CONFIG_MACH_SMDK is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_MACH_SMDK (not configurable)

modulename: common-smdk.ko

configname: CONFIG_MACH_SMDK

Linux Kernel Configuration
└─>S3C24XX Implementations
└─>MACH_SMDK
In linux kernel since version 2.6.17 (release Date: 2006-06-17)  
Common machine code for SMDK2410 and SMDK2440

source code:

is depended by
CONFIG_MACH_SMDK2413