Debugging Zephyr hello world on nRF52840 using eclipse and GDB

[moose]

Hello, I am trying to debug Zephyr hello world example on an nRF52840 DK. For my setup, I am using eclipse with the zephyr plugin. Following the plugin readme documentation, I am able to build the project and run it on the hardware ( I see "hello world" on the output). However, I am unable to debug the project using GDB and the built-in JLink debugger. The debugger stops at line 82 of reset.S file. The line is: bl z_platform_init. See screenshots below for reference. If I run it, it will never stop on any breakpoint I have in my main. Any ideas as to what is going on?

It may be something to do with my startup configuration so I copied the screenshots here. I am assuming I have to load the image and symbols but not sure if I need to specify any offset. I recall from when I used the nordic SDK, I had to worry about the soft device and the MBR block for the bootloader but not sure if this is the same here with zephyr. Any input would be appreciated.

Thanks!

[Håkon Alseth]

Hi,

 

Your program is in the idle-thread, meaning that it has exited the main thread.

The compiler opimizes for size by default, and you're not able to break on the specific print in main.c.

If you take the blinky sample instead, you should be able to hit a breakpoint.

 

Kind regards,

Håkon

[moose]

Hello Hakon,

I don't know why it existed main if I have a verified breakpoint. I also was not breaking on the printk statement, as you see from this screenshot. I added some dummy code for debugging.

Anyhow, I went ahead and created a new project based on the blinky example, and I still get the same error. See screenshot below.

[Håkon Alseth]

Hi,

 

z_arm_reset is the reset vector, ie. the very first function that you're booting into.

Is the "gdb console" showing the same breakpoint as you set in the UI? "info b" should give you a list of the breakpoints in gdb.

 

Kind regards,

Håkon

[moose]

I figured it out. I think it is something to do with optimization. I added "volatile" to my variables and now I can breakpoint at their modifier statements.

How do I adjust the optimization level? I can't find that setting in the project settings.

[Håkon Alseth]

Hi,

 

Go into your prj.conf and set "CONFIG_DEBUG_OPTIMIZATION=y" (https://docs.zephyrproject.org/latest/reference/kconfig/choice_485.html#choice-485)

 

Kind regards,

Håkon