Re: [Qemu-devel] [PATCH v2 2/8] exec: Factor out core logic of check_watchpoint()

[Philippe Mathieu-Daudé]

On 8/30/19 3:21 AM, Richard Henderson wrote:
> On 8/29/19 10:26 AM, Philippe Mathieu-Daudé wrote:
>>> -            wp->hitaddr = vaddr;
>>> +            wp->hitaddr = MAX(addr, wp->vaddr);
>>
>> When is addr > wp->vaddr?
> 
> Both the watchpoint and the access are arbitrary ranges.
> 
>   wp:    [ 1000               - 1008 ]
>   store:     [ 1002 - 1004 ]
> 
>   wp:               [ 1004    - 1008 ]
>   store: [ 1000               - 1008 ]
> 
> The old code would, for the first case, return 1002 and not the 1000 of the
> watch point, which seems reasonable.  For the second case, we would set 1000,
> an address outside of the watchpoint.
> 
> David's change makes sure that the address signaled is inside the watchpoint.
> I.e. leaving the first case unchanged and making the second  set 1004.
> 
> It seems very reasonable to me.

Thanks for the very clear explanation :)

If you have time, few lines of comment around would be very appreciated...

Now that it is clearer:
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

Regards,

Phil.