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

Set custom page offset address

configname: CONFIG_PAGE_OFFSET_BOOL

Linux Kernel Configuration
└─>Advanced setup
└─>Set custom page offset address
In linux kernel since version 2.6.26 (release Date: 2008-07-13)  
This option allows you to set the kernel virtual address at which
the kernel will map low memory. This can be useful in optimizing
the virtual memory layout of the system.

Say N here unless you know what you are doing.