OpenWrt编译自己的应用程序

  编译OpenWrt的应用程序可以参考OpenWrt内部其他应用程序的例程，来编写成自己的应用程序

一、OpenWrt源代码获取与编译

1.1、搭建环境

  下载OpenWrt的官方源码：

git clone https://github.com/openwrt/openwrt.git

1.2、安装编译依赖项

sudo apt update -y
sudo apt full-upgrade -y
sudo apt install -y ack antlr3 asciidoc autoconf automake autopoint binutils bison build-essential \
bzip2 ccache cmake cpio curl device-tree-compiler fastjar flex gawk gettext gcc-multilib g++-multilib \
git gperf haveged help2man intltool libc6-dev-i386 libelf-dev libglib2.0-dev libgmp3-dev libltdl-dev \
libmpc-dev libmpfr-dev libncurses5-dev libncursesw5-dev libreadline-dev libssl-dev libtool lrzsz \
mkisofs msmtp nano ninja-build p7zip p7zip-full patch pkgconf python2.7 python3 python3-pyelftools \
libpython3-dev qemu-utils rsync scons squashfs-tools subversion swig texinfo uglifyjs upx-ucl unzip \
vim wget xmlto xxd zlib1g-dev python3-setuptools

1.3、更新 feeds

  进入openwrt目录后执行以下指令

./scripts/feeds update -a
./scripts/feeds install -a

1.4、配置编译选项

  根据自己的平台来选择编译选项

make menuconfig

1.5、下载 dl 库

  进入openwrt目录后执行以下指令

make download -j8

1.6、编译

make V=s -j1

二、OpenWrt应用源代码分析

  OpenWrt应用源代码存放目录为package/utils

  以fbtest应用程序为例进行分析。在fbtest文件夹下面有一个Makefile文件和src文件夹，而src文件夹下有模块源码fbtest.c和源码编译Makefile
 

2.1、顶层makefile分析

  顶层makefile内容如下

#
# Copyright (C) 2012 OpenWrt.org
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#

include $(TOPDIR)/rules.mk

PKG_NAME:=fbtest
PKG_RELEASE:=1

PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)

include $(INCLUDE_DIR)/package.mk

define Package/fbtest
  SECTION:=utils
  CATEGORY:=Utilities
  TITLE:=Frame buffer device testing tool
  DEPENDS:=@DISPLAY_SUPPORT
endef

define Build/Configure
endef

define Build/Compile
	$(MAKE) -C $(PKG_BUILD_DIR) \
		CC="$(TARGET_CC)" \
		CFLAGS="$(TARGET_CFLAGS) -Wall" \
		LDFLAGS="$(TARGET_LDFLAGS)"
endef

define Package/fbtest/install
	$(INSTALL_DIR) $(1)/usr/sbin
	$(INSTALL_BIN) $(PKG_BUILD_DIR)/fbtest $(1)/usr/sbin/
endef

$(eval $(call BuildPackage,fbtest))

2.2、源码makefile

CC = gcc
CFLAGS = -Wall
OBJS = fbtest.o

all: fbtest

%.o: %.c
	$(CC) $(CFLAGS) -c -o $@ $<

fbtest: $(OBJS)
	$(CC) -o $@ $(OBJS)

clean:
	rm -f fbtest *.o

2.3、源码fbtest.c

  fbtest.c就是应用程序的实际代码

三、编写自己的OpenWrt应用代码

  将fbtest文件夹复制为myapp_test，放置到fbtest相同的目录下

3.1、顶层makefile

  修改顶层makefile如下：

#
# Copyright (C) 2012 OpenWrt.org
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#

include $(TOPDIR)/rules.mk

PKG_NAME:=myapp_test
PKG_RELEASE:=1

PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)

include $(INCLUDE_DIR)/package.mk

define Package/myapp_test
  SECTION:=utils
  CATEGORY:=Utilities
  TITLE:=Frame buffer device testing tool
  DEPENDS:=@DISPLAY_SUPPORT
endef

define Build/Configure
endef

define Build/Compile
	$(MAKE) -C $(PKG_BUILD_DIR) \
		CC="$(TARGET_CC)" \
		CFLAGS="$(TARGET_CFLAGS) -Wall" \
		LDFLAGS="$(TARGET_LDFLAGS)"
endef

define Package/myapp_test/install
	$(INSTALL_DIR) $(1)/usr/sbin
	$(INSTALL_BIN) $(PKG_BUILD_DIR)/myapp_test $(1)/usr/sbin/
endef

$(eval $(call BuildPackage,myapp_test))

3.2、源码makefile

CC = gcc
CFLAGS = -Wall
OBJS = myapp_test.o

all: myapp_test

%.o: %.c
	$(CC) $(CFLAGS) -c -o $@ $<

myapp_test: $(OBJS)
	$(CC) -o $@ $(OBJS)

clean:
	rm -f myapp_test *.o

3.3、源码myapp_test.c

#include 
#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 

int main (int argc,char **argv)
{
	printf ("myapp_test\n");
	return 0;
}

四、编译自己的OpenWrt应用代码

4.1、配置

  在OpenWrt源码顶级目录下输入下面的命令配置内核

make menuconfig

  依次按照如下顺序选择：

4.2、编译

  在OpenWrt源码顶级目录下输入下面的命令编译应用程序

make package/myapp_test/compile V=s

  编译完成之后会在下面的目录中看到我们的应用程序

  此应用程序和普通的linux应用程序的装载方法一样，不再赘述。