CONFIG_ARCH_MX3 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
MX3-based
configname: CONFIG_ARCH_MX3
MXC/iMX System Type
└─>MX3-based
In linux kernel since version 2.6.23 (release Date: 2007-10-09)
This enables support for systems based on the Freescale i.MX3 family