Broken UEFI Dual boot : Debian 12 + encrypted Debian 11

[Yvan Masson <yvan@masson-informatique.fr>]

Hi list,

I have a laptop with two drive, historically installed with an encrypted 
Debian 11 booting in UEFI mode (done with Debian Installer).

I just installed Debian 12 without encryption in a small partition. 
Unfortunately, I can not boot Debian 11 anymore, grub-efi only shows the 
Debian 12 install.

Any help to make both install boot would greatly appreciated. Being able 
to boot Debian 11 only would also be great if the dual boot is not possible.

Below is a reworked `lsblk` output:

sda
|-sda1 -> a data partition
|-sda2 -> D12 /
`-sda3 -> D12 swap
sdb
|-sdb1 -> EFI partition
|-sdb2 -> D11 /boot
`-sdb3
  `-luks-73072c13-9ffa-4b03-b82b-91db0c063069
    |-crypt-root -> D11 /
    |-crypt-swap -> D11 swap
    `-crypt-home -> D11 /home


$ sudo tree /boot/efi/
/boot/efi/
└── EFI
    └── debian
        ├── BOOTX64.CSV
        ├── fbx64.efi
        ├── grub.cfg
        ├── grubx64.efi
        ├── mmx64.efi
        └── shimx64.efi


$ sudo efibootmgr
BootCurrent: 0000
Timeout: 0 seconds
BootOrder: 0000,0001
Boot0000* debian
Boot0001* UEFI: Flash


Regards,
Yvan

Attachment: OpenPGP_signature
Description: OpenPGP digital signature