android编译分析之4—product.mk

android编译系统中有两个概念product和device，product.mk是关于product相关的函数和变量。
下面的函数找到编译系统中的AndroidProducts.mk，在AndroidProducts.mk中一般都定义了具体产品相关makefile的文件。

#
# Functions for including AndroidProducts.mk files
# PRODUCT_MAKEFILES is set up in AndroidProducts.mks.
# Format of PRODUCT_MAKEFILES:
# :
# If the  is the same as the base file name (without dir
# and the .mk suffix) of the product makefile, ":" can be
# omitted.

#
# Returns the list of all AndroidProducts.mk files.
# $(call ) isn't necessary.
#
# 找到所有的AndroidProducts.mk,在device和vendor中找，最大深入6层子目录
# 这里还有个SRC_TARGET_DIR为build/target，aosp_arm等的mk在这个文件夹下
define _find-android-products-files
$(shell test -d device && find device -maxdepth 6 -name AndroidProducts.mk) \
  $(shell test -d vendor && find vendor -maxdepth 6 -name AndroidProducts.mk) \
  $(SRC_TARGET_DIR)/product/AndroidProducts.mk
endef

下面的函数的输入为AndroidProducts.mk，将这些makefile include进来，这些makefile中其实都是定义了一些PRODUCT_MAKEFILES变量，函数的返回值为将这些PRODUCT_MAKEFILES的值进行sort，sort就是按字母排序，同时删除重复的，所以返回值就是一些产品makefile文件的列表。例如
build/target/product/aosp_arm.mk build/target/product/full.mk

#
# Returns the sorted concatenation of PRODUCT_MAKEFILES
# variables set in the given AndroidProducts.mk files.
# $(1): the list of AndroidProducts.mk files.
#
define get-product-makefiles
$(sort \
  $(foreach f,$(1), \
    $(eval PRODUCT_MAKEFILES :=) \
    $(eval LOCAL_DIR := $(patsubst %/,%,$(dir $(f)))) \
    $(eval include $(f)) \
    $(PRODUCT_MAKEFILES) \
   ) \
  $(eval PRODUCT_MAKEFILES :=) \
  $(eval LOCAL_DIR :=) \
 )
endef

调用上面两个函数，

#
# Returns the sorted concatenation of all PRODUCT_MAKEFILES
# variables set in all AndroidProducts.mk files.
# $(call ) isn't necessary.
#
define get-all-product-makefiles
$(call get-product-makefiles,$(_find-android-products-files))
endef

下面这些变量都非常有用，每个产品都有一组这样的变量。在lunch时，会首先设置个变量TARGET_PRODUCT，而执行完makefile命令后，就会实现TARGET_PRODUCT的翻译，完成后就会得到这样一组变量。

