u-boot/doc/device-tree-bindings/bootmeth.txt

U-Boot standard boot methods (bootmeth)
======================================

This provides methods (called bootmeths) for locating bootflows on a boot
device (bootdev). These are normally created as children of the bootstd device.

Required properties:

compatible:
   "u-boot,extlinux" - distro boot from a block device
   "u-boot,extlinux-pxe" - distro boot from a network device
   "u-boot,distro-efi" - EFI boot from an .efi file
   "u-boot,efi-bootmgr" - EFI boot using boot manager (bootmgr)


Example:

	bootstd {
		compatible = "u-boot,boot-std";

		filename-prefixes = "/", "/boot/";
		bootdev-order = "mmc2", "mmc1";

		extlinux {
			compatible = "u-boot,extlinux";
		};

		efi {
			compatible = "u-boot,distro-efi";
		};
	};