Re: [ECOS] building and debugging

[Andrew Lunn <andrew at lunn dot ch>]

On Mon, Feb 19, 2007 at 06:22:56PM +1100, Laurie Gellatly wrote:
> Hi All,
> I've been using eclipse to develop my arm based system for some time.
> The application runs multiple threads and I had been able to debug them
> reasonably well (the program did not always flow the way I expected when
> single stepping and sometimes local variables are not able to be displayed).

Try disabling the optimizer, i.e. remove the -O2 flag. It will then
flow in a more logical, but less efficient way.

> What I have now is that although the main thread seems to be able to be
> debugged, the other threads have problems.
> I can set a breakpoint in a thread and it will stop, but single stepping or
> trying to display local variables etc no longer works.

Part of the problem is that gdb is not fully thread aware. It cannot
stop a thread context change at a time slice. It cannot stop a higher
priority thread taking over, it cannot stop a timer tick happening
etc. So when every you do a single step something else can take over
control from the current thread. What you can do is run the thread you
are trying to debug at a higher priority than anything else. That will
reduce the likelihood of it being preempted. However if you are
looking for a race condition this is not going to help you...

        Andrew

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