CONFIG_GENERIC_TBSYNC is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_GENERIC_TBSYNC (not configurable)

modulename: smp-tbsync.ko

configname: CONFIG_GENERIC_TBSYNC

Linux/PowerPC Kernel Configuration
└─>GENERIC_TBSYNC
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
arch/powerpc/kernel/smp-tbsync.c