CONFIG_X86_32 is not available for thedefaultarchitecture x86.
Result is shown for architecture i386

CONFIG_X86_32 (not configurable)

modulename: amd.ko

configname: CONFIG_X86_32

Linux Kernel Configuration
└─>X86_32
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
This is Linux's home port. Linux was originally native to the Intel
386, and runs on all the later x86 processors including the Intel
486, 586, Pentiums, and various instruction-set-compatible chips by
AMD, Cyrix, and others.

source code: