CONFIG_IRQ_GT641XX is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_IRQ_GT641XX (not configurable)

modulename: irq-gt641xx.ko

configname: CONFIG_IRQ_GT641XX

Linux Kernel Configuration
└─>IRQ_GT641XX
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
source code:
arch/mips/kernel/irq-gt641xx.c
is depended by
CONFIG_MIPS_COBALT