如何在OpenWrt平台新增一个package
背景
OpenWrt的编译框架做得非常好，只需要在固定的目录下，放置通用的Makefile，其编译框架即可正常读取该Makefile，并用指定的toolchains开始编译。
自定义的pacakge可以放在SDK根目录下的这个位置openwrt/package。
每个package的目录架构都是相似的：
package
├── files
├── Makefile
└── src
├── main.c
└── Makefile
本文所描述的是上层的Makefile。
示例
既可以编译用户进态的模块，也可以编译内核模块。以下为具体示例。
用户态模块
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#
include $(TOPDIR)/rules.mk
PKG_NAME:=app-monitor
PKG_VERSION:=1.0
include $(INCLUDE_DIR)/package.mk
define Package/app-monitor
SECTION:=XXXX
CATEGORY:=XXXX platform apps
MAINTAINER:=XXXX
DEPENDS:=
TITLE:=App module test for XXXX
endef
define Package/app-monitor/Description
This is a app module test for XXXX
endef
define Build/Prepare
mkdir -p $(PKG_BUILD_DIR)
$(CP) -u ./src/* $(PKG_BUILD_DIR)/
endef
define Package/app-monitor/install
$(INSTALL_DIR) $(1)/etc
$(INSTALL_DATA) ./filesystem/etc/app-monitor.config $(1)/etc
$(INSTALL_DIR) $(1)/usr/bin
$(INSTALL_BIN) $(PKG_BUILD_DIR)/app-monitor $(1)/usr/bin
endef
$(eval $(call BuildPackage,app-monitor))
内核模块
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#
include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/kernel.mk
PKG_NAME:=app-monitor
PKG_VERSION:=0.1
define KernelPackage/app-monitor
SECTION:=XXXX
CATEGORY:=XXXX platform apps
MAINTAINER:=XXXX
DEPENDS:=
TITLE:=app-monitor
FILES:=$(PKG_BUILD_DIR)/app_monitor.ko
AUTOLOAD:=$(call AutoLoad,99,app_monitor)
endef
define KernelPackage/app-monitor/description
This is a kernel package which used by xxx
endef
define Build/Prepare
mkdir -p $(PKG_BUILD_DIR)
$(CP) -u ./src/* $(PKG_BUILD_DIR)/
endef
define Build/Compile
$(MAKE) -C "$(LINUX_DIR)" \
CROSS_COMPILE="$(TARGET_CROSS)" \
ARCH="$(LINUX_KARCH)" \
SUBDIRS="$(PKG_BUILD_DIR)" \
EXTRA_CFLAGS="$(EXTRA_CFLAGS)" \
modules
endef
define KernelPackage/app-monitor
SECTION:=XXXX
CATEGORY:=XXXX platform apps
MAINTAINER:=XXXX
DEPENDS:=
TITLE:=app-monitor
FILES:=$(PKG_BUILD_DIR)/app_monitor.ko
AUTOLOAD:=$(call AutoLoad,99,app_monitor)
endef
define KernelPackage/app-monitor/description
This is a kernel package which used by xxx
endef
define Build/Prepare
mkdir -p $(PKG_BUILD_DIR)
$(CP) -u ./src/* $(PKG_BUILD_DIR)/
endef
define Build/Compile
$(MAKE) -C $(LINUX_DIR) M=$(PKG_BUILD_DIR) $(strip $(MAKE_OPTS))
endef
define Build/InstallDev
$(INSTALL_DIR) $(1)/usr/include
$(CP) $(PKG_BUILD_DIR)/app_monitor.h $(1)/usr/include
endef
define KernelPackage/app-monitor/install
$(INSTALL_DIR) $(1)/etc
endef
$(eval $(call KernelPackage,$(PKG_NAME)))
用户态模块+内核模块
即可以在同一个package中，同时包含两种。
有了上面两个例子，下面的例子更多是拼接，最核心在于后面的BuildPackage和KernelPackage。
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#
include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/kernel.mk
PKG_NAME:=app-monitor
PKG_VERSION:=1.0
include $(INCLUDE_DIR)/package.mk
define KernelPackage/$(PKG_NAME)
SECTION:=XXXX
CATEGORY:=XXXX platform apps
MAINTAINER:=XXXX
DEPENDS:=
TITLE:=app monitor kernel module for you
FILES:=$(PKG_BUILD_DIR)/ipt/app-monitor.ko
AUTOLOAD:=$(call AutoLoad,99,app-monitor)
endef
TARGET_CFLAGS += -I$(STAGING_DIR)/usr/include
