CONFIG_ROM is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

Specify ROM linker regions

modulename: romvec.ko

configname: CONFIG_ROM

Linux Kernel Configuration
└─>Specify ROM linker regions
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  
Define a ROM region for the linker script. This creates a kernel
that can be stored in flash, with possibly the text, and data
regions being copied out to RAM at startup.

source code: