From: Nathan Chancellor nathan@kernel.org
commit 8ba14d9f490aef9fd535c04e9e62e1169eb7a055 upstream.
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 EFI libstub Makefile uses its own set of KBUILD_CFLAGS for x86 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 cflags to resolve the error and consistently use the same C standard version for the entire kernel. All other architectures reuse KBUILD_CFLAGS from the rest of the kernel, so this issue is not visible for them.
Cc: stable@vger.kernel.org Reported-by: Kostadin Shishmanov kostadinshishmanov@protonmail.com Closes: https://lore.kernel.org/4OAhbllK7x4QJGpZjkYjtBYNLd_2whHx9oFiuZcGwtVR4hIzvduu... Reported-by: Jakub Jelinek jakub@redhat.com Closes: https://lore.kernel.org/Z4467umXR2PZ0M1H@tucnak/ Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Ard Biesheuvel ardb@kernel.org [ Conflict in the context, because commit bbf8e8b0fe04 ("efi/libstub: Optimize for size instead of speed") is not in this version. '-std=gnu11' can still be added at the same place. ] Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- drivers/firmware/efi/libstub/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 8c5b5529dbc0..0dc80564bbd2 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -7,7 +7,7 @@ # cflags-$(CONFIG_X86_32) := -march=i386 cflags-$(CONFIG_X86_64) := -mcmodel=small -cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 \ +cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 -std=gnu11 \ -fPIC -fno-strict-aliasing -mno-red-zone \ -mno-mmx -mno-sse -fshort-wchar \ -Wno-pointer-sign \