Available options are:
+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.
+
u-boot,efi-partition-entries-offset (int)
If present, this provides an offset (in bytes, from the start of a
device) that should be skipped over before the partition entries.
This setting will override any values configured via Kconfig.
+kernel-offset (int)
+ This allows setting the 'kernaddr' environment variable, used to select
+ the address to load the kernel. It is useful for systems that use U-Boot
+ to flash a device, so the scripts that do this know where to put the
+ kernel to be flashed.
+
+load-environment (int)
+ Allows control over whether U-Boot loads its environment after
+ relocation (0=no, 1 or not present=yes).
+
u-boot,mmc-env-offset (int)
u-boot,mmc-env-offset-redundant (int)
If present, the values of the 'u-boot,mmc-env-offset' and/or
precedence. In that case, only if the partition is not found,
mmc-env-offset* will be tried.
+u-boot,no-apm-finalize (bool)
+ For x86 devices running on coreboot, this tells U-Boot not to lock
+ down the Intel Management Engine (ME) registers. This allows U-Boot to
+ access the hardware more fully for platforms that need it.
+
u-boot,no-keyboard (bool)
Tells U-Boot not to expect an attached keyboard with a VGA console.
+rootdisk-offset (int)
+ This allows setting the 'rootdisk' environment variable, used to select
+ the address to load the rootdisk. It is useful for systems that use
+ U-Boot to flash a device, so the scripts that do this know where to put
+ the root disk to be flashed.
+
silent-console (int)
If present and non-zero, the console is silenced by default on boot.