| Message ID | 20170410210904.68211-1-mka@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Matthias, 2017-04-11 6:09 GMT+09:00 Matthias Kaehlcke <mka@chromium.org>: > COMPILER is previously set to "clang" if CC=clang was set from the > make command line. So -target and -gcc-toolchain can be added to CC, > since we already know that it is set. Can you reword or delete this paragraph? I think this is confusing because COMPILER was replaced with cc-name by commit 5631d9c4. > Clang will fallback to using things like ld, as, and libgcc if > (respectively) one of the llvm linkers isn't available, the integrated > assembler is turned off, or an appropriately cross-compiled version of > compiler-rt isn't available. To this end, you can specify the path to > this fallback gcc toolchain with GCC_TOOLCHAIN. > > From: Behan Webster <behanw@converseincode.com> > Signed-off-by: Behan Webster <behanw@converseincode.com> > Reviewed-by: Jan-Simon Möller <dl9pf@gmx.de> > Reviewed-by: Mark Charlebois <charlebm@gmail.com> > Signed-off-by: Greg Hackmann <ghackmann@google.com> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org> > --- > Changes in v2: > - Fix GCC_TOOLCHAIN definition. $(LD) is needed to link the kernel, use > its path to determine the installation prefix of the toolchain. > (From: Greg Hackmann <ghackmann@google.com>) > > Makefile | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/Makefile b/Makefile > index e11989d36c87..d3a02786bb53 100644 > --- a/Makefile > +++ b/Makefile > @@ -375,6 +375,16 @@ LDFLAGS_vmlinux = > CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized > CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) > > +ifeq ($(cc-name),clang) > +ifneq ($(CROSS_COMPILE),) > +CLANG_TARGET := -target $(notdir $(CROSS_COMPILE:%-=%)) > +GCC_TOOLCHAIN := $(realpath $(dir $(shell which $(LD)))/..) > +endif > +ifneq ($(GCC_TOOLCHAIN),) > +CLANG_GCC_TC := -gcc-toolchain $(GCC_TOOLCHAIN) > +endif > +CLANG_FLAGS := $(CLANG_TARGET) $(CLANG_GCC_TC) > +endif > > # Use USERINCLUDE when you must reference the UAPI directories only. > USERINCLUDE := \ > @@ -395,18 +405,18 @@ LINUXINCLUDE := \ > > LINUXINCLUDE += $(filter-out $(LINUXINCLUDE),$(USERINCLUDE)) > > -KBUILD_CPPFLAGS := -D__KERNEL__ > +KBUILD_CPPFLAGS := -D__KERNEL__ $(CLANG_FLAGS) > > KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ > -fno-strict-aliasing -fno-common \ > -Werror-implicit-function-declaration \ > -Wno-format-security \ > - -std=gnu89 $(call cc-option,-fno-PIE) > - > + -std=gnu89 $(call cc-option,-fno-PIE) \ > + $(CLANG_FLAGS) > > KBUILD_AFLAGS_KERNEL := > KBUILD_CFLAGS_KERNEL := > -KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE) > +KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE) $(CLANG_FLAGS) This adds multiple -gcc-toolchain because both KBUILD_CPPFLAGS and KBUILD_CFLAGS are added to c_flags. See scripts/Makefile.lib orig_c_flags = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \ $(ccflags-y) $(CFLAGS_$(basetarget).o) Pre-processing is related to the front-end part, so -target and -gcc-toolchain are not necessary for KBUILD_CPPFLAGS? Maybe, adding it to KBUILD_CFLAGS and KBUILD_AFLAGS could be enough? Is it possible to move these to around line 700? ifeq ($(cc-name),clang) < add here ? > KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,) I do not want to sprinkle ugly ifeq ($(cc-name,clang).
Hi Masahiro, Thanks for your comments. El Fri, Apr 21, 2017 at 05:24:31PM +0900 Masahiro Yamada ha dit: > 2017-04-11 6:09 GMT+09:00 Matthias Kaehlcke <mka@chromium.org>: > > > > COMPILER is previously set to "clang" if CC=clang was set from the > > make command line. So -target and -gcc-toolchain can be added to CC, > > since we already know that it is set. > > Can you reword or delete this paragraph? > I think this is confusing because COMPILER was replaced with cc-name > by commit 5631d9c4. Ok, I think not much is lost by deleting it. <snip> > > -KBUILD_CPPFLAGS := -D__KERNEL__ > > +KBUILD_CPPFLAGS := -D__KERNEL__ $(CLANG_FLAGS) > > > > KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ > > -fno-strict-aliasing -fno-common \ > > -Werror-implicit-function-declaration \ > > -Wno-format-security \ > > - -std=gnu89 $(call cc-option,-fno-PIE) > > - > > + -std=gnu89 $(call cc-option,-fno-PIE) \ > > + $(CLANG_FLAGS) > > > > KBUILD_AFLAGS_KERNEL := > > KBUILD_CFLAGS_KERNEL := > > -KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE) > > +KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE) $(CLANG_FLAGS) > > > This adds multiple -gcc-toolchain because both KBUILD_CPPFLAGS and KBUILD_CFLAGS > are added to c_flags. See scripts/Makefile.lib > > orig_c_flags = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \ > $(ccflags-y) $(CFLAGS_$(basetarget).o) > > > Pre-processing is related to the front-end part, > so -target and -gcc-toolchain are not necessary for KBUILD_CPPFLAGS? > > Maybe, adding it to KBUILD_CFLAGS and KBUILD_AFLAGS could be enough? Indeed it seems it is not needed in KBUILD_CPPFLAGS, at least I encountered no issues in a x86 and arm64 build. > Is it possible to move these to around line 700? > > ifeq ($(cc-name),clang) > < add here ? > > KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,) > > I do not want to sprinkle ugly ifeq ($(cc-name,clang). I agree, better concentrate clang specific stuff when possible. I'll rework the patch and send out an update shortly. Cheers Matthias -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index e11989d36c87..d3a02786bb53 100644 --- a/Makefile +++ b/Makefile @@ -375,6 +375,16 @@ LDFLAGS_vmlinux = CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) +ifeq ($(cc-name),clang) +ifneq ($(CROSS_COMPILE),) +CLANG_TARGET := -target $(notdir $(CROSS_COMPILE:%-=%)) +GCC_TOOLCHAIN := $(realpath $(dir $(shell which $(LD)))/..) +endif +ifneq ($(GCC_TOOLCHAIN),) +CLANG_GCC_TC := -gcc-toolchain $(GCC_TOOLCHAIN) +endif +CLANG_FLAGS := $(CLANG_TARGET) $(CLANG_GCC_TC) +endif # Use USERINCLUDE when you must reference the UAPI directories only. USERINCLUDE := \ @@ -395,18 +405,18 @@ LINUXINCLUDE := \ LINUXINCLUDE += $(filter-out $(LINUXINCLUDE),$(USERINCLUDE)) -KBUILD_CPPFLAGS := -D__KERNEL__ +KBUILD_CPPFLAGS := -D__KERNEL__ $(CLANG_FLAGS) KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common \ -Werror-implicit-function-declaration \ -Wno-format-security \ - -std=gnu89 $(call cc-option,-fno-PIE) - + -std=gnu89 $(call cc-option,-fno-PIE) \ + $(CLANG_FLAGS) KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := -KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE) +KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE) $(CLANG_FLAGS) KBUILD_AFLAGS_MODULE := -DMODULE KBUILD_CFLAGS_MODULE := -DMODULE KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds