Re: [PATCH] efi: fix -Wmissing-variable-declarations warning

[Andy Shevchenko]

On Wed, Aug 30, 2023 at 2:04 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
> On Wed, 30 Aug 2023 at 00:54, Justin Stitt <justinstitt@xxxxxxxxxx> wrote:

...

> > When building x86/defconfig with Clang-18 I encounter the following warnings:
> > | arch/x86/platform/efi/efi.c:934:23: warning: no previous extern declaration for non-static variable 'efi_attr_fw_vendor' [-Wmissing-variable-declarations]
> > |   934 | struct kobj_attribute efi_attr_fw_vendor = __ATTR_RO(fw_vendor);
> > | arch/x86/platform/efi/efi.c:935:23: warning: no previous extern declaration for non-static variable 'efi_attr_runtime' [-Wmissing-variable-declarations]
> > |   935 | struct kobj_attribute efi_attr_runtime = __ATTR_RO(runtime);
> > | arch/x86/platform/efi/efi.c:936:23: warning: no previous extern declaration for non-static variable 'efi_attr_config_table' [-Wmissing-variable-declarations]
> > |   936 | struct kobj_attribute efi_attr_config_table = __ATTR_RO(config_table);
> >
> > These variables are not externally declared anywhere (AFAIK)
>
> They are:
>
> drivers/firmware/efi/efi.c:extern __weak struct kobj_attribute
> efi_attr_fw_vendor;
> drivers/firmware/efi/efi.c:extern __weak struct kobj_attribute efi_attr_runtime;
> drivers/firmware/efi/efi.c:extern __weak struct kobj_attribute
> efi_attr_config_table;
>
> > so let's add the static keyword and ensure we follow the ODR.

> This won't work.
>
> Those variables are referenced via weak references in generic code.
> The idea is that the weak references resolve to NULL pointers on
> architectures other than x86, terminating the array early and hiding
> the non-existent variables.
>
> Making them static in arch/x86/platform/efi/efi.c means that these
> references will remain unsatisfied, and so the variables will no
> longer be exposed on x86 either.

So it means that we have no definitions in the header for these, right?

-- 
With Best Regards,
Andy Shevchenko