Microsoft confirmed to PC manufacturers that they must enable Secure Boot by default on PCs to be “Certified for Windows 8” The purpose of Secure Boot is to put an end to computer viruses that sneak between the hardware and the operating system. Microsoft’s stance has been “not our problem”, and in the everyone for themselves sense, they’re right. The problem boils down to the way Microsoft and PC manufacturers will implement Secure Boot, and how difficult it will be for many, if not all, alternative operating systems to follow suit.
Source: https://thehackernews.com/2012/07/no-boot-for-you-will-windows-8-kill.html