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Re: [RFA/commit] arm-tdep.c: Do not single-step after hitting a watchpoint
- From: Will Deacon <will dot deacon at arm dot com>
- To: Peter Maydell <peter dot maydell at linaro dot org>
- Cc: Joel Brobecker <brobecker at adacore dot com>, Marcus Shawcroft <marcus dot shawcroft at gmail dot com>, Terry Guo <Terry dot Guo at arm dot com>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>, "lgustavo at codesourcery dot com" <lgustavo at codesourcery dot com>, "yao at codesourcery dot com" <yao at codesourcery dot com>, "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>, "gareth at blacksphere dot co dot nz >> Gareth, McMullin" <gareth at blacksphere dot co dot nz>
- Date: Tue, 30 Sep 2014 09:57:46 +0100
- Subject: Re: [RFA/commit] arm-tdep.c: Do not single-step after hitting a watchpoint
- Authentication-results: sourceware.org; auth=none
- References: <CAFEAcA_0C+UqGwM39A4EQCQLg59fNbJ2du8rhrt++Q-pdE9rgQ at mail dot gmail dot com>
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