openWRT构建helloworld示例

概述

版本号：OpenWrt 18.06.2, r7676-cddd7b4c77

helloworld示例

参考：OpenWrt：构建helloworld应用

1. 在package目录下新建helloworld文件夹，存放helloworld应用程序。

$ tree helloworld/
helloworld/
├── Makefile    # openwrt规则Makefile
└── src
    ├── helloworld.c
    └── Makefile   # 普通Makefile

helloworld/src目录下存放helloworld例程和编译Makefile：

#include <stdio.h>

int main(int argc, char *argv[])
{
    printf("hello world\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

helloworld/Makefile为符合openWrt规则的Makefile，完成包编译安装等。

Makefile语法官网

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

2. 添加软件helloworld到openwrt中。

在openwrt/目录下执行make menuconfig，Utilities->helloworld选配为M。

3. 编译

~/openwrt$ make package/helloworld/compile V=s
~/openwrt$ ls bin/packages/arm_cortex-a9_neon-vfpv3/base/helloworld_1_arm_cortex-a9_neon-vfpv3.ipk
bin/packages/arm_cortex-a9_neon-vfpv3/base/helloworld_1_arm_cortex-a9_neon-vfpv3.ipk

4. 安装运行

openwrt板卡上运行opkg安装helloworld ipk程序。

root@Bonanza:~# opkg install helloworld_1_arm_cortex-a9_neon-vfpv3.ipk
Installing helloworld (1) to root...
Configuring helloworld.
root@Bonanza:~# helloworld
hello world

参考

1. OpenWrt 编译步骤与命令详解