TARGET_LDFLAGS += -L$(STAGING_DIR)/usr/lib
TARGET_LDFLAGS += -L$(STAGING_DIR)/lib
PKG_DEPENDS:=+libc
APP_MONITOR_MAKE_OPTS:=
ifeq ($(CONFIG_XXXX), y)
EXTRA_CFLAGS += -I$(LINUX_DIR)/../bcmkernel/include
EXTRA_CFLAGS += -DCONFIG_XXXX=1
endif
TARGET_LDFLAGS += -L$(STAGING_DIR)/usr/lib
APP_DPI_MAKE_OPTS+= \
CROSS_COMPILE=$(KERNEL_CROSS) \
ARCH=$(LINUX_KARCH) \
KERNELPATH="$(LINUX_SRC_DIR)" \
KBUILDPATH=$(LINUX_DIR) \
EXTRA_CFLAGS="$(EXTRA_CFLAGS)" \
SUBDIRS=$(PKG_BUILD_DIR)
define Package/$(PKG_NAME)
SECTION:=XXXX
CATEGORY:=XXXX platform apps
TITLE:=app-monitor application for XXXX
MAINTAINER:=XXXX
DEPENDS:=$(PKG_DEPENDS)
endef
define KernelPackage/$(PKG_NAME)/description
This is a kernel module which do xxxxx thing
endef
define Package/$(PKG_NAME)/Description
This is app-monitor module for XXXX
endef
define Package/$(PKG_NAME)/config
config PACKAGE_MONITOR_VENDOR
string "monitor vendor name(must be setted)"
default name_of_provider
config PACKAGE_MONITOR_VERSION
string "monitor version(must be setted)"
default X.Y.Z
config PACKAGE_MONITOR_USE_IPT
bool "monitor module use iptables to intercept packet"
default n
endef
CONFIG_PACKAGE_MONITOR_USE_IPT ?= y
ifeq ($(CONFIG_PACKAGE_MONITOR_USE_IPT), y)
SRC_PATH:=ipt
PKG_DEPENDS+=+iptables
else #CONFIG_PACKAGE_MONITOR_USE_IPT
TARGET_LDFLAGS += -lpcap
PKG_DEPENDS+=+libnetfilter-queue +libpcap
SRC_PATH:=frame
endif #CONFIG_PACKAGE_MONITOR_USE_IPT
MONITOR_VENDOR ?= $(CONFIG_PACKAGE_MONITOR_VENDOR)
MONITOR_VERSION ?= $(CONFIG_PACKAGE_MONITOR_VERSION)
MONITOR_USE_IPT ?= $(CONFIG_PACKAGE_MONITOR_USE_IPT)
$(info $$MONITOR_VENDOR is [${MONITOR_VENDOR}])
$(info $$MONITOR_VERSION is [${MONITOR_VERSION}])
$(info $$MONITOR_USE_IPT is [${MONITOR_USE_IPT}])
INSTALL_BIN:=$(SRC_PATH)/app-monitor
INSTALL_LIB:=$(SRC_PATH)/libxt_monitor.so
define Build/Prepare
mkdir -p $(PKG_BUILD_DIR)
$(CP) -u ./src-$(MONITOR_VENDOR)/* $(PKG_BUILD_DIR)/
endef
define Build/Compile
$(MAKE) -C $(PKG_BUILD_DIR)/$(SRC_PATH) \
$(TARGET_CONFIGURE_OPTS) \
TARGET_LDFLAGS="$(TARGET_LDFLAGS)" \
TARGET_CFLAGS="$(TARGET_CFLAGS) $(TARGET_CPPFLAGS)" \
MONITOR_VERSION="$(MONITOR_VERSION)" \
CC="$(TARGET_CC)"
$(MAKE) -C $(LINUX_DIR) M=$(PKG_BUILD_DIR)/$(SRC_PATH) MONITOR_VERSION=$(MONITOR_VERSION) $(strip $(APP_MONITOR_MAKE_OPTS))
endef
define Package/$(PKG_NAME)/install
$(CP) -rf ./filesystem/* $(1)/
$(INSTALL_DIR) $(1)/usr/lib/monitor/
$(CP) $(PKG_BUILD_DIR)/sdk-$(MONITOR_VERSION)/lib/* $(1)/usr/lib/monitor/
$(INSTALL_DIR) $(1)/usr/bin
$(if $(INSTALL_BIN),$(CP) $(foreach bin,$(INSTALL_BIN),$(PKG_BUILD_DIR)/$(bin)) $(1)/usr/bin/)
$(INSTALL_DIR) $(1)/usr/lib/iptables
$(if $(INSTALL_LIB),$(CP) $(foreach lib,$(INSTALL_LIB),$(PKG_BUILD_DIR)/$(lib)) $(1)/usr/lib/iptables/)
endef
define Build/InstallDev
endef
define KernelPackage/$(PKG_NAME)/install
$(INSTALL_DIR) $(1)/etc
endef
$(eval $(call KernelPackage,$(PKG_NAME)))
$(eval $(call BuildPackage,$(PKG_NAME)))
当然，具体到src目录下，用户态模块仍然用Makefile控制，而内核模块则Kbuild控制：
MODULE_NAME = app-monitor
$(MODULE_NAME)-objs := app-monitor-kmod.o component.o
obj-m += $(MODULE_NAME).o