grub doesn't control anything, it transfers control to the OS and is never contacted or heard from again. More concretely, in the case of Linux, the init task (

grub doesn't control anything, it transfers control to the OS and is never contacted or heard from again. More concretely, in the case of Linux, the init task (first task and parent of every other task) function has a "tail" call to cpu_idle which never turns. http://lxr.free-electrons.com/source/init/main.c?a=arm#L359 http://lxr.free-electrons.com/source/init/main.c?a=arm#L359