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    SubjectRe: [PATCH 1/3] kbuild: Add cc-option-no-kbuild macro
    On Tue, Jun 13, 2017 at 9:49 AM, Michal Marek <mmarek@suse.com> wrote:
    > On 2017-06-13 02:55, Matthias Kaehlcke wrote:
    >> cc-option uses KBUILD_CFLAGS and KBUILD_CPPFLAGS when it determines
    >> whether an option is supported or not. This is fine for options used to
    >> build the kernel itself, however some components like the x86 boot code
    >> use a different set of flags.
    >>
    >> Add the new macro cc-option-no-kbuild which does the same as cc-option
    >> except that it has an additional parameter with the compiler options
    >> which are used instead of KBUILD_CFLAGS and KBUILD_CPPFLAGS.
    >>
    >> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
    >> ---
    >> scripts/Kbuild.include | 5 +++++
    >> 1 file changed, 5 insertions(+)
    >>
    >> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
    >> index 61f87a99bf0a..d9fdc740105f 100644
    >> --- a/scripts/Kbuild.include
    >> +++ b/scripts/Kbuild.include
    >> @@ -128,6 +128,11 @@ cc-option-yn = $(call try-run,\
    >> cc-option-align = $(subst -functions=0,,\
    >> $(call cc-option,-falign-functions=0,-malign-functions=0))
    >>
    >> +# cc-option-no-kbuild
    >> +# Usage: cflags-no-kbuild-y += $(call cc-option-no-kbuild,<other flags>,-march=winchip-c6,-march=i586)
    >> +cc-option-no-kbuild = $(call try-run,\
    >> + $(CC) -Werror $(filter-out $(GCC_PLUGINS_CFLAGS),$(1)) $(2) -c -x c /dev/null -o "$$TMP",$(2),$(3))
    >
    > As this is a version of cc-option with an extrra argument, how about
    > implementing cc-option as a shorthand for cc-option-no-kbuild? It would
    > make it more obvious what cc-option-no-kbuild does differently (it's
    > probably just me, but I was unable to infer the semantics from its name).

    Agreed, also the hostcc-option could be based on the same I think, if we
    also make the $(CC) an argument of the low-level helper.

    For reference, these seem to be the files that might be affected here,
    as they override KBUILD_CFLAGS:

    $ git grep -w KBUILD_CFLAGS.*:
    arch/cris/Makefile:KBUILD_CFLAGS := $(subst
    -fomit-frame-pointer,,$(KBUILD_CFLAGS)) -g
    arch/ia64/Makefile:KBUILD_CFLAGS_KERNEL := -mconstant-gp
    arch/m68k/Makefile:KBUILD_CFLAGS := $(subst
    -fomit-frame-pointer,,$(KBUILD_CFLAGS)) -g
    arch/mips/boot/compressed/Makefile:KBUILD_CFLAGS := $(filter-out -pg,
    $(KBUILD_CFLAGS))
    arch/mips/boot/compressed/Makefile:KBUILD_CFLAGS := $(filter-out
    -fstack-protector, $(KBUILD_CFLAGS))
    arch/mips/boot/compressed/Makefile:KBUILD_CFLAGS := $(KBUILD_CFLAGS)
    -D__KERNEL__ \
    arch/mips/vdso/Makefile:$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso)
    $(native-abi)
    arch/mips/vdso/Makefile:$(obj-vdso-o32): KBUILD_CFLAGS :=
    $(cflags-vdso) -mabi=32
    arch/mips/vdso/Makefile:$(obj-vdso-n32): KBUILD_CFLAGS :=
    $(cflags-vdso) -mabi=n32
    arch/s390/boot/compressed/Makefile:KBUILD_CFLAGS := -m64 -D__KERNEL__ -O2
    arch/s390/kernel/vdso32/Makefile:KBUILD_CFLAGS_31 := $(filter-out
    -m64,$(KBUILD_CFLAGS))
    arch/s390/kernel/vdso64/Makefile:KBUILD_CFLAGS_64 := $(filter-out
    -m64,$(KBUILD_CFLAGS))
    arch/tile/kernel/vdso/Makefile:KBUILD_CFLAGS_32 := $(filter-out
    -m64,$(KBUILD_CFLAGS))
    arch/x86/boot/Makefile:KBUILD_CFLAGS := $(REALMODE_CFLAGS) -D_SETUP
    arch/x86/boot/compressed/Makefile:KBUILD_CFLAGS := -m$(BITS) -D__KERNEL__ -O2
    arch/x86/entry/vdso/Makefile:$(vobjs): KBUILD_CFLAGS := $(filter-out
    $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
    arch/x86/entry/vdso/Makefile:KBUILD_CFLAGS_32 := $(filter-out
    -m64,$(KBUILD_CFLAGS))
    arch/x86/entry/vdso/Makefile:KBUILD_CFLAGS_32 := $(filter-out
    -mcmodel=kernel,$(KBUILD_CFLAGS_32))
    arch/x86/entry/vdso/Makefile:KBUILD_CFLAGS_32 := $(filter-out
    -fno-pic,$(KBUILD_CFLAGS_32))
    arch/x86/entry/vdso/Makefile:KBUILD_CFLAGS_32 := $(filter-out
    -mfentry,$(KBUILD_CFLAGS_32))
    arch/x86/entry/vdso/Makefile:KBUILD_CFLAGS_32 := $(filter-out
    $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
    arch/x86/purgatory/Makefile:KBUILD_CFLAGS := -fno-strict-aliasing
    -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin
    -ffreestanding -c -MD -Os -mcmodel=large
    arch/x86/realmode/rm/Makefile:KBUILD_CFLAGS := $(REALMODE_CFLAGS)
    -D_SETUP -D_WAKEUP \
    drivers/firmware/efi/libstub/Makefile:KBUILD_CFLAGS
    := $(cflags-y) -DDISABLE_BRANCH_PROFILING \

    Arnd

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