基于Linux内核的应用程序构造（二）——应用程序编译

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依据oplonu产品为例，着重解析编译过程

Kernel Version：linux2.6.21.5

SDK:https://github.com/DavionKnight/oplonu

执行编译脚本$ ./f23p-v1e-build

执行make f23pv1e为内核配置见上个博文

执行make

一.分别编译apps和busybox

//oplonu/Makefile：

all: $(COMPONENTS)

$(COMPONENTS):
@echo "=== make COMPONENT ./$@"
@$(MAKE) -rw -C $@

//oplonu/Makefile.conf:

COMPONENTS = \
apps \
busybox

二.进入apps目录，编译opconn和pppoe两个app

# List of directories to make
SUBDIRS = \
opconn \
pppoe

# Define at least one rule before commonrules, otherwise the first commonrule will be the default.
# Here, default rule all: should be to build all SUBDIRS.
all: $(SUBDIRS)

//oplonu/Makefile.rules:

# Rule to make a subdirectory
$(SUBDIRS):
@$(MAKE) -r -C $@

三.进入opconn目录，进行编译，最终生成opconn可执行文件

all: libdir $(COMPONENTS) image

//libdir主要创建build目录以存放编译结果

libdir:
   @if [ -d $(LIBDIR) ]; then \
       echo "Output directory is $(LIBDIR)."; \
   else \
       echo "Output directory $(LIBDIR) does not exists. Creating ..."; \
       mkdir $(LIBDIR); \
   fi

//编译生成各个库文件

$(COMPONENTS):
@echo "=== make COMPONENT ./$@"
@$(MAKE) -rw -C $@

其中COMPONENTS如下：

COMPONENTS = \
   bridge \
   cli \
   dvrs \
   hal \
   oamp \
   port \
   multicast \
   sys \
   vos \
   stats\
   rstp \
   qos \
   exchange \
   ipc   \
   run_led \
   uart_init   \
   trmsvr   \
   product   \
   gwdPlatform

进入各个目录下，Makefile如下

all: $(LIBDIR)/$(LIB)

//oplonu/Makefile.rules:

$(LIBDIR)/$(LIB): $(OBJECTS) Makefile
@echo "--- Building library $(LIBDIR)/$(LIB) ---"
@$(AR) -rsv $(LIBDIR)/$(LIB) $(OBJECTS);sleep 1

$(LIBDIR)/%.o: %.c Makefile
@echo "--- $< -> $@"
@$(CC) -W -c -x c $(OPTIMIZATION) $(CCFLAGS) $(LOCALINCLUDE) -o $@ $<

通过红色字体代码，生成对应的.a文件

//oplonu/Makefile.rules:

image: rmmain $(LIBDIR)/main.o
   @echo ""
   @echo "   +++ Building $(TARGET) image +++"
   @echo ""
   -@rm -f $(LIBDIR)/$(TARGET)
   @if [ -e $(LIBDIR)/$(TARGET) ]; then \
       echo "==============================================="; \
       echo "=== ERROR : $(TARGET) access denied        ==="; \
       echo "=== File is used by another process        ==="; \
       echo "=== check your debugger                    ==="; \
       echo "==============================================="; \
       return 1;\
   fi
   $(CC) $(OPTIMIZATION) $(CCFLAGS) $(LIBDIR)/main.o $(TARGETDIR)/linux/opl_modif.o -L$(LIBDIR) $(LIBS) \
   -o $(LIBDIR)/$(TARGET)
   @if [ $$? != 0 ]; then echo "NOT DONE. Terminated due to make error"; return 1; fi
   @echo ""
   @echo "   +++ Done. File is here: +++"
   @echo ""
   @echo "   $(LIBDIR)/$(TARGET)"
   @$(STRIP) --strip-debug --strip-unneeded --discard-all $(LIBDIR)/$(TARGET) -o $(LIBDIR)/$(TARGET).stripped

   @if command -v lzma &>/dev/null; \
   then \
       lzma e $(LIBDIR)/$(TARGET).stripped $(LIBDIR)/$(TARGET).img; \
#       lzma $(LIBDIR)/$(TARGET).stripped \
       rm -f $(LIBDIR)/$(TARGET).stripped; \
#       mv -f $(LIBDIR)/$(TARGET).stripped.lzma $(LIBDIR)/$(TARGET).img; \
       echo ""; \
   else \
        gzip -9 $(LIBDIR)/$(TARGET).stripped; \
       mv -f $(LIBDIR)/$(TARGET).stripped.gz $(LIBDIR)/$(TARGET).img; \
   fi
   @if [ -e $(LIBDIR)/$(TARGET).img ]; then \
       echo "   $(LIBDIR)/$(TARGET).img"; \
   fi
   @echo ""

命令image 编译main.c并链接所有静态库文件生成最后的可执行文件opconn

并通过lzma压缩，生成opconn.img文件

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