openwrt使用sdk编译应用程序

在openwrt源码目录下make menuconfig时，选择  [*] Build the OpenWrt SDK ，之后就会在bin/ar71xx/下生产SDK文件OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2.tar.bz2

解压之后就是OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2，此目录结构跟openwrt的目录结构基本一致

song@song-virtual-machine:attitude_adjustment# ls bin/ar71xx/OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2bin        Config.in  docs                include  logs      package   Packages.gz  rules.mk  staging_dir  tmpbuild_dir  dl         feeds.conf.default  LICENSE  Makefile  Packages  README.SDK   scripts   target

song@song-virtual-machine:attitude_adjustment# lsbin          build_dir  dl    feeds.conf.default  LICENSE  Makefile  README    scripts      target  toolchainBSDmakefile  Config.in  docs  feeds           include             logs     package   rules.mk  staging_dir  tmp     tools

概述：源码在SDK/pakage目录，生成文件在SDK/bin/ar71xx/packages目录。如果没有SDK/bin/ar71xx/packages目录也可手动创建。SDK/bin/packages目录没用到。
1.在OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2/package目录下新建helloworld目录

song@song-virtual-machine:package$ lshelloworld  Makefile  rules.mk

2.在helloworld目录下新建Makefile文件和src目录

song@song-virtual-machine:helloworld$ lsMakefile  src

此Makefile内容

############################################### OpenWrt Makefile for helloworld program### Most of the variables used here are defined in# the include directives below. We just need to# specify a basic description of the package,# where to build our program, where to find# the source files, and where to install the# compiled program on the router.## Be very careful of spacing in this file.# Indents should be tabs, not spaces, and# there should be no trailing whitespace in# lines that are not commented.###############################################include $(TOPDIR)/rules.mk# Name and release number of this packagePKG_NAME:=helloworldPKG_RELEASE:=1# This specifies the directory where we're going to build the program. # The root build directory, $(BUILD_DIR), is by default the build_mipsel# directory in your OpenWrt SDK directoryPKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)include $(INCLUDE_DIR)/package.mk # Specify package information for this program.# The variables defined here should be self explanatory.# If you are running Kamikaze, delete the DESCRIPTION# variable below and uncomment the Kamikaze define# directive for the description belowdefine Package/helloworldSECTION:=utilsCATEGORY:=UtilitiesTITLE:=Helloworld -- prints a snarky messageendef# Uncomment portion below for Kamikaze and delete DESCRIPTION variable abovedefine Package/helloworld/description        If you can't figure out what this program does, you're probably        brain-dead and need immediate medical attention.endef # Specify what needs to be done to prepare for building the package.# In our case, we need to copy the source files to the build directory.# This is NOT the default.  The default uses the PKG_SOURCE_URL and the# PKG_SOURCE which is not defined here to download the source from the web.# In order to just build a simple program that we have just written, it is# much easier to do it this way.define Build/Preparemkdir -p $(PKG_BUILD_DIR)$(CP) ./src/* $(PKG_BUILD_DIR)/endef# We do not need to define Build/Configure or Build/Compile directives# The defaults are appropriate for compiling a simple program such as this one# Specify where and how to install the program. Since we only have one file,# the helloworld executable, install it by copying it to the /bin directory on# the router. The $(1) variable represents the root directory on the router running# OpenWrt. The $(INSTALL_DIR) variable contains a command to prepare the install# directory if it does not already exist.  Likewise $(INSTALL_BIN) contains the# command to copy the binary file from its current location (in our case the build# directory) to the install directory.define Package/helloworld/install$(INSTALL_DIR) $(1)/bin$(INSTALL_BIN) $(PKG_BUILD_DIR)/helloworld $(1)/bin/endef# This line executes the necessary commands to compile our program.# The above define directives specify all the information needed, but this# line calls BuildPackage which in turn actually uses this information to# build a package.$(eval $(call BuildPackage,helloworld))

3.在src目录下新建helloworld.c文件和Makefile文件，分别如下

#include<stdio.h>int main(void){printf("yyyy\n");return 0;}

# build helloworld executable when user executes "make"helloworld: helloworld.o$(CC) $(LDFLAGS) helloworld.o -o helloworldhelloworld.o: helloworld.c$(CC) $(CFLAGS) -c helloworld.c# remove object files and executable when user executes "make clean"clean:rm *.o helloworld

4.在OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2目录下执行编译

song@song-virtual-machine:OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2$ make V=s

5.成功之后会在OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2/bin/ar71xx/packages/ 下生产helloworld_1_ar71xx.ipk

song@song-virtual-machine:OpenWrt-SDK-ar71xx-for-linux-i686-gcc-4.6-linaro_uClibc-0.9.33.2$ ls bin/ar71xx/packages/helloworld_1_ar71xx.ipk  Packages  Packages.gz

6.拷贝ipk到板子执行

opkg install helloworld_1_ar71xx.ipk

会生成/bin/helloworld

通过opkg list可查看