Android OTA在线升级二（升级包编译原理分析） 【转】
本文转载自：http://blog.csdn.net/huryjiang/article/details/7590015
1 升级包的制作
基本命令：
Ø makeMtk [project[flavor]] new –编译整个项目
Ø makeMtk [project[flavor]] otapackage –编译otapackage
Ø /build/tools/releasetools/ota_from_target_files –n –i oldotapackage newotapackage update.zip –制作差分包
生成的otapackage为整包，update.zip为差分包，这两个包拷贝到SD卡上，进入recovery模式后便可以进行升级了。–n –i 这两个是编译差分包的参数，-n是忽略UTC时间戳对版本升级的限制，-i是生成的差分包。因为整包和差分包都是通过./build/tools/releasetools/ota_from_target_files这个脚本生成的，这个文件的分析详细查看，这位大侠的分析，非常的详细：http://blog.csdn.net/zjujoe/article/details/6209393
编译过程：
1、Android 的编译原理
参见下面：http://www.cnblogs.com/fly-fish/archive/2012/05/07/2489274.html
下面说明otapackage的编译原理：
(build/core/Makefile)
# -----------------------------------------------------------------
# host tools needed to build OTA packages
OTATOOLS := $(HOST_OUT_EXECUTABLES)/minigzip \
$(HOST_OUT_EXECUTABLES)/mkbootfs \
$(HOST_OUT_EXECUTABLES)/mkbootimg \
$(HOST_OUT_EXECUTABLES)/fs_config \
$(HOST_OUT_EXECUTABLES)/mkyaffs2image \
$(HOST_OUT_EXECUTABLES)/zipalign \
$(HOST_OUT_EXECUTABLES)/aapt \
$(HOST_OUT_EXECUTABLES)/bsdiff \
$(HOST_OUT_EXECUTABLES)/imgdiff \
$(HOST_OUT_JAVA_LIBRARIES)/dumpkey.jar \
$(HOST_OUT_JAVA_LIBRARIES)/signapk.jar \
$(HOST_OUT_EXECUTABLES)/mkuserimg.sh \
$(HOST_OUT_EXECUTABLES)/make_ext4fs
.PHONY: otatools
otatools: $(OTATOOLS)
# -----------------------------------------------------------------
# A zip of the directories that map to the target filesystem.
# This zip can be used to create an OTA package or filesystem image
# as a post-build step.
#
name := $(TARGET_PRODUCT)
ifeq ($(TARGET_BUILD_TYPE),debug)
name := $(name)_debug
endif
name := $(name)-target_files-$(FILE_NAME_TAG)
intermediates := $(call intermediates-dir-for,PACKAGING,target_files)
BUILT_TARGET_FILES_PACKAGE := $(intermediates)/$(name).zip
$(BUILT_TARGET_FILES_PACKAGE): intermediates := $(intermediates)
$(BUILT_TARGET_FILES_PACKAGE): \
zip_root := $(intermediates)/$(name)
# $(1): Directory to copy
# $(2): Location to copy it to
# The "ls -A" is to prevent "acp s/* d" from failing if s is empty.
define package_files-copy-root
if [ -d "$(strip $(1))" -a "$$(ls -A $(1))" ]; then \
mkdir -p $(2) && \
$(ACP) -rd $(strip $(1))/* $(2); \
fi
endef
built_ota_tools := \
$(call intermediates-dir-for,EXECUTABLES,applypatch)/applypatch \
$(call intermediates-dir-for,EXECUTABLES,applypatch_static)/applypatch_static \
$(call intermediates-dir-for,EXECUTABLES,check_prereq)/check_prereq \
$(call intermediates-dir-for,EXECUTABLES,updater)/updater
$(BUILT_TARGET_FILES_PACKAGE): PRIVATE_OTA_TOOLS := $(built_ota_tools)
$(BUILT_TARGET_FILES_PACKAGE): PRIVATE_RECOVERY_API_VERSION := $(RECOVERY_API_VERSION)
ifeq ($(TARGET_RELEASETOOLS_EXTENSIONS),)
# default to common dir for device vendor
$(BUILT_TARGET_FILES_PACKAGE): tool_extensions := $(TARGET_DEVICE_DIR)/../common
else
$(BUILT_TARGET_FILES_PACKAGE): tool_extensions := $(TARGET_RELEASETOOLS_EXTENSIONS)
