Default EFI bootloader isn't installed leaving system unbootable

[Shantur Rathore]

Hi,

I am using Curtin via MAAS to setup ARM based systems running u-boot firmware.
Current state of u-boot doesn't support EFI variables and hence needs grub update_nvram: false setting.

There is not EFI Boot entry created for the newly installed OS and there is no default bootloader EFI/BOOT/BootXXXX.efi so there is way for firmware to know which bootloader to load.

grub-install also has --removable option which forces grub to also install default bootloader in EFI/BOOT/BootXXXX.efi but curtin doesn't use this.
This bootloader is also needed when NVRAM is cleared and system needs to boot. Some systems don't have support to select EFI files to boot and they are rendered unbootable.

As a fix, curtin could

1. Always setup a default bootloader by adding --removable flag here https://github.com/canonical/curtin/blob/master/curtin/commands/install_grub.py#L340

2. Setup a default bootloader when update_nvram is false.

Thanks

[Shantur Rathore (rathore4u)]

Update

2. Setup a default bootloader when update_nvram is false by adding --removable flag