驱动模块添加：
1：make menuconfig中的 kernel modules

其中的各个配置选项来自于下面目录中的.mk文件

这里以other.mk为对照，后续我们添加的驱动模块，添加到other分支当中

2：建立模块目录，路径是package/kernel/example。mkdir -p package/kernel/example

3：进行package/kernel/example目录，建立Makefile文件，内容如下

#Kernel module example
include $(TOPDIR)/rules.mk
 
include $(INCLUDE_DIR)/kernel.mk
 
PKG_NAME:=example
PKG_RELEASE:=1
 
include $(INCLUDE_DIR)/package.mk
 
 
EXTRA_CFLAGS:= \
    $(patsubst CONFIG_%, -DCONFIG_%=1, $(patsubst %=m,%,$(filter %=m,$(EXTRA_KCONFIG)))) \
    $(patsubst CONFIG_%, -DCONFIG_%=1, $(patsubst %=y,%,$(filter %=y,$(EXTRA_KCONFIG)))) \
 
MAKE_OPTS:=ARCH="$(LINUX_KARCH)" \
    CROSS_COMPILE="$(TARGET_CROSS)" \
    SUBDIRS="$(PKG_BUILD_DIR)" \
    EXTRA_CFLAGS="$(EXTRA_CFLAGS)"
 
define KernelPackage/example
  SUBMENU:=Other modules
  TITLE:=Support Module for example
  # DEPENDS:=@XXX   #如果有依赖，这个名字可去make menuconfig里面找到 Symbol:XXX
  FILES:=$(PKG_BUILD_DIR)/example.ko
  AUTOLOAD:=$(call AutoLoad,81,example) #系统启动时自动装载
endef
 
#PKG_BUILD_DIR：/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7621/example 
#建立 PKG_BUILD_DIR ，并将代码拷贝到此处
define Build/Prepare
    mkdir -p $(PKG_BUILD_DIR)/              
    $(CP) -R ./src/* $(PKG_BUILD_DIR)/
endef
define Build/Compile
    $(MAKE) -C "$(LINUX_DIR)" $(MAKE_OPTS) CONFIG_EXAMPLE=m modules
endef
$(eval $(call KernelPackage,example))

4：在package/kernel/example目录下建立src目录，mkdir -p package/kernel/example/src
5：在package/kernel/example/src目录下建立源码文件example.c和对应的Makefile，Kconfig

example.c

#include <linux/module.h>
#include <linux/version.h>
#include <linux/kmod.h>
 
 
 
 
static int __init example_init(void)
{
    printk("hello example openwrt\n");
    return 0;
}
 
static void __exit example_exit(void)
{
    printk("hello example openwrt exit\n");
}
 
module_init(example_init);
module_exit(example_exit);
 
MODULE_AUTHOR("hello world");
MODULE_DESCRIPTION("example driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);
Makefile:

obj-${CONFIG_EXAMPLE}+= example.o

Kconfig:

config EXAMPLE
    tristate "Just a example"
    help
    This is a example, for debugging kernel model.
    If unsure, say N.

6：在trunk目录make menuconfig-->kernel module-->other module-->kmod-example选中。保存Config后，输入make ./package/kernel/example/compile V=s进行编译

应用程序编译

1：在trunk/package应用目录。参考其他的应用文件。创建helloworld文件夹，并进入。创建Makefile：

##############################################
# 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
define Build/Configure
endef
define Build/Compile
    $(MAKE) -C $(PKG_BUILD_DIR) \
        CC="$(TARGET_CC)" \
        CFLAGS="$(TARGET_CFLAGS) -Wall" \
        LDFLAGS="$(TARGET_LDFLAGS)"
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：在helloworld目录创建src文件夹，并进入。创建Makefile和helloworld.c：

# 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.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
 
int main(int argc, char**argv)
{
    printf("Hell! O' world, why won't my code compile?\n\n");
    return 0;
}

3：返回trunk目录，make menuconfig-->Utilities-->helloworld。然后make ./package/helloworld/compile V=s

转至：https://blog.csdn.net/cupidove/article/details/45093385