Win11Pro changes UEFI boot order -- on its own

NavyLCDR · Dec 10, 2023

No, it is a Windows 10 installation. I got an error when starting the Windows 11 installation saying the computer was not compatible with Windows 11, so instead of fixing that, I just did a quick Windows 10 install. I can fix it and show you a Windows 11 install on drive E: as the only drive on the computer if you really want it.

trumpy81 · Dec 10, 2023

Ah OK, that explains it then ... lol

I just saw the Win11 drive name and assumed you were running Windows 11.

NavyLCDR · Dec 10, 2023

Here you go, Windows 11 on E: drive:

Code:

E:\Windows\System32>diskpart

Microsoft DiskPart version 10.0.22621.1

Copyright (C) Microsoft Corporation.
On computer: WIN-11

DISKPART> lis vol

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     E   WIN11        NTFS   Partition    126 GB  Healthy    Boot
  Volume 1                      FAT32  Partition    100 MB  Healthy    System

DISKPART> sel dis 0

Disk 0 is now the selected disk.

DISKPART> lis par

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    System             100 MB  1024 KB
  Partition 2    Reserved            16 MB   101 MB
  Partition 3    Primary            126 GB   117 MB

DISKPART> lis dis

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
* Disk 0    Online          127 GB      0 B        *

E:\Windows\System32>bcdeit
'bcdeit' is not recognized as an internal or external command,
operable program or batch file.

E:\Windows\System32>bcdedit

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
default                 {current}
resumeobject            {3cbfc697-8bc7-11ee-b2b0-84e9f6fdd286}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=E:
path                    \Windows\system32\winload.efi
description             Windows 11
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=E:
systemroot              \Windows
resumeobject            {3cbfc697-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

E:\Windows\System32>

trumpy81 · Dec 10, 2023

Now, dual boot the machine with Windows 10 on each drive/partition and see what happens.

Place a unique text file in the root of each drive/partition so you may identify each drive.

Something like E Drive.txt and D Drive.txt on their respective drives.

NavyLCDR · Dec 10, 2023

trumpy81 said:
Now, dual boot the machine with Windows 10 on each drive/partition and see what happens.

Place a unique text file in the root of each drive/partition so you may identify each drive.

Something like E Drive.txt and D Drive.txt on their respective drives.

Oh, ye of little faith. Patience, grasshopper, patience.

NavyLCDR · Dec 10, 2023

Here is the computer booted into Windows 10 installed on D: drive:

Code:

Microsoft Windows [Version 10.0.19045.2965]
(c) Microsoft Corporation. All rights reserved.

D:\Windows\system32>bcdedit

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
default                 {current}
resumeobject            {3cbfc69b-8bc7-11ee-b2b0-84e9f6fdd286}
displayorder            {current}
                        {3cbfc698-8bc7-11ee-b2b0-84e9f6fdd286}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=D:
path                    \Windows\system32\winload.efi
description             Windows 10
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=D:
systemroot              \Windows
resumeobject            {3cbfc69b-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

Windows Boot Loader
-------------------
identifier              {3cbfc698-8bc7-11ee-b2b0-84e9f6fdd286}
device                  partition=E:
path                    \Windows\system32\winload.efi
description             Windows 11
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=E:
systemroot              \Windows
resumeobject            {3cbfc697-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

D:\Windows\system32>dir D:\
 Volume in drive D is WIN10
 Volume Serial Number is B898-F692

 Directory of D:\

12/07/2019  01:14 AM    <DIR>          PerfLogs
12/10/2023  06:09 PM    <DIR>          Program Files
05/05/2023  04:27 AM    <DIR>          Program Files (x86)
12/10/2023  06:21 PM    <DIR>          Users
12/10/2023  06:21 PM    <DIR>          Windows
12/10/2023  06:15 PM                21 Windows 10 on D Drive.txt
               1 File(s)             21 bytes
               5 Dir(s)  47,985,438,720 bytes free

D:\Windows\system32>dir E:\
 Volume in drive E is WIN11
 Volume Serial Number is 9889-23EB

