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

Export atags in procfs

modulename: atags_proc.ko

configname: CONFIG_ATAGS_PROC

Linux Kernel Configuration
└─>Boot options
└─>Export atags in procfs
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
Should the atags used to boot the kernel be exported in an "atags"
file in procfs. Useful with kexec.

source code: