CONFIG_DEFAULT_UIMAGE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
CONFIG_DEFAULT_UIMAGE (not configurable)
configname: CONFIG_DEFAULT_UIMAGE
Linux Kernel Configuration
└─>DEFAULT_UIMAGE
In linux kernel since version 2.6.16 (release Date: 2006-03-19)
Used to allow a board to specify it wants a uImage built by default