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

Set custom kernel base address


Linux Kernel Configuration
└─>Advanced setup
└─>Set custom kernel base address
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
This option allows you to set the kernel virtual address at which
the kernel will be loaded. Normally this should match PAGE_OFFSET
however there are times (like kdump) that one might not want them
to be the same.

Say N here unless you know what you are doing.