CONFIG_MACH_E800 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Toshiba e800

configname: CONFIG_MACH_E800

Select target board
└─>Toshiba e800
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
Say Y here if you intend to run this kernel on a Toshiba
e800 family PDA.

depends
CONFIG_ARCH_PXA_ESERIES |
NOT | CONFIG_ARCH_PXA_V7