CONFIG_ETRAX_SYNCHRONOUS_SERIAL is not available for thedefaultarchitecture x86.
Result is shown for architecture cris
Synchronous serial-port support
modulename: sync_serial.ko
configname: CONFIG_ETRAX_SYNCHRONOUS_SERIAL
Linux Kernel Configuration
└─>Drivers for built-in interfaces
└─>Synchronous serial-port support
In linux kernel since version 2.6.13 (release Date: 2005-08-28)
Select this to enable the synchronous serial port driver.