CONFIG_MACH_MX21ADS is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
MX21ADS platform
modulename: mx21ads.ko
configname: CONFIG_MACH_MX21ADS
Linux Kernel Configuration
└─>MX21ADS platform
In linux kernel since version 2.6.31 (release Date: 2009-09-09)
Include support for MX21ADS platform. This includes specific
configurations for the board and its peripherals.
configurations for the board and its peripherals.