Re: [XEN PATCH][for-4.19 v2 2/2] docs/misra: add deviations.rst to document additional deviations.

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

+Henry

On Mon, 9 Oct 2023, Nicola Vetrini wrote:
> This file contains the deviation that are not marked by
> a deviation comment, as specified in
> docs/misra/documenting-violations.rst.
> 
> Suggested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>

This is great! Thank you so much!

I have a few questions below but even as-is it is way better than
nothing. I think we should add this for 4.18


> ---
>  docs/index.rst            |   1 +
>  docs/misra/deviations.rst | 240 ++++++++++++++++++++++++++++++++++++++
>  docs/misra/rules.rst      |   2 +-
>  3 files changed, 242 insertions(+), 1 deletion(-)
>  create mode 100644 docs/misra/deviations.rst
> 
> diff --git a/docs/index.rst b/docs/index.rst
> index 2c47cfa999f2..f3f779f89ce5 100644
> --- a/docs/index.rst
> +++ b/docs/index.rst
> @@ -63,6 +63,7 @@ Xen hypervisor code.
>     :maxdepth: 2
> 
>     misra/rules
> +   misra/deviations
> 
> 
>  Miscellanea
> diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
> new file mode 100644
> index 000000000000..19743e34ce03
> --- /dev/null
> +++ b/docs/misra/deviations.rst
> @@ -0,0 +1,240 @@
> +.. SPDX-License-Identifier: CC-BY-4.0
> +
> +MISRA C deviations for Xen
> +==========================
> +
> +The following is the list of MISRA C:2012 deviations for the Xen codebase 
> that
> +are not covered by a `SAF-x-safe` or `SAF-x-false-positive-<tool>` comment, 
> as
> +specified in docs/misra/documenting-violations.rst; the lack of
> +such comments is usually due to the excessive clutter they would bring to the
> +codebase or the impossibility to express such a deviation (e.g., if it's
> +composed of several conditions).
> +
> +Deviations related to MISRA C:2012 Directives:
> +----------------------------------------------
> +
> +.. list-table::
> +   :header-rows: 1
> +
> +   * - Directive identifier
> +     - Justification
> +     - Notes
> +
> +   * - D4.3
> +     - Accepted for the ARM64 codebase
> +     - Tagged as `disapplied` for ECLAIR on any other violation report.

This mean it has been applied for ARM64 but not x86, right?


> +   * - D4.3
> +     - The inline asm in 'xen/arch/arm/arm64/lib/bitops.c' is tightly coupled
> +       with the surronding C code that acts as a wrapper, so it has been 
> decided
> +       not to add an additional encapsulation layer.
> +     - Tagged as `deliberate` for ECLAIR.
> +
> +Deviations related to MISRA C:2012 Rules:
> +-----------------------------------------
> +
> +.. list-table::
> +   :header-rows: 1
> +
> +   * - Rule identifier
> +     - Justification
> +     - Notes
> +
> +   * - R2.1
> +     - The compiler implementation guarantees that the unreachable code is
> +       removed. Constant expressions and unreachable branches of if and 
> switch
> +       statements are expected.
> +     - Tagged as `safe` for ECLAIR.
> +
> +   * - R2.1
> +     - Some functions are intended not to be referenced.
> +     - Tagged as `deliberate` for ECLAIR.

What does it mean "some functions" in this case? Should we list which
functions?

Other than this, I checked and everything else looks great