+bootcmd (string)
+ Allows overwriting of the boot command used by U-Boot on startup. If
+ present, U-Boot uses this command instead. Note that this feature can
+ work even if loading the environment is disabled, e.g. for security
+ reasons. See also bootsecure.
+
+bootdelay (int)
+ This allows selecting of the U-Boot bootdelay, to control whether U-Boot
+ waits on boot or for how long. This allows this option to be configured
+ by the build system or by a previous-stage binary. For example, if the
+ images is being packed for testing or a user holds down a button, it may
+ allow a delay, but disable it for production.
+
+u-boot,boot-led (string)
+u-boot,error-led (string)
+ This is used to specify the label for an LED to indicate an error and
+ a successful boot, on supported hardware.
+
+bootsecure (int)
+ Indicates that U-Boot should use secure_boot_cmd() to run commands,
+ rather than the normal CLI. This can be used in production images, to
+ restrict the amount of parsing done or the options available, to cut
+ back on the available surface for security attacks.
+