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RE: Thread-aware debugging w/ Redboot on ARM?


> From: grante@visi.com [mailto:grante@visi.com]
>
> >>> Obviously, there's some Redboot code that waits at the serial
> >>> or Ethernet port for commands, but isn't the eCos kernel
> >>> frozen out at that point, so that no instructions are being
> >>> executed outside of Redboot?
> >>
> >> No.  Redboot has the ability via the Virtual Vector table to
> >> make calls into the eCos kernel to retrieve thread info and (I
> >> think) do things like lock/unlock the scheduler.
> >
> > But those are just subroutine calls to eCos utility functions,
> > taking place within the Redboot stack, aren't they?
>
> I'm not sure what you mean.  RedBoot is calling functions
> within the eCos scheduler (the one linked with your application
> code) to access/modify the thread state info in your
> application.

Yes, but when it does that, I assume that those scheduler functions,
whatever they may do to an eCos thread, are running in the Redboot stack.
That is, those scheduler functions are nothing more than subroutines, so the
CPU stack pointer remains pointed into the Redboot stack throughout the
operation.

In other words, if I've got this right, to the eCos+application system,
debugger halts look just like hardware interrupts that take a very long time
to complete. And single-stepping looks like a return from an interrupt that
is followed by a fresh hardware interrupt after one instruction.

At least that's how I hope it all works.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com



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