Makefile: Replace flag -DX with -DX= to be supported by IS_ENABLED().

IS_ENABLED works for an empty-string-defined macro.
However, -D options default to define the macro to 1.  This CL forces
those macros, such as BOARD_* CHIP_*, CORE_*, CHIP_VARIANT_* and
CHIP_FAMILIY_*, to be defined as an empty string, so that it can
be supported by IS_ENABLED macro.

TEST=use if(IS_ENABLED(BOARD_KRANE)) and see compilation success.
TEST=compares build directory w/ and w/o this CL, and see the .smap
     are the same:
     ls build/*/*/ec.*.smap | sed -e 's|build/||' | \
     xargs -I{} diff -u -a build/{} build.new/{}
BUG=none
BRANCH=None

Change-Id: I96e2aa1cb5f3369e5e445a674595a9234f26707a
Signed-off-by: Yilun Lin <yllin@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1627840
Commit-Ready: Yilun Lin <yllin@chromium.org>
Tested-by: Yilun Lin <yllin@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Jett Rink <jettrink@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

9 files changed, 59 insertions, 49 deletions

diff --git a/Makefile b/Makefile
index 354c0bf14a..3ccef58b91 100644
--- a/Makefile
+++ b/Makefile
@@ -41,6 +41,11 @@ endif
 
 PROJECT?=ec
 
+# An empty string.
+# "-DMACRO" leads to MACRO=1.  Define an empty string "-DMACRO=" to take
+# advantage of IS_ENABLED magic macro, which only allows an empty string.
+EMPTY=
+
 # Output directory for build objects
 ifdef CTS_MODULE
 # CTS builds need different directories per board per suite.
@@ -98,7 +103,7 @@ endif
 # Baseboard directory
 ifneq (,$(BASEBOARD))
 BASEDIR:=baseboard/$(BASEBOARD)
-CFLAGS_BASEBOARD=-DHAS_BASEBOARD -DBASEBOARD_$(UC_BASEBOARD)
+CFLAGS_BASEBOARD=-DHAS_BASEBOARD=$(EMPTY) -DBASEBOARD_$(UC_BASEBOARD)=$(EMPTY)
 include $(BASEDIR)/build.mk
 else
 # If BASEBOARD is not defined, then assign BASEDIR to BDIR. This avoids
@@ -130,8 +135,8 @@ includes+=cts/$(CTS_MODULE) cts
 endif
 ifeq "$(TEST_BUILD)" "y"
 	_tsk_lst_file:=ec.tasklist
-	_tsk_lst_flags:=$(if $(TEST_FUZZ),-Ifuzz,-Itest) -DTEST_BUILD -imacros \
-			$(PROJECT).tasklist
+	_tsk_lst_flags:=$(if $(TEST_FUZZ),-Ifuzz,-Itest) -DTEST_BUILD=$(EMPTY) \
+			-imacros $(PROJECT).tasklist
 else ifdef CTS_MODULE
 	_tsk_lst_file:=ec.tasklist
 	_tsk_lst_flags:=-I cts/$(CTS_MODULE) -Icts -DCTS_MODULE=$(CTS_MODULE) \
@@ -141,13 +146,13 @@ else
 	_tsk_lst_flags:=
 endif
 
-_tsk_lst_flags+=-I$(BDIR) -DBOARD_$(UC_BOARD) -I$(BASEDIR) \
-		-DBASEBOARD_$(UC_BASEBOARD) -D_MAKEFILE \
-		-imacros $(_tsk_lst_file)
+_tsk_lst_flags+=-I$(BDIR) -DBOARD_$(UC_BOARD)=$(EMPTY) -I$(BASEDIR) \
+		-DBASEBOARD_$(UC_BASEBOARD)=$(EMPTY) \
+		-D_MAKEFILE=$(EMPTY) -imacros $(_tsk_lst_file)
 
-_tsk_lst_ro:=$(shell $(CPP) -P -DSECTION_IS_RO \
+_tsk_lst_ro:=$(shell $(CPP) -P -DSECTION_IS_RO=$(EMPTY) \
 	$(_tsk_lst_flags) include/task_filter.h)
-_tsk_lst_rw:=$(shell $(CPP) -P -DSECTION_IS_RW \
+_tsk_lst_rw:=$(shell $(CPP) -P -DSECTION_IS_RW=$(EMPTY) \
 	$(_tsk_lst_flags) include/task_filter.h)
 
