GDB fails when developing without soft device.

[TLloydUom]

I've been developing firmware for the nrf52840 for a few months using armgcc+openocd+arm-none-eabi-gcc working successfully. I recently upgraded my ubuntu version (18.04) and now find that I cannot debug my code using gdb anymore.  I use the following commands to intialise openocd and gdb:

open ocd:

    openocd -f /usr/share/openocd/scripts/interface/jlink.cfg -c "transport select swd" -f /usr/share/openocd/scripts/target/nrf52.cfg

gdb:

 arm-none-eabi-gdb -ex "target remote localhost:3333" _build/nrf52840_xxaa.out

This is the error I get:

nrfx_rng_handler (
/tmp/jenkins/jenkins-GCC-7-build_toolchain_docker-775_20180622_1529687456/src/gdb/gdb/frame.c:542: internal-error: frame_id get_frame_id(frame_info*): Assertion `stashed' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.

Any thoughts?  This is frustrating as everything worked perfectly on my previous ubuntu installation (16.04).  I tried debugging a project without the softdevice and it seemed to work fine so I'm a little confused.

[TLloydUom]

I tried using the JlinkGdb server instead using:

JLinkGDBServer -if swd -device nrf52

And it seems to work, but would welcome any suggestions as to why trying to debug with openocd gives the error?

[Vidar Berg]

Glad you found a workaround. I'm don't have much experience with openOCD unfortunately. But it's a bit strange that is stopped working after updating your Linux distribution. Are you using the same version of the GCC toolchain?   

[TLloydUom]

HI Vidar.  I started using the latest GCC toolchain and then back dated to the one suggested in the nrfconnect desktop app.  Further experimentation found that I could debug devices that had a softdevices successfully using openocd, but not those that didn't use the softdevice.

[Vidar Berg]

Hi,maybe there is something with the "Softdevice" examples that trigger a bug in GDB. We recommend using the toolchain version listed in the SDK release notes. Did you download the toolchain from https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm?  

[Nguyen Hoan Hoang]

Try this openocd target nrf52.cfg from https://github.com/I-SYST/EHAL/tree/master/ARM/Nordic/nRF52/src 

It is known to work on with all version of GCC from 4.9 to 8 under Windows/Linux/OSX