#
# Functions for including product makefiles
#

_product_var_list := \
    PRODUCT_NAME \
    PRODUCT_MODEL \
    PRODUCT_LOCALES \
    PRODUCT_AAPT_CONFIG \
    PRODUCT_AAPT_PREF_CONFIG \
    PRODUCT_AAPT_PREBUILT_DPI \
    PRODUCT_PACKAGES \
    PRODUCT_PACKAGES_DEBUG \
    PRODUCT_PACKAGES_ENG \
    PRODUCT_PACKAGES_TESTS \
    PRODUCT_DEVICE \
    PRODUCT_MANUFACTURER \
    PRODUCT_BRAND \
    PRODUCT_PROPERTY_OVERRIDES \
    PRODUCT_DEFAULT_PROPERTY_OVERRIDES \
    PRODUCT_CHARACTERISTICS \
    PRODUCT_COPY_FILES \
    PRODUCT_OTA_PUBLIC_KEYS \
    PRODUCT_EXTRA_RECOVERY_KEYS \
    PRODUCT_PACKAGE_OVERLAYS \
    DEVICE_PACKAGE_OVERLAYS \
    PRODUCT_SDK_ATREE_FILES \
    PRODUCT_SDK_ADDON_NAME \
    PRODUCT_SDK_ADDON_COPY_FILES \
    PRODUCT_SDK_ADDON_COPY_MODULES \
    PRODUCT_SDK_ADDON_DOC_MODULES \
    PRODUCT_SDK_ADDON_SYS_IMG_SOURCE_PROP \
    PRODUCT_DEFAULT_WIFI_CHANNELS \
    PRODUCT_DEFAULT_DEV_CERTIFICATE \
    PRODUCT_RESTRICT_VENDOR_FILES \
    PRODUCT_VENDOR_KERNEL_HEADERS \
    PRODUCT_BOOT_JARS \
    PRODUCT_SUPPORTS_BOOT_SIGNER \
    PRODUCT_SUPPORTS_VBOOT \
    PRODUCT_SUPPORTS_VERITY \
    PRODUCT_OEM_PROPERTIES \
    PRODUCT_SYSTEM_PROPERTY_BLACKLIST \
    PRODUCT_SYSTEM_SERVER_JARS \
    PRODUCT_VBOOT_SIGNING_KEY \
    PRODUCT_VERITY_SIGNING_KEY \
    PRODUCT_SYSTEM_VERITY_PARTITION \
    PRODUCT_VENDOR_VERITY_PARTITION \
    PRODUCT_DEX_PREOPT_MODULE_CONFIGS \
    PRODUCT_DEX_PREOPT_DEFAULT_FLAGS \
    PRODUCT_DEX_PREOPT_BOOT_FLAGS \

下面的函数将每个产品的上面的一组变量都打印出来，从函数可以看出，AOSP中有很多的产品(PRODUCTS)，每个产品对应的PRODUCT_*相关的变量v的值是通过PRODUCTS.*.v来区分，其中两个点中间的星号是不同产品的makefile的名字（带路径）。

define dump-product
$(info ==== $(1) ====)\
$(foreach v,$(_product_var_list),\
$(info PRODUCTS.$(1).$(v) := $(PRODUCTS.$(1).$(v))))\
$(info --------)
endef

define dump-products
$(foreach p,$(PRODUCTS),$(call dump-product,$(p)))
endef

下面定义了非常重要的函数，继承某个产品，android不同的产品肯定是有一些共性的东东，这些东东就可以作为公共的部分让其他产品去继承。

#
# $(1): product to inherit
#
# Does three things:
#  1. Inherits all of the variables from $1.
#  2. Records the inheritance in the .INHERITS_FROM variable
#  3. Records that we've visited this node, in ALL_PRODUCTS
#  这个函数的参数为需要继承的产品的makefile，例如build/target/product/full.mk
#  函数在执行时，首先获取原_product_var_list中的值，例如PRODUCT_NAME=aosp_arm，在
#  值后加后缀@inherit:build/target/product/full.mk，表明从哪个node去继承
#  inherit_var= PRODUCTS.aosp_arm.mk.INHERITS_FROM，这里_include_stack就是类似一个需要import
#  的node的一个栈，正在import的node在最前面(word 1)，假如此时为aosp_arm.mk,变量的含义很清楚，
#  aosp_arm.mk从哪继承。并将inherit_var赋值为build/target/product/full.mk
#  android编译系统有个全局的变量ALL_PRODUCTS，用来描述已经import的product。
define inherit-product
  $(foreach v,$(_product_var_list), \
      $(eval $(v) := $($(v)) $(INHERIT_TAG)$(strip $(1)) )) \
  $(eval inherit_var := \
      PRODUCTS.$(strip $(word 1,$(_include_stack))).INHERITS_FROM) \
  $(eval $(inherit_var) := $(sort $($(inherit_var)) $(strip $(1)))) \
  $(eval inherit_var:=) \
  $(eval ALL_PRODUCTS := $(sort $(ALL_PRODUCTS) $(word 1,$(_include_stack))))
endef

