This option is enabled by default for U-Boot.
+menuconfig EXPERT
+ bool "Configure standard U-Boot features (expert users)"
+ help
+ This option allows certain base U-Boot options and settings
+ to be disabled or tweaked. This is for specialized
+ environments which can tolerate a "non-standard" U-Boot.
+ Only use this if you really know what you are doing.
+
endmenu # General setup
menu "Boot images"