On Sat, Mar 29, 2025 at 08:39:03AM -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 as specified in KBUILD_CFLAGS 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@gmail.com Cc: stable@vger.kernel.org

---

v2: Filter the -std flag from KBUILD_CFLAGS instead of hardcoding v3: Adjust subject and commit message

arch/mips/vdso/Makefile | 1 + 1 file changed, 1 insertion(+)

diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile index fb4c493aaffa..69d4593f64fe 100644 --- a/arch/mips/vdso/Makefile +++ b/arch/mips/vdso/Makefile @@ -27,6 +27,7 @@ endif # offsets. cflags-vdso := $(ccflags-vdso) \ $(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \

• $(filter -std=%,$(KBUILD_CFLAGS)) \ -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 \

applied to mips-next.

Thomas.