On Mon, 28 Oct 2024, Arnd Bergmann wrote:
+ Hans
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> After the file got split, there are now W=1 warnings for users that
> include it without referencing hsmp_msg_desc_table:
>
> In file included from arch/x86/include/asm/amd_hsmp.h:6,
> from drivers/platform/x86/amd/hsmp/plat.c:12:
> arch/x86/include/uapi/asm/amd_hsmp.h:91:35: error: 'hsmp_msg_desc_table' defined but not used [-Werror=unused-const-variable=]
> 91 | static const struct hsmp_msg_desc hsmp_msg_desc_table[] = {
> | ^~~~~~~~~~~~~~~~~~~
>
> Mark it as __attribute__((maybe_unused)) to shut up the warning but
> keep it in the file in case it is used from userland. The __maybe_unused
> shorthand unfurtunately isn't available in userspace, so this has to
unfortunately
> be the long form.
>
> Fixes: e47c018a0ee6 ("platform/x86/amd/hsmp: Move platform device specific code to plat.c")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> Ideally this array wouldn't be part of the UAPI at all, since it is
> not really a interface, but it's hard to know what part of the header
> is actually used outside of the kernel.
Sadly this slipped through during review even if it was brought up by
somebody back then. The (rather weak) reasoning for having it as a part of
UAPI was seemingly accepted uncontested :-(.
> ---
> arch/x86/include/uapi/asm/amd_hsmp.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/uapi/asm/amd_hsmp.h b/arch/x86/include/uapi/asm/amd_hsmp.h
> index e5d182c7373c..4a7cace06204 100644
> --- a/arch/x86/include/uapi/asm/amd_hsmp.h
> +++ b/arch/x86/include/uapi/asm/amd_hsmp.h
> @@ -88,7 +88,8 @@ struct hsmp_msg_desc {
> *
> * Not supported messages would return -ENOMSG.
> */
> -static const struct hsmp_msg_desc hsmp_msg_desc_table[] = {
> +static const struct hsmp_msg_desc hsmp_msg_desc_table[]
> + __attribute__((unused)) = {
It seems that the main goal why it was put into UAPI was "to give the user
some reference about proper num_args and response_size for each message":
https://lore.kernel.org/all/CAPhsuW5V0BJT+YSwv1U=hRG0k9zBWXeRd=E1n4U5hvcnwEV3mQ@xxxxxxxxxxxxxx/
Are we actually expecting userspace to benefit from this in C form?
Suma? Hans?
> /* RESERVED */
> {0, 0, HSMP_RSVD},
--
i.
