[Xen-devel] [XEN PATCH v2 11/12] xen/build: introduce ccflags-y and CFLAGS_$@

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

We are going to want $(CFLAGS) to be static and never change during
the build, so introduce new variables that can be use to change the
flags of a single target or of a whole directory.

Those two variables are taken from Kbuild, in Linux v5.4.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 xen/Rules.mk               | 7 ++++++-
 xen/arch/arm/efi/Makefile  | 2 +-
 xen/arch/x86/Makefile      | 6 +++---
 xen/arch/x86/efi/Makefile  | 2 +-
 xen/common/libelf/Makefile | 2 +-
 xen/common/libfdt/Makefile | 2 +-
 xen/xsm/flask/Makefile     | 2 +-
 xen/xsm/flask/ss/Makefile  | 2 +-
 8 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/xen/Rules.mk b/xen/Rules.mk
index c98d5372f3db..f0111f2bc1b4 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -39,6 +39,7 @@ ALL_OBJS-$(CONFIG_CRYPTO)   += $(BASEDIR)/crypto/built_in.o
 
 # Initialise some variables
 CFLAGS_UBSAN :=
+ccflags-y :=
 
 ifeq ($(CONFIG_DEBUG),y)
 CFLAGS += -O1
@@ -137,9 +138,13 @@ endif
 # Always build obj-bin files as binary even if they come from C source. 
 $(obj-bin-y): CFLAGS := $(filter-out -flto,$(CFLAGS))
 
+# target with its suffix stripped
+target-stem = $(basename $@)
+
 c_flags = -MMD -MF $(@D)/.$(@F).d \
           $(CFLAGS) \
-          '-D__OBJECT_FILE__="$@"'
+          '-D__OBJECT_FILE__="$@"' \
+          $(ccflags-y) $(CFLAGS_$(target-stem).o)
 
 a_flags = -MMD -MF $(@D)/.$(@F).d \
           $(AFLAGS)
diff --git a/xen/arch/arm/efi/Makefile b/xen/arch/arm/efi/Makefile
index d34c9168914a..e4aaba3e074b 100644
--- a/xen/arch/arm/efi/Makefile
+++ b/xen/arch/arm/efi/Makefile
@@ -1,4 +1,4 @@
-CFLAGS += -fshort-wchar
+ccflags-y += -fshort-wchar
 
 obj-y +=  boot.init.o runtime.o
 obj-$(CONFIG_ACPI) +=  efi-dom0.init.o
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 472e3fadb719..acf4c145c896 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -174,14 +174,14 @@ EFI_LDFLAGS += --major-subsystem-version=2 
--minor-subsystem-version=0
 export XEN_BUILD_EFI := $(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) 
-c efi/check.c -o efi/check.o 2>/dev/null && echo y)
 # Check if the linker supports PE.
 XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep --subsystem=10 
-o efi/check.efi efi/check.o 2>/dev/null && echo y))
-CFLAGS-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI
+ccflags-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI
 
 $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A 
VIRT_START$$,,p')
 $(TARGET).efi: ALT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A 
ALT_START$$,,p')
 
 ifneq ($(build_id_linker),)
 ifeq ($(call ld-ver-build-id,$(LD) $(filter -m%,$(EFI_LDFLAGS))),y)
-CFLAGS += -DBUILD_ID_EFI
+ccflags-y += -DBUILD_ID_EFI
 EFI_LDFLAGS += $(build_id_linker)
 note_file := efi/buildid.o
 # NB: this must be the last input in the linker call, because inputs following
@@ -227,7 +227,7 @@ efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o 
efi/relocs-dummy.o: ;
 asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c 
$(BASEDIR)/include/asm-x86/asm-macros.h
        $(CC) $(filter-out -Wa$(comma)% -flto,$(c_flags)) -S -o $@ $<
 
-asm-macros.i: CFLAGS += -D__ASSEMBLY__ -P
+CFLAGS_asm-macros.o += -D__ASSEMBLY__ -P
 
 $(BASEDIR)/include/asm-x86/asm-macros.h: asm-macros.i Makefile
        echo '#if 0' >$@.new
diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 4bc0a196e9ca..2cbb3de3a8ab 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -1,4 +1,4 @@
-CFLAGS += -fshort-wchar
+ccflags-y += -fshort-wchar
 
 %.o: %.ihex
        $(OBJCOPY) -I ihex -O binary $< $@
diff --git a/xen/common/libelf/Makefile b/xen/common/libelf/Makefile
index 3d9e38f27e65..9a433f01fbd4 100644
--- a/xen/common/libelf/Makefile
+++ b/xen/common/libelf/Makefile
@@ -3,7 +3,7 @@ nocov-y += libelf.o
 
 SECTIONS := text data $(SPECIAL_DATA_SECTIONS)
 
-CFLAGS += -Wno-pointer-sign
+ccflags-y += -Wno-pointer-sign
 
 libelf.o: libelf-temp.o Makefile
        $(OBJCOPY) $(foreach s,$(SECTIONS),--rename-section .$(s)=.init.$(s)) 
$< $@
diff --git a/xen/common/libfdt/Makefile b/xen/common/libfdt/Makefile
index c075bbf5462a..9ea5c696d52a 100644
--- a/xen/common/libfdt/Makefile
+++ b/xen/common/libfdt/Makefile
@@ -5,7 +5,7 @@ SECTIONS := text data $(SPECIAL_DATA_SECTIONS)
 obj-y += libfdt.o
 nocov-y += libfdt.o
 
-CFLAGS += -I$(BASEDIR)/include/xen/libfdt/
+ccflags-y += -I$(BASEDIR)/include/xen/libfdt/
 
 libfdt.o: libfdt-temp.o Makefile
        $(OBJCOPY) $(foreach s,$(SECTIONS),--rename-section .$(s)=.init.$(s)) 
$< $@
diff --git a/xen/xsm/flask/Makefile b/xen/xsm/flask/Makefile
index b1fd45421993..3bf0a6fa0456 100644
--- a/xen/xsm/flask/Makefile
+++ b/xen/xsm/flask/Makefile
@@ -4,7 +4,7 @@ obj-y += flask_op.o
 
 obj-y += ss/
 
-CFLAGS += -I./include
+ccflags-y += -I./include
 
 AWK = awk
 
diff --git a/xen/xsm/flask/ss/Makefile b/xen/xsm/flask/ss/Makefile
index 046ce8f53326..30f910a9c9c1 100644
--- a/xen/xsm/flask/ss/Makefile
+++ b/xen/xsm/flask/ss/Makefile
@@ -8,4 +8,4 @@ obj-y += services.o
 obj-y += conditional.o
 obj-y += mls.o
 
-CFLAGS += -I../include
+ccflags-y += -I../include
-- 
Anthony PERARD


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