CONFIG_MACH_AT91SAM_DT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
Atmel AT91SAM Evaluation Kits with device-tree support
modulename: board-dt.ko
configname: CONFIG_MACH_AT91SAM_DT
Linux Kernel Configuration
└─>Atmel AT91 System-on-Chip
└─>Atmel AT91SAM Evaluation Kits with device-tree support
In linux kernel since version 3.3 (release Date: 2012-03-18)
Select this if you want to experiment device-tree with
an Atmel Evaluation Kit.
an Atmel Evaluation Kit.