CONFIG_ETRAX_SERIAL_PORT3_DMA2_OUT is not available for thedefaultarchitecture x86.
Result is shown for architecture cris
default or selected kernelversion does not have config value CONFIG_ETRAX_SERIAL_PORT3_DMA2_OUT.
Result is shown for kernelversion 6.2.5

Ser3 uses DMA2 for output


Ser3 DMA out channel
└─>Ser3 uses DMA2 for output
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
Enables the DMA2 output channel for ser3 (ttyS3).
If you do not enable DMA, an interrupt for each character will be
used when transmitting data.
Normally you want to use DMA, unless you use the DMA channel for
something else.