Grub2-configuration:

menuentry "Windows 10" --class windows --class os { # Insert modules needed in order to access the iso-file insmod part_gpt #insmod part_msdos insmod ntfs #insmod ext2 # Insert module needed in order to find partition insmod search_fs_uuid # Set UUID of partition with the iso-image # and let grub2 find the partition # (save it's identifier to the variable $root) set uuid="XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX" search --no-floppy --set=root --fs-uuid $uuid # Mount the iso image by addressing it with (partition)/path set iso=/images/Win10_English_x64.iso loopback loop ($root)$iso # boot (chain-load) the image using the cdboot.efi file located # on the win10-image chainloader (loop)/efi/microsoft/boot/cdboot.efi }

Instructions:

Replace XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX with the UUID of the partition, that holds the Windows 10 image.

insmod part_gpt: This module is needed, if the Win10-ISO-Image lies on a drive with a GPT-partitiontable.

insmod part_msdos: Choose this one over insmod part_gpt, if the image lies on a drive with DOS-partitiontable.

insmod ntfs: This module is needed, if the Win10-ISO-Image lies a NTFS-partition.

insmod ext2: Replace insmod ntfs with insmod ext2, when the image lies on a ext2/ext3 or ext4 partition.