[SOLVED] Used an Empty Partition for the Device Element in BCDEdit, PC still Boots! How?

[Modify_inc]

I'm trying to understand why when I changed the Device element's partition under Windows Boot Manager in BCDEdit to an empty partition I created (nothing is in the partition other than Recycle Bin & System Volume Information folder that is added by Windows), how the damn PC still boots. I was certain I would get an error during startup, but it booted straight into Windows with no issues. I confirmed in BCDEdit that the device element's partition was still set to the empty partition.

So how is Windows able to still boot when it clearly points to an empty partition that does not contain the bootmgfw.efi file or anything for that matter? I'm testing BCDEdit trying to learn more about it. I've already made a system backup, so I'm not too worried if I "break" anything.

 

[hotaru.hino]

Likely because it didn't actually replace anything in the bootloader's table of where OS partitions are at.

However it helps to know the exact configuration of your system. Like how many drives you have, which drives have a system partition, etc.

 

[Modify_inc]

It's a laptop with one drive (SSD) in it.

I have provided 3 screenshots including Disk Management, DiskPart, and BCDEdit.

If more info or pics are needed, let me know. I'll be glad to assist because I'm really confused how it can still boot.

Notice in the BCDEdit pic, I also changed the spelling of bootmgfw.efi to bootmgfwx.efi, and it still boots.

 

[Modify_inc]

Likely because it didn't actually replace anything in the bootloader's table of where OS partitions are at.

However it helps to know the exact configuration of your system. Like how many drives you have, which drives have a system partition, etc.

If it didn't replace anything in the bootloader's table, then what is the purpose of the Device and Path elements in BCDEdit? It appears that I can basically put anything for these two elements, and my laptop will still boot to Windows without any issues. I even altered the spelling of bootmgfw.efi for the Path element, and it still booted right up.

Also, I have provided info on my hdd configuration with screenshots. Let me know if anything else is needed.

Thank you

 

[Colif]

Its possible bios has the GUID and partition details of the EFI partition in Windows Boot Manager (many bios have an item in their boot order called Windows boot manager, its like an index, can be used to store all details of bootable devices in PC, Its not same thing as the windows one)

bios will look for it anyway.

That command is meant to do what you say

The device element specifies the volume that contains Windows Boot Manager. For UEFI systems, the device element for Windows Boot Manager is set to the system partition volume letter.

https://docs.microsoft.com/en-us/wi...ystem-store-settings-for-uefi?view=windows-11

EFI partition is normally the system drive.

I can't find an answer as to why it works if you change that.

 

[hotaru.hino]

This post might shed some light:

So.. As you can probably guess from running bcdedit (in Windows) or efibootmgr (in Linux), bootmgfw.efi is the Windows UEFI bootloader, which will then load winload.efi and thus the remainder of the OS.

The fallback executable in \EFI\Boot\bootx64.efi also happen to be a copy of this one.

But there really seems to be next to no information about bootmgr.efi. After being tipped by its only mention on MSDN, I found out that once you rename it W8 Advanced Startup Options becomes bust (while the system can still normally boot).