openwrt可用helloworld

在package目录中建立src目录，并创建helloworld.c文件内容如下：

#include <stdio.h>

int main()
{
    printf("\nHello openwrt!\n");
    return 0;
}

创建Makefile文件，内容如下：

PROGS = helloworld

OBJS = helloworld.o

all: $(PROGS)
$(PROGS): $(OBJS)
	@echo "CC = " $(CC)
	@echo "CFLAGS = " $(CFLAGS)
	@echo "LDFLAGS = " $(LDFLAGS)
	$(CC) $(CFLAGS) $(LDFLAGS) $^ $(LDLIBS) -o $@

%.o: %.c
	$(CC) -c $(CFLAGS) $^ -o $@

clean:
	rm -f $(PROGS) *.o core

退回到helloworld目录，创建Makefile文件，内容如下：

##############################################
# 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
define Build/Compile
	$(MAKE) -C $(PKG_BUILD_DIR) \
		$(TARGET_CONFIGURE_OPTS) CFLAGS="$(TARGET_CFLAGS) -I$(LINUX_DIR)/include"
endef

# 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))

首先在make menuconfig中选中helloworld包，在openwrt目录下运行

make package/helloworld/compile V=s

编译，编译之前要在helloworld的src目录下make clean一下。