Originally Windows 8 required machines to support a feature calledUEFI Secure Boot.
If any files had been tampered with, breaking their signature, the system wouldnt boot.
This time, however, Microsoft is changing the rules for UEFI.
Microsoft says that the switch to allow UEFI Secure Boot to be turned off is now optional for them.
There is no word on whether OEMS can or should provide support for adding custom certificates.
source: www.techworm.net
