Bug#925591: grub-install fails on raid1+efi setup

[Giorgio Bonfiglio]

Just stumbled upon this after converting a system from Legacy Boot to 
UEFI (boot into live, sort out partitions, remove grub-pc, install 
grub-efi, reboot, reconfigure bios).

After running `apt install grub-efi` and rebooting, although the former 
fails with the error mentioned above, debian correctly shows up in my 
boot menu and I can boot from it.

This is the partition tree on my boot devices:

nvme0n1         259:0    0 119.2G  0 disk
├─nvme0n1p1     259:2    0   512M  0 part
│ └─md10          9:10   0   512M  0 raid1 /boot/efi
├─nvme0n1p2     259:3    0   512M  0 part
│ └─md11          9:11   0   511M  0 raid1 /boot
└─nvme0n1p3     259:4    0 118.2G  0 part
   └─md12          9:12   0 118.2G  0 raid1
     └─nvme-root 253:0    0    25G  0 lvm   /
nvme1n1         259:1    0 119.2G  0 disk
├─nvme1n1p1     259:5    0   512M  0 part
│ └─md10          9:10   0   512M  0 raid1 /boot/efi
├─nvme1n1p2     259:6    0   512M  0 part
│ └─md11          9:11   0   511M  0 raid1 /boot
└─nvme1n1p3     259:7    0 118.2G  0 part
   └─md12          9:12   0 118.2G  0 raid1
     └─nvme-root 253:0    0    25G  0 lvm   /

I ended up cleaning UEFI's config up and adding the second drive to the 
boot sequence with:

efibootmgr -c -d /dev/nvme0n1 -p 1 -L "Debian nvme0n1" -l 
\\EFI\\debian\\grubx64.efi
efibootmgr -c -d /dev/nvme1n1 -p 1 -L "Debian nvme1n1" -l 
\\EFI\\debian\\grubx64.efi

Although everything seems to be working as it should, it would be good 
if `grub2-install` could handle this to prevent unexpected 
errors/failures during installation, upgrades or even just minor updates.

Firmware info requested above (although I'm fairly sure this is not 
firmware-specific):

     Vendor: American Megatrends Inc.
     Version: 1.3
     Release Date: 11/25/2020
     Address: 0xF0000
     Runtime Size: 64 kB
     ROM Size: 32 MB
     [...]
     BIOS Revision: 5.14

-- 
Giorgio Bonfiglio

www: grg.pw
email: me at grg.pw