bcdedit and BIOS disk order, how do I setup multibooting?

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  1. shockwaveriderz's Avatar
    Posts : 58
    Windows 10 Pro 1903 18362.267
       #51

    the nuclear option is to just rebuild your bcd store :

    How to Rebuild the BCD in Windows

    assuming you first use bcdedit to export your current bcd store, if rebuild doesn't work, you can always bcdedit import the exported bcd store back to the original...
    this obviously will have to be done from winpe, winre or an install media usb.....

    I find bcdedit /enum All to be confusing....Until I saw you use it I didn't know it existed...I have always used bcdedit /enum /v or bcdedit /enum firmware /v

    as long as you backup the current bcd store first with bcdedit /export you could delete an entry from the current bcd store one by one and see what effect it has... if it won't boot just bcdedit import the oldbcd store and you are back to where you started from .

    - - - Updated - - -

    dictum said: View Post
    How do I know it's safe to delete an entry? I am deeply concerned I will make my machine unbootable.

    And how about the bcfg command, would that be helpful?
    I have the ability to boot from a uefi shell in my bios from a usb flash drive. I've played about just looking at stuff, but be sure to read the uefi shell command reference first.

    To dump a list of current boot entries:

    Shell> bcfg boot dump -v

    For bcfg help text:

    Shell> help bcfg -v -b
    or:

    Shell> bcfg -? -v -b

    be very careful
      My ComputersSystem Spec


  2. Posts : 334
    Windows 10
    Thread Starter
       #52

    How do I boot into the EFI shell?

    you can always bcdedit import the exported bcd store back to the original...
    this obviously will have to be done from winpe, winre or an install media usb.
    this makes sense. I think I will try that.
      My ComputerSystem Spec

  3. shockwaveriderz's Avatar
    Posts : 58
    Windows 10 Pro 1903 18362.267
       #53

    dictum said: View Post
    How do I boot into the EFI shell?



    this makes sense. I think I will try that.
    Here's a bcdedit command that may help

    bcdedit /import "C:\exportedBCD" /clean

    /clean

    Optional. The /clean option is used only for UEFI systems. It directs BCDEdit to delete all NVRAM entries and then re-initialize NVRAM based on the firmware namespace objects in filename.

    Never used this switch so I'm not 100% sure what it will do so caveat emptor.
    bcdedit and BIOS disk order, how do I setup multibooting? Attached Files
      My ComputersSystem Spec

  4. NavyLCDR's Avatar
    Posts : 11,820
    Windows 10 LTSC
       #54

    Hmmm... and to think I've always just formatted the system partition and used only the bcdboot command to recreate the BCD.
      My ComputerSystem Spec


  5. Posts : 334
    Windows 10
    Thread Starter
       #55

    I think I will just use the EasyUEFI to delete the bogus/redundant entries after I backup the BCD. I always keep a backup but will redo it just in case and put it on both disks C:\ and G:\ in the root of the drives.

    When I click on a bootmanager entries, the first 2 highlight the EFI partition in the diagram with the faint red box. The other 3 don't do anything so I assume these are the bogus ones.

    Worst case scenario, I will have to boot with a recovery flash and import the backup BCD configuration.
      My ComputerSystem Spec

  6. NavyLCDR's Avatar
    Posts : 11,820
    Windows 10 LTSC
       #56

    I'm just curious, why the need to waste all this time trying to fix what is broken when it is so easy and quick to just start fresh? Heck you could even just create a new 100mb FAT32 partition, run bcdboot on it and give it a test drive before removing the old system partition.

    The ultimate fix really only takes 5 minutes and you've spent weeks on this now!
      My ComputerSystem Spec



  7. Posts : 334
    Windows 10
    Thread Starter
       #57

    NavyLCDR said: View Post
    I'm just curious, why the need to waste all this time trying to fix what is broken when it is so easy and quick to just start fresh? Heck you could even just create a new 100mb FAT32 partition, run bcdboot on it and give it a test drive before removing the old system partition.

    The ultimate fix really only takes 5 minutes and you've spent weeks on this now!



    this sounds really nice on the high level but it's devoid of any low level nuts and bolts commands and algorithms.
      My ComputerSystem Spec

  8. NavyLCDR's Avatar
    Posts : 11,820
    Windows 10 LTSC
       #58

    Boot from a Windows 10 USB flash drive and get to a command prompt.

    diskpart
    list disk
    select disk # <-replace # with the drive you want to fix
    list part
    select part # <-replace # with the partition number of the system partition
    delete partition override
    create part pri
    format fs=FAT32 quick
    assign letter T:
    list vol
    exit
    bcdboot C:\Windows /s T: /f UEFI <-Might need to change drive letter C:\ to whatever the primary Windows letter is
    exit

    Boot from the new system partition into your primary Windows then open a Command Prompt (Admin) or Powershell (Admin) and run:
    bcdboot G:\Windows /d /addlast <- change drive letter G: to whatever your second Windows is you want to dual boot.

    I did the first part on my laptop just now in less than 5 minutes just for you:

    Code:
    X:\windows\System32>diskpart
    
    Microsoft DiskPart version 10.0.17134.1
    
    Copyright (C) Microsoft Corporation.
    On computer: Win10XPE
    
    DISKPART> list disk
    
      Disk ###  Status         Size     Free     Dyn  Gpt
      --------  -------------  -------  -------  ---  ---
      Disk 0    Online          476 GB      0 B        *
      Disk 1    Online          476 GB  1024 KB        *
    
    DISKPART> select disk 1
    
    Disk 1 is now the selected disk.
    
    DISKPART> list part
    
      Partition ###  Type              Size     Offset
      -------------  ----------------  -------  -------
      Partition 1    Primary            100 MB  1024 KB
      Partition 2    Reserved            16 MB   101 MB
      Partition 3    Primary            348 GB   117 MB
      Partition 4    Primary            128 GB   348 GB
      Partition 5    Recovery           478 MB   476 GB
    
    DISKPART> select part 1
    
    Partition 1 is now the selected partition.
    
    DISKPART> delete part override
    
    DiskPart successfully deleted the selected partition.
    
    DISKPART> create part EFI
    
    DiskPart succeeded in creating the specified partition.
    
    DISKPART> format fs=FAT32 quick
    
      100 percent completed
    
    DiskPart successfully formatted the volume.
    
    DISKPART> assign letter=T
    
    DiskPart successfully assigned the drive letter or mount point.
    
    DISKPART> list vol
    
      Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
      ----------  ---  -----------  -----  ----------  -------  ---------  --------
      Volume 0     D   Data         NTFS   Partition    404 GB  Healthy
      Volume 1                      NTFS   Partition     64 GB  Healthy
      Volume 2     R   RECOVERY     FAT32  Partition      8 GB  Healthy
    * Volume 3     T                FAT32  Partition    100 MB  Healthy    Hidden
      Volume 4     C   Win10        NTFS   Partition    348 GB  Healthy
      Volume 5     E   Insider      NTFS   Partition    128 GB  Healthy
      Volume 6                      NTFS   Partition    478 MB  Healthy
    
    DISKPART> exit
    
    Leaving DiskPart...
    
    X:\windows\System32>bcdboot C:\Windows /s T: /f UEFI
    Boot files successfully created.
    Code:
    Microsoft Windows [Version 10.0.18362.267]
    (c) 2019 Microsoft Corporation. All rights reserved.
    
    C:\Windows\system32>bcdboot E:\Windows /d /addlast
    Boot files successfully created.
    
    C:\Windows\system32>bcdedit
    
    Windows Boot Manager
    --------------------
    identifier              {bootmgr}
    device                  partition=\Device\HarddiskVolume5
    path                    \EFI\Microsoft\Boot\bootmgfw.efi
    description             Windows Boot Manager
    locale                  en-us
    inherit                 {globalsettings}
    flightsigning           Yes
    default                 {current}
    resumeobject            {897691c6-be16-11e9-97f4-be41aee8f2e6}
    displayorder            {897691c7-be16-11e9-97f4-be41aee8f2e6}
                            {current}
    toolsdisplayorder       {memdiag}
    timeout                 30
    
    Windows Boot Loader
    -------------------
    identifier              {897691c7-be16-11e9-97f4-be41aee8f2e6}
    device                  partition=E:
    path                    \Windows\system32\winload.efi
    description             Windows 10
    locale                  en-us
    inherit                 {bootloadersettings}
    isolatedcontext         Yes
    flightsigning           Yes
    allowedinmemorysettings 0x15000075
    osdevice                partition=E:
    systemroot              \Windows
    resumeobject            {897691c6-be16-11e9-97f4-be41aee8f2e6}
    nx                      OptIn
    bootmenupolicy          Standard
    
    Windows Boot Loader
    -------------------
    identifier              {current}
    device                  partition=C:
    path                    \Windows\system32\winload.efi
    description             Windows 10
    locale                  en-us
    inherit                 {bootloadersettings}
    isolatedcontext         Yes
    allowedinmemorysettings 0x15000075
    osdevice                partition=C:
    systemroot              \Windows
    resumeobject            {897691c4-be16-11e9-97f4-be41aee8f2e6}
    nx                      OptIn
    bootmenupolicy          Standard
    Last edited by NavyLCDR; 13 Aug 2019 at 19:12.
      My ComputerSystem Spec


  9. Posts : 334
    Windows 10
    Thread Starter
       #59

    There is nothing wrong with my EFI partition on either disk. There is no need to run diskpart and rebuild anything.
    The problem is exclusively in the NVRAM (BIOS). The entries there are problematic and redundant or bogus.

    Each of my individual disks boots. Thus there is no issue with EFI or any other Windows 10 partition. They work just fine. They are identical.

    For some reason when the two disks are in the machine at the same time, they cannot boot in conjunction with the bcdedit stuff, it gets confused likely by the false and redundant entries. I had this working for a number of years and it just broke down a few weeks ago. I think I can trace it to the Linux install I had on one of these disks, which I have since deleted (and cleaned out the EFI) but apparently more than one ghost image is still floating around in BIOS/NVRAM. That breaks my dual Windows boot. It looks like I have at least 3 false entries in BIOS that don't correspond to the actual disks in the machine.

    As I already explained, I can boot either the primary disk or the mirror. The EFI is fine since it boots just fine. If I make my primary disk bootable in BIOS, the mirror does not boot. It cannot find UEFI. I have to go into BIOS and move around disks, then the mirror boots but the primary does not. Somehow the BIOS entry points to the wrong disk, I am not really sure but removing false entries is a good start.
    I had this working probably for 3 years, it can work and I cannot figure what broke it.

    I am deeply concerned about hosing my machine by removing the wrong thing from the UEFI and then what. Your solution is quick, efficient and 5-minute and does not address my problem.
      My ComputerSystem Spec

  10. NavyLCDR's Avatar
    Posts : 11,820
    Windows 10 LTSC
       #60

    dictum said: View Post
    There is nothing wrong with my EFI partition on either disk. There is no need to run diskpart and rebuild anything.
    The problem is exclusively in the NVRAM (BIOS). The entries there are problematic and redundant or bogus.

    Each of my individual disks boots. Thus there is no issue with EFI or any other Windows 10 partition. They work just fine. They are identical.

    For some reason when the two disks are in the machine at the same time, they cannot boot in conjunction with the bcdedit stuff, it gets confused likely by the false and redundant entries. I had this working for a number of years and it just broke down a few weeks ago. I think I can trace it to the Linux install I had on one of these disks, which I have since deleted (and cleaned out the EFI) but apparently more than one ghost image is still floating around in BIOS/NVRAM. That breaks my dual Windows boot. It looks like I have at least 3 false entries in BIOS that don't correspond to the actual disks in the machine.

    As I already explained, I can boot either the primary disk or the mirror. The EFI is fine since it boots just fine. If I make my primary disk bootable in BIOS, the mirror does not boot. It cannot find UEFI. I have to go into BIOS and move around disks, then the mirror boots but the primary does not. Somehow the BIOS entry points to the wrong disk, I am not really sure but removing false entries is a good start.
    I had this working probably for 3 years, it can work and I cannot figure what broke it.

    I am deeply concerned about hosing my machine by removing the wrong thing from the UEFI and then what. Your solution is quick, efficient and 5-minute and does not address my problem.
    Suit yourself. My dual boot is working. Yours isn't. Just sayin'. I've also used the bcdboot command to dual boot separate drives on my desktop computer.
      My ComputerSystem Spec


 
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