Why is Chainloading useful on Chromebooks?

What is Chainloading again?

For those who didn't read the Anchorboot and the future of Armor article. Chainloading is when things are well chainloaded for example look at the RW_LEAGCY payload chainload

Chrome OS Firmware > CTRL + L Press > RW_LEAGCY Payload (Leagcy "Firmware")

An Example of Chainloading

Well chainloading is used in the RW_LEAGCY "firmware" you can install on x86_64 chromebooks RW_Leagcy shouldn't be mistaken for firmware because this is just an payload because if it was said firmware would need to be flashed and in order for firmware to be flashed write protect needs to be removed you

"Well I flashed Leagcy firmware on my chromebook" well in wasn't flashed it just installed a payload that get's chainloaded when you press CTRL + L. If you install firmware it would delete the Chrome OS firmware (Recovery and Dev Mode Screens) like the Full rom firmware

How is Chainloading useful on ARM chromebooks

Well if you do not know on the Chrome OS firmware if you enable Dev USB Boot, and unsigned boot (Which is just you being able to self sign your images, it doesn't let you enable you to boot unsigned images) you can use U-Boot to boot self signed images.

But you can build your own U-Boot to make it to where you don't have to sign it, and remove the need for Chrome OS kernel partitions and then when your build your own version of U-Boot you can chainload it instead of Chrome OS' U-Boot

Which means you can boot off any USB drive without any modifcation which is an step closer to Armor's goal getting to boot other OS' on ARM chromebooks