Grub
GRUB2 is the latest version of GNU GRUB, the GRand Unified Bootloader. A bootloader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel.
installing grub on slackware
grub-install /dev/XXX grub-mkconfig -o /boot/grub/grub.cfg
after updating kernel dont forget to update your initrd then run
grub-mkconfig -o /boot/grub/grub.cfg