How to see LOG in Bootloader if app moves into bootloader ?

Question

Hello, Nordic. 
 I use SDK15.3.0, s340 softdevice, nrf52840. 
 Recently, I am testing dfu service. So I merge App, softdevice, and bootloader. 
 Dfu service's test has done very well. 
 But I don't see any Log in bootloader. I also use pca10056_ble_debug and NRF_LOG_ENABLED is 1. So I think I must have seen any log in bootloader. 
 If you know any way, please let me know how to do that.

Vidar Berg · Accepted Answer

Hello, 
 RTT uses a section of RAM to hold log messages which are accessed by the debugger. When you connect the debugger, it will automatically search through RAM to locate this block and start retrieving the log messages. The problem is that it's not stored at a fixed address, so the block will be placed at a new address when the device "jumps" from the bootloader to the application (and vice versa). The solution is to place it at a fixed address in your bootloader and application. Please refer to Hung's answer here: https://devzone.nordicsemi.com/f/nordic-q-a/20708/rtt-logging-from-application-started-by-bootloader/80814#80814

How to see LOG in Bootloader if app moves into bootloader ?

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