+config ARM_BOOT_HOOK_RMR
+ bool
+ depends on ARM64
+ default y
+ select ENABLE_ARM_SOC_BOOT0_HOOK
+ ---help---
+ Insert some ARM32 code at the very beginning of the U-Boot binary
+ which uses an RMR register write to bring the core into AArch64 mode.
+ The very first instruction acts as a switch, since it's carefully
+ chosen to be a NOP in one mode and a branch in the other, so the
+ code would only be executed if not already in AArch64.
+ This allows both the SPL and the U-Boot proper to be entered in
+ either mode and switch to AArch64 if needed.
+