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

PXA2xx/PXA3xx-based

configname: CONFIG_ARCH_PXA

ARM system type
└─>PXA2xx/PXA3xx-based
In linux kernel since version 2.6.12  
Support for Intel/Marvell's PXA2xx/PXA3xx processor line.


depends
CONFIG_MMU

is selected by
CONFIG_DEBUG_PXA_UART1
CONFIG_MACH_PXA25X_DT
CONFIG_MACH_PXA27X_DT
CONFIG_MACH_PXA3XX_DT
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_ARMCORE
CONFIG_MACH_EM_X270
CONFIG_MACH_EXEDA
CONFIG_MACH_CM_X300
CONFIG_MACH_CAPC7117
CONFIG_ARCH_GUMSTIX
CONFIG_MACH_INTELMOTE2
CONFIG_MACH_STARGATE2
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
CONFIG_PXA25x
CONFIG_PXA27x
CONFIG_CPU_PXA26x
CONFIG_PXA3xx
CONFIG_CPU_PXA300
CONFIG_CPU_PXA310
CONFIG_CPU_PXA320
CONFIG_CPU_PXA930
CONFIG_CPU_PXA935
CONFIG_PXA_SHARP_C7xx
CONFIG_PXA_SHARP_Cxx00
CONFIG_SHARPSL_PM
CONFIG_SHARPSL_PM_MAX1111
CONFIG_MMP_PDMA
CONFIG_PXA_DMA
CONFIG_PHY_PXA_USB