It's possible to boot into Windows 7 using secure boot with a trick from cdob which involves modifying the BCD entry. However if I try to boot with secure boot enabled, there is an error about windows\system32\winload.efi not supporting secure boot. So I tried to overwrite it with the Windows 10 version (including en-US\winload.efi.mui) , however it still fails with the secure boot error. I don't understand much about the booting process, I'm just guessing, but why does this fail to work as winload.efi is signed? Is there more than just having the right efi files?