#
# Do inherit-product only if $(1) exists
#
define inherit-product-if-exists
  $(if $(wildcard $(1)),$(call inherit-product,$(1)),)
endef

下面是个非常重要的函数，import-products，将产品的相关makefile导入，import-nodes在node_fns.mk中，记住，所有node相关的函数都在node_fns.mk中。如果某个产品的makefile中定义了PRODUCT_NAME=aosp_arm，通过这个函数，变量存储到另外一个变量，_nic.PRODUCTS.[[build/target/product/aosp_arm.mk]].build/target/product/aosp_arm.mk.PRODUCT_NAME=aosp_arm，将变量的值和相应的产品的makefile的联系了起来。

#
# $(1): product makefile list
#
#TODO: check to make sure that products have all the necessary vars defined
define import-products
$(call import-nodes,PRODUCTS,$(1),$(_product_var_list))
endef

下面这个函数检查某个产品参数是否设置正确，后续如果要添加自己的产品，起码要满足下面的条件。

#
# Does various consistency checks on all of the known products.
# Takes no parameters, so $(call ) is not necessary.
#
# PRODUCT_NAME必须定义
# 且多个PRODUCTS名字不能重复，名字命名符合c描述符
# PRODUCT_BRAND必须定义，
# PRODUCT_COPY_FILES 格式为<source file>:file>[:].file> 所以最后
# 的words可以是2 也可以是3
define check-all-products
$(if ,, \
  $(eval _cap_names :=) \
  $(foreach p,$(PRODUCTS), \
    $(eval pn := $(strip $(PRODUCTS.$(p).PRODUCT_NAME))) \
    $(if $(pn),,$(error $(p): PRODUCT_NAME must be defined.)) \
    $(if $(filter $(pn),$(_cap_names)), \
      $(error $(p): PRODUCT_NAME must be unique; "$(pn)" already used by $(strip \
          $(foreach \
            pp,$(PRODUCTS),
              $(if $(filter $(pn),$(PRODUCTS.$(pp).PRODUCT_NAME)), \
                $(pp) \
               ))) \
       ) \
     ) \
    $(eval _cap_names += $(pn)) \
    $(if $(call is-c-identifier,$(pn)),, \
      $(error $(p): PRODUCT_NAME must be a valid C identifier, not "$(pn)") \
     ) \
    $(eval pb := $(strip $(PRODUCTS.$(p).PRODUCT_BRAND))) \
    $(if $(pb),,$(error $(p): PRODUCT_BRAND must be defined.)) \
    $(foreach cf,$(strip $(PRODUCTS.$(p).PRODUCT_COPY_FILES)), \
      $(if $(filter 2 3,$(words $(subst :,$(space),$(cf)))),, \
        $(error $(p): malformed COPY_FILE "$(cf)") \
       ) \
     ) \
   ) \
)
endef

通过短的产品名称，例如generic，返回产品makefile的路径

#
# Returns the product makefile path for the product with the provided name
#
# $(1): short product name like "generic"
#
define _resolve-short-product-name
  $(eval pn := $(strip $(1)))
  $(eval p := \
      $(foreach p,$(PRODUCTS), \
          $(if $(filter $(pn),$(PRODUCTS.$(p).PRODUCT_NAME)), \
            $(p) \
       )) \
   )
  $(eval p := $(sort $(p)))
  $(if $(filter 1,$(words $(p))), \
    $(p), \
    $(if $(filter 0,$(words $(p))), \
      $(error No matches for product "$(pn)"), \
      $(error Product "$(pn)" ambiguous: matches $(p)) \
    ) \
  )
endef
define resolve-short-product-name
$(strip $(call _resolve-short-product-name,$(1)))
endef

