On Wed, 30 Aug 2023 at 15:25, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > 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? > Indeed. If there are better ways of fixing this that don't involve weak references, I am also fine with that, but just moving the existing extern declarations into linux/efi.h is probably the easiest approach here.
