[PATCH 5.10 179/462] efi: libstub: Use -std=gnu11 to fix build with GCC 15
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2025-03-11 15:28:32
Also in:
stable
5.10-stable review patch. If anyone has any objections, please let me know.
------------------
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 <redacted>
Closes: https://lore.kernel.org/4OAhbllK7x4QJGpZjkYjtBYNLd_2whHx9oFiuZcGwtVR4hIzvduultkgfAIRZI3vQpZylu7Gl929HaYFRGeMEalWCpeMzCIIhLxxRhq4U-Y=@protonmail.com/ (local)
Reported-by: Jakub Jelinek <redacted>
Closes: https://lore.kernel.org/Z4467umXR2PZ0M1H@tucnak/ (local)
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/firmware/efi/libstub/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 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__ \ +cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -std=gnu11 \ -fPIC -fno-strict-aliasing -mno-red-zone \ -mno-mmx -mno-sse -fshort-wchar \ -Wno-pointer-sign \