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-0.9.33.2
bin        Config.in  docs                include  logs      package   Packages.gz  rules.mk  staging_dir  tmp
build_dir  dl         feeds.conf.default  LICENSE  Makefile  Packages  README.SDK   scripts   target

song@song-virtual-machine:attitude_adjustment# ls
bin          build_dir  dl    feeds.conf.default  LICENSE  Makefile  README    scripts      target  toolchain
BSDmakefile  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$ ls
helloworld  Makefile  rules.mk

2.在helloworld目录下新建Makefile文件和src目录

song@song-virtual-machine:helloworld$ ls
Makefile  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 package
PKG_NAME:=helloworld
PKG_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 directory
PKG_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 below
define Package/helloworld
	SECTION:=utils
	CATEGORY:=Utilities
	TITLE:=Helloworld -- prints a snarky message
endef


# Uncomment portion below for Kamikaze and delete DESCRIPTION variable above
define 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/Prepare
	mkdir -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 helloworld

helloworld.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