Hi MJ,
On Mon, Sep 16, 2013 at 8:23 PM, MJ embd mj.embd@gmail.com wrote:
PS: Last message was sent without body, please ignore
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I am trying to understand a second level makefile of uboot (this makefile was in a sub directory)
a) What is the difference between $(COBJS:.o=.c) and COBJS := test_main.o
$(COBJS:.o=.c) means to evaluate $(COBJS) but replace every .o with .c
COBJS := test_main.o means that COBJS is assigned the value test_main.o
b) What is the meaning of $(call cmd_link_o_target, $(OBJS)). What is the cmd_link_o_target and what is the call statement doing
This is linking the object files together with a partial link (ld -r). See config.mk for the definition.
c) Does this line creating 2 targets ?
ALL := $(obj).depend $(LIB)
It defines variable ALL to be those two things (the depend file and the library). So that
all: $(ALL)
means that we need to build the depend file and the library.
===================================Makefile===================
include $(TOPDIR)/config.mk
LIB = $(obj)libtest.o
SOBJS := test.o
COBJS := test_main.o COBJS += diagnostic.o
SRCS := $(SOBJS:.o=.S) $(COBJS:.o=.c) OBJS := $(addprefix $(obj),$(COBJS) $(SOBJS))
ALL := $(obj).depend $(LIB)
all: $(ALL)
$(LIB): $(OBJS) $(call cmd_link_o_target, $(OBJS))
#########################################################################
# defines $(obj).depend target include $(SRCTREE)/rules.mk
sinclude $(obj).depend
#########################################################################
This might help a bit:
http://www.gnu.org/software/make/manual/make.html
Regards, Simon