[Mono-list] remote debugging on ARM

[Ian Norton]

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On 15/01/13 21:01, Ian Norton wrote:
> On 15/01/13 20:50, Ian Norton wrote:
>> On Tue, Jan 15, 2013 at 08:35:25PM +0000, mickeyf wrote:
>>> So I am now able to run my app on the ARM, but I am not able
>>> to debug it there.
>>> 
>>> The debugger waits, and apparently connects: When I click
>>> Connect a dialog box flashes by too quickly for me to read it,
>>> 'Stop' is enabled in the MD menu, and my app is apparently
>>> paused (no start up messages seen).
>>> 
>>> If I have a break point the break point icon changes
>>> appearance, but I don't get the regular "paused' indication I'd
>>> see when debugging locally. Whether there is a breakpoint or
>>> not, if I try to 'continue debugging', step in, step out, do
>>> anything other than 'stop' I get either a SIGABRT or SIGILL
>>> message and am bumped back to the command line.
>>> 
>>> At one point I got exactly this:
>>> 
>>> http://stackoverflow.com/questions/13925625/sigabrt-error-on-monodevelops-custom-command-mono-soft-debugger-on-remote-devic
>>>
>>>
>>>
>
>>> 
but no one has responded to that query.
> 
>> I get very similar things when my mono program calls into
>> unmanaged libraries, particularly if they are multi-threaded.
> 
>> I find that it is not stepping over the breakpoint that does it
>> but it is the Locals or Immediate window trying to evauluate
>> objects that kills things for me.
> 
> 
> Specifically, I get:
> 
>> * Assertion at debugger-agent.c:4471, condition `tls' not met

Aha, What I seem to see happening is thiss.

1. My program hits a c# breakpoint and stops.
2. The mono runtime is suspended.
3. One of my unmanaged threads is merrily still running waiting for
some network traffic on a socket.
4. A network event happens which causes the unmanaged code to execute
a callback which actually turns out to be managed code.

When #4 happens, the pointer appears invalid and the program gets a
SEGV signal, the debugger takes this signal to mean "step next" and so
crashes.

You might be seeing somthing similar.

Ian

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