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I'm trying to debug a Raspberry Pi Pico project using openOCD + Picoprobe. I go through the steps that appear to be correct to do all this from my Linux PC (the Get started with Pico and C++ guide is for the Raspberry Pi, but there are tutorials online for PC), but when trying to set breakpoints in gdb, it appears to be looking at a different file.
My steps are the following:
In a console, navigate to the openOCD folder and run:
sudo src/openocd -s tcl/ -f tcl/interface/picoprobe.cfg -f tcl/target/rp2040.cfg
I get only info messages, no errors, until it waits for the gdb to connect

Info : starting gdb server for rp2040.core0 on 3333
Info : Listening on port 3333 for gdb connections

Then, in a different console, I navigate to what I want to debug, in this case the blink.c example. I stand inside the build folder with my .elf file and run

sudo gdb-multiarch blink.elf

    (gdb) target extended-remote localhost:3333
    (gdb) monitor reset init
    (gdb) break 15

where 15 is a relevant debuggable line. But the thing is, the breakpoints are said to be set in a different file:

Breakpoint 1 at 0x20000178: file ../../../../../../libgcc/config/arm/lib1funcs.S, line 1461

and then on, all breakpoints are also set there. Here's an example trying to set 3 different breakpoints:

(gdb) b 15
Breakpoint 1 at 0x20000178: file ../../../../../../libgcc/config/arm/lib1funcs.S, line 1461.
(gdb) b 16
Note: breakpoint 1 also set at pc 0x20000178.
Breakpoint 2 at 0x20000178: file ../../../../../../libgcc/config/arm/lib1funcs.S, line 1461.
(gdb) b 17
Note: breakpoints 1 and 2 also set at pc 0x20000178.
Breakpoint 3 at 0x20000178: file ../../../../../../libgcc/config/arm/lib1funcs.S, line 1461.

So that. I am totally lost on what's happening here. Could anyone point me to why this is happening, or what that file does?

Jonas
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Francisco Ayrolo
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1 Answers1

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I see it's been a few months but I just ran into the same problem, here's what I've learned.

When you compile the C/C++ program that you're trying to debug, you need to compile it in debug mode, which tells the compiler to include debug symbols in the program. If compiling directly with gcc, you can use the -g flag. However, I'm assuming you're using CMake, in which case you can just add set(CMAKE_BUILD_TYPE Debug) to your CMakeLists.txt (found a few other options here as well)

Probably goes without saying, but after recompiling this way, you'll need to re-load your new program onto your target Pico by holding the bootsel button and plugging it into your machine directly (ie. not via your debugger Pico).

I also found that after doing this, setting breakpoints just to specific lines still didn't behave as expected, and I had to actually specify the name of the file as well, ex: break main.c:15

Kaleb
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