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

shockwaveriderz · 12 Aug 2019

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:

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

dictum · 12 Aug 2019

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.

shockwaveriderz · 13 Aug 2019

dictum said:

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.

NavyLCDR · 13 Aug 2019

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

dictum · 13 Aug 2019

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.

NavyLCDR · 13 Aug 2019

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!

dictum · 13 Aug 2019

NavyLCDR said:

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.

NavyLCDR · 13 Aug 2019

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

dictum · 13 Aug 2019

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.

NavyLCDR · 13 Aug 2019

dictum said:

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.