Phantom breakpoint - why does this happen?

[scottm]

I've had this happen before, but it's been a while.  Occasionally the IDE will act like there's a breakpoint set when none exists.  I've attached a video showing an occurrence of the problem.  I'm using the menu commands here rather than keyboard shortcuts so you can see what I'm doing, which is why I'm a little slow finding some options and I clicked on the wrong 'step into' at one point, but you get the idea.

'info b' at the gdb prompt shows no breakpoints.  Setting 'skip all breakpoints' didn't help.  Setting a breakpoint at that line and removing it also didn't seem to work the first time, which is how I've usually fixed it.  I was finally able to clear it by setting a breakpoint at the previous line and stepping through, and then removing the breakpoint.  I should also mention that the next time the debugger is launched, when it's been in this state, it'll give a 'target not available' error even though it finishes loading and launching.

I'm using a P&E Cyclone ACP.  The breakpoint must be getting stuck somewhere, and I power cycled the Cyclone and restarted MCUXpresso with no change.  Are hardware breakpoints retained across resets?  And does gdb check them, or does it only report what it thinks the current breakpoints are?  Is there a command to clear hardware breakpoints from the gdb console or from the IDE?

Thanks,

Scott

[kackle123]

(This is more for future readers) I don't whether this applies in your case @scottm, but I was successful by closing the IDE and deleting the file ".markers" found in the workspace within ".metadata/.plugins/org.eclipse.core.resources/.projects/(PROJECT NAME)".  This likely works for other Eclipse IDE variants, too, that exhibit the phantom/ghost breakpoints.

(For clarity, I saw the symptom thusly: I think my debugger DID stop at the correct breakpoint, but the text EDITOR displayed the wrong file.  That is, I could look in my Debug tab and see that the FreeRTOS task where my breakpoint was set was properly showing, and clicking there caused the text editor to display the correct file, highlighting the correct code line.)

[zaharr_]

Hi Scott, 

Thank you for bringing this to our attention. Is there any chance you can share the project you are using? If you can, please send it to zahar dot rasking at pemicro dot com. 

Also, can you please update to the latest PEmicro plugin version 4.0.6 by going to Help -> Install New Software -> pointing to our update site PEMicro - http://www.pemicro.com/eclipse/updates and choosing GNU ARM PEmicro Interface Debugging Support plugin v4.0.6.

Can you also please go to debug configurations and enter -outputdebugfile parameter into Server Parameters before you run a debug session. This will generate .out file in your {MCUXpresso Installation Folder}\plugins\com.pemicro.debug.gdbjtag.pne_4.0.6.201904042048\win32 folder. Can you please share it with me as well. 

Thank you,

Zahar

P&E

[scottm]

Hi Zahar,

I think I've probably sent this particular project to PEMicro before - it's kind of a pain to set up because it relies on some linked folders and has some (non-critical) custom build steps.  And right now the phantom breakpoint is gone anyway, but next time it pops up again I'll gather more information and get back to you.

Thanks,

Scott