Generally the ROM if it exists is very minimal and contains just enough to load the next stage of the boot process. Some devices can boot directly from flash and generally you want the ability to update the boot chain because these things are never perfect on release.
I’ve been using an Orange Pi and the problem I ran into is that there seems to be no way to disable booting from SD card if one is present. Some people online were reporting it would fail to boot if the SD card was just data. I’d love to make it always boot from its MMC (with jumper pins or something to fall back to SD when needed).
I thought these things had some sort of boot ROM that fixed what peripherals and in what order they are able to boot from.
Generally the ROM if it exists is very minimal and contains just enough to load the next stage of the boot process. Some devices can boot directly from flash and generally you want the ability to update the boot chain because these things are never perfect on release.
I’ve been using an Orange Pi and the problem I ran into is that there seems to be no way to disable booting from SD card if one is present. Some people online were reporting it would fail to boot if the SD card was just data. I’d love to make it always boot from its MMC (with jumper pins or something to fall back to SD when needed).