RTT logging in bootloader does not work well.

[vliedel]

With the following config:

CS_SERIAL_ENABLED=SERIAL_ENABLE_RX_AND_TX
SERIAL_VERBOSITY=SERIAL_INFO
CS_UART_BINARY_PROTOCOL_ENABLED=1
CS_SERIAL_NRF_LOG_ENABLED=0
CS_SERIAL_NRF_LOG_PIN_TX=6
CS_SERIAL_BOOTLOADER_NRF_LOG_ENABLED=1

I do not always get RTT logs from the bootloader. I only seem to get bootloader RTT logs when:

• No application has been uploaded.
• Debugging the bootloader (make debug_bootloader).

Other things I tried:

• RTT logs from the application work fine (CS_SERIAL_NRF_LOG_ENABLED=1).
• UART logs from the bootloader work fine (CS_SERIAL_BOOTLOADER_NRF_LOG_ENABLED=2).
• Adding NRF_LOG_FINAL_FLUSH(); just before app_start(); in nrf_bootloader_app_start_final.c did not help.

[mrquincle]

Perhaps https://devzone.nordicsemi.com/f/nordic-q-a/20708/rtt-logging-from-application-started-by-bootloader helps. The JLink page provides quite some information on RTT: https://www.segger.com/products/debug-probes/j-link/technology/about-real-time-transfer/ but it narrows down to setting the .rtt_cb and .rtt_buffers sections.

Plain UART is almost always easier. As is just using gdb to step through stuff.

[vliedel]

Today I've been working with RTT logs in the application, and that only works after resetting the crownstone: make reset. The make debug_server probably halts the cpu.

[mrquincle]

Does this require action? Or is just debugging the bootloader alone without app (with RTT) or debugging both with the app (with UART) sufficient?

[mrquincle]

There are issues with debugging that have to do with bugs in the Nordic code. Would say about this: won't fix.