openwrt在RT5350上编译安装运行helloworld.ipk

在上一篇：openwrt针对RT5350代码下载，配置和编译

我们在trunk/bin/下编译出OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2.tar.bz2

在此，我们用到它来编译出我们的helloworld.ipk.

解压：

cd /trunk/ramips/bin

tar -xjvf OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2.tar.bz2

cd OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2

cd package

在trunk/bin/ramips/OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2/package这个目录下建立helloworld

mkdir  helloworld

cd helloworld

mkdir src

cd src

vim helloworld.c

#include <stdio.h>
#include <unistd.h>

int main(void)
{
    printf("Hello world, why won't my code compile?\n\n");
    return 0;
}

vim Makefile  //注意TAB,不能被替换空格，Makefile的编写规则,此Makfile是编译helloworld.c

helloworld:helloworld.o
	$(CC) $(LDFLAGS) helloworld.o -o helloworld
helloworld.o:helloworld.c
	$(CC) $(CFLAGS) -c helloworld.c
clean:
	rm *.o helloworld

回到上一层目录，：trunk/bin/ramips/OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2/package/helloworld

cd ..

vim Makefile  //此Makefile是给SDK读取，编译src目录的

##############################################
# 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))

特别提醒：格式务必使用TAB，不然会出现编译问题。特别最后一行：

<span style="color:#FF0000;">$(eval $(call BuildPackage,helloworld))</span>

不需要TAB，当初以为这一行也需要TAB，结果怎么编译bin目录下都没有生成ipk。

回到SDK根目录：trunk/bin/ramips/OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2

执行：make V=s

最后生成目标文件都在trunk/bin/ramips/OpenWrt-SDK-ramips-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2/bin/ramips/packages:

drwxr-xr-x 2 dean dean 4096  7月  5 19:07 ./
drwxr-xr-x 3 dean dean 4096  7月  5 19:07 ../
-rw-r--r-- 1 dean dean 1796  7月  5 19:07 helloworld_1_ramips_24kec.ipk
-rw-r--r-- 1 dean dean  432  7月  5 19:07 Packages
-rw-r--r-- 1 dean dean  331  7月  5 19:07 Packages.gz

这个helloworld_1_ramips_24kec.ipk就是我们编译出来的helloworld

开发板正常运行到系统后，使用wget下载helloworld_1_ramips_24kec.ipk

安装：opkg install helloworld_1_ramips_24kec.ipk

运行：hello  //打完hello按TAB自动补全，然后运行即可。