定义stash相关的变量

_product_stash_var_list := $(_product_var_list) \
    PRODUCT_BOOTCLASSPATH \
    PRODUCT_SYSTEM_SERVER_CLASSPATH \
    TARGET_ARCH \
    TARGET_ARCH_VARIANT \
    TARGET_CPU_VARIANT \
    TARGET_BOARD_PLATFORM \
    TARGET_BOARD_PLATFORM_GPU \
    TARGET_BOARD_KERNEL_HEADERS \
    TARGET_DEVICE_KERNEL_HEADERS \
    TARGET_PRODUCT_KERNEL_HEADERS \
    TARGET_BOOTLOADER_BOARD_NAME \
    TARGET_NO_BOOTLOADER \
    TARGET_NO_KERNEL \
    TARGET_NO_RECOVERY \
    TARGET_NO_RADIOIMAGE \
    TARGET_HARDWARE_3D \
    TARGET_PROVIDES_INIT_RC \
    TARGET_CPU_ABI \
    TARGET_CPU_ABI2 \


_product_stash_var_list += \
    BOARD_WPA_SUPPLICANT_DRIVER \
    BOARD_WLAN_DEVICE \
    BOARD_USES_GENERIC_AUDIO \
    BOARD_KERNEL_CMDLINE \
    BOARD_KERNEL_BASE \
    BOARD_HAVE_BLUETOOTH \
    BOARD_VENDOR_USE_AKMD \
    BOARD_EGL_CFG \
    BOARD_BOOTIMAGE_PARTITION_SIZE \
    BOARD_RECOVERYIMAGE_PARTITION_SIZE \
    BOARD_SYSTEMIMAGE_PARTITION_SIZE \
    BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE \
    BOARD_USERDATAIMAGE_FILE_SYSTEM_TYPE \
    BOARD_USERDATAIMAGE_PARTITION_SIZE \
    BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE \
    BOARD_CACHEIMAGE_PARTITION_SIZE \
    BOARD_FLASH_BLOCK_SIZE \
    BOARD_VENDORIMAGE_PARTITION_SIZE \
    BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE \
    BOARD_INSTALLER_CMDLINE \


_product_stash_var_list += \
    DEFAULT_SYSTEM_DEV_CERTIFICATE \
    WITH_DEXPREOPT \
    WITH_DEXPREOPT_BOOT_IMG_ONLY

_product_stash_var_list += \
    GLOBAL_CFLAGS_NO_OVERRIDE \
    GLOBAL_CPPFLAGS_NO_OVERRIDE \

下面两个函数，

#
# Stash values of the variables in _product_stash_var_list.
# $(1): Renamed prefix
#
define stash-product-vars
$(foreach v,$(_product_stash_var_list), \
        $(eval $(strip $(1))_$(call rot13,$(v)):=$$($$(v))) \
 )
endef

#
# Assert that the the variable stashed by stash-product-vars remains untouched.
# $(1): The prefix as supplied to stash-product-vars
#
define assert-product-vars
$(strip \
  $(eval changed_variables:=)
  $(foreach v,$(_product_stash_var_list), \
    $(if $(call streq,$($(v)),$($(strip $(1))_$(call rot13,$(v)))),, \
        $(eval $(warning $(v) has been modified: $($(v)))) \
        $(eval $(warning previous value: $($(strip $(1))_$(call rot13,$(v))))) \
        $(eval changed_variables := $(changed_variables) $(v))) \
   ) \
  $(if $(changed_variables),\
    $(eval $(error The following variables have been changed: $(changed_variables))),)
)
endef

define add-to-product-copy-files-if-exists
$(if $(wildcard $(word 1,$(subst :, ,$(1)))),$(1))
endef

模块dex preopt相关的配置？

# whitespace placeholder when we record module's dex-preopt config.
_PDPMC_SP_PLACE_HOLDER := |@SP@|
# Set up dex-preopt config for a module.
# $(1) list of module names
# $(2) the modules' dex-preopt config
define add-product-dex-preopt-module-config
$(eval _c := $(subst $(space),$(_PDPMC_SP_PLACE_HOLDER),$(strip $(2))))\
$(eval PRODUCT_DEX_PREOPT_MODULE_CONFIGS += \
  $(foreach m,$(1),$(m)=$(_c)))
endef