Issue with debugging

[rei-vilo]

I am using the blinky example on the BGM220 Explorer kit. Build and link, upload and run work fine.

When trying to debug according to the procedure,

[2024-01-13T17:34:00.769Z] SERVER CONSOLE DEBUG: onBackendConnect: gdb-server session connected. You can switch to "DEBUG CONSOLE" to see GDB interactions.
JLinkGDBServer -singlerun -nogui -if SWD -port 50000 -swoport 50001 -telnetport 50002 -device BGM220PC22HNA
[2024-01-13T17:34:05.970Z] SERVER CONSOLE DEBUG: onBackendConnect: gdb-server session closed
GDB server session ended. This terminal will be reused, waiting for next session to start...

The debug_custom.json file contains

{
  "servertype": "jlink",
  "device": "BGM220PC22HNA",
  "interface": "SWD",
  "serverpath": "JLinkGDBServer"
}

The installed JLinkGDBServer version is

SEGGER J-Link GDB Server V7.94d Command Line Version
JLinkARM.dll V7.94d (DLL compiled Jan 11 2024 09:42:08)

on

Linux NUC-12 6.1.0-17-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.69-1 (2023-12-30) x86_64 GNU/Linux

However, Simplicity Studio debugs fine.

What am I missing? Thank you!

[silabs-bozont]

Hello rei-vilo,
Excuse me for my late reply, I needed some time to take a deeper dive on this.
I can confirm your issue - debugging is broken on Linux for me as well. The good news is that I found the issue and there's a workaround available.

When I tried to launch a debugging session I got the same error that
GDB server session ended. This terminal will be reused, waiting for next session to start...
I tried launching JLinkGDBServer independently of the Arduino IDE - that worked fine, it recognized the connected MCU.
Then I tried connecting to it with a gdb session from the command line when I noticed that arm-none-eabi-gdb is crashing hard. This is what causes the Arduino IDE session to end prematurely.

I suggest you try and launch the supplied arm-none-eabi-gdb on your system and see if it crashes for you as well.
It's located at /home/<user>/.arduino15/packages/SiliconLabs/tools/gcc-arm-none-eabi/12.2.rel1/bin/arm-none-eabi-gdb.
When I launched it first it complained about missing an ncurses shared library. I solved this by installing the ncurses5-compat-libs package.
On the second launch I got further, now I had a python error:

Could not find platform dependent libraries <exec_prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Python path configuration:
  PYTHONHOME = (not set)
  PYTHONPATH = (not set)
  program name = '/usr/local/bld-tools/bld-tools-virtual-env/bin/python'
  isolated = 0
  environment = 1
  user site = 1
  import site = 1
  sys._base_executable = '/usr/local/bld-tools/bld-tools-virtual-env/bin/python'
  sys.base_prefix = '/usr'
  sys.base_exec_prefix = '/usr'
  sys.executable = '/usr/local/bld-tools/bld-tools-virtual-env/bin/python'
  sys.prefix = '/usr'
  sys.exec_prefix = '/usr'
  sys.path = [
    '/usr/lib/python38.zip',
    '/usr/lib/python3.8',
    '/usr/lib/lib-dynload',
  ]
Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

Current thread 0x000073ca44203c00 (most recent call first):
<no Python frame>

This seems to be a known issue with GDB hard requiring python3.8 to be in a specific location on Linux:
https://www.linuxquestions.org/questions/slackware-14/can%92t-run-arm%92s-gdb-python-problem-4175724434/
https://stackoverflow.com/questions/72187185/arm-none-eabi-gdb-cannot-start-because-of-some-python-error

I managed to work this around by installing python3.8.18 with pyenv and linking it to the location specified by the error message:
pyenv install 3.8.18
sudo mkdir -p /usr/local/bld-tools/bld-tools-virtual-env/bin
sudo ln -s /home/<user>/.pyenv/versions/3.8.18/bin/python python
After this arm-none-eabi-gdb launched without any errors and debugging could be successfully started from the Arduino IDE.

Let me know if this works out for you!
If not - please post the output from running the built-in arm-none-eabi-gdb at /home/<user>/.arduino15/packages/SiliconLabs/tools/gcc-arm-none-eabi/12.2.rel1/bin/arm-none-eabi-gdb and we can dive further!
I know this is not very user friendly having to hack your system like this in order to use debugging - we'll try to figure something out for the next release to make this easier on Linux users.

[rei-vilo]

Thank you for the thorough investigation and detailed instructions.

I installed the missing library with sudo apt install libncursesw5.

JLinkGDBServer starts fine when called outside the Arduino IDE.

$ JLinkGDBServer -singlerun -nogui -if SWD -port 50000 -swoport 50001 -telnetport 50002 -device BGM220PC22HNA
SEGGER J-Link GDB Server V7.94f Command Line Version

JLinkARM.dll V7.94f (DLL compiled Jan 17 2024 15:36:44)

However, calling it from the Arduino IDE still fails. It may be the same issue I reported at arduino/arduino-ide#2115. Using the Arduino IDE FlatPak distribution limits access to external tools.

Instead of arm-none-eabi-gdb, I am using gdb-multiarch. It allows to get rid of the Python limitation.

$ gdb-multiarch BGM220_Blink_Debug.ino.elf
(gdb) target extended :50000
(gdb) load
(gdb) list loop
(gdb) br 34
(gdb) c
Continuing.

Thread 2 hit Breakpoint 1, loop ()
    at BGM220_Blink_Debug.ino:34
34	  delay(100);                      // wait for a second
(gdb)

I managed to debug against the BGM220 and the BG24 Explorer boards using emCode, a tool I have designed to develop with the Arduino SDK on the Visual Studio Code IDE.

For the BG24 Explorer board, please note that the recommended MCU EFR32MG24B210F1536IM48 is unknown: EFR32MG24BXXXF1536 seems to be the correct one, according to my tests and the list of Supported Devices from the Segger documentation.

The last board to perform tests is the xG27 Dev Kit. Is there a way to get a sample to test Matter?

[silabs-bozont]

That's a quite impressive project you got going on! Thanks for adding support for our boards quickly.
I'm glad you could work the issue around.
The EFR32MG24B210F1536IM48 and EFR32MG24BXXXF1536 are both seem to be accepted as targets by JLinkGDBServer - I just checked it. I'm on version V7.94g.
The xG27 Dev Kit does not support Matter, it's BLE only. It can be purchased from our website, but it's a bit pricey at 75 USD. Unfortunately development kits are not included in our sample program.