 _tsk_cfg_ro:=$(foreach t,$(_tsk_lst_ro) ,HAS_TASK_$(t))
@@ -157,22 +162,22 @@ _tsk_cfg:= $(filter $(_tsk_cfg_ro), $(_tsk_cfg_rw))
 _tsk_cfg_ro:= $(filter-out $(_tsk_cfg), $(_tsk_cfg_ro))
 _tsk_cfg_rw:= $(filter-out $(_tsk_cfg), $(_tsk_cfg_rw))
 
-CPPFLAGS_RO+=$(foreach t,$(_tsk_cfg_ro),-D$(t)) \
-		$(foreach t,$(_tsk_cfg_rw),-D$(t)_RW)
-CPPFLAGS_RW+=$(foreach t,$(_tsk_cfg_rw),-D$(t)) \
-		$(foreach t,$(_tsk_cfg_ro),-D$(t)_RO)
-CPPFLAGS+=$(foreach t,$(_tsk_cfg),-D$(t))
+CPPFLAGS_RO+=$(foreach t,$(_tsk_cfg_ro),-D$(t)=$(EMPTY)) \
+		$(foreach t,$(_tsk_cfg_rw),-D$(t)_RW=$(EMPTY))
+CPPFLAGS_RW+=$(foreach t,$(_tsk_cfg_rw),-D$(t)=$(EMPTY)) \
+		$(foreach t,$(_tsk_cfg_ro),-D$(t)_RO=$(EMPTY))
+CPPFLAGS+=$(foreach t,$(_tsk_cfg),-D$(t)=$(EMPTY))
 ifneq ($(ENV_VARS),)
-CPPFLAGS += -DINCLUDE_ENV_CONFIG
+CPPFLAGS += -DINCLUDE_ENV_CONFIG=$(EMPTY)
 CFLAGS += -I$(realpath $(out))
 endif
 # Get the CONFIG_ and VARIANT_ options that are defined for this target and make
 # them into variables available to this build script
 _flag_cfg_ro:=$(shell $(CPP) $(CPPFLAGS) -P -dM -Ichip/$(CHIP) \
-	-I$(BASEDIR) -I$(BDIR) -DSECTION_IS_RO include/config.h | \
+	-I$(BASEDIR) -I$(BDIR) -DSECTION_IS_RO=$(EMPTY) include/config.h | \
 	grep -o "\#define \(CONFIG\|VARIANT\)_[A-Z0-9_]*" | cut -c9- | sort)
 _flag_cfg_rw:=$(_tsk_cfg_rw) $(shell $(CPP) $(CPPFLAGS) -P -dM -Ichip/$(CHIP) \
-	-I$(BASEDIR) -I$(BDIR) -DSECTION_IS_RW include/config.h | \
+	-I$(BASEDIR) -I$(BDIR) -DSECTION_IS_RW=$(EMPTY) include/config.h | \
 	grep -o "\#define \(CONFIG\|VARIANT\)_[A-Z0-9_]*" | cut -c9- | sort)
 
 _flag_cfg:= $(filter $(_flag_cfg_ro), $(_flag_cfg_rw))
diff --git a/Makefile.rules b/Makefile.rules
index a86ac62869..8a894e4542 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -55,7 +55,7 @@ cmd_libec = $(LD) -r $^ -o $@.1.o && \
 	$(OBJCOPY) --localize-hidden $@.1.o $@.2.o && \
 	$(AR) scr $@ $@.2.o
 cmd_lds = $(CPP) -P -C -MMD -MF $@.d -MT $@ $(CPPFLAGS) $< -o $@
-cmd_lds_b = $(cmd_lds) -DRW_B_LDS
+cmd_lds_b = $(cmd_lds) -DRW_B_LDS=$(EMPTY)
 # Allow obj_to_bin to be overridden by board or chip specific commands
 cmd_obj_to_bin ?= $(OBJCOPY) --gap-fill=0xff -O binary $^ $(out)/$*.bin.tmp
 cmd_flat_to_obj = $(CC) -Wl,-T $(out)/firmware_image.lds -nostdlib $(CPPFLAGS) \
@@ -110,8 +110,8 @@ cmd_sharedlib_elf = $(CC) $(libsharedobjs_deps) \
 	-o $(out)/$(SHOBJLIB)/$(SHOBJLIB).elf \
 	-Wl,-Map,$(out)/$(SHOBJLIB)/$(SHOBJLIB).map
 cmd_c_to_taskinfo = $(BUILDCC) \
-	$(filter-out -DSECTION_IS_$(BLD),$(BUILD_CFLAGS)) -DSECTION_IS_$(3) \
-	-MMD -MF $@.d -c $< -flto -o $@
+	$(filter-out -DSECTION_IS_$(BLD)=$(EMPTY),$(BUILD_CFLAGS)) \
+	-DSECTION_IS_$(3)=$(EMPTY) -MMD -MF $@.d -c $< -flto -o $@
 cmd_link_taskinfo = $(BUILDCC) $(BUILD_CFLAGS) --shared -fPIC $^ \
 	$(BUILD_LDFLAGS) -flto -o $@
 cmd_proto_to_cxx = $(PROTOC) -I. --cpp_out=$(out)/gen $^
@@ -504,7 +504,7 @@ $(out)/gen/%.pb.cc:%.proto
 $(out)/gen/%.pb.h:%.proto
 	$(call quiet,proto_to_cxx,PROTOC )
 
-$(out)/$(SHOBJLIB)/%.o: override LATE_CFLAGS_DEFINE:=-DSHAREDLIB_IMAGE
+$(out)/$(SHOBJLIB)/%.o: override LATE_CFLAGS_DEFINE:=-DSHAREDLIB_IMAGE=$(EMPTY)
 $(out)/$(SHOBJLIB)/%.o:%.c
 	$(call quiet,c_to_o,CC     )
 
@@ -571,7 +571,7 @@ $(npcx-monitor-fw-bin):
 	-@ $(OBJCOPY) -O binary $(out)/$(npcx-monitor-fw).elf $@
 
 $(out)/$(npcx-monitor-hdr)_ro.o:$(npcx-monitor-hdr).c
-	-@ $(CC) $(CFLAGS) -D SECTION_IS_RO -MMD -c $(npcx-monitor-hdr).c -o $@
+	-@ $(CC) $(CFLAGS) -DSECTION_IS_RO=$(EMPTY) -MMD -c $(npcx-monitor-hdr).c -o $@
 
 $(npcx-monitor-hdr-ro-bin):$(out)/$(npcx-monitor-hdr)_ro.o
 	$(if $(V),,@echo '  EXTBIN ' $(subst $(out)/,,$@) ; )
@@ -627,14 +627,14 @@ print-configs:
 	@echo "----------------------------------------------------------------"
 	@echo "| RO Config:                                                   |"
 	@echo "----------------------------------------------------------------"
-	@$(CPP) $(CPPFLAGS) -P -dM -Ichip/$(CHIP) \
-		-I$(BASEDIR) -I$(BDIR) -DSECTION_IS_RO include/config.h | \
+	@$(CPP) $(CPPFLAGS) -P -dM -Ichip/$(CHIP) -I$(BASEDIR) -I$(BDIR) \
+		-DSECTION_IS_RO=$(EMPTY) include/config.h | \
 		grep "#define CONFIG_" | cut -c9- | sort
 	@echo "----------------------------------------------------------------"
 	@echo "| RW Config:                                                   |"
 	@echo "----------------------------------------------------------------"
-	@$(CPP) $(CPPFLAGS) -P -dM -Ichip/$(CHIP) \
-		-I$(BASEDIR) -I$(BDIR) -DSECTION_IS_RW include/config.h | \
+	@$(CPP) $(CPPFLAGS) -P -dM -Ichip/$(CHIP) -I$(BASEDIR) -I$(BDIR) \
+		-DSECTION_IS_RW=$(EMPTY) include/config.h | \
 		grep "#define CONFIG_" | cut -c9- | sort
 
