CONFIG_ETRAX_RS485_DISABLE_RECEIVER is not available for thedefaultarchitecture x86.
Result is shown for architecture cris
default or selected kernelversion does not have config value CONFIG_ETRAX_RS485_DISABLE_RECEIVER.
Result is shown for kernelversion 6.7-rc3

Disable serial receiver

configname: CONFIG_ETRAX_RS485_DISABLE_RECEIVER

Linux Kernel Configuration
└─>Disable serial receiver
In linux kernel since version 2.6.12  
It is necessary to disable the serial receiver to avoid serial
loopback. Not all products are able to do this in software only.