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I have 3 partitions on the usb sticks. p1 is EFI partition, p2 is a grub boot partition, p3 is a fat32 partition contain content from windows10 installation dvd. I can boot from p1 and enter grub menu. I can boot from p3 and enter windows10 installer.

However, when I try to chainload the windows cdboot.efi from grub it fails.

When dropped into the console grub>. I did:

set root="hd0,msdos3"
chainloader /efi/microsoft/boot/cdboot.efi
boot

it raised:

error: cannot load image

if I chainload the cdboot_noprompt.efi and then boot It seems did not do anything at all. What is wrong?

I did set debug=all. Then during the chainload cmd, it said

Kernel signature verification passed.
chainloader.c:1047: linuxefi_secure_validate: 1
...

I cannot see any useful info from boot. I said:

sectiion 8 ".reloc" at ....
...
Discarding section
relocate_coff(): reloc_base ...
booting via entry point
entry_point returned -9223372036854775791
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4
  • Is there a /efi/boot/bootx64.efi or /efi/microsoft/boot/bootmgfw.efi for you to load like an installation?
    – Tom Yan
    Commented Oct 28, 2019 at 4:38
  • the content is from an installer image, so there is no bootmgfw.efi. The bootx64.efi is not for this yet.
    – Wang
    Commented Oct 28, 2019 at 10:18
  • not for this yet? what do you mean? I think it is the binary that get executed by the UEFI when you boot from p3.
    – Tom Yan
    Commented Oct 28, 2019 at 15:26
  • @Wang Two things to try: (1) have part_msdos.mod and fat.mod on p1 and do insmod part_msdos insmod fat commands before the chainloader command, (2) try chainloader (hd0,msdos3)/efi/microsoft/boot/cdboot.efi (and use cdboot_noprompt.efi instead). What does ls (hd0,msdos3)/ give from the interactive Grub prompt?
    – RolKau
    Commented Sep 23, 2020 at 8:54

1 Answer 1

Reset to default
-2

Make use of grub-mkconfig:

grub-mkconfig -o /boot/grub/grub.cfg

It will write your partitions properly.

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