CONFIG_32BIT is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Support 32-bit physical addressing through PMB

modulename: pmb.ko

and/or

div64.ko

and/or

ioremap.ko

and/or

scall32-o32.ko

configname: CONFIG_32BIT

Linux Kernel Configuration
└─>Memory management options
└─>Support 32-bit physical addressing through PMB
In linux kernel since version 2.6.14 (release Date: 2005-10-27)  
If you say Y here, physical addressing will be extended to
32-bits through the SH-4A PMB. If this is not set, legacy
29-bit physical addressing will be used.