I finally had to use this script.
I think it changed the /etc/mkinitcpio.conf + /etc/grub/default/grub file to add the kernel config.

But after the run of this script I had an error with ni hibernation drive drive found at the startup of the laptop.
This was because of an error in the grub file. there is a "resume" parameter to insert.
This parameter was present twice. The first occurence was ok, but the 2nd was empty.
I just had to delete de empty one and to run the update-grub command.
After that it was working fine.

Comment hiberner sur une partition chiffrée