Voici ce que contient mon fichier /etc/default/grub :
$ cat /etc/default/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="vconsole.keymap=fr rd.dm=0 $([ -x /usr/sbin/rhcrashkernel-param ] && /usr/sbin/rhcrashkernel-param || :) rd.md=0 rd.luks=0 vconsole.font=latarcyrheb-sun16 rd.lvm.lv=fedora_seraphim/root rd.lvm.lv=fedora_seraphim/swap rhgb quiet"
GRUB_DISABLE_RECOVERY="true"