Native UART communication

I wanted to enable native uart communication on the odrive board. I can configure the uart protocol as native in the tup configfile. Then the Tupfile.lua parses the config and compiles with the UART_PROTOCOL_NATIVE flag. However, this flag is never used on the current master branch, so setting it does not do anything. Why is that? How can I enable it? Or is it not supported anymore?

Any help is appreciated, thanks!