CONFIG_ARCH_IXDP2X01 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_ARCH_IXDP2X01 (not configurable)

modulename: ixdp2x01.ko

configname: CONFIG_ARCH_IXDP2X01

Linux Kernel Configuration
└─>Intel IXP2400/2800 Implementation Options
└─>ARCH_IXDP2X01
In linux kernel since version 2.6.12  
source code: