I thought uBoot was more or less the standard way of booting embedded Linux? Is it really worth bringing the entire UEFI environment, which is basically a mini OS, to such devices? Embedded devices are often designed to handle power loss or even be unplugged by users, so the boot up process is generally as lean as possible.
New Android devices all use a UEFI bootloader: https://source.android.com/docs/core/architecture/bootloader...
The grub EFI shim is signed, but does or doesn't verify kernel image and initrd and module (and IDK optionally drive and CPU and RAM hw) signatures?
mokutil does module signature key enrollment. Kernel modules must be signed with a key enrolled in the BIOS otherwise they won't be loaded.
To implement SecureBoot without UEFI would be to develop an alternate bootloader verification system.
But what does grub or uboot or p-boot do after the signed grub shim is verified?
