CONFIG_XEN_DOM0 is not available for the selected architecture x86.
Result is shown for architecture arm

CONFIG_XEN_DOM0 (not configurable)

modulename: vga.ko

configname: CONFIG_XEN_DOM0

Linux Kernel Configuration
└─>Kernel Features
└─>XEN_DOM0
In linux kernel since version 2.6.37 (release Date: 2011-01-04)
source code:
arch/x86/xen/vga.c
depends
CONFIG_XEN