[U-Boot] [PATCH v2 01/19] Makefile: prepare for using Kbuild-style Makefile
Masahiro Yamada
yamada.m at jp.panasonic.com
Thu Sep 26 13:51:08 CEST 2013
In every sub directory, Makefile is like follows:
include $(TOPDIR)/config.mk
LIB = $(obj)libfoo.o
COBJS := ...
COBJS += ...
SOBJS := ...
SRCS := $(SOBJS:.o=.S) $(COBJS:.o=.c)
OBJS := $(addprefix $(obj),$(COBJS) $(SOBJS))
all: $(obj).depend $(LIB)
$(LIB): $(OBJS)
$(call cmd_link_o_target, $(OBJS))
#########################################################################
include $(SRCTREE)/rules.mk
sinclude $(obj).depend
#########################################################################
Top and bottom parts are common in almost all sub-makefiles.
This is a big waste.
This commit pushes common parts of makefiles into script/Makefile.build.
Going forward sub-makefiles only need to describe this part:
COBJS := ...
COBJS += ...
SOBJS := ...
But, script/Makefile.build includes the glue code to support obj-y,
the following style (the same as Kbuild) is preferable:
obj-y := ...
obj-$(CONFIG_FOO) += ...
obj-$(CONFIG_BAR) += ...
The conventional (non-Kbuild) Makefile style is still supported.
This is achieved by greping the Makefile before entering into it.
U-Boot conventional sub makefiles always include some other makefiles.
So the build system searches a line beginning with "include" keyword
in the makefile in order to distinguish which style it is.
If the Makefile include a "include" line, we assume it is a conventional
U-Boot style. Otherwise, it is treated as a Kbuild-style makefile.
(At first, I tried to grep "rules.mk" keyword instead,
but I found it does not work.
Almost all sub makefiles include "rules.mk", but there exist three exception:
- board/avnet/fx12mm/Makefile
- board/avnet/v5fx30teval/Makefile
- board/xilinx/ml507/Makefile
These three makefiles include "rules.mk" indirectly.
Anyway, they look weird, so they should be fixed lator.)
With this tweak, we can switch sub-makefiles
from U-Boot style to Kbuild style little by little.
This refactoring of sub makefiles is the first step towards Kbuild,
and makes it easy to import a "real" Kbuild from Linux Kernel.
Note that this refactoring breaks nothing because it just moves
the common parts into scripts/Makefile.build.
Note one more thing:
obj-y := foo/ # descending into foo sub directory
syntax is not supported yet.
(This feature will be implemented in the upcoming commit.)
Of course, scripts/Makefile.build added by this commit is temporary.
It shall be replaced with the one of Linux Kernel in future.
Signed-off-by: Masahiro Yamada <yamada.m at jp.panasonic.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Tom Rini <trini at ti.com>
---
Changes for v2:
- fix commit log (purely cosmetic)
Makefile | 34 ++++++++++++++++++++++++++++++----
scripts/Makefile.build | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
spl/Makefile | 20 ++++++++++++++++++--
3 files changed, 96 insertions(+), 6 deletions(-)
create mode 100644 scripts/Makefile.build
diff --git a/Makefile b/Makefile
index 07abef4..36bbd09 100644
--- a/Makefile
+++ b/Makefile
@@ -593,14 +593,35 @@ ifeq ($(CONFIG_KALLSYMS),y)
$(GEN_UBOOT) $(obj)common/system_map.o
endif
+# Tentative step for Kbuild-style makefiles coexist with conventional U-Boot style makefiles
+# U-Boot conventional sub makefiles always include some other makefiles.
+# So, the build system searches a line beginning with "include" before entering into the sub makefile
+# in order to distinguish which style it is.
+# If the Makefile include a "include" line, we assume it is an U-Boot style makefile.
+# Otherwise, it is treated as a Kbuild-style makefile.
+
+# We do not need to build $(OBJS) explicitly.
+# It is built while we are at $(CPUDIR)/lib$(CPU).o build.
$(OBJS): depend
- $(MAKE) -C $(CPUDIR) $(if $(REMOTE_BUILD),$@,$(notdir $@))
+ if grep -q "^include" $(CPUDIR)/Makefile; then \
+ $(MAKE) -C $(CPUDIR) $(if $(REMOTE_BUILD),$@,$(notdir $@)); \
+ fi
$(LIBS): depend $(SUBDIR_TOOLS)
- $(MAKE) -C $(dir $(subst $(obj),,$@))
+ if grep -q "^include" $(dir $(subst $(obj),,$@))Makefile; then \
+ $(MAKE) -C $(dir $(subst $(obj),,$@)); \
+ else \
+ $(MAKE) -C $(dir $(subst $(obj),,$@)) -f $(TOPDIR)/scripts/Makefile.build; \
+ mv $(dir $@)built-in.o $@; \
+ fi
$(LIBBOARD): depend $(LIBS)
- $(MAKE) -C $(dir $(subst $(obj),,$@))
+ if grep -q "^include" $(dir $(subst $(obj),,$@))/Makefile; then \
+ $(MAKE) -C $(dir $(subst $(obj),,$@)); \
+ else \
+ $(MAKE) -C $(dir $(subst $(obj),,$@)) -f $(TOPDIR)/scripts/Makefile.build; \
+ mv $(dir $@)built-in.o $@; \
+ fi
$(SUBDIRS): depend
$(MAKE) -C $@ all
@@ -637,7 +658,12 @@ depend dep: $(TIMESTAMP_FILE) $(VERSION_FILE) \
$(obj)include/generated/generic-asm-offsets.h \
$(obj)include/generated/asm-offsets.h
for dir in $(SUBDIRS) $(CPUDIR) $(LDSCRIPT_MAKEFILE_DIR) ; do \
- $(MAKE) -C $$dir _depend ; done
+ if grep -q "^include" $$dir/Makefile; then \
+ $(MAKE) -C $$dir _depend ; \
+ else \
+ $(MAKE) -C $$dir -f $(TOPDIR)/scripts/Makefile.build _depend; \
+ fi; \
+ done
TAG_SUBDIRS = $(SUBDIRS)
TAG_SUBDIRS += $(dir $(__LIBS))
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
new file mode 100644
index 0000000..f969ec5
--- /dev/null
+++ b/scripts/Makefile.build
@@ -0,0 +1,48 @@
+# our default target
+.PHONY: all
+all:
+
+include $(TOPDIR)/config.mk
+
+LIB := $(obj)built-in.o
+LIBGCC = $(obj)libgcc.o
+SRCS :=
+
+include Makefile
+
+# Backward compatible: obj-y is preferable
+COBJS := $(sort $(COBJS) $(COBJS-y))
+SOBJS := $(sort $(SOBJS) $(SOBJS-y))
+
+# Going forward use the following
+obj-y := $(sort $(obj-y))
+extra-y := $(sort $(extra-y))
+lib-y := $(sort $(lib-y))
+
+SRCS += $(COBJS:.o=.c) $(SOBJS:.o=.S) \
+ $(wildcard $(obj-y:.o=.c) $(obj-y:.o=.S) $(lib-y:.o=.c) $(lib-y:.o=.S) $(extra-y:.o=.c) $(extra-y:.o=.S))
+OBJS := $(addprefix $(obj),$(COBJS) $(SOBJS) $(obj-y))
+
+LGOBJS := $(addprefix $(obj),$(sort $(GLSOBJS) $(GLCOBJS)) $(lib-y))
+
+all: $(LIB) $(addprefix $(obj),$(extra-y))
+
+$(LIB): $(obj).depend $(OBJS)
+ $(call cmd_link_o_target, $(OBJS))
+
+ifneq ($(strip $(lib-y)),)
+all: $(LIBGCC)
+
+$(LIBGCC): $(obj).depend $(LGOBJS)
+ $(call cmd_link_o_target, $(LGOBJS))
+endif
+
+#########################################################################
+
+# defines $(obj).depend target
+
+include $(TOPDIR)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################
diff --git a/spl/Makefile b/spl/Makefile
index 174d0a7..48f2c65 100644
--- a/spl/Makefile
+++ b/spl/Makefile
@@ -199,11 +199,27 @@ GEN_UBOOT = \
$(obj)$(SPL_BIN): depend $(START) $(LIBS) $(obj)u-boot-spl.lds
$(GEN_UBOOT)
+# Tentative step for Kbuild-style makefiles coexist with conventional U-Boot style makefiles
+# U-Boot conventional sub makefiles always include some other makefiles.
+# So, the build system searches a line beginning with "include" before entering into the sub makefile
+# in order to distinguish which style it is.
+# If the Makefile include a "include" line, we assume it is an U-Boot style makefile.
+# Otherwise, it is treated as a Kbuild-style makefile.
+
+# We do not need to build $(START) explicitly.
+# It is built while we are at $(CPUDIR)/lib$(CPU).o build.
$(START): depend
- $(MAKE) -C $(SRCTREE)/$(START_PATH) $@
+ if grep -q "^include" $(SRCTREE)$(dir $(subst $(SPLTREE),,$@))Makefile; then \
+ $(MAKE) -C $(SRCTREE)/$(START_PATH) $@; \
+ fi
$(LIBS): depend
- $(MAKE) -C $(SRCTREE)$(dir $(subst $(SPLTREE),,$@))
+ if grep -q "^include" $(SRCTREE)$(dir $(subst $(SPLTREE),,$@))Makefile; then \
+ $(MAKE) -C $(SRCTREE)$(dir $(subst $(SPLTREE),,$@)); \
+ else \
+ $(MAKE) -C $(SRCTREE)$(dir $(subst $(SPLTREE),,$@)) -f $(TOPDIR)/scripts/Makefile.build; \
+ mv $(dir $@)built-in.o $@; \
+ fi
$(obj)u-boot-spl.lds: $(LDSCRIPT) depend
$(CPP) $(CPPFLAGS) $(LDPPFLAGS) -I$(obj). -ansi -D__ASSEMBLY__ -P - < $< > $@
--
1.8.1.2
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