Re: [XEN PATCH][for-next][for-4.19 v2 1/8] xen/include: add macro LOWEST_BIT

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.10.2023 21:58, Stefano Stabellini wrote:
>>>>>> --- a/xen/include/xen/macros.h
>>>>>> +++ b/xen/include/xen/macros.h
>>>>>> @@ -8,8 +8,10 @@
>>>>>>  #define DIV_ROUND(n, d) (((n) + (d) / 2) / (d))
>>>>>>  #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
>>>>>>
>>>>>> -#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
>>>>>> -#define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))
>>>>>
>>>>> a SAF-<n>-safe comment here?
>>>>>
>>>>
>>>> One reason is that now that violations only belonging to tool
>>>> configurations
>>>> and similar are documented in docs/misra/deviations.rst (committed in
>>>> Stefano's
>>>> branch for-4.19 [1]).
>>>
>>> But tool configuration means every analysis tool needs configuring
>>> separately. That's why the comment tagging scheme was decided to be
>>> preferred, iirc.
>>>
>>>> Also, there were disagreements on the SAF naming
>>>> scheme, and
>>>> patches like those would not be accepted at the moment.
>>>
>>> Well, that needs resolving. The naming there shouldn't lead to patches
>>> being accepted that later may need redoing.
>>>
>>> Jan
>>
>> While this is true, in this case I'm not willing to deviate with a SAF, given
>> that
>> some ECLAIR-specific configuration would be needed anyways, given that I'm
>> deviating a macro definition, rather than the line where it's actually used
>> (and maybe other tools would need
>> that as well).
> 
> Did I get it right that the problem with using SAF in this case is that
> it wouldn't be sufficient to add a SAF comment on top of the MACRO
> definition, but we would need a SAF comment on top of every MACRO
> invocation?
> 
> If so, then not just for this MACRO but in general basically we have to
> use deviations.rst.

That would be pretty sad.

Jan

> Luca, do you know what would be the behavior for cppcheck and/or
> Coverity? I imagine it will be the same and they would also need a
> deviation at every MACRO invocation, not just the definition?