CONFIG_M68040 is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

68040 support

configname: CONFIG_M68040

Linux Kernel Configuration
└─>68040 support
In linux kernel since version 2.6.12  
If you anticipate running this kernel on a computer with a MC68LC040
or MC68040 processor, say Y. Otherwise, say N. Note that an
MC68EC040 will not work, as it does not include an MMU (Memory
Management Unit).

depends
NOT CONFIG_MMU_SUN3

is depended by
CONFIG_VIRT