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

Set number of CAMs to use to map low memory


Linux Kernel Configuration
└─>Advanced setup
└─>Set number of CAMs to use to map low memory
In linux kernel since version 2.6.30 (release Date: 2009-06-09)  
This option allows you to set the maximum number of CAM slots that
will be used to map low memory. There are a limited number of slots
available and even more limited number that will fit in the L1 MMU.
However, using more entries will allow mapping more low memory. This
can be useful in optimizing the layout of kernel virtual memory.

Say N here unless you know what you are doing.