 Directory of E:\

05/06/2022  09:24 PM    <DIR>          PerfLogs
12/10/2023  04:22 PM    <DIR>          Program Files
11/25/2023  09:20 AM    <DIR>          Program Files (x86)
12/10/2023  04:31 PM    <DIR>          Users
12/10/2023  04:24 PM    <DIR>          Windows
12/10/2023  06:16 PM                21 Windows 11 on E Drive.txt
               1 File(s)             21 bytes
               5 Dir(s)  44,792,688,640 bytes free

D:\Windows\system32>

NavyLCDR · Dec 10, 2023

And the same computer booted into Windows 11 on E: drive:

Code:

Microsoft Windows [Version 10.0.22635.2771]
(c) Microsoft Corporation. All rights reserved.

E:\Windows\System32>bcdedit

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
default                 {default}
resumeobject            {3cbfc69b-8bc7-11ee-b2b0-84e9f6fdd286}
displayorder            {default}
                        {current}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {default}
device                  partition=D:
path                    \Windows\system32\winload.efi
description             Windows 10
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=D:
systemroot              \Windows
resumeobject            {3cbfc69b-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=E:
path                    \Windows\system32\winload.efi
description             Windows 11
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=E:
systemroot              \Windows
resumeobject            {3cbfc697-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

E:\Windows\System32>dir D:\
 Volume in drive D is WIN10
 Volume Serial Number is B898-F692

 Directory of D:\

12/07/2019  01:14 AM    <DIR>          PerfLogs
12/10/2023  06:09 PM    <DIR>          Program Files
05/05/2023  04:27 AM    <DIR>          Program Files (x86)
12/10/2023  06:21 PM    <DIR>          Users
12/10/2023  06:21 PM    <DIR>          Windows
12/10/2023  06:15 PM                21 Windows 10 on D Drive.txt
               1 File(s)             21 bytes
               5 Dir(s)  47,999,475,712 bytes free

E:\Windows\System32>dir E:\
 Volume in drive E is WIN11
 Volume Serial Number is 9889-23EB

 Directory of E:\

05/06/2022  09:24 PM    <DIR>          PerfLogs
12/10/2023  04:22 PM    <DIR>          Program Files
11/25/2023  09:20 AM    <DIR>          Program Files (x86)
12/10/2023  04:31 PM    <DIR>          Users
12/10/2023  04:24 PM    <DIR>          Windows
12/10/2023  06:16 PM                21 Windows 11 on E Drive.txt
               1 File(s)             21 bytes
               5 Dir(s)  44,785,946,624 bytes free

E:\Windows\System32>

NavyLCDR · Dec 10, 2023

trumpy81 said:
Now, dual boot the machine with Windows 10 on each drive/partition and see what happens.

Place a unique text file in the root of each drive/partition so you may identify each drive.

Something like E Drive.txt and D Drive.txt on their respective drives.

Want to see anything else?

trumpy81 · Dec 10, 2023

Kewl, so Diskpart and BCDEdit to the rescue ... lol

Thanks for that

NavyLCDR · Dec 10, 2023

trumpy81 said:
Kewl, so Diskpart and BCDEdit to the rescue ... lol

Thanks for that

I can tell you what the secret is, if you really want to know.

trumpy81 · Dec 10, 2023

Sure, go ahead.

NavyLCDR · Dec 10, 2023

trumpy81 said:
Sure, go ahead.

First, you have to already be booted into a Windows installation. Create an empty partition that you want the new Windows to install to, format it as NTFS and give it a drive letter. Then from either a mounted Windows 10/11 ISO file or a Windows 10/11 USB flash drive run setup.exe from the sources folder, not from the root folder. Go through setup normally, select the custom install option, then select the partition with the drive letter that you created. Windows setup will create dual booting, restart the computer with a Windows Setup option in the boot menu. Select Windows Setup to boot from and Windows Setup will continue to install Windows. It will then keep whatever drive letter the partition was originally assigned to. On the examples I posted, I started from the standard C: drive Windows installation and after I had Windows installed to the D or E drive partitions, deleted the original C: drive Windows partition.

