Re: [XEN PATCH 7/7] xen/page_alloc: deviate first_valid_mfn for MISRA C Rule 8.4

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

On 2023-12-04 08:44, Jan Beulich wrote:
> On 02.12.2023 04:03, Stefano Stabellini wrote:
>> On Fri, 1 Dec 2023, Jan Beulich wrote:
>>> On 01.12.2023 03:47, Stefano Stabellini wrote:
>>>> On Wed, 29 Nov 2023, Nicola Vetrini wrote:
>>>>> No functional change.
>>>>> 
>>>>> Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
>>>>> ---
>>>>> The preferred way to deviate is to use asmlinkage, but this 
>>>>> modification is only
>>>>> the consequence of NUMA on ARM (and possibly PPC) being a work in 
>>>>> progress.
>>>>> As stated in the comment above the textual deviation, 
>>>>> first_valid_mfn will
>>>>> likely then become static and there would be no need for the 
>>>>> comment anymore.
>>>>> This works towards having the analysis for this rule clean (i.e. no 
>>>>> violations);
>>>>> the interest in having a clean rule is that then it could be used 
>>>>> to signal
>>>>> newly introduced violations by making the analysis job fail.
>>>> 
>>>> Please add this text as part of the commit message. It can be done 
>>>> on
>>>> commit.
>>> 
>>> I assume you saw my reply on another of the patches in this series as 
>>> to
>>> asmlinkage use on variables? IOW I think this paragraph would also 
>>> need
>>> adjustment to account for that.
>> 
>> I was going to ask you about that: reading your reply
>> https://marc.info/?l=xen-devel&m=170142048615336 it is not clear to me
>> what you are asking or suggesting as next step in regard to asmlinkage
>> use on variables.
> 
> Either we need a separate attribute, or we need affirmation that 
> calling
> convention attributes are ignored (and going to be going forward) for
> variables, or we need to resort to SAF-* comments. I'm not sure what's
> best (assuming the "affirm" wouldn't really be possible).
> 

Well, gcc does warn on unsupported attributes for the entity which are 
being dropped. This appears to be the case for calling convention 
attributes, as they are not listed in their documentation for variable 
attributes, but some more digging would be required to determine whether 
that's always the case.

-- 
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)