Re: [RFA/commit] arm-tdep.c: Do not single-step after hitting a watchpoint

Will Deacon
2014-09-30T08:57:49Z

On Mon, Sep 29, 2014 at 07:23:05PM +0100, Peter Maydell wrote:
> Joel Brobecker wrote:
> > I have been trying to understand the various contributions, and
> > I admit I am still not quite sure...
> >
> > Does it look like the patch I proposed is correct? It seems to be
> > supported by Terry Guo's experiments as well...
>
> Note that the ARMv7 architecture allows watchpoints to
> be implemented as *asynchronous*, in which case what
> you will see is that you take a watchpoint exception
> but it may not fire until after the instruction that
> triggers the watchpoint and possibly several following
> instructions have all finished execution. This may be
> what you are seeing in your hardware tests.

No you won't; the kernel will swallow the async watchpoint and complain in
dmesg. I'm not aware of any CPU implementations that actually generate
these.

Will