CONFIG_ROCKHOPPER is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Support for Rockhopper baseboard

modulename: irq.ko

configname: CONFIG_ROCKHOPPER

Linux Kernel Configuration
└─>Support for Rockhopper baseboard
In linux kernel since version 2.6.12  
source code:
arch/mips/vr41xx/nec-cmbvr4133/irq.c