 .PHONY: print-chip-variant
diff --git a/Makefile.toolchain b/Makefile.toolchain
index c7ab5ac106..857f32158d 100644
--- a/Makefile.toolchain
+++ b/Makefile.toolchain
@@ -61,34 +61,38 @@ CXXFLAGS_WARN = $(COMMON_WARN)
 CFLAGS_DEBUG= -g
 CFLAGS_DEBUG+=$(CFLAGS_DEBUG_CHIP)
 CFLAGS_INCLUDE=$(foreach i,$(includes),-I$(i) ) -I.
-CFLAGS_TEST=$(if $(TEST_BUILD),-DTEST_BUILD \
+CFLAGS_TEST=$(if $(TEST_BUILD),-DTEST_BUILD=$(EMPTY) \
                                -DTEST_TASKFILE=$(PROJECT).tasklist,) \
             $(if $(CTS_MODULE), $(CFLAGS_CTS)) \
-            $(if $(EMU_BUILD),-DEMU_BUILD) \
+            $(if $(EMU_BUILD),-DEMU_BUILD=$(EMPTY)) \
             $(if $($(PROJECT)-scale),-DTEST_TIME_SCALE=$($(PROJECT)-scale)) \
-            -DTEST_$(PROJECT) -DTEST_$(UC_PROJECT) \
+            -DTEST_$(PROJECT)=$(EMPTY) -DTEST_$(UC_PROJECT)=$(EMPTY) \
             $(if $(TEST_ASAN),-fsanitize=address) \
             $(if $(TEST_MSAN),-fsanitize=memory) \
             $(if $(TEST_UBSAN),$(UBSAN_FLAGS)) \
-            $(if $(TEST_FUZZ),-fsanitize=fuzzer-no-link -DTEST_FUZZ)
+            $(if $(TEST_FUZZ),-fsanitize=fuzzer-no-link -DTEST_FUZZ=$(EMPTY))
 CFLAGS_COVERAGE=$(if $(TEST_COVERAGE),-fprofile-arcs -ftest-coverage \
-				      -DTEST_COVERAGE,)
+				      -DTEST_COVERAGE=$(EMPTY),)
 CFLAGS_DEFINE=-DOUTDIR=$(out)/$(BLD) -DCHIP=$(CHIP) -DBOARD_TASKFILE=$(_tsk_lst_file) \
               -DBOARD=$(BOARD) -DCORE=$(CORE) -DPROJECT=$(PROJECT) \
               -DCHIP_VARIANT=$(CHIP_VARIANT) -DCHIP_FAMILY=$(CHIP_FAMILY) \
-              -DBOARD_$(UC_BOARD) -DCHIP_$(UC_CHIP) -DCORE_$(UC_CORE) \
-              -DCHIP_VARIANT_$(UC_CHIP_VARIANT) -DCHIP_FAMILY_$(UC_CHIP_FAMILY) \
-              -DFINAL_OUTDIR=$(out) -DPROTOBUF_MIN_PROTOC_VERSION=0 \
+              -DBOARD_$(UC_BOARD)=$(EMPTY) \
+	      -DCHIP_$(UC_CHIP)=$(EMPTY) \
+	      -DCORE_$(UC_CORE)=$(EMPTY) \
+              -DCHIP_VARIANT_$(UC_CHIP_VARIANT)=$(EMPTY) \
+	      -DCHIP_FAMILY_$(UC_CHIP_FAMILY)=$(EMPTY) \
+	      -DFINAL_OUTDIR=$(out) \
+	      -DPROTOBUF_MIN_PROTOC_VERSION=0 \
               $(CFLAGS_BASEBOARD)
 CPPFLAGS=$(CFLAGS_DEFINE) $(CFLAGS_INCLUDE) $(CFLAGS_TEST) \
 	 $(EXTRA_CFLAGS) $(CFLAGS_COVERAGE) $(LATE_CFLAGS_DEFINE) \
-	-DSECTION_IS_$(BLD) -DSECTION=$(BLD) $(CPPFLAGS_$(BLD))
+	-DSECTION_IS_$(BLD)=$(EMPTY) -DSECTION=$(BLD) $(CPPFLAGS_$(BLD))
 BUILD_CPPFLAGS=$(CFLAGS_DEFINE) -Icore/host $(CFLAGS_INCLUDE) $(CFLAGS_TEST) \
 	 $(EXTRA_CFLAGS) $(CFLAGS_COVERAGE) $(LATE_CFLAGS_DEFINE) \
-	 -DSECTION_IS_$(BLD) -DSECTION=$(BLD) $(CPPFLAGS_$(BLD))
+	 -DSECTION_IS_$(BLD)=$(EMPTY) -DSECTION=$(BLD) $(CPPFLAGS_$(BLD))
 HOST_CPPFLAGS=$(CFLAGS_DEFINE) $(CFLAGS_INCLUDE) $(CFLAGS_TEST) \
 	 $(EXTRA_CFLAGS) $(CFLAGS_COVERAGE) $(LATE_CFLAGS_DEFINE) \
-	 -DSECTION_IS_$(BLD) -DSECTION=$(BLD) $(CPPFLAGS_$(BLD))
+	 -DSECTION_IS_$(BLD)=$(EMPTY) -DSECTION=$(BLD) $(CPPFLAGS_$(BLD))
 ifneq ($(BOARD),host)
 CPPFLAGS+=-ffreestanding -fno-builtin -nostdinc -nostdlib
 CPPFLAGS+=-Ibuiltin/
@@ -101,7 +105,7 @@ CFLAGS+= -fno-delete-null-pointer-checks
 ifneq ($(cc-name),clang)
 CFLAGS+= -fconserve-stack
 endif
-CFLAGS+= -DCHROMIUM_EC
+CFLAGS+= -DCHROMIUM_EC=$(EMPTY)
 CXXFLAGS+=-DPROTOBUF_INLINE_NOT_IN_HEADERS=0
 
 FTDIVERSION:=$(shell $(PKG_CONFIG) --modversion libftdi1 2>/dev/null)
@@ -126,7 +130,8 @@ endif
 
 BUILD_CFLAGS = $(LIBFTDIUSB_CFLAGS) $(BUILD_CPPFLAGS) -O3 $(CFLAGS_DEBUG)
 BUILD_CFLAGS += $(CFLAGS_WARN)
-HOST_CFLAGS=$(HOST_CPPFLAGS) -O3 $(CFLAGS_DEBUG) $(CFLAGS_WARN) -DHOST_TOOLS_BUILD
+HOST_CFLAGS=$(HOST_CPPFLAGS) -O3 $(CFLAGS_DEBUG) $(CFLAGS_WARN) \
+	    -DHOST_TOOLS_BUILD=$(EMPTY)
 HOST_CFLAGS+=$(LIBFTDIUSB_CFLAGS)
 ifneq (${SYSROOT},)
   LDFLAGS_EXTRA+=--sysroot=${SYSROOT}
diff --git a/board/cr50/build.mk b/board/cr50/build.mk
index 845d5ac9bf..613d716ff7 100644
--- a/board/cr50/build.mk
+++ b/board/cr50/build.mk
@@ -68,7 +68,7 @@ board-y += wp.o
 board-$(CONFIG_U2F) += u2f.o
 
 ifneq ($(H1_RED_BOARD),)
-CPPFLAGS += -DH1_RED_BOARD
+CPPFLAGS += -DH1_RED_BOARD=$(EMPTY)
 endif
 
 # Build and link with an external library
diff --git a/chip/mchp/build.mk b/chip/mchp/build.mk
index c3883a0e6f..60682d2ed9 100644
--- a/chip/mchp/build.mk
+++ b/chip/mchp/build.mk
@@ -80,7 +80,7 @@ objs_lfw += $(out)/RW/common/version.o
 dirs-y+=chip/$(CHIP)/lfw
 
 # objs with -lfw suffix are to include lfw's gpio
-$(out)/RW/%-lfw.o: private CC+=-I$(BDIR)/lfw -DLFW
+$(out)/RW/%-lfw.o: private CC+=-I$(BDIR)/lfw -DLFW=$(EMPTY)
 # Remove the lto flag for the loader.  It actually causes it to bloat in size.
 ifeq ($(CONFIG_LTO),y)
 $(out)/RW/%-lfw.o: private CFLAGS_CPU := $(filter-out -flto, $(CFLAGS_CPU))
diff --git a/chip/mec1322/build.mk b/chip/mec1322/build.mk
index 30ab8d7622..71b9d7ae0e 100644
--- a/chip/mec1322/build.mk
+++ b/chip/mec1322/build.mk
@@ -59,7 +59,7 @@ objs_lfw += $(out)/RW/common/version.o
 dirs-y+=chip/$(CHIP)/lfw
 