endif
# Depending on the various images guarantees that the underlying
# directories are up-to-date.
$(BUILT_TARGET_FILES_PACKAGE): \
$(INSTALLED_BOOTIMAGE_TARGET) \
$(INSTALLED_RADIOIMAGE_TARGET) \
$(INSTALLED_RECOVERYIMAGE_TARGET) \
$(INSTALLED_SYSTEMIMAGE) \
$(INSTALLED_USERDATAIMAGE_TARGET) \
$(INSTALLED_ANDROID_INFO_TXT_TARGET) \
$(built_ota_tools) \
$(APKCERTS_FILE) \
$(HOST_OUT_EXECUTABLES)/fs_config \
| $(ACP)
@echo "Package target files: $@"
$(hide) rm -rf $@ $(zip_root)
$(hide) mkdir -p $(dir $@) $(zip_root)
@# Components of the recovery image
$(hide) mkdir -p $(zip_root)/RECOVERY
$(hide) $(call package_files-copy-root, \
$(TARGET_RECOVERY_ROOT_OUT),$(zip_root)/RECOVERY/RAMDISK)
ifdef INSTALLED_KERNEL_TARGET
$(hide) $(ACP) $(INSTALLED_KERNEL_TARGET) $(zip_root)/RECOVERY/kernel
endif
ifdef INSTALLED_2NDBOOTLOADER_TARGET
$(hide) $(ACP) \
$(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/RECOVERY/second
endif
ifdef BOARD_KERNEL_CMDLINE
$(hide) echo "$(BOARD_KERNEL_CMDLINE)" > $(zip_root)/RECOVERY/cmdline
endif
ifdef BOARD_KERNEL_BASE
$(hide) echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/RECOVERY/base
endif
ifdef BOARD_KERNEL_PAGESIZE
$(hide) echo "$(BOARD_KERNEL_PAGESIZE)" > $(zip_root)/RECOVERY/pagesize
endif
@# Components of the boot image
$(hide) mkdir -p $(zip_root)/BOOT
$(hide) $(call package_files-copy-root, \
$(TARGET_ROOT_OUT),$(zip_root)/BOOT/RAMDISK)
ifdef INSTALLED_KERNEL_TARGET
$(hide) $(ACP) $(INSTALLED_KERNEL_TARGET) $(zip_root)/BOOT/kernel
endif
ifdef INSTALLED_2NDBOOTLOADER_TARGET
$(hide) $(ACP) \
$(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/BOOT/second
endif
ifdef BOARD_KERNEL_CMDLINE
$(hide) echo "$(BOARD_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
endif
ifdef BOARD_KERNEL_BASE
$(hide) echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/BOOT/base
endif
ifdef BOARD_KERNEL_PAGESIZE
$(hide) echo "$(BOARD_KERNEL_PAGESIZE)" > $(zip_root)/BOOT/pagesize
endif
$(hide) $(foreach t,$(INSTALLED_RADIOIMAGE_TARGET),\
mkdir -p $(zip_root)/RADIO; \
$(ACP) $(t) $(zip_root)/RADIO/$(notdir $(t));)
@# Contents of the system image
$(hide) $(call package_files-copy-root, \
$(SYSTEMIMAGE_SOURCE_DIR),$(zip_root)/SYSTEM)
@# Contents of the data image
$(hide) $(call package_files-copy-root, \
$(TARGET_OUT_DATA),$(zip_root)/DATA)
@# Extra contents of the OTA package
$(hide) mkdir -p $(zip_root)/OTA/bin
$(hide) $(ACP) $(INSTALLED_ANDROID_INFO_TXT_TARGET) $(zip_root)/OTA/
$(hide) $(ACP) $(PRIVATE_OTA_TOOLS) $(zip_root)/OTA/bin/
@# Files that do not end up in any images, but are necessary to
@# build them.
