How does SLM use RTT?

How does the slm routine of ncs1.9.1 use rtt log. Below is my configuration:

Fullscreen
1
2
3
4
5
6
7
8
CONFIG_LOG=y
CONFIG_LOG_DEFAULT_LEVEL=3
CONFIG_USE_SEGGER_RTT=y
CONFIG_RTT_CONSOLE=y
CONFIG_LOG_BACKEND_RTT=y
CONFIG_UART_CONSOLE=n
CONFIG_LOG_BACKEND_UART=n
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

With the default configuration, there should be RTT log output, but nothing happens in the actual window.