 # objs with -lfw suffix are to include lfw's gpio
-$(out)/RW/%-lfw.o: private CC+=-I$(BDIR)/lfw -DLFW
+$(out)/RW/%-lfw.o: private CC+=-I$(BDIR)/lfw -DLFW=$(EMPTY)
 # Remove the lto flag for the loader.  It actually causes it to bloat in size.
 ifeq ($(CONFIG_LTO),y)
 $(out)/RW/%-lfw.o: private CFLAGS_CPU := $(filter-out -flto, $(CFLAGS_CPU))
diff --git a/common/build.mk b/common/build.mk
index 3e08cab72d..923c284949 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -183,7 +183,7 @@ ifneq ($(CONFIG_BOOTBLOCK),)
 build-util-bin += gen_emmc_transfer_data
 
 # Bootblock is only packed in RO image.
-$(out)/util/gen_emmc_transfer_data: BUILD_LDFLAGS += -DSECTION_IS_RO
+$(out)/util/gen_emmc_transfer_data: BUILD_LDFLAGS += -DSECTION_IS_RO=$(EMPTY)
 $(out)/bootblock_data.h: $(out)/util/gen_emmc_transfer_data $(out)/.bootblock
 	$(call quiet,emmc_bootblock,BTBLK  )
 
diff --git a/cts/build.mk b/cts/build.mk
index ddbcb1e95f..3f0cd750db 100644
--- a/cts/build.mk
+++ b/cts/build.mk
@@ -3,14 +3,14 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-CFLAGS_CTS=-DCTS_MODULE -DCTS_TASKFILE=cts.tasklist
+CFLAGS_CTS=-DCTS_MODULE=$(EMPTY) -DCTS_TASKFILE=cts.tasklist
 
 ifeq "$(CTS_MODULE)" "gpio"
-CFLAGS_CTS+=-DCTS_MODULE_GPIO
+CFLAGS_CTS+=-DCTS_MODULE_GPIO=$(EMPTY)
 endif
 
 ifeq "$(CTS_MODULE)" "i2c"
-CFLAGS_CTS+=-DCTS_MODULE_I2C
+CFLAGS_CTS+=-DCTS_MODULE_I2C=$(EMPTY)
 CONFIG_I2C=y
 ifneq ($(BOARD),stm32l476g-eval)
 CONFIG_I2C_MASTER=y
@@ -25,4 +25,4 @@ ifeq ($(BOARD),stm32l476g-eval)
 else
 	cts-y+=$(CTS_MODULE)/dut.o
 	cts-y+=common/dut_common.o
-endif
\ No newline at end of file
+endif
diff --git a/util/build.mk b/util/build.mk
index 4fb6b7e1f0..3238fb749a 100644
--- a/util/build.mk
+++ b/util/build.mk
@@ -52,7 +52,7 @@ $(out)/util/genvif: $(genvif-pd-objs) board/$(BOARD)/board.h \
 $(out)/util/genvif: BUILD_LDFLAGS+=$(genvif-pd-objs) -flto
 
 STANDALONE_FLAGS=-ffreestanding -fno-builtin -nostdinc \
-			-Ibuiltin/ -D"__keep= " -DVIF_BUILD
+			-Ibuiltin/ -D"__keep= " -DVIF_BUILD=$(EMPTY)
 
 $(out)/util/%/usb_pd_policy.o: %/usb_pd_policy.c
 	-@ mkdir -p $(@D)
@@ -63,7 +63,7 @@ ifneq ($(CONFIG_BOOTBLOCK),)
 build-util-bin += gen_emmc_transfer_data
 
 # Bootblock is only packed in RO image.
-$(out)/util/gen_emmc_transfer_data: BUILD_LDFLAGS += -DSECTION_IS_RO
+$(out)/util/gen_emmc_transfer_data: BUILD_LDFLAGS += -DSECTION_IS_RO=$(EMPTY)
 endif # CONFIG_BOOTBLOCK
 
 ifneq ($(CONFIG_IPI),)
@@ -78,7 +78,7 @@ ifneq ($(CONFIG_TOUCHPAD_HASH_FW),)
 build-util-bin += gen_touchpad_hash
 
 # Assume RW section (touchpad FW must be identical for both RO+RW)
-$(out)/util/gen_touchpad_hash: BUILD_LDFLAGS += -DSECTION_IS_RW
+$(out)/util/gen_touchpad_hash: BUILD_LDFLAGS += -DSECTION_IS_RW=$(EMPTY)
 
 OPENSSL_CFLAGS := $(shell $(PKG_CONFIG) --libs openssl)
 OPENSSL_LDFLAGS := $(shell $(PKG_CONFIG) --libs openssl)