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Re: question about ARM watchpoints
- From: Joel Brobecker <brobecker at adacore dot com>
- To: Pedro Alves <palves at redhat dot com>
- Cc: Gareth McMullin <gareth at blacksphere dot co dot nz>, gdb at sourceware dot org
- Date: Thu, 4 Sep 2014 20:51:27 -0700
- Subject: Re: question about ARM watchpoints
- Authentication-results: sourceware.org; auth=none
- References: <20140901085743 dot GG4981 at adacore dot com> <CAL8qUbqTyBAkrXnN=DxmL5d3h5nwnfv=dO-vDdqxB+kVrZNzSQ at mail dot gmail dot com> <540903B0 dot 3000009 at redhat dot com>
> So sounds like this line should be skipped on ARMv7-M:
>
> arm-tdep.c: set_gdbarch_have_nonsteppable_watchpoint (gdbarch, 1);
>
> Could you try removing it?
>
> But then I wonder why we never heard of this before. Are there
> ARMv7-M's that behave differently? And what about ARMv6-M ?
That's what I wanted to try too, and will do soon. As to why we never
heard of this before - the only affirmative answer would be from someone
better able to undertand the docs than me. But here's a wild guess: the
fact that GDB stopped one instruction too late is invisible to the user
99% of the time. What triggered me seeing it was a change in code
generation which caused the update to be at the penultimate instruction
of a function. I wouldn't have seen it if the update was anywhere before
that.
--
Joel