CONFIG_Q40 is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

Q40/Q60 support

configname: CONFIG_Q40

Linux/68k Kernel Configuration
└─>Platform dependent setup
└─>Q40/Q60 support
In linux kernel since version 2.6.12  
The Q40 is a Motorola 68040-based successor to the Sinclair QL
manufactured in Germany. There is an official Q40 home page at
<http://www.q40.de/>. This option enables support for the Q40 and
Q60. Select your CPU below. For 68LC060 don't forget to enable FPU
emulation.

selects

CONFIG_MMU_MOTOROLA
CONFIG_LEGACY_TIMER_TICK

depends
NOT CONFIG_MMU_SUN3 or CONFIG_M68KCLASSIC or &

is selected by
CONFIG_NE2000
CONFIG_FB_Q40