Raspbian, the default operating system for the Raspberry Pi, comes with a configuration script that’s called raspi-config. You can set all kind of options with that script, amongst others the way you want the system to reboot. This raspi-config script is not available when you download the new PIXEL version of Raspbian that is meant to install on other machines (i.e. old laptops to revive them).
I wrote a script to be able to select the way I want to reboot the non-Raspberry Pi machine.(an old ASUS Eee PC 900) I installed the Raspbian PIXEL operating system on. You can find the code here on GitHub.