Re: [Qemu-devel] [PATCH v2] oslib-posix: Fix compiler warning and some data types

[Stefan Weil]

Am 15.10.2017 um 19:46 schrieb Stefan Weil:
> Am 15.10.2017 um 17:32 schrieb Paolo Bonzini:
>> On 14/10/2017 18:53, Philippe Mathieu-Daudé wrote:
>>>> @@ -328,7 +328,7 @@ static void *do_touch_pages(void *arg)
>>>>               * don't need to write at all so we don't cause
>>>>               * wear on the storage backing the region...
>>>>               */
>>>> -            *(volatile char *)addr = *addr;
>>>> +            *addr = *addr;
>>> I personally prefer the other form which is mostly self-explicit when
>>> reviewing this code.
>>>
>>> Declaring addr non volatile and using volatile cast here:
>>> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
>>>
>>
>> I agree with Philippe; in general, volatile is more of a property of
>> the access rather than the variable.
>>
>> Paolo
> 
> Thanks for the feedback.
> 
> I see your arguments. Maybe that part can be removed from my patch
> when it is applied, or should I send a v3 (cc'ing qemu-trivial)?
> 
> Stefan

While thinking more about that line of code, I wonder whether
it would make sense to replace the byte r/w by a 32 bit r/w.
Would that be faster on architectures with a 32 bit memory bus?

Stefan