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Re: Notes from FuSa meeting 2022-06-22 about Deviations
- To: Roger Pau Monné <roger.pau@xxxxxxxxxx>
- From: Luca Fancellu <Luca.Fancellu@xxxxxxx>
- Date: Tue, 28 Jun 2022 08:16:33 +0000
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, "fusa-sig@xxxxxxxxxxxxxxxxxxxx" <fusa-sig@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Tue, 28 Jun 2022 08:16:49 +0000
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- Thread-topic: Notes from FuSa meeting 2022-06-22 about Deviations
> On 28 Jun 2022, at 08:37, Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:
>
> On Mon, Jun 27, 2022 at 12:23:32PM -0700, Stefano Stabellini wrote:
>> Hi all,
>>
>> These are some of the notes that I took today during the meeting about
>> deviations
>>
>> Cheers,
>>
>> Stefano
>>
>>
>> ---
>>
>>
>> reasons for deviations:
>> - code quality
>> - access to hardware (need compiler extensions to access hardware)
>> - adopted code integration
>> - non-compliant adopted code
>>
>> Purpose of tagging:
>> - I don't want to see this report from the tools again
>> - This is the reason why I am deviating
>>
>>
>> Tags:
>> - adopted
>> this is adopted code
>> - safe
>> it is a violation but actually the code is safe
>> - relied
>> this is for adopted code again and only concern dev confusion
>> - false-positive
>> - compliant
>> for *possible* violations which are safe
>> - false-negative
>> Flagging a violation that is present in the code even if the tool
>> doesn't spot it. Probably not applicable to Xen as we want to enable
>> multiple tools
>>
>>
>> Probably none of our code can be claimed to be "adopted" according to
>> MISRA, even the one coming from Linux.
>
> So that would limit the tags that we use to: safe, compliant and
> false-positive?
Hi Roger,
I’m afraid we don’t have an answer yet, the meeting run out of time
yesterday because there was a lot to talk about each tag, probably
In the following meetings we will have the chance to talk about it.
>
> I'm not sure the difference between safe and compliant is worth having
> a different tag: both will need a written justification anyway. Maybe
> would be clearer if there was some example of the different usage of
> safe vs compliant.
my understanding from Roberto Bagnara’s explanation is that Compliant is
a tag marking a *possible* violation emitted by the tool, so the tool tells you
that there might be a violation because there are probably variables above its
control (for example it doesn’t have a full path graph because a function is
called
by interrupt vectors, architectural behaviours, …) so the tool’s job is to warn
you
about that and our job is to have a look on that piece of code and prove that it
works under all the conditions the code is meant to work.
Safe instead is a certain violation emitted by the tool, there is no
uncertainty in this
finding, but with a proper justification (tagged by Safe) its possible to use
that code
and be compliant.
Cheers,
Luca
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