CONFIG_SPARC32 is not available for thedefaultarchitecture x86.
Result is shown for architecture sparc

CONFIG_SPARC32 (not configurable)

modulename: atomic32.ko

and/or

srmmu.ko

and/or

srmmu_access.ko

and/or

hypersparc.ko

and/or

leon_mm.ko

and/or

entry.ko

and/or

etrap_32.ko

and/or

rtrap_32.ko

and/or

sun4m_irq.ko

and/or

ioport.ko

and/or

systbls_32.ko

and/or

windows.ko

and/or

devices.ko

and/or

leon_kernel.ko

and/or

leon_pmc.ko

configname: CONFIG_SPARC32

Linux Kernel Configuration
└─>SPARC32
In linux kernel since version 2.6.12  
source code:
arch/sparc/lib/