Re: [PATCH v2 1/4] docs: add xen_ulong_t to the documented integers sizes/alignments

[Julien Grall <julien.grall.oss@xxxxxxxxx>]

On Thu, 11 Apr 2024 at 18:08, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:

On Wed, 10 Apr 2024, Julien Grall wrote:
> On Wed, 10 Apr 2024 at 19:47, Stefano Stabellini <stefano.stabellini@xxxxxxx> wrote:
>       xen_ulong_t is widely used in public headers.
>
>       Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
>       ---
>
>       Given that xen_ulong_t is used in public headers there could be a better
>       place for documenting it but this was the most straightforward to add.
>       ---
>        docs/misra/C-language-toolchain.rst | 11 +++++++++++
>        1 file changed, 11 insertions(+)
>
>       diff --git a/docs/misra/C-language-toolchain.rst b/docs/misra/C-language-toolchain.rst
>       index 5ddfe7bdbe..7a334260e6 100644
>       --- a/docs/misra/C-language-toolchain.rst
>       +++ b/docs/misra/C-language-toolchain.rst
>       @@ -531,6 +531,17 @@ A summary table of data types, sizes and alignment is below:
>             - 64 bits
>             - x86_64, ARMv8-A AArch64, RV64, PPC64
>
>       +   * - xen_ulong_t
>       +     - 32 bits
>       +     - 32 bits
>       +     - x86_32
>       +
>       +   * - xen_ulong_t
>       +     - 64 bits
>       +     - 64 bits
>       +     - x86_64, ARMv8-A AArch64, RV64, PPC64, ARMv8-A AArch32, ARMv8-R
>       +       AArch32, ARMv7-A
>
>
> We support neither ARMv8-R nor ARMv8-A Aarch32.
>
> I could possibly accept the latter because it works to. But the former is so far misleading.

Yes I think you are right. Moreover this document
(C-language-toolchain.rst) is meant for the Xen build. While this patch
is trying to document the types used in the public headers for the
external-facing ABI.

I'll move the information this patch is adding to a separate document,
specific to the public headers. I will only add the architectures
currently working: I'll add ARMv8-A Aarch32 because although it is
unsupported it is interesting to know the size of xen_ulong_t for
aarch32 in the public headers. I will remove ARMv8-R as it is not
available upstream.

Thinking a bit more. What about Armv9? Rather than listing each version, should we instead use ARMv7-A aarch32 and later, ARMv8-A aarch64 and later?