I was asked by my company to start offering our customers Windows 7 64 Bit in UEFI Mode and the ability to perform an In-Place upgrade of the same device running on Windows 7 64 Bit UEFI to Windows 10 in the future, Sounds easy, but the requirement doesn't
end there. During the course of an In-place upgrade the device should run on Native UEFI (Secure Boot ON) despite the fact that Windows 7 doesnt support secure boot.
I was caught totally off guard as to what i have been told about UEFI and CSM. As i have been thinking that UEFI CSM is nothing but Legacy BIOS similar to the way we have been imaging Windows 7 all these years by formatting the disk as an MBR Partition.
Though CSM (Compatibility support Module) is a component of the UEFI firmware that provides legacy BIOS compatibility by emulating a BIOS environment, allowing legacy operating systems and some option ROMs that do not support UEFI to still be used.
Until i realized that you could restore Windows 7 in UEFI Mode by converting the Disk to GPT and ensuring that you set the BIOS to UEFI CSM Mode (Yes UEFI CSM Mode!before that) of course minus the secure boot as Windows 7 64 bit doesnt support it yet unless you do an inplace upgrade to Windows 10 later and turn on the Secure Boot . Now nobody in the world tells you that or may be not explained in simple terms that you need to use UEFI CSM Mode for Windows 7 64 bit to work on UEFI and additionally also qualify for an In-Place upgrade for Windows 10 with Native UEFI Setting (Secure Boot ON) without having to re-image the device.
Now that i have accomplished this task. My question is does MS support switching over to Native UEFI after an in-place upgrade to Windows 10 from Windows 7 64 Bit UEFI CSM? if Yes i could then simply turn on Secure Boot after the in-place upgrade. Please let me know if my question is not clear enough i will try to rephrase it. And sorry for the long post i couldnt shorten it as it had to be comprehensive.