CONFIG_KEXEC_FILE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

kexec file based system call

modulename: kexec-purgatory.ko

and/or

kexec-bzimage64.ko

and/or

kexec_file.ko

configname: CONFIG_KEXEC_FILE

Linux Kernel Configuration
└─>Kernel options
└─>kexec file based system call
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This is a new version of the kexec system call. This call is
file based and takes in file descriptors as system call arguments
for kernel and initramfs as opposed to a list of segments as is the
case for the older kexec call.