On Fri, Mar 21, 2025 at 05:09:40PM -0700 Khem Raj wrote:
> GCC 15 changed the default C standard dialect from gnu17 to gnu23,
> which should not have impacted the kernel because it explicitly requests
> the gnu11 standard in the main Makefile. However, mips/vdso code uses
> its own CFLAGS without a '-std=' value, which break with this dialect
> change because of the kernel's own definitions of bool, false, and true
> conflicting with the C23 reserved keywords.
>
> include/linux/stddef.h:11:9: error: cannot use keyword 'false' as enumeration constant
> 11 | false = 0,
> | ^~~~~
> include/linux/stddef.h:11:9: note: 'false' is a keyword with '-std=c23' onwards
> include/linux/types.h:35:33: error: 'bool' cannot be defined via 'typedef'
> 35 | typedef _Bool bool;
> | ^~~~
> include/linux/types.h:35:33: note: 'bool' is a keyword with '-std=c23' onwards
>
> Add '-std=gnu11' to the decompressor and purgatory CFLAGS to eliminate
> these errors and make the C standard version of these areas match the
> rest of the kernel.
>
> Signed-off-by: Khem Raj <raj.khem@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> arch/mips/vdso/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
> index b289b2c1b294..15521004c563 100644
> --- a/arch/mips/vdso/Makefile
> +++ b/arch/mips/vdso/Makefile
> @@ -30,7 +30,7 @@ cflags-vdso := $(ccflags-vdso) \
> -O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
> -mrelax-pic-calls $(call cc-option, -mexplicit-relocs) \
> -fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
> - $(call cc-option, -fno-asynchronous-unwind-tables)
> + $(call cc-option, -fno-asynchronous-unwind-tables) -std=gnu11
> aflags-vdso := $(ccflags-vdso) \
> -D__ASSEMBLY__ -Wa,-gdwarf-2
>
Thanks for the patch. Did you evaluate adding a line like
$(filter -std=%,$(KBUILD_CFLAGS)) \
to the assignment of ccflags-vdso? Then MIPS VDSO C standard keeps aligned
with top-level.
Nevertheless,
Reviewed-by: Nicolas Schier <nicolas@xxxxxxxxx>
