The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: ee2ab467bddfb2d7f68d996dbab94d7b88f8eaf7 Gitweb: https://git.kernel.org/tip/ee2ab467bddfb2d7f68d996dbab94d7b88f8eaf7 Author: Nathan Chancellor nathan@kernel.org AuthorDate: Tue, 21 Jan 2025 18:11:33 -07:00 Committer: Dave Hansen dave.hansen@linux.intel.com CommitterDate: Thu, 30 Jan 2025 09:59:24 -08:00

x86/boot: Use '-std=gnu11' to fix build with GCC 15

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.

Closes: https://lore.kernel.org/4OAhbllK7x4QJGpZjkYjtBYNLd_2whHx9oFiuZcGwtVR4hIzvduu... Closes: https://lore.kernel.org/Z4467umXR2PZ0M1H@tucnak/ Reported-by: Kostadin Shishmanov kostadinshishmanov@protonmail.com Reported-by: Jakub Jelinek jakub@redhat.com Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Dave Hansen dave.hansen@linux.intel.com Reviewed-by: Ard Biesheuvel ardb@kernel.org Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250121-x86-use-std-consistently-gcc-15-v1-1-8a... --- 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 f205164..606c74f 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