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Re: Can "redboot + gdb stub" debug an application that has its own vector?


Fu-Yuan Lee wrote:
> Hi all,
> 
> I am new to eCos and have one question about redboot and gdb-stub.
> Please kindly help us
> if you have any experience on this subject.  Any hint is highly appreciated.
> 
> As far as we know, the gdb stub heavily depends on the exception
> handling, which is
> coded in vectors.S. This exception code will normally be placed at
> address 0x0 (low vector)
> or 0xFFFF0000 (high vector) (take ARM as an example). Then it is confusing that
> how can the "redboot + gdb stub" debug an application that needs to
> deal with interrupts.
> 
> What I mean is: if the application needs to handle interrupts, it has
> to prepare its own
> vector and the hal_interrupt_handlers. And this vector will overwrite
> redboot's vector.
> As a result, there will be no way to enter gdb stub after loading the
> application (because
> the vector has changed).
> 
> Is there any misunderstanding here? Debugging an application via
> redboot+gdb is really
> an excellent feature. But vector part does also confuse us a lot. Can
> anyone give us
> some advice?

Debugging uses exceptions, not interrupts.  Care is taken to allow
GDB (via RedBoot) to still handle the exceptions which are used for
debugging, while still allowing the application to handle interrupts
(as well as non-debug related exceptions when this makes sense)



-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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