高通kernel顶层目录下的AndroidKernel.mk文件
高通kernel顶层目录下的AndroidKernel.mk文件是Android的编译系统的一部分,用来编译kernel。
它的位置是在aosp/kernel目录下。
文件层级结构
定义变量【第一处】ifeq ($(TARGET_PREBUILT_KERNEL),) 定义变量【第二处】 ifeq ($(KERNEL_DEFCONFIG)$(wildcard $(KERNEL_CONFIG)),) $(error Kernel configuration not defined, cannot build kernel) else 定义变量【第三处】 定义一些目标和依赖 endifendif
文件具体内容(带注释)
定义变量【第一处】
PERL变量
#Android makefile to build kernel as a part of Android BuildPERL = perl
KERNEL_TARGET 和 INSTALLED_KERNEL_TARGET 变量
KERNEL_TARGET := $(strip $(INSTALLED_KERNEL_TARGET))ifeq ($(KERNEL_TARGET),)INSTALLED_KERNEL_TARGET := $(PRODUCT_OUT)/kernelendif
在build/core/Makefile文件中,定义了INSTALLED_KERNEL_TARGET变量
ifneq ($(strip $(TARGET_NO_KERNEL)),true) INSTALLED_KERNEL_TARGET := $(PRODUCT_OUT)/kernelelse INSTALLED_KERNEL_TARGET :=endif
TARGET_NO_KERNEL是在device/厂商/产品名/BoardConfig.mk中定义的
TARGET_NO_KERNEL := false
Makefile中,
ifeq关键字用来判断参数是否相等,
ifneq的关键字是用来判断参数是否不相等,
格式为:
ifneq (ARG1, ARG2) / ifneq (ARG1, ARG2)ifneq 'ARG1' 'ARG2' / ifneq 'ARG1' 'ARG2'ifneq "ARG1" "ARG2" / ifneq "ARG1" "ARG2"ifneq "ARG1" 'ARG2' / ifneq "ARG1" 'ARG2'ifneq 'ARG1' "ARG2" / ifneq 'ARG1' "ARG2"
综上所述可知,不论TARGET_NO_KERNEL为false还是true,则KERNEL_TARGET和INSTALLED_KERNEL_TARGET的值都为$(PRODUCT_OUT)/kernel。
TARGET_KERNEL_ARCH 和 KERNEL_ARCH 变量
TARGET_KERNEL_ARCH := $(strip $(TARGET_KERNEL_ARCH))ifeq ($(TARGET_KERNEL_ARCH),)KERNEL_ARCH := armelseKERNEL_ARCH := $(TARGET_KERNEL_ARCH)endif
TARGET_KERNEL_ARCH是在device/厂商/产品名/BoardConfig.mk中定义的。
如果已经定义为某值(如arm64),KERNEL_ARCH就设定为该值(如arm64)。
反之,则设定为默认值arm
TARGET_KERNEL_HEADER_ARCH := $(strip $(TARGET_KERNEL_HEADER_ARCH))ifeq ($(TARGET_KERNEL_HEADER_ARCH),)KERNEL_HEADER_ARCH := $(KERNEL_ARCH)else$(warning Forcing kernel header generation only for '$(TARGET_KERNEL_HEADER_ARCH)')KERNEL_HEADER_ARCH := $(TARGET_KERNEL_HEADER_ARCH)endif
TARGET_KERNEL_ARCH是在device/厂商/产品名/BoardConfig.mk中定义的。
如果TARGET_KERNEL_HEADER_ARCH为空,KERNEL_HEADER_ARCH就设定为KERNEL_ARCH的值。
反之,则警告并将KERNEL_HEADER_ARCH设定为TARGET_KERNEL_HEADER_ARCH
KERNEL_HEADER_DEFCONFIG := $(strip $(KERNEL_HEADER_DEFCONFIG))ifeq ($(KERNEL_HEADER_DEFCONFIG),)KERNEL_HEADER_DEFCONFIG := $(KERNEL_DEFCONFIG)endif
KERNEL_DEFCONFIG是在device/厂商/产品名/AndroidBoard.mk中定义的。
KERNEL_HEADER_DEFCONFIG未找到定义的地方。
当KERNEL_HEADER_DEFCONFIG为空,则被赋值为KERNEL_DEFCONFIG。
binder
ifeq ($(KERNEL_ARCH),arm64)ifeq ($(TARGET_ARCH),arm)KERNEL_CONFIG_OVERRIDE := CONFIG_ANDROID_BINDER_IPC_32BIT=yendifendif
通过条件判断,是否让32-bit的binder IPC(进程间通信机制) 强制运行于64bit的kernel的32bit用户空间。
TARGET_KERNEL_CROSS_COMPILE_PREFIX 和 KERNEL_CROSS_COMPILE 变量
TARGET_KERNEL_CROSS_COMPILE_PREFIX := $(strip $(TARGET_KERNEL_CROSS_COMPILE_PREFIX))ifeq ($(TARGET_KERNEL_CROSS_COMPILE_PREFIX),)KERNEL_CROSS_COMPILE := arm-eabi-elseKERNEL_CROSS_COMPILE := $(TARGET_KERNEL_CROSS_COMPILE_PREFIX)endif
TARGET_KERNEL_CROSS_COMPILE_PREFIX是在device/厂商/产品名/AndroidBoard.mk中定义的。
例:TARGET_KERNEL_CROSS_COMPILE_PREFIX := aarch64-linux-android-
定义变量【第二处】
KERNEL_CFLAGS变量
KERNEL_GCC_NOANDROID_CHK := $(shell (echo "int main() {return 0;}" | $(KERNEL_CROSS_COMPILE)gcc -E -mno-android - > /dev/null 2>&1 ; echo $$?))ifeq ($(strip $(KERNEL_GCC_NOANDROID_CHK)),0)KERNEL_CFLAGS := KCFLAGS=-mno-androidendif
KERNEL_GCC_NOANDROID_CHK 变量如果为0,则定义KERNEL_CFLAGS为KCFLAGS=-mno-android
mkfile_path变量
mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST)))
获得mk文件路径
current_dir变量
current_dir := $(notdir $(patsubst %/,%,$(dir $(mkfile_path))))
TARGET_KERNEL_VERSION变量
ifeq ($(TARGET_KERNEL_VERSION),) TARGET_KERNEL_VERSION := 3.18endif
TARGET_KERNEL变量
TARGET_KERNEL := msm-$(TARGET_KERNEL_VERSION)
通过TARGET_KERNEL变量,定义KERNEL_OUT等变量
ifeq ($(TARGET_KERNEL),$(current_dir)) BUILD_ROOT_LOC := ../../ TARGET_KERNEL_SOURCE := kernel/$(TARGET_KERNEL) KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/kernel/$(TARGET_KERNEL) KERNEL_SYMLINK := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ KERNEL_USR := $(KERNEL_SYMLINK)/usrelse KERNEL_LEGACY_DIR := true BUILD_ROOT_LOC := ../ TARGET_KERNEL_SOURCE := kernel KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJendif
KERNEL_CONFIG变量
KERNEL_CONFIG := $(KERNEL_OUT)/.config
定义变量【第三处】
TARGET_PREBUILT_INT_KERNEL变量
ifeq ($(TARGET_USES_UNCOMPRESSED_KERNEL),true)$(info Using uncompressed kernel)TARGET_PREBUILT_INT_KERNEL := $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/Imageelseifeq ($(KERNEL_ARCH),arm64)TARGET_PREBUILT_INT_KERNEL := $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/Image.gzelseTARGET_PREBUILT_INT_KERNEL := $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/zImageendifendif
依据TARGET_KERNEL_APPEND_DTB变量,定义TARGET_PREBUILT_INT_KERNEL变量
ifeq ($(TARGET_KERNEL_APPEND_DTB), true)$(info Using appended DTB)TARGET_PREBUILT_INT_KERNEL := $(TARGET_PREBUILT_INT_KERNEL)-dtbendif
KERNEL_HEADERS_INSTALL := $(KERNEL_OUT)/usr
KERNEL_MODULES_INSTALL变量
KERNEL_MODULES_INSTALL := system
KERNEL_MODULES_OUT变量
KERNEL_MODULES_OUT := $(TARGET_OUT)/lib/modules
TARGET_PREBUILT_KERNEL变量
TARGET_PREBUILT_KERNEL := $(TARGET_PREBUILT_INT_KERNEL)
宏mv-modules
define mv-modulesmdpath=`find $(KERNEL_MODULES_OUT) -type f -name modules.dep`;\if [ "$$mdpath" != "" ];then\mpath=`dirname $$mdpath`;\ko=`find $$mpath/kernel -type f -name *.ko`;\for i in $$ko; do mv $$i $(KERNEL_MODULES_OUT)/; done;\fiendef
宏clean-module-folder
define clean-module-foldermdpath=`find $(KERNEL_MODULES_OUT) -type f -name modules.dep`;\if [ "$$mdpath" != "" ];then\mpath=`dirname $$mdpath`; rm -rf $$mpath;\fiendef
目标和依赖
ifneq ($(KERNEL_LEGACY_DIR),true)$(KERNEL_USR): $(KERNEL_HEADERS_INSTALL) rm -rf $(KERNEL_SYMLINK) ln -s kernel/$(TARGET_KERNEL) $(KERNEL_SYMLINK)$(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_USR)endif$(KERNEL_OUT): mkdir -p $(KERNEL_OUT)$(KERNEL_CONFIG): $(KERNEL_OUT) $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG) $(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \ echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \ echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) oldconfig; fi$(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_OUT) $(KERNEL_HEADERS_INSTALL) $(hide) echo "Building kernel..." $(hide) rm -rf $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/dts $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS) $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS) modules $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) INSTALL_MOD_PATH=$(BUILD_ROOT_LOC)../$(KERNEL_MODULES_INSTALL) INSTALL_MOD_STRIP=1 ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) modules_install $(mv-modules) $(clean-module-folder)$(KERNEL_HEADERS_INSTALL): $(KERNEL_OUT) $(hide) if [ ! -z "$(KERNEL_HEADER_DEFCONFIG)" ]; then \ rm -f $(BUILD_ROOT_LOC)$(KERNEL_CONFIG); \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_HEADER_DEFCONFIG); \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) headers_install; fi $(hide) if [ "$(KERNEL_HEADER_DEFCONFIG)" != "$(KERNEL_DEFCONFIG)" ]; then \ echo "Used a different defconfig for header generation"; \ rm -f $(BUILD_ROOT_LOC)$(KERNEL_CONFIG); \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG); fi $(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \ echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \ echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) oldconfig; fikerneltags: $(KERNEL_OUT) $(KERNEL_CONFIG) $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) tagskernelconfig: $(KERNEL_OUT) $(KERNEL_CONFIG) env KCONFIG_NOTIMESTAMP=true \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) menuconfig env KCONFIG_NOTIMESTAMP=true \ $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) savedefconfig cp $(KERNEL_OUT)/defconfig $(TARGET_KERNEL_SOURCE)/arch/$(KERNEL_ARCH)/configs/$(KERNEL_DEFCONFIG)