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

Support for the traditional ATAGS boot data passing

modulename: atags_parse.ko

configname: CONFIG_ATAGS

Linux Kernel Configuration
└─>Boot options
└─>Support for the traditional ATAGS boot data passing
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This is the traditional way of passing data to the kernel at boot
time. If you are solely relying on the flattened device tree (or
the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
to remove ATAGS support from your kernel binary.

source code:
is selected by
CONFIG_ARCH_EP93XX
CONFIG_ARCH_FOOTBRIDGE
CONFIG_ARCH_IOP32X
CONFIG_ARCH_DOVE
CONFIG_ARCH_RPC
CONFIG_ARCH_SA1100
CONFIG_ARCH_S3C24XX
CONFIG_ARCH_OMAP1
CONFIG_MACH_TAVOREVB
CONFIG_MACH_TTC_DKB
CONFIG_MACH_SMDK6400
CONFIG_MACH_ANW6410
CONFIG_MACH_MINI6410
CONFIG_MACH_REAL6410
CONFIG_MACH_SMDK6410
CONFIG_MACH_NCP
CONFIG_MACH_HMT
CONFIG_MACH_SMARTQ5
CONFIG_MACH_SMARTQ7
CONFIG_MACH_WLF_CRAGG_6410
CONFIG_ARCH_LUBBOCK
CONFIG_MACH_MAINSTONE
CONFIG_MACH_ZYLONITE
CONFIG_MACH_ZYLONITE300
CONFIG_MACH_ZYLONITE320
CONFIG_MACH_LITTLETON
CONFIG_MACH_TAVOREVB
CONFIG_MACH_SAAR
CONFIG_ARCH_PXA_IDP
CONFIG_ARCH_VIPER
CONFIG_MACH_ARCOM_ZEUS
CONFIG_MACH_BALLOON3
CONFIG_MACH_CSB726
CONFIG_MACH_CM_X300
CONFIG_MACH_CAPC7117
CONFIG_ARCH_GUMSTIX
CONFIG_MACH_XCEP
CONFIG_MACH_TRIZEPS4
CONFIG_MACH_TRIZEPS4WL
CONFIG_MACH_LOGICPD_PXA270
CONFIG_MACH_PCM027
CONFIG_MACH_COLIBRI
CONFIG_MACH_COLIBRI_PXA270_INCOME
CONFIG_MACH_COLIBRI300
CONFIG_MACH_COLIBRI320
CONFIG_MACH_VPAC270
CONFIG_MACH_H4700
CONFIG_MACH_H5000
CONFIG_MACH_HIMALAYA
CONFIG_MACH_MAGICIAN
CONFIG_MACH_MIOA701
CONFIG_PXA_EZX
CONFIG_MACH_MP900C
CONFIG_MACH_PALMTE2
CONFIG_MACH_PALMTC
CONFIG_MACH_PALMT5
CONFIG_MACH_PALMTX
CONFIG_MACH_PALMZ72
CONFIG_MACH_PALMLD
CONFIG_MACH_CENTRO
CONFIG_MACH_TREO680
CONFIG_PXA_SHARPSL
CONFIG_MACH_POODLE
CONFIG_MACH_CORGI
CONFIG_MACH_SHEPHERD
CONFIG_MACH_HUSKY
CONFIG_MACH_AKITA
CONFIG_MACH_SPITZ
CONFIG_MACH_BORZOI
CONFIG_MACH_TOSA
CONFIG_TOSA_BT
CONFIG_MACH_ICONTROL
CONFIG_ARCH_PXA_ESERIES
CONFIG_MACH_ZIPIT2

is depended by
CONFIG_ARCH_S3C24XX