I have read the datasheet of Altera's new HPS. It shows a chart where it shows: Boot ROM -> Preloader -> Bootloader -> OS
I am wondering, why do we need a "pre-loader" and than the "bootloader" and than the OS? I have already read questions concerning bootloaders on this great forum and have some idea of what it is supposed to do. I understand that there are different type of bootloaders and their purpose is not the same in every case.
What I am confused about is this thing that we describe as preloader, why is it there?