CONFIG_ARCH_IXP2000 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
IXP2400/2800-based
configname: CONFIG_ARCH_IXP2000
ARM system type
└─>IXP2400/2800-based
In linux kernel since version 2.6.12
Support for Intel's IXP2400/2800 (XScale) family of processors.