CONFIG_IRQ_TXX9 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_IRQ_TXX9 (not configurable)

modulename: irq_txx9.ko

configname: CONFIG_IRQ_TXX9

Linux/MIPS Kernel Configuration
└─>IRQ_TXX9
In linux kernel since version 2.6.23 (release Date: 2007-10-09)  
source code:
arch/mips/kernel/irq_txx9.c