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OpenWrt 编译分析(22.03)

Edward201804 2024-06-27 06:01:02
简介OpenWrt 编译分析(22.03)

文章目录

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1. 单独编译内核模块

make target/linux/compile
make package/kernel/linux/compile
make package/install
make target/install

2. package相关

2.1. package编译路径

includepackage.mk

PKG_BUILD_DIR ?= ( B U I L D D I R ) / (BUILD_DIR)/ (BUILDD​IR)/(if ( B U I L D V A R I A N T ) , (BUILD_VARIANT), (BUILDV​ARIANT),(PKG_NAME)- ( B U I L D V A R I A N T ) / ) (BUILD_VARIANT)/) (BUILDV​ARIANT)/)(PKG_NAME)$(if ( P K G V E R S I O N ) , − (PKG_VERSION),- (PKGV​ERSION),−(PKG_VERSION))

如果定义了PKG_BUILD_DIR，那就用PKG_BUILD_DIR；否则就是 ( B U I L D D I R ) / (BUILD_DIR)/ (BUILDD​IR)/(if ( B U I L D V A R I A N T ) , (BUILD_VARIANT), (BUILDV​ARIANT),(PKG_NAME)- ( B U I L D V A R I A N T ) / ) (BUILD_VARIANT)/) (BUILDV​ARIANT)/)(PKG_NAME)$(if ( P K G V E R S I O N ) , − (PKG_VERSION),- (PKGV​ERSION),−(PKG_VERSION))
以dnsmasq为例

Makefile中定义了VARIANT:=nodhcpv6
include/package-dumpinfo.mk，将Build-Variant: nodhcpv6写入tmp/.packageinfo
scriptsmetadata.pm，将tmp/.packageinfo中的Build-Variant: nodhcpv6写入KaTeX parse error: Undefined control sequence: package at position 23: …ariant} scripts̲p̲a̲c̲k̲a̲g̲e̲-metadata.pl，将(curdir)/network/services/dnsmasq/variants += $(if KaTeX parse error: Undefined control sequence: subdir at position 62: …gedeps include̲s̲u̲b̲d̲i̲r̲.mk，通过(call log_make, ( 1 ) / (1)/ (1)/(bd), ( t a r g e t ) , , (target),, (target),,(filter-out __default,$(variant)))传递到package.mk

2.2 package为什么能看到BOARD变量

因为./rules.mk中有如下定义：

BOARD:=$(call qstrip,$(CONFIG_TARGET_BOARD))

3. includedownload.mk

下载过程的入口为package.mk中的"$(call Download,default)"，代码如下，其中default是Download函数的参数。
define Build/DefaultTargets
$(if ( U S E S O U R C E D I R ) (USE_SOURCE_DIR) (USES​OURCED​IR)(USE_GIT_TREE) ( U S E G I T S R C C H E C K O U T ) , , (USE_GIT_SRC_CHECKOUT),, (USEG​ITS​RCC​HECKOUT),,(if $(strip ( P K G S O U R C E U R L ) ) , (PKG_SOURCE_URL)), (PKGS​OURCEU​RL)),(call Download,default)))
$(if ( D U M P ) , , (DUMP),, (DUMP),,(Build/CoreTargets))

define Build/DefaultTargets
endef
endef
Download通过"$(eval ( D o w n l o a d / (Download/ (Download/(1)))“调用Download/default函数，定义下载的URL，文件名等变量。
为了避免dl下的文件重复下载，可以将Download函数做如下修改(增加了ifeq (”$(wildcard ( D L D I R ) / (DL_DIR)/ (DLD​IR)/(FILE))“,”“))：
define Download
$(eval $(Download/Defaults))
$(eval ( D o w n l o a d / (Download/ (Download/(1)))
ifeq (”$(wildcard ( D L D I R ) / (DL_DIR)/ (DLD​IR)/(FILE))“,”")
$(foreach FIELD,URL FILE ( V a l i d a t e / (Validate/ (Validate/(call dl_method, ( U R L ) , (URL), (URL),(PROTO))),
ifeq ( ( ( ((FIELD)),)
$ ( e r r o r D o w n l o a d / (error Download/ (errorDownload/(1) is missing the $(FIELD) field.)
endif
)

$(foreach dep,$(DOWNLOAD_RDEP),
  $(dep): $(DL_DIR)/$(FILE)
)
download: $(DL_DIR)/$(FILE)

$(DL_DIR)/$(FILE):
	mkdir -p $(DL_DIR)
	$(call locked, 
		$(if $(DownloadMethod/$(call dl_method,$(URL),$(PROTO))), 
			$(call DownloadMethod/$(call dl_method,$(URL),$(PROTO)),check,$(if $(filter default,$(1)),PKG_,Download/$(1):)), 
			$(DownloadMethod/unknown) 
		),
		$(FILE))

endif
endef

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