CONFIG_XIP_KERNEL is not available for the default architecture x86.
Result is shown for architecture arm

Kernel Execute-In-Place from ROM


Linux Kernel Configuration
└─> Boot options
└─> Kernel Execute-In-Place from ROM

Execute-In-Place allows the kernel to run from non-volatile storage
directly addressable by the CPU, such as NOR flash. This saves RAM
space since the text section of the kernel is not loaded from flash
to RAM. Read-write sections, such as the data section and stack,
are still copied to RAM. The XIP kernel is not compressed since
it has to run directly from flash, so it will take more space to
store it. The flash address used to link the kernel object files,
and for storing it, is configuration dependent. Therefore, if you
say Y here, you must know the proper physical address where to
store the kernel image depending on your own flash memory usage.

Also note that the make target becomes "make xipImage" rather than
"make zImage" or "make Image". The final kernel binary to put in
ROM memory will be arch/arm/boot/xipImage.

If unsure, say N.