Allow the user to specify CFLAGS without breaking the build

GNU make has a very interesting quirk: If you set a variable on the
command line, any changes to that variable in the Makefile are ignored
unless marked with the "override" keyword.

Use CFLAGS only for optimization and warning options, and use CPPFLAGS
for the dependency and other preprocessor related options.
That way packagers can specify their own CFLAGS without breaking the
build.

As a side benefit, the ich_descriptors_tool Makefile now behaves exactly
the same whether called standalone or as part of the main Makefile.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>


git-svn-id: https://code.coreboot.org/svn/flashrom/trunk@1574 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

1 files changed, 23 insertions, 8 deletions

diff --git a/util/ich_descriptors_tool/Makefile b/util/ich_descriptors_tool/Makefile
index d8a79f5..4d18aec 100644
--- a/util/ich_descriptors_tool/Makefile
+++ b/util/ich_descriptors_tool/Makefile
@@ -1,4 +1,8 @@
-CC ?= gcc
+#
+# This file is part of the flashrom project.
+#
+# This Makefile works standalone, but it is usually called from the main
+# Makefile in the flashrom directory.
 
 PROGRAM=ich_descriptors_tool
 EXTRAINCDIRS = ../../ .
@@ -6,19 +10,30 @@ DEPPATH = .dep
 OBJATH = .obj
 SHAREDSRC = ich_descriptors.c
 SHAREDSRCDIR = ../..
+# If your compiler spits out excessive warnings, run make WARNERROR=no
+# You shouldn't have to change this flag.
+WARNERROR ?= yes
 
 SRC = $(wildcard *.c)
 
-CFLAGS += -Wall
-CFLAGS += -MMD -MP -MF $(DEPPATH)/$(@F).d
-# enables functions that populate the descriptor structs from plain binary dumps
-CFLAGS += -D ICH_DESCRIPTORS_FROM_DUMP
-CFLAGS += $(patsubst %,-I%,$(EXTRAINCDIRS))
+CC ?= gcc
 
+# If the user has specified custom CFLAGS, all CFLAGS settings below will be
+# completely ignored by gnumake.
+CFLAGS ?= -Os -Wall -Wshadow
 ifeq ($(TARGET_OS), DOS)
 # DJGPP has odd uint*_t definitions which cause lots of format string warnings.
 CFLAGS += -Wno-format
 endif
+ifeq ($(WARNERROR), yes)
+CFLAGS += -Werror
+endif
+
+
+CPPFLAGS += -MMD -MP -MF $(DEPPATH)/$(@F).d
+# enables functions that populate the descriptor structs from plain binary dumps
+CPPFLAGS += -D ICH_DESCRIPTORS_FROM_DUMP
+CPPFLAGS += $(patsubst %,-I%,$(EXTRAINCDIRS))
 
 OBJ = $(OBJATH)/$(SRC:%.c=%.o)
 
@@ -27,12 +42,12 @@ SHAREDOBJ = $(OBJATH)/$(notdir $(SHAREDSRC:%.c=%.o))
 all:$(PROGRAM)$(EXEC_SUFFIX)
 
 $(OBJ): $(OBJATH)/%.o : %.c
-	$(CC) $(CFLAGS) -o $@ -c $<
+	$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ -c $<
 
 # this enables us to share source files without simultaneously sharing .o files
 # with flashrom, which would lead to unexpected results (w/o running make clean)
 $(SHAREDOBJ): $(OBJATH)/%.o : $(SHAREDSRCDIR)/%.c
-	$(CC) $(CFLAGS) -o $@ -c $<
+	$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ -c $<
 
 $(PROGRAM)$(EXEC_SUFFIX): $(OBJ) $(SHAREDOBJ)
 	$(CC) -o $(PROGRAM)$(EXEC_SUFFIX) $(OBJ) $(SHAREDOBJ)