default or selected kernelversion does not have config value CONFIG_KEXEC_ELF.
Result is shown for kernelversion 6.9.9

CONFIG_KEXEC_ELF (not configurable)

modulename: kexec_elf.ko

configname: CONFIG_KEXEC_ELF

Linux Kernel Configuration
└─>General architecture-dependent options
└─>KEXEC_ELF
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
source code:
kernel/kexec_elf.c