I believe there is also an option to set the installation drive letter assignment in unattend.txt if you are doing that type of install, but I don't know what it is. I have never used unattend.txt.

trumpy81 · Dec 10, 2023

Yeah, there are many ways you can circumvent things, which is handy, but under normal circumstances that would not happen.

It's kewl to see it work though, thanks.

NavyLCDR · Dec 10, 2023

trumpy81 said:
Yeah, there are many ways you can circumvent things, which is handy, but under normal circumstances that would not happen.

It's kewl to see it work though, thanks.

Well... it is just proof that a previously made statement that the Windows boot manager assigns drive letters was erroneous. The drive letters are contained in the Windows registry and it isn't until Windows itself starts to load that drive letters are assigned.

trumpy81 · Dec 10, 2023

No, it is the Windows Boot Manager that sends the selected drive letter to Windows so it can then make the changes needed.

Of course, that only happens in dual/multi boot situations when the Windows Boot Manager is employed and the drive letters have not been otherwise manipulated.

If you follow the usual method of installing the first OS, then install the second OS via DVD or USB, letting Windows handle the setup of BCD etc. Then you get exactly what I showed and stated.

NavyLCDR · Dec 10, 2023

trumpy81 said:
No, it is the Windows Boot Manager that sends the selected drive letter to Windows so it can then make the changes needed.

You would be wrong.

trumpy81 · Dec 10, 2023

Show me how I am wrong.

NavyLCDR · Dec 10, 2023

trumpy81 said:
Show me how I am wrong.

This is the BCD (the "Windows Boot Manager") from the computer I posted my examples from. Notice there are no drive letters in it except for the drive letter it was accessed from, which I manually assigned to S: drive using diskpart so that I could access the BCD. The Windows Boot Manager uses device ID's, not drive letters. If you run BCDEDIT in a Windows installation that has assigned drive letters to the device IDs, then it will substitute drive letters for the device ID's. But that happens inside the Windows OS, not the boot manager.

Code:

S:\EFI\Microsoft\Boot>bcdedit /store BCD

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=S:
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
default                 {default}
resumeobject            {3cbfc69b-8bc7-11ee-b2b0-84e9f6fdd286}
displayorder            {default}
                        {3cbfc698-8bc7-11ee-b2b0-84e9f6fdd286}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {default}
device                  partition=\Device\HarddiskVolume11
path                    \Windows\system32\winload.efi
description             Windows 10
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=\Device\HarddiskVolume11
systemroot              \Windows
resumeobject            {3cbfc69b-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

Windows Boot Loader
-------------------
identifier              {3cbfc698-8bc7-11ee-b2b0-84e9f6fdd286}
device                  partition=\Device\HarddiskVolume10
path                    \Windows\system32\winload.efi
description             Windows 11
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=\Device\HarddiskVolume10
systemroot              \Windows
resumeobject            {3cbfc697-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

S:\EFI\Microsoft\Boot>

The same concept can be seen when using reagentc to determine the location of the recovery environment - notice that no drive letters are used:

Code:

C:\Windows\System32>reagentc /info
Windows Recovery Environment (Windows RE) and system reset configuration
Information:

    Windows RE status:         Enabled
    Windows RE location:       \\?\GLOBALROOT\device\harddisk1\partition3\Recovery\WindowsRE
    Boot Configuration Data (BCD) identifier: b55ec758-3f18-11ee-b0d5-e4bf6b2589ed
    Recovery image location:
    Recovery image index:      0
    Custom image location:
    Custom image index:        0

REAGENTC.EXE: Operation Successful.

SIW2 · Dec 10, 2023

Navy is correct.

trumpy81 · Dec 10, 2023

You are still relying on Windows BCD to do the selecting.

Remove the Windows Boot Manager and then try selecting the drive to boot to, without resorting to manual manipulation and without entering your BIOS.

See how far you get then.