Boot Loader

Grub 1

Change the boot menu (and kernel parameters) in /boot/grub/grub.cfg, then run command

update-grub

Reinstallation of boot loader in the MBR can be forced by:

grub-install --recheck /dev/sda

Change kernel parameters in /etc/default/grub, then run command update-grub.¹⁾ Verify after reboot with:

cat /proc/cmdline

¹⁾

Which is a stub for: grub2-mkconfig -o /boot/grub/grub.cfg.