CONFIG_ARCH_MX3 is not available for the default architecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_MX3.
Result is shown for kernelversion 5.6.17


configname: CONFIG_ARCH_MX3

MXC/iMX Base Type
└─> MX3-based

This enables support for systems based on the Freescale i.MX3 family