On Tue, Nov 19, 2024 at 1:47 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > On Tue, Nov 19, 2024 at 04:24:41AM +0000, Sam James wrote: > > This is the conclusion I just reached, although I'm struggling to figure > > out a nice place to put it without sprinkling it all over the place. I'm > > inclined to wait until kbuild folks weigh in so I don't do a lot of > > (trivial, but tedious) work that needs changing. > > Sure. Masahiro, do you have any thoughts here? You can see the beginning > of the thread at [1]. > > I think the diff below would be a good first patch in a series that adds > it to every other place that needs it. As you noticed, it probably makes > sense to add it to most places that have CLANG_FLAGS, as that is a good > indicator that KBUILD_CFLAGS is not being used properly in those spots. I do not think this would solve the issue. The attached diff will be useful when we bump -std=gnu* next time; we would only need to change the single line. However, this kind of change does not occur quite often. Anyway, we would do "git grep std=gnu11" to make sure there is no left-over. It is not helpful to detect the reported issue in drivers/firmware/efi/libstub/Makefile. Some Makefile overriding KBUILD_CFLAGS would forget to add $(CSTD_FLAG), for the same reason as they would forget to add -std=gnu11. > > As a hack, I've injected it into CLANG_FLAGS locally for now as it > > happens to appear in all the right places ;) > > :) exactly why I am quite familiar with this issue... > > [1]: https://lore.kernel.org/4OAhbllK7x4QJGpZjkYjtBYNLd_2whHx9oFiuZcGwtVR4hIzvduultkgfAIRZI3vQpZylu7Gl929HaYFRGeMEalWCpeMzCIIhLxxRhq4U-Y=@protonmail.com/ > > Cheers, > Nathan > > diff --git a/Makefile b/Makefile > index 68a8faff2543..33cc6bcf39b5 100644 > --- a/Makefile > +++ b/Makefile > @@ -416,6 +416,8 @@ export KCONFIG_CONFIG > # SHELL used by kbuild > CONFIG_SHELL := sh > > +CSTD_FLAG := -std=gnu11 > + > HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null) > HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null) > HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null) > @@ -437,7 +439,7 @@ HOSTRUSTC = rustc > HOSTPKG_CONFIG = pkg-config > > KBUILD_USERHOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \ > - -O2 -fomit-frame-pointer -std=gnu11 > + -O2 -fomit-frame-pointer $(CSTD_FLAG) > KBUILD_USERCFLAGS := $(KBUILD_USERHOSTCFLAGS) $(USERCFLAGS) > KBUILD_USERLDFLAGS := $(USERLDFLAGS) > > @@ -545,7 +547,7 @@ LINUXINCLUDE := \ > KBUILD_AFLAGS := -D__ASSEMBLY__ -fno-PIE > > KBUILD_CFLAGS := > -KBUILD_CFLAGS += -std=gnu11 > +KBUILD_CFLAGS += $(CSTD_FLAG) > KBUILD_CFLAGS += -fshort-wchar > KBUILD_CFLAGS += -funsigned-char > KBUILD_CFLAGS += -fno-common > @@ -589,7 +591,7 @@ export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AW > export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX > export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD > export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE > -export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS > +export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS CSTD_FLAG > > export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS > export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE > diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile > index 25a2cb6317f3..5f9d5c38ed9e 100644 > --- a/arch/arm64/kernel/vdso32/Makefile > +++ b/arch/arm64/kernel/vdso32/Makefile > @@ -65,7 +65,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ > -fno-strict-aliasing -fno-common \ > -Werror-implicit-function-declaration \ > -Wno-format-security \ > - -std=gnu11 > + $(CSTD_FLAG) > VDSO_CFLAGS += -O2 > # Some useful compiler-dependent flags from top-level Makefile > VDSO_CFLAGS += $(call cc32-option,-Wno-pointer-sign) > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 5b773b34768d..d5c851dd0653 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -47,7 +47,7 @@ endif > > # How to compile the 16-bit code. Note we always compile for -march=i386; > # that way we can complain to the user if the CPU is insufficient. > -REALMODE_CFLAGS := -std=gnu11 -m16 -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \ > +REALMODE_CFLAGS := $(CSTD_FLAG) -m16 -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \ > -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \ > -fno-strict-aliasing -fomit-frame-pointer -fno-pic \ > -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none) -- Best Regards Masahiro Yamada
