Zephyr logger: how to enable timestamp

I'm using the logger (LOG_INF, LOG)_DBG...etc) to print out debug messages. I'd like to have timestamp printed out. Right now it looks like this: D: xxxx or I: xxxxx

I found 3 CONFIGs that has the word timestamp in it. But seems none of them work. I'm not sure if I'm looking at the right direction.




So how to enable times tamping in logging?

Another logger question is, I keep getting warning like this.

"warning: LOG_BACKEND_RTT (defined at subsys/logging\Kconfig.backends:87) was assigned the value 'y'
but got the value 'n'. Check these unsatisfied dependencies: (!LOG_MINIMAL) (=n). See
docs.zephyrproject.org/.../CONFIG_LOG_BACKEND_RTT.html and/or look up
LOG_BACKEND_RTT in the menuconfig/guiconfig interface. The Application Development Primer, Setting
Configuration Values, and Kconfig - Tips and Best Practices sections of the manual might be helpful

Looking up the document, there's no LOG_MINIMAL, only LOG_MODE_MINIAL. And whether I set it or not, it appears RTT is working because I can see output from RTT window so it must be working. I wonder what the warning message mean?