$(hide) mkdir -p $(zip_root)/META
$(hide) $(ACP) $(APKCERTS_FILE) $(zip_root)/META/apkcerts.txt
$(hide) echo "$(PRODUCT_OTA_PUBLIC_KEYS)" > $(zip_root)/META/otakeys.txt
$(hide) echo "recovery_api_version=$(PRIVATE_RECOVERY_API_VERSION)" > $(zip_root)/META/misc_info.txt
ifdef BOARD_FLASH_BLOCK_SIZE
$(hide) echo "blocksize=$(BOARD_FLASH_BLOCK_SIZE)" >> $(zip_root)/META/misc_info.txt
endif
ifdef BOARD_BOOTIMAGE_PARTITION_SIZE
$(hide) echo "boot_size=$(BOARD_BOOTIMAGE_PARTITION_SIZE)" >> $(zip_root)/META/misc_info.txt
endif
ifdef BOARD_RECOVERYIMAGE_PARTITION_SIZE
$(hide) echo "recovery_size=$(BOARD_RECOVERYIMAGE_PARTITION_SIZE)" >> $(zip_root)/META/misc_info.txt
endif
ifdef BOARD_SYSTEMIMAGE_PARTITION_SIZE
$(hide) echo "system_size=$(BOARD_SYSTEMIMAGE_PARTITION_SIZE)" >> $(zip_root)/META/misc_info.txt
endif
ifdef BOARD_USERDATAIMAGE_PARTITION_SIZE
$(hide) echo "userdata_size=$(BOARD_USERDATAIMAGE_PARTITION_SIZE)" >> $(zip_root)/META/misc_info.txt
endif
$(hide) echo "tool_extensions=$(tool_extensions)" >> $(zip_root)/META/misc_info.txt
ifdef mkyaffs2_extra_flags
$(hide) echo "mkyaffs2_extra_flags=$(mkyaffs2_extra_flags)" >> $(zip_root)/META/misc_info.txt
endif
@# Zip everything up, preserving symlinks
$(hide) (cd $(zip_root) && zip -qry ../$(notdir $@) .)
@# Run fs_config on all the system files in the zip, and save the output
$(hide) zipinfo -1 $@ | awk -F/ 'BEGIN { OFS="/" } /^SYSTEM\// {$$1 = "system"; print}' | $(HOST_OUT_EXECUTABLES)/fs_config > $(zip_root)/META/filesystem_config.txt
$(hide) (cd $(zip_root) && zip -q ../$(notdir $@) META/filesystem_config.txt)
target-files-package: $(BUILT_TARGET_FILES_PACKAGE)
ifneq ($(TARGET_SIMULATOR),true)
ifneq ($(TARGET_PRODUCT),sdk)
ifneq ($(TARGET_DEVICE),generic)
ifneq ($(TARGET_NO_KERNEL),true)
ifneq ($(recovery_fstab),)
# -----------------------------------------------------------------
# OTA update package
name := $(TARGET_PRODUCT)
ifeq ($(TARGET_BUILD_TYPE),debug)
name := $(name)_debug
endif
name := $(name)-ota-$(FILE_NAME_TAG)
INTERNAL_OTA_PACKAGE_TARGET := $(PRODUCT_OUT)/$(name).zip
$(INTERNAL_OTA_PACKAGE_TARGET): KEY_CERT_PAIR := $(DEFAULT_KEY_CERT_PAIR)
$(INTERNAL_OTA_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(OTATOOLS)
@echo "Package OTA: $@"
$(hide) ./build/tools/releasetools/ota_from_target_files -v \
-n \
-p $(HOST_OUT) \
-k $(KEY_CERT_PAIR) \
$(BUILT_TARGET_FILES_PACKAGE) $@
.PHONY: otapackage
otapackage: $(INTERNAL_OTA_PACKAGE_TARGET)
# -----------------------------------------------------------------
# The update package
name := $(TARGET_PRODUCT)
ifeq ($(TARGET_BUILD_TYPE),debug)
name := $(name)_debug
endif
name := $(name)-img-$(FILE_NAME_TAG)
INTERNAL_UPDATE_PACKAGE_TARGET := $(PRODUCT_OUT)/$(name).zip
ifeq ($(TARGET_RELEASETOOLS_EXTENSIONS),)
# default to common dir for device vendor
$(INTERNAL_UPDATE_PACKAGE_TARGET): extensions := $(TARGET_DEVICE_DIR)/../common
else
$(INTERNAL_UPDATE_PACKAGE_TARGET): extensions := $(TARGET_RELEASETOOLS_EXTENSIONS)
endif
$(INTERNAL_UPDATE_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(OTATOOLS)
@echo "Package: $@"
$(hide) ./build/tools/releasetools/img_from_target_files -v \
-s $(extensions) \
-p $(HOST_OUT) \
$(BUILT_TARGET_FILES_PACKAGE) $@
.PHONY: updatepackage
updatepackage: $(INTERNAL_UPDATE_PACKAGE_TARGET)
endif # recovery_fstab is defined
endif # TARGET_NO_KERNEL != true
endif # TARGET_DEVICE != generic
endif # TARGET_PRODUCT != sdk
endif # TARGET_SIMULATOR != true
上面红色标注的地方说明：
1、OTATOOLS 升级包制作的差分工具
2、$(hide) ./build/tools/releasetools/ota_from_target_files -v \
-n \调用脚本生成otapackage包，这里Android源码是没有-n这个参数的，没有这个参数会导致版本之间无法升级，-n忽略ro.build.date.utc检查。
