Re: [PATCH] docs/misra: document the expected sizes of integer types

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.03.2024 00:23, Stefano Stabellini wrote:
> Xen makes assumptions about the size of integer types on the various
> architectures. Document these assumptions.

This all reads as if we required exact widths. Is that really the case? Imo
we e.g. merely depend upon sizeof(int) >= 4 * CHAR_BITS. (I can see that,
while not technically required, we may want to specify CHAR_BITS == 8, at
least for the time being.)

Jan

> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> ---
>  docs/misra/C-language-toolchain.rst | 44 +++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/docs/misra/C-language-toolchain.rst 
> b/docs/misra/C-language-toolchain.rst
> index b7c2000992..0d3bb2fe6e 100644
> --- a/docs/misra/C-language-toolchain.rst
> +++ b/docs/misra/C-language-toolchain.rst
> @@ -480,4 +480,48 @@ The table columns are as follows:
>       - See Section "4.13 Preprocessing Directives" of GCC_MANUAL and Section 
> "11.1 Implementation-defined behavior" of CPP_MANUAL.
>  
>  
> +Sizes of Integer types
> +______________________
> +
> +.. list-table::
> +   :widths: 10 10 45
> +   :header-rows: 1
> +
> +   * - Type
> +     - Size
> +     - Architectures
> +
> +   * - char 
> +     - 8 bits
> +     - all architectures
> +
> +   * - short
> +     - 16 bits
> +     - all architectures
> +
> +   * - int
> +     - 32 bits
> +     - all architectures
> +
> +   * - long
> +     - 32 bits 
> +     - 32-bit architectures (x86_32, ARMv8-A AArch32, ARMv8-R AArch32)
> +
> +   * - long
> +     - 64 bits 
> +     - 64-bit architectures (x86_64, ARMv8-A AArch64, RV64, PPC64)
> +
> +   * - long long
> +     - 64-bit
> +     - all architectures
> +
> +   * - pointer
> +     - 32-bit
> +     - 32-bit architectures (x86_32, ARMv8-A AArch32, ARMv8-R AArch32)
> +
> +   * - pointer
> +     - 64-bit
> +     - 64-bit architectures (x86_64, ARMv8-A AArch64, RV64, PPC64)
> +
> +
>  END OF DOCUMENT.