Re: [PATCH] x86: coco: mark cc_mask as __maybe_unused

Borislav Petkov
2025-03-05T22:51:22Z

On Wed, Mar 05, 2025 at 11:45:11PM +0100, Arnd Bergmann wrote:
> There is a twist here: clang by default warns about unused const
> variables in .c files but not in headers, while gcc doesn't

What is the point of this warning, do you know?

Someone defines a const, forgets to use it and? Oh big deal. This should be
a -Wunused anyway, no?

I must be missing something here...

> warn about them at all unless it's explictly enabled, and then
> it warns about both of them. Newer gcc versions have a distinct
> -Wunused-const-variable=1 for the clang behavior and
> -Wunused-const-variable=2 that warns for both, so we could
> reasonably decide to enable the =1 version by default and
> leave the =2 version for W=2.
>
> On the other hand, most of the users of 'static const' variables
> in headers are rather dumb and should just be moved into the
> file that uses them, or they can be replaced with a #define
> or an enum.
>
> In this case, the only user is a macro:
> #define _PAGE_CC (_AT(pteval_t, cc_mask))
>
> so maybe '#define cc_mask 0' would be appropriate.

Sounds a lot better to me.

Thx.

--
Regards/Gruss,
Boris.