Grub2 chainload other gpt partition on stick

Question

I'm searching for a way to chainload another bootable partition from my USB stick, where a windows10.iso contents is resided.

My partition layout in GPT looks like the following:

- bios_grub raw (for legacy boot)
- EFI Fat32 (UEFI directory)
- WIN Fat32 (windows 10 iso contents)
- BOOT Fat32 (grub2 config and iso images for loopback loading)

What I try is to get from the UEFI-Grub-Menu to start windows installation by pointing the chainloader to the other partition, my approach:

menuentry "Windows 10 Install" {
  search --set=root --fs-uuid A1C7-8413 --hint hd0,gpt3
  set prefix=($root)
  chainloader +1
}

But the bootloader claims, that a wrong EFI path is set.

What am I doing wrong? Any hints welcome.

Answer 1

Got it.

menuentry "Windows 10 Install" {
  search --set=root --fs-uuid DEAD-BEEF --hint hd0,gpt3
  chainloader ($root)/efi/microsoft/boot/cdboot.efi
}