GRUB2 config make

If you change grub parameters (example /etc/default/grub), you need to make GRUB2 configurations in /boot.

grub2-mkconfig -o /boot/grub2/grub.cfg

If your grub installed with EFI, you may need some configurations. Example for CentOS:

grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
rm -f /boot/grub2/grubenv
ln -s ../efi/EFI/centos/grubenv /boot/grub2/grubenv
grublinux
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