CONFIG_ARCH_AT91 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AT91/Microchip SoCs

configname: CONFIG_ARCH_AT91

Linux Kernel Configuration
└─>AT91/Microchip SoCs
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  


is selected by
CONFIG_VIDEO_ATMEL_XISC