CONFIG_MACH_MX21 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
i.MX21 support
modulename: clock_imx21.ko
configname: CONFIG_MACH_MX21
CPUs:
└─>i.MX21 support
In linux kernel since version 2.6.30 (release Date: 2009-06-09)
This enables support for Freescale's MX2 based i.MX21 processor.