Cannot make VHD bootable

Question

I cannot make my VHD bootable.

I'm following this guild word for word, trying to create a Bootable VHD.

The BCDboot is supposed to create boot configuration entry so that windows bootloader can boot from the VHD, and I've seen it went successful, however, it just doesn't work:

D:>P:\windows\system32\bcdboot P:\windows /s P:
Boot files successfully created.

D:>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            {c605aeaf-...8}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=C:
path                    \Windows\system32\winload.efi
description             Windows 10
locale                  en-US
inherit                 {bootloadersettings}
recoverysequence        {c605aeb1-...8}
displaymessageoverride  Recovery
recoveryenabled         Yes
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=C:
systemroot              \Windows
resumeobject            {c605aeaf-...8}
nx                      OptIn
bootmenupolicy          Standard
hypervisorlaunchtype    Auto

I.e., the device partition=P: entry is not there. When I tried to boot it from Hyper-V, Hyper-V tells me that there is no boot-loader.

What could possibly wrong and how can I fix it? (again, I'm followed this guild word for word successfully until I came to the bcdboot & BCDEdit step. I.e., all my steps are exactly as shown there.)

UPDATE:

I'm not sure if I'm using UEFI though, because these are all it takes for me to create my disk:

select vdisk file=e:\vhd\winboot.vhd
attach vdisk
create partition primary
assign letter=v
active
format quick FS=NTFS Label=VHD

Most importanly, when select the Generation type for hyper-v, I chose Generation 1, which I think don't support UEFI.

Answer 1

If you are using UEFI, you need to convert the attached VHD's partition table to GPT:

1. Access WinPE Open Command Prompt
2. Prepare the UEFI disk by creating three partitions via diskpart:

   diskpart
    select disk 0
    clean
    convert gpt
   
    rem == 1. System partition =========================
    create partition efi size=100
    format quick fs=fat32 label="System"
    assign letter="S"
   
    rem == 2. Microsoft Reserved (MSR) partition =======
    create partition msr size=128
   
    rem == 3. Main partition ===========================
    create partition primary
    format quick fs=ntfs label="Main"
    assign letter="M"
   
    exit
   

3. Add the entry in the boot menu with /f UEFI

Answer 2

The tutorial followed left out the step for creating the boot partition, as well as WinRE:

1. Create correct partition structure via DiskPart:
   1. It's simpler to clear the VHD's partition table and re-partition (VHD: disk 0):

      # Select disk and clear the partition table:
        Sel Dis 0
        Clean
      
      # Create WinRE partition:
        Cre Par Pri Offset=1024 Size=665 Id=27
        Format Quick Fs=ntfs Label=WinRE
      
      # Create Boot partition:
        Cre Par Pri Size=100
        Format Quick Fs=ntfs Label=Boot
        Active
      
      # Create System partition:
        Cre Par Pri
        Format Quick Fs=ntfs Label=System
      
      # Verify:
        Lis Par
        Lis Vol
      
        Exit
      

   2. If preserving existing data on the VHD's [OS] System partition:

      # Select disk and [OS] System partition:
        Sel Dis 0
        Sel Par 1
      
      # Shrink System partition by 765MB [RAW]:
        Shrink Desired=765 Minimum=750
          # WinRE: 665MB, min 650MB
            # WinRE partition must have 320MB free (WinRE.wim is ~300MB in size)
          # Boot: 100MB
      
      # Create WinRE partition:
        Cre Par Pri Offset=1024 Size=665 Id=27
          # If it fails, remove Offset=1024
        Format Quick Fs=ntfs Label=WinRE
      
      # Create Boot partition:
        Cre Par Pri Size=100
        Format Quick Fs=ntfs Label=Boot
        Active
      
      # Verify:
        Lis Par
        Lis Vol
      

   
   
2. Configure boot partition:
   1. While booted to Windows in the VHD's VM:

      BCDboot C:\Windows /v
      

   2. From WinPE/WinRE:
      1. Boot the VHD's VM to WinPE via a Windows install ISO
      2. Open terminal via SHIFT+F10:

         BootRec /FixMBR && BootRec /FixBoot && BootRec /RebuildBCD
         

         /RebuildBCD may or may not find an OS, either is okay
      3. Reboot the VM
         
         
3. Configure WinRE partition via this answer:
   • #2: If VHD doesn't have WinRE at C:\Recovery or %WinDir%\System32\Recovery\, copy the host's WinRE.wim to the VHD's %WinDir%\System32\Recovery\
   • #3: Skip (WinRE partition creation)