Finally ...
4a) Verify that it's broken after rollback of grub:
``` $ sudo eatmydata apt install ~i~ngrub/focal -V [...] The following packages will be DOWNGRADED: grub-common (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4) grub-efi-arm64 (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4) grub-efi-arm64-bin (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4) grub-efi-arm64-signed (1.142.7+2.04-1ubuntu26.5 => 1.142.6+2.04-1ubuntu26.4) grub2-common (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4) [...] ```
Produces
``` BdsDxe: loading Boot0007 "ubuntu" from HD(15,GPT,6849AD57-3BC8-45BF-8BBD-33D9B49A4CCC,0x800,0x31801)/\EFI\ubuntu\shimaa64.efi BdsDxe: starting Boot0007 "ubuntu" from HD(15,GPT,6849AD57-3BC8-45BF-8BBD-33D9B49A4CCC,0x800,0x31801)/\EFI\ubuntu\shimaa64.efi error: no suitable video mode found. error: cannot load image.
Failed to boot both default and fallback entries.
Press any key to continue... ```
As expected.
Finally ...
4a) Verify that it's broken after rollback of grub:
``` efi-arm64- bin (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4) efi-arm64- signed (1.142. 7+2.04- 1ubuntu26. 5 => 1.142.6+ 2.04-1ubuntu26. 4)
$ sudo eatmydata apt install ~i~ngrub/focal -V
[...]
The following packages will be DOWNGRADED:
grub-common (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4)
grub-efi-arm64 (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4)
grub-
grub-
grub2-common (2.04-1ubuntu26.5 => 2.04-1ubuntu26.4)
[...]
```
Produces
``` 6849AD57- 3BC8-45BF- 8BBD-33D9B49A4C CC,0x800, 0x31801) /\EFI\ubuntu\ shimaa64. efi 6849AD57- 3BC8-45BF- 8BBD-33D9B49A4C CC,0x800, 0x31801) /\EFI\ubuntu\ shimaa64. efi
BdsDxe: loading Boot0007 "ubuntu" from HD(15,GPT,
BdsDxe: starting Boot0007 "ubuntu" from HD(15,GPT,
error: no suitable video mode found.
error: cannot load image.
Failed to boot both default and fallback entries.
Press any key to continue...
```
As expected.