IA32 Emulation

modulename: ia32entry.ko

configname: CONFIG_IA32_EMULATION

Linux Kernel Configuration
└─>Executable file formats / Emulations
└─>IA32 Emulation
In linux kernel since version 2.6.12  
Include code to run 32-bit programs under a 64-bit kernel. You should likely
turn this on, unless you're 100% sure that you don't have any 32-bit programs
left.

source code:
is selected by
CONFIG_COMPAT_32