WRTnode-make V=s出错解决办法

WRTnode是基于Wi-Fi AP-Soc的开源硬件开发板。官方网址 http://wiki.wrtnode.com/index.php?title=Main_Page/zh-cn

对于初始学习WRTnode，尤其是之前没有学过Linux开发的人来说，总会遇到各种各样的问题，即使你是照着官方文档按流程做的。这不，按照官网的流程做个 helloworld，都遇到了困难。下面介绍一下我遇到的问题以及解决方法：

1.以下过程参考WRTnode官方教程：http://wiki.wrtnode.com/index.php?title=Openwrt_development/zh-cn

2.首先配置WRTnode的交叉编译环境OpenWrt，可以参考我的博客 http://blog.youkuaiyun.com/zhyulo/article/details/78732348

3.在package目录下创建helloworld目录，并进入helloworld目录：

$cd ~/OpenWrt/package
$mkdir helloworld
$cd helloworld

4.在helloworld目录下，创建新目录 src，并进入到src目录。在src目录下创建hellowrold.c以及编译helloworld.c所需要的Makefile文件

$mkdir src
$cd src
$touch helloworld.c
$touch Makefile

5.分别编辑helloworld.c和Makefile

注意：在命令行编辑文档时，编辑前先按下 'i'；保存并退出时按下 Esc 按键，输入":wq"(输入" "中的)，按回车。

$vim helloworld.c

#include <stdio.h>
#include <unistd.h>
int main(void)
{
    printf("a hellowrold ipk for openwrt !!! \n");
    return 0;
}

$vim Makefile

#build a Makefile for helloworld.c
helloworld: helloworld.o
	$(CC) $(LDFLAGS) helloworld.o -o helloworld
helloworld.o: helloworld.c
	$(CC) $(CFLAGS) -c helloworld.c
clean:
	rm *.o helloworld

6.编写Makefile，这个Makefile文件是给OpenWRT读的。是用来生成软件包的，在上一步中我们写的Makefile是为了编译helloworld.c的，两个Makefile不同，也不在同一层目录下。在上一步中我们是在src目录下，现在我们要编写的Makefile要在上层目录，既是helloworld目录下。

$cd ../
$touch Makefile
$vim Makefile

###############################################
#OpenWrt Makefile for helloworld program
##############################################
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))

7.以上过程问题都不大，下面就是编译了。首先回到顶层目录，执行make进行编译。这下问题来了：

$ cd ../../
$make V=s

8.啊哈，好多"failed"，好多"error"。看的人好想哭！我就是按步骤做的，怎么会出问题。不过问题出现了，就要解决问题。下面是出现该问题的原因:

Makefile是make命令所需要执行的文件，文件中所有的执行命令(也就是缩进的部分)之前都要加Tab，注意：这里只能是Tab，不能是空格。官网上的Makefile文件代码由于网页版制的问题，所有应该是Tab的地方，全部变成了4个空格。所以解决问题的方法也就出来了：把所有的执行命令前的空格该成Tab。再次执行下make：

$make V=s

9.还是有好多的"failed"和"error"，但是上一个错误已经没有了，这说明上一个问题已经解决了。但是，又有了新的问题。我们再来想办法解决掉这个问题：

首先，查看一下最先出错的位置：/home/user/OpenWrt/staging_dir/host/bin/ccache_cc: 2: exec: ccache: not found。它说的是 ccache 这个程序没有发现，我们可以执行下这个命令再试试：

$ ccache

果然，ccache 这个程序不能执行了。

10.ccache 这个程序执行不了的解决方法：

$ sudo apt-get install ccache

11.好了，我们再执行一下 ccache 试试看：

$ ccache

好了，ccache 问题解决！

12.再次执行一次make，看看是否编译成功：

$ make V=s

helloworld 编译成功！可以在 bin/ramips/packages/base 中找到编译好的文件 helloworld_1_ramips_24kec.ipk

$ cd ~/OpenWrt/bin/ramips/packages/base
$ ls