This kexec-tools package was built from kexec-tools git repository at . Installing this package also installs two init scripts under /etc/init.d - kexec-load and kexec. On sysvinit syustems, kexec-load is called upon reboot to load a new kexec kernel if kexec is enabled in /etc/default/kexec. kexec script is called just before reboot script. It checks if kexec is enabled and a kexec'able kernel is loaded. If yes, it kexecs a new kernel instead of reboot. As a result, kexec is automatically enabled upon installation of kexec-tools package if kexec is enabled in /etc/default/kexec through debconf option. "reboot" command with ystemd will by default do a cold reboot. To kexec a new kernel with systemd, use "systemctl kexec".