On Wed, 22 Jan 2025 at 02:12, Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > GCC 15 changed the default C standard version to C23, which should not > have impacted the kernel because it requests the gnu11 standard via > '-std=' in the main Makefile. However, the x86 compressed boot Makefile > uses its own set of KBUILD_CFLAGS without a '-std=' value (i.e., using > the default), resulting in errors from the kernel's definitions of bool, > true, and false in stddef.h, which are reserved keywords under C23. > > ./include/linux/stddef.h:11:9: error: expected identifier before ‘false’ > 11 | false = 0, > ./include/linux/types.h:35:33: error: two or more data types in declaration specifiers > 35 | typedef _Bool bool; > > Set '-std=gnu11' in the x86 compressed boot Makefile to resolve the > error and consistently use the same C standard version for the entire > kernel. > > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Kostadin Shishmanov <kostadinshishmanov@xxxxxxxxxxxxxx> > Closes: https://lore.kernel.org/4OAhbllK7x4QJGpZjkYjtBYNLd_2whHx9oFiuZcGwtVR4hIzvduultkgfAIRZI3vQpZylu7Gl929HaYFRGeMEalWCpeMzCIIhLxxRhq4U-Y=@protonmail.com/ > Reported-by: Jakub Jelinek <jakub@xxxxxxxxxx> > Closes: https://lore.kernel.org/Z4467umXR2PZ0M1H@tucnak/ > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > --- > arch/x86/boot/compressed/Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile > index f2051644de94..606c74f27459 100644 > --- a/arch/x86/boot/compressed/Makefile > +++ b/arch/x86/boot/compressed/Makefile > @@ -25,6 +25,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \ > # avoid errors with '-march=i386', and future flags may depend on the target to > # be valid. > KBUILD_CFLAGS := -m$(BITS) -O2 $(CLANG_FLAGS) > +KBUILD_CFLAGS += -std=gnu11 > KBUILD_CFLAGS += -fno-strict-aliasing -fPIE > KBUILD_CFLAGS += -Wundef > KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING > Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
