vars set up with grub2 running on a GPT partition table, all booting beside windows, as purely as the air you breathe, and I'm loading custom Linux kernels daily and haven't ran into an issue since I originally set it up. Grub2 itself is my primary boot partition, which can then jump into the windows boot manager on the other disk. Grub2 itself has the capacity to act as a custom-signed EFI boot partition (Not sure if I've got the wording on that correct -- but the gist is there!). This means grub can be what your bios looks for the signature from. You don't absolutely need your kernel to be signed, provided you can get a signature produced from grub, OR you have the ability to write one while in a signed O/S. IF you want the easiest approach, look no further than any Linux distribution that purchased a key to find such a signed environment that permits the further writing of EFI variables. Or, even easier -- just write then boot grub 2's EFI-signed bootloader to a usb key to get started. After that, writing a new OS entry to UEFI should be the most straightforward thing to do in the world! *(You can even boot any kernel in the world with such a signed grub2 USB disk!)