Comment 7 for bug 1948895

@Brian

There are two issues here. Please help to take a look at these two issues.

1. Please see comment#3
2. grub.cfg in the EFI partition won't get updated when we execute update-grub.
In the IoT image, the real grub.cfg is located at the EFI partition.

In stock Ubuntu, the grub.cfg in the EFI partition is
---
# cat /boot/efi/EFI/ubuntu/grub.cfg
search.fs_uuid XXXXXXXXX root hd0,gpt2
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg
---
The real grub.cfg (/boot/grub/grub.cfg) is in the writable (rootfs) partition.
And, this one is the one which will get updated by update-grub.