Re: [PATCH] RISC-V: enable have_nonsteppable_watchpoint by default

[Paul Koning <paulkoning@comcast.net>]

> On Oct 9, 2018, at 1:20 PM, Craig Blackmore <craig.blackmore@embecosm.com> wrote:
> 
> 
> 
> On 08/10/18 15:51, Joel Brobecker wrote:
>>>> I think MIPS is one.  The documentation is not entirely clear but
>>>> that's what I remember from using it.
>>> x86 is another.  But my question is -- do we know of any RISC-V
>>> implementation that triggers after the write, given that the spec
>>> says it should trigger before the write.
> I don't know of any RISC-V implementations that trigger after the write.
> The debug spec has 'suggested breakpoint timings' but the triggers are
> allowed to fire at whatever point is most convenient for the implementation.

I missed that the question was specific to RISC-V.

If the spec says that timing is up to the implementation, that seems to mean GDB can't rely on the break occurring before the write -- the fact that current implementations do so isn't sufficient if later implementation are allowed to differ.

I assume GDB cares which it is, which suggests that the implementation has to tell GDB which flavor of write watchpoint it has.

	paul