On Tue, Feb 25, 2014 at 05:08:39PM -0800, behanw@xxxxxxxxxxxxxxxxxx wrote: > From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx> > > Add support to toplevel Makefile for compiling with clang, both for > HOSTCC and CC. Use cc-option to prevent gcc option from breaking clang, and > from clang options from breaking gcc. > > Clang 3.4 semantics are the same as gcc semantics for unsupported flags. For > unsupported warnings clang 3.4 returns true but shows a warning and gcc shows > a warning and returns false. > > Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Jan-Simon Möller <dl9pf@xxxxxx> > Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx> > Cc: PaX Team <pageexec@xxxxxxxxxxx> > --- > Makefile | 32 +++++++++++++++++++++++++++++++- > 1 file changed, 31 insertions(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index 831b36a..c4ab30d 100644 > --- a/Makefile > +++ b/Makefile > @@ -247,6 +247,15 @@ HOSTCXX = g++ > HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer > HOSTCXXFLAGS = -O2 > > +ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1) > +HOSTCOMPILER := clang > +HOSTCFLAGS += -Wno-unused-value -Wno-unused-parameter \ > + -Wno-missing-field-initializers -fno-delete-null-pointer-checks > +else > +HOSTCOMPILER := gcc > +endif > +export HOSTCOMPILER I see no use of HOSTCOMPLIER anywhere in this patchset not in the kernel. Can we drop this? > + > # Decide whether to build built-in, modular, or both. > # Normally, just do built-in. > > @@ -323,6 +332,12 @@ endif > > export quiet Q KBUILD_VERBOSE > > +ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1) > +COMPILER := clang > +else > +COMPILER := gcc > +endif > +export COMPILER Likewise - COMPILER seems unsued- can it be dropped? > > # Look for make include files relative to root of kernel src > MAKEFLAGS += --include-dir=$(srctree) > @@ -382,7 +397,7 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ > -fno-strict-aliasing -fno-common \ > -Werror-implicit-function-declaration \ > -Wno-format-security \ > - -fno-delete-null-pointer-checks > + $(call cc-option,-fno-delete-null-pointer-checks,) > KBUILD_AFLAGS_KERNEL := > KBUILD_CFLAGS_KERNEL := > KBUILD_AFLAGS := -D__ASSEMBLY__ > @@ -620,9 +635,24 @@ else > endif > KBUILD_CFLAGS += $(stackp-flag) > > +ifeq ($(COMPILER),clang) Except that COMPILER is used here. But this does not warrant the export. > +KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) Is this really needed today? https://bugzilla.mozilla.org/show_bug.cgi?id=717713 suggest that this is default. > +KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,) https://bugzilla.mozilla.org/show_bug.cgi?id=731316 seems to suggest this is default > +KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable) > +KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > +KBUILD_CFLAGS += $(call cc-disable-warning, gnu) Is it really justified to disable these warnings? # of warnign for a defconfig build would be a nice figure to judge from. > +# Quiet clang warning: comparison of unsigned expression < 0 is always false > +KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) Same with this. > +# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > +# source of a reference will be _MergedGlobals and not on of the whitelisted names. > +# See modpost pattern 2 > +KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) Should we fix modpost? Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
