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Pawel Debski
Asked: 2021-03-20 11:11:47 +0800 CST

How to chainload winload.efi / exe from Grub2

  • 772

I have a nice and running LUbuntu being booted in EFI by Grub2.

Now I want to chainload Windows 10 from another partition that I copied-over from another disk to the local partition. I want to have it booted directly by winload.efi without intermediary MS-Windows bootmanager BCD hassle.

Here is my /etc-grub.d/40_custom menu:

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry "MS-Windows 10" --class windows --class os {
        insmod chain
        insmod ntfs
        search --no-floppy --set=root --fs-uuid 4E589F8E589F7405
        echo (${root})/Windows/System32/Boot
        ls (${root})/Windows/System32/Boot
        echo (${root})/Windows/System32/Boot/winload.efi
        chainloader /Windows/System32/Boot/winload.efi
}

Unfortunately when I select MS-Windows 10 menu option I get:

(hd0,gpt4)/Windows/System32/Boot
pl-PL/ winload.efi winload.exe winresume.efi winresume.exe
(hd0,gpt4)/Windows/System32/Boot/winload.efi
error: cannot load image.

Press any key to continue...

and Grub cycles.

I am pretty sure that winload.efi is there, since when I drop to Grub2 command line and manually do

insmod ntfs
ls (hd0,gpt4)/Windows/System32/Boot

the files are there.

I think that winload.efi needs some arguments like C:\Windows or something similar that Windows Boot Manager takes from BCD and passes to winload.

  1. What are the exact options to winload?
  2. How to make it load Windows?
dual-boot

0 Answers