NCS: MCUBoot RTT Logs lost when performing DFU

[mesh777]

We have difficulties to get RTT prints from MCUBoot while performing DFU.

As far as I understand Segger RTT is reinitialized when booting Application and this might be the reason of lost MCUBoot log messages.

One solution I have tried to set CONFIG_SEGGER_RTT_SECTION_DTCM=y, but this did not help.

Any suggestions on how to retrieve MCUBoot log printed during DFU?

[tesc]

Hi,

The memory block used for RTT is dynamically placed, so it will almost always be placed at a different location for the bootloader than for the application. When connecting over the J-Link, only the first RTT memory block is found (and assumed to be the only one), leaving the other RTT unused.

This is a known limitation. While there has been some efforts at solving it, with further efforts here, the easiest workaround by far is to enable RTT only in MCUBoot or only in the application.

Regards,
Terje

[mackz]

Hi, i am also having issues with RTT. When i enable mcuboot i cant see any output from the application and mcuboot. i have tried to disable rtt in mcuboot by putting:

CONFIG_USE_SEGGER_RTT=n
CONFIG_LOG_BACKEND_RTT=n
CONFIG_MCUBOOT_UTIL_LOG_LEVEL_OFF=y
CONFIG_LOG=n

in child_image/mcuboot.conf
but i still get no output, do i need to disable anything else?

[tesc]

Hi,

In addition to the configs you have already disabled, please check and see if there is also a CONFIG_RTT_CONSOLE (which should also be set to n), and check if there are any other RTT, CONSOLE, or SERIAL related settings that may be interfering with the application's use of RTT.

Regards,
Terje