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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.10.2023 18:17, Nicola Vetrini wrote:
> On 16/10/2023 17:33, Jan Beulich wrote:
>> On 12.10.2023 17:28, Nicola Vetrini wrote:
>>> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
>>> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
>>> @@ -274,6 +274,12 @@ still non-negative."
>>>  -config=MC3R1.R10.1,etypes+={safe, 
>>> "stmt(operator(logical)||node(conditional_operator||binary_conditional_operator))",
>>>  
>>> "dst_type(ebool||boolean)"}
>>>  -doc_end
>>>
>>> +-doc_begin="The macro LOWEST_BIT encapsulates a well-known pattern to 
>>> obtain the value
>>> +2^ffs(x) for unsigned integers on two's complement architectures
>>> +(all the architectures supported by Xen satisfy this requirement)."
>>> +-config=MC3R1.R10.1,reports+={safe, 
>>> "any_area(any_loc(any_exp(macro(^LOWEST_BIT$))))"}
>>> +-doc_end
>>
>> Why is this added here rather than by ...
